Questions Re ATN Viper in Darkroom

[Richard K.]

Those of you that have used infra-red viewers in the darkroom, can you please tell me:

Will black & white or colour film be fogged if you are cutting it down and observing with the viewer?

Will black & white film be fogged if observed infraredly while it's developing?

Thank you!

[Ken Lee]

B&W film and paper: no and no

[Robert Ley]

I can tell you from very sad experience that these will NOT work with any color film or paper.

[IanMazursky]

I have had great luck with my ATN Viper with color and b&w film.
No fogging what so ever. I do however cover the infra red emitter with a cloth doubled over a few time and secured with a rubber band.
This cuts down on the IR light emitted from the ATN. What probably will fog the film more then the IR light emitter is the eye piece.
Its very bright and does not seat well to the eye. Light leaks like a sieve around it and can definitely fog film.
I angle the whole unit down a bit and smoosh it to my face. Seems to work fine without fogging anything so far.
Make sure to test, test and then test again for your specific darkroom and eye shape.

I pretty much only use the ATN now for loading 12x20 film.
Its just too uncomfortable for me to use it to cut film and if you knock it away from your face, the eye piece could fog color film and maybe B&W.
The big problem with it is the focusing, eye piece and headgear. Its not designed for closeup work, its not auto focus and definitely not designed for people who wear glasses.
Everytime you move you have to refocus or just accept the out of focus image. Also the headgear is designed for a larger (normal) head. Mine is too small :D
Ive learned to live with it for loading 12x20 film but for cutting, its easier sometimes to use a few guides in the dark.

[John Bowen]

Ian,

If you leave the cover over the light multiplier you will get drastically better depth of field.

I use my ATN Viper with Tmax 400 and have yet to notice any fogging. I only use it for DBI. I can load/unload film in the dark.

[R Mann]

I love mine - use it for film loading and developing, but I have only used it with b/w materials. I wear glasses, but when I use the viper, I adjust it so I can use it without glasses and have not had a problem with light spilling from the eyepiece. It is important that the headgear is adjusted correctly, the one that came with my unit has a number of straps that need to be tight. It has a "pinhole" in the lens cap that I use for more depth of field and when I get it in focus for working at arms length, I have no problems with it. I have never had a fogging issue with the built in IR light, but you can block it off and use another IR source. There are some very cheap IR flashlights that you could use. I have one and tried it once, but prefer to just use the headgear as is. It makes loading & unloading film holders so easy, it would be one of the last things I would part with.

[IanMazursky]

John, Thanks for the tip, i have tried that but i sometimes have trouble seeing with the cap on.
Im using it more to just give me a general idea where everything is and so i don’t jam my knees into anything.
I also have a small head, yah i know let the jokes fly :D
My head is too small and I ran out of velcro on all of the straps!! It makes it hard for me to keep the ATN on my head but it works…somehow!
But its fantastic and for the price, you cant beat it!

[jeroldharter]

I was curious awhile back and took advice from Ken Lee. At this point, I consider it well worth the money. The optics are not great but you can see good enough to handle film. I use it for loading film holders, loading film reels, loading Jobo drums (not necessary but I think it is cool to see in the dark). I use TMY with no fogging.

I will try the lens cap idea for better depth of field. I was a sucker for the brighter image without the lens cap but the depth of field is quite thin in that case. I plan to use it when traveling also - loading film holders in darkened bathrooms is much easier than with a changing tent but it helps to see the unfamiliar surroundings.

[IanMazursky]

Btw, one other fantastic use for the ATN is finding light leaks in your darkroom.
One of my darkrooms is in my boiler room and boy did it leak like a sieve.
I used put the ATN on and spent a few hours sealing every little leak with metal tape and dark bags.
Just for that it was worth every penny!

[Bill Burk]

I thought I didn't need anything else. But now I see I gotta get one of these.

Maybe it will keep me from developing my film in the stop bath.

[Michael Roberts]

Ian, have you tried wearing your Yankees cap, turned backwards like a catcher, and putting the Viper headgear on over the cap?

BTW, Michael Kadillak has tested the IR light on the Viper and has found it does cause fogging--check out this post for a solution (scan down to post #20):
http://www.largeformatphotography.info/forum/showthread.php?t=13322&page=2


John, Thanks for the tip, i have tried that but i sometimes have trouble seeing with the cap on.
Im using it more to just give me a general idea where everything is and so i don’t jam my knees into anything.
I also have a small head, yah i know let the jokes fly :D
My head is too small and I ran out of velcro on all of the straps!! It makes it hard for me to keep the ATN on my head but it works…somehow!
But its fantastic and for the price, you cant beat it!

[Michael Kadillak]

Ian, have you tried wearing your Yankees cap, turned backwards like a catcher, and putting the Viper headgear on over the cap?

BTW, Michael Kadillak has tested the IR light on the Viper and has found it does cause fogging--check out this post for a solution (scan down to post #20):
http://www.largeformatphotography.info/forum/showthread.php?t=13322&page=2

On one end of the technical spectrum people are concerned about the illuminated dials on their Gralab darkroom timers and then we have others on the other end of the spectrum that claim the IR illuminators are not a problem.

If you can see the red glow on your illuminator that is battery powered and orders of magnitude stronger than the glowing hands on a dial, we do not need a physics degree to conclude that your film can as well. The variables in this equation are the unit that you are using (the power of the visible portion of the IR illuminator you are using), the film speed and the distance that you are working from your film.

Many people have stated that they do not experience any negative consequences when using the monocle IR light source. I can only conclude that what they are saying is that it is no problem printing through it and that is perfectly fine. The analogy I would put forth is it is comparable to working with slightly outdated to seriously outdated sheet film even though the film is fresh.

John Sexton goes to great lengths to strongly encourage his photography students to conduct a rigorous safelight test in their darkrooms. Many feel that this is a complete waste of valuable time and that is your call. The reason he does so is that optimal results come from the utilization of optimal materials and assuming that your safelight is not adding unnecessary FB+F to your paper even if your eye cannot ascertain that it is present is not acceptable to some folks including John Sexton. You are only sure when you assume nothing but that is your call.

Both the safe light test and the IF illuminator test are very quick and easy to perform.

When I pulled the developed test film from the fixer tray after the IR illuminator test I was shocked at how much visible fog was not present behind the black tape I put down the center of the sheet film before I turned on the IR light source on the monocle for the test. Yes I was using 400 speed film at about arms length for about my normal development time.

At the end of the day we each have to make decisions with our photography relative to how we want to proceed. I simply want to point out to many perusing though old threads and possibly this one that because someone states that then do not have a problem with fog using the IR illuminator on the monocle does not conclusively mean that it is not there. If you have completed this test and have realized different results then share them with us please.

Onward!

[jeroldharter]

...When I pulled the developed test film from the fixer tray after the IR illuminator test I was shocked at how much visible fog was not present behind the black tape I put down the center of the sheet film before I turned on the IR light source on the monocle for the test. Yes I was using 400 speed film at about arms length for about my normal development time.

Do you mean fog was present or absent?

[Michael Kadillak]

The sheet of film was fogged.

I simply took a sheet of unexposed fresh sheet of T Max 400 film and in complete darkness put a piece of black electricians tape down the center of it. Then I turned on the IR illuminator and set it on my counter about arms length from the piece of film I propped up sideways to the monocle simulating me developing a single sheet of film in a tray of developer with the IR on. After leaving this in place for about my normal developing time (9-10 minutes) I turned off the IR device and pulled the tape off of the sheet film and developed, stopped and fixed the sheet in complete darkness. I could see perfectly with my naked eye the clearer center of the sheet film where the tape was covering the film. I could see it so plainly I did not even need to pull out my densitometer. I took the batteries out of my IR illuminator device and have bounced IR light from a 24 LED lightbank off of my wall on the other side of my darkroom and this works perfectly. I tested this set up and there was absolutely no fog added whatsoever.

[Ken Lee]

Michael - Could the tape itself have reacted with the film ? Did you place the tape on the emulsion side ?

[Michael Kadillak]

Michael - Could the tape itself have reacted with the film ? Did you place the tape on the emulsion side ?

Good question. I believe that I put the tape over the emulsion side.

Considering that I did not have the black tape on the film that long and that sheet film has a protective coating over the emulsion I doubt if it had any adverse effect on the emulsion.

That said I know what clear unexposed emulsion looks like and there was definitely added fog to the rest of the film. I acquired a number of boxes of Super XX from 1989 and fixed a sheet to see what the increased fog looked like and while the IR increased fog was not as significant as the Super XX, it was about half as much eyeballing it. It surely was not insignificant.

On the flip side I spent a week with Michael Smith assisting him print in his darkroom and I saw him print negatives from film that was older and likely had been unintentionally subjected to some intense heat that you could have safely watched an eclipse through they were that overall dense and they still printed just fine. When you have a film like Super XX that builds density to incredible levels you can realize acceptable or better results under less than optimal conditions. Sometimes you do not have a choice but do the best you can.

All I am saying is that given a choice we should strive to understand the dynamics of the process we have control of.

There are clearly a wide range of IR monocles photographers are using in this application that emit varying visible and invisible wavelengths and power power levels within the IR illuminator. My Argus monocle seemed to be fairly powerful in this regard. Is adding 0.05 to 0.15 units of film density really that big a deal? I believe that the answer can concurrently be yes and no. It is possible to print right through it and not know or care that it is there so it may not matter. But at the same time not taking the time to assess how much of a adverse consequence it could be is not optimal. I would place this situation in the same context as an errant shutter or a mis calibrated f stop.

Personally when I am shooting 8x20 or 11x14 the cost of film drives the process to insuring that I am using my head to take as many variables I control out of the equation. I have calibrated my shutters and tested my safe light.

I admit that sometimes the differentiation between paranoid and responsible is a thin line on the horizon.....

[Mark Sampson]

This all reminds me of the days, not that long ago, when I operated a Kreonite C-41 roller-transport processor that used IR sensors to determine when film was passing into the processor (to determine on/off sequence and to replenish automatically). It was necessary to unplug the sensors and run everything manually when we ran the Kodak IR color film. Whatever level of IR was emitted, it must have been mighty low, not to fog the regular C-41 film I used to shoot on that job.

[Cor]

Michael,

I am not doubting your results and rightly you say that each should test on it's own what is acceptable or not, but..

..I seem to recall that film is somewhat desensitised/less sensitive to light when it is in the developer fluid (that's the reason why you can develop by inspection under an extremely dim green light right?). And you exposed the sheet on the table, and developed later.

OTOH people seem to use them to load film as well.

I have no experience with these IR devices, but do people keep them on all the time when developing, or switch them on at 3/4 of the time?

Best,

Cor

[Ken Lee]

Next time I develop some film, I will leave a sheet out for 10 minutes - with 1/2 the sheet covered under an unopened box of film - and then develop the sheet.

[Michael Kadillak]

Next time I develop some film, I will leave a sheet out for 10 minutes - with 1/2 the sheet covered under an unopened box of film - and then develop the sheet.

Excellent. Leave it about arms length at the same angle from the IR illuminator that you employ when you develop film and let us know what you conclude.

Cheers!

[George W.]

How about using a filter in front of your IR illuminator,
that just lets pass IR, and cutting all visible light?

Couldn't you use the same filter being used in IR photography
for cutting off all visible light?

The only difficulty would be how to attach this filter to the rest(?)

[Michael Kadillak]

How about using a filter in front of your IR illuminator,
that just lets pass IR, and cutting all visible light?

Couldn't you use the same filter being used in IR photography
for cutting off all visible light?

The only difficulty would be how to attach this filter to the rest(?)

Surely that would work. Rather than fuss around with trying to find some filter material assuming that it is up to the task and find a way to affix it to the monocle I took the easy route.

IR LED light banks are cheap and turning them away from your work area so that only IR light is reflected back to where you need it is quick and easy. It is not as luminous as having the IR light blazing directly in front of you but it comes without the added baggage.

A while back there was a guy at another forum came up with the idea to use glass trays to develop one sheet of film at a time about foot above a large scale series of LED IR light banks that claimed to have zero increase in fog levels with his set up. I told him to put water in his tray and leave an unexposed sheet in there above the IR light source and in total darkness develop it with a second sheet straight from his film box and put them side by side on a light box and I never hear another word.

[jeroldharter]

I don't use mine to develop film, just to load film holders, reels, and drums. Nevertheless, I would like to avoid any fogging.

Michael, do you have a source for the IR LED lights that you use? Thanks.

[Michael Kadillak]

I don't use mine to develop film, just to load film holders, reels, and drums. Nevertheless, I would like to avoid any fogging.

Michael, do you have a source for the IR LED lights that you use? Thanks.

It has been several years since I acquired my LED IR light bank and I am not sure where I got it But I would be happy to see if a comparable product can be located.

Since there are a wide range of variables in this unique application of IR in photography, I would strongly encourage anyone that is using this system to expend a sheet of 4x5 film and a small allocation of your time as Ken is doing perform a quick test and see for yourself what your specific situation involves.

I purposefully tested my worse case scenario in using the highest ASA film with my monocle. But other devices and other choices of sheet film will likely arrive at different results. I am simply advocating that we see the net effect one way or another and make the best decision for each of us.

[Keith Pitman]

I don't use mine to develop film, just to load film holders, reels, and drums. Nevertheless, I would like to avoid any fogging.

Michael, do you have a source for the IR LED lights that you use? Thanks.

Jerold,

You can find IR illuminators inexpensively on Ebay.

Just to add to Michael's testing results, I've also found that both the light from the Viper and the separate illuminator can fog film. I got fog from the illuminator positioned about eight feet away and aimed away from the film (ISO400). I need to work with this some more to find a way to aim the illuminator that will eliminate the fog risk.

Good tool, but it needs to be used carefully.

[Michael Kadillak]

Jerold,

You can find IR illuminators inexpensively on Ebay.

Just to add to Michael's testing results, I've also found that both the light from the Viper and the separate illuminator can fog film. I got fog from the illuminator positioned about eight feet away and aimed away from the film (ISO400). I need to work with this some more to find a way to aim the illuminator that will eliminate the fog risk.

Good tool, but it needs to be used carefully.

Thanks for sharing your experiences Keith. Every time I hear people say on this forum and other places casually state that "no increase in film density has been experienced" with the use of the IR monocle absent supporting comments for these statements I cringe. I guess getting tattooed in corporate management presentation meetings early in my engineering career for lacking technical support or making bold assumptions has stuck with me over these years.

I turn my LED light bank directly into an adjacent wall in my darkroom and bounce IR into the room and tests have shown negligible added FB+F. But maybe I should do another test just to make sure.

[Michael Kadillak]

Ebay item #120562530863 appears to be an LED IR supply light bank similar to what I previously acquired. There are many like this offered from Hong Kong or China that do not have a power supply cord.

I would want to make sure that the domestic seller includes a power supply cord included in the sale.

[IanMazursky]

Ian, have you tried wearing your Yankees cap, turned backwards like a catcher, and putting the Viper headgear on over the cap?

BTW, Michael Kadillak has tested the IR light on the Viper and has found it does cause fogging--check out this post for a solution (scan down to post #20):
http://www.largeformatphotography.info/forum/showthread.php?t=13322&page=2

Michael, Thanks for the suggestion! I will have to give that a try. A cap might just eat up enough slack to make the headgear fit.

I think the little IR emitter on the ATN could fog film if its left exposed. You can see a little red dot when its turned on.
Thats why i wrap one of those white rags in a box (folded over a few times) over the emitter.
You cant see the red light anymore but it does seem to pass a small amount of IR through and light up the room just enough.
So far its been fine for B&W and color film. No fogging that i can see on any LF or Aerial film.
But i haven’t done exhaustive testing, as they say YMMV.

[George W.]

see following tutotial on IR diodes
http://www.gizmology.net/LEDs.htm

it clearly states:

""HOWEVER - keep in mind that LEDs are not perfectly monochromatic. If
their peak output is close to the visible spectrum, then their bandwidth may overlap
the visible spectrum enough to be visible as a dim cherry-red light. Furthermore, some
people can see further into the red region than can others, seeing as deep-red colors
that to others are invisible infrared. While it would be possible to give such an LED a
rating in millicandella, it would be misleading. ""

this should be warning enough to *not* use near-IR diodes with unknown spectrum distribution

I guess that far-IR diodes might be less exposed to this phenomena, but I have no
idea up to what wavelength in the far-IR the detectors in the Viper work

[Michael Kadillak]

see following tutotial on IR diodes
http://www.gizmology.net/LEDs.htm

it clearly states:


this should be warning enough to *not* use near-IR diodes with unknown spectrum distribution

I guess that far-IR diodes might be less exposed to this phenomena, but I have no
idea up to what wavelength in the far-IR the detectors in the Viper work

Excellent reference material George. I agree that knowing the spectrum distribution is an excellent first step. Even with this information testing is the only way to adequately put this tool to proper use.

[Bill Burk]

Called ATN support. Very friendly. Should have just driven over there and picked one up they are about 10 miles from me.

The Viper emitter is 850-890nm.

I'll let you know the results when I get it Monday.

My benchmark for fog is .07 to .09 for TMY-2 D-76 12:30 68*F developed in darkness.

[Ken Lee]

"The Viper emitter is 850-890nm"

Thanks for that helpful piece of information !

HP5+, according to the official Ilford HP5+ tech sheet (http://www.ilfordphoto.com/Webfiles/20106281054152313.pdf), is insensitive to light at those wavelengths.

FP4+ is also insensitive at that portion of the spectrum, according to the Ilford FP4+ tech sheet (http://www.ilfordphoto.com/Webfiles/2010712125850702.pdf).

According to the Kodak tech sheet (http://www.kodak.com/global/en/professional/support/techPubs/f4016/f4016.pdf), TMY and TMX are also insensitive to that spectral range.

[Michael Kadillak]

"The Viper emitter is 850-890nm"

Thanks for that helpful piece of information !

HP5+, according to the official Ilford HP5+ tech sheet (http://www.ilfordphoto.com/Webfiles/20106281054152313.pdf), is insensitive to light at those wavelengths.

FP4+ is also insensitive at that portion of the spectrum, according to the Ilford FP4+ tech sheet (http://www.ilfordphoto.com/Webfiles/2010712125850702.pdf).

According to the Kodak tech sheet (http://www.kodak.com/global/en/professional/support/techPubs/f4016/f4016.pdf), TMY and TMX are also insensitive to that spectral range.

If the Viper monocle does in fact operate outside of the spectral sensitivity of these films I will be kicking my Argus unit to the curb and picking up one of these.

I am not discounting the specs as relayed by their support staff, but I would surely feel a whole lot better if someone could follow up with an expedient test.

This may turn out to be a quick tutorial in physics and that is perfectly fine as long as we learn from this experience and move on. That is what forums such as this one are for - the power of collective experience and intellect. Thanks

[Brian C. Miller]

All monocles operate outside of the visible range. They only intensify light, not emit it. The real question is, does the illuminator emit light which fogs the film or paper?

As for the specific brand you have, there are other factors. How well it fits, how well it inensifies light, and its focus. Some units only focus to a minimum of 10ft, so that's something to check.

[Michael Kadillak]

All monocles operate outside of the visible range. They only intensify light, not emit it. The real question is, does the illuminator emit light which fogs the film or paper?

As for the specific brand you have, there are other factors. How well it fits, how well it inensifies light, and its focus. Some units only focus to a minimum of 10ft, so that's something to check.

It was my understanding that the statement was made was intended to say that the Viper illuminator operates in the higher IR wavelength band above the spectral sensitivity of the film.

Visible IR appears to start at about 750 nm to 780 nm which would explain the fact that one can clearly see that the IR illuminator is ON (that red glow) which was likely the intent of the manufacturers of these products for weekend warriors and not photographers.

[Bill Burk]

Hi Michael,

I know you're excited to find out the results. I'll run definitive tests Monday unless UPS misses me.

I'll try a few different tests.

Average distance 18-inch for 12 minutes - an actual use test.

Similar but with diminished emitter light.

A test of the danger of the eyepiece light.

I'll be using a sensitometer and densitometer - if there is any effect, I should be able to measure it.

Your original test with tape might have shown you the normal film base vs. film base plus fog. I tried a tape and penny safelight test once, the tape came off and the penny moved around. My paper was fogged because it was too old anyway.

[George W.]

I fully support Michaels request for a life test. "The proof of the pudding is in the
eating!!!".

However we must be aware, that:
this test is only concluant for this special test set-up:
-with the same illuminator
-with the same film/paper
-with the same distance and the same exposure time

I wonder if among the audience there is somebody with access to a professional
spectrometer. That must exist in advanced university labs.
I really would like to see the real spectrum for different IR diodes.

[Richard K.]

"The Viper emitter is 850-890nm"

Thanks for that helpful piece of information !

HP5+, according to the official Ilford HP5+ tech sheet (http://www.ilfordphoto.com/Webfiles/20106281054152313.pdf), is insensitive to light at those wavelengths.

FP4+ is also insensitive at that portion of the spectrum, according to the Ilford FP4+ tech sheet (http://www.ilfordphoto.com/Webfiles/2010712125850702.pdf).

According to the Kodak tech sheet (http://www.kodak.com/global/en/professional/support/techPubs/f4016/f4016.pdf), TMY and TMX are also insensitive to that spectral range.

Thanks for this information. Is there a spec sheet published for the spectral sensitivity of colour film? (I couldn't find one...)

[Ken Lee]

Here's a nice illustration from http://www.infraredphoto.co.uk/guide/

http://www.kenleegallery.com/images/forum/spectrum.jpg

I just tried pointing my Zone VI Modified Pentax Spot Meter at the emitter of my ATN Viper IR viewing device. The meter didn't register any value at all. I tried this in a well-lit room, and in a darkroom too. If the meter can't see it, and the meter is filtered to match the spectral sensitivity of B&W film, then it's no surprise if the film can't see it either.

What the graph shows - more alarmingly - is that panchromatic films are sensitive to (invisible) UV radiation. The spec sheets agree. Apparently, glass does not block the entire UV spectrum. What good are so-called UV or "Skylight" filters then ?

[George W.]

Very nice and instructive graphic!

I would be cautious to use even the modified pentax meter for concluding
whether film fogging might occurr.
I think in the modified version a special IR cutting filter has been added,
to avoid wrong readings by IR radiation.

The person knowledgeable about these details would be Richard Ritter,
who used to implement these modifications or repair the meters.

[Michael Kadillak]

I put some batteries in my Argus IR monocle illuminator and used my Pentax digital spotmeter modified by Zone VI and in complete darkness pointed it at the "Red Glow" and got a reading of 5.

Similarly I pointed it in the direction of my IR LED light and its Red Glow and I got a digital light meter reading of 5 as well. When I point the meter at the reflected IFF that is coming off of the wall when I point the LED light bank into it I get a zero spot meter reading.

What this comes down to is this simple question.

Can a red glow of an IR illuminator be seen by the human eye and still remain outside of the film sensitivity spectrum? There are obviously considerable variables in how IR LED's are manufactured and either a test or a spectrometer are the ultimate answer. All I know for absolute certainty is what I see with my set up.

[Richard K.]

|||||||||Can a red glow of an IR illuminator be seen by the human eye and still remain outside of the film sensitivity spectrum? |||||

If you are seeing a red glow (650 - 700 nm) from the illuminator, then either the illuminator has a supplementary red diode to indicate the IR beam is on or the IR diode is so broadband that it includes visible red light. Human vision tops out at around 700nm. Unless you are a super-hero of course!! :D

[jeroldharter]

I wonder if something like this could substitute for a simple IR safelight after putting some opaque tape over the glowing red illuminator on the ATN Viper?

http://www.bhphotovideo.com/c/product/488597-REG/Insight_INS_SNG_001.html

http://www.bhphotovideo.com/images/images150x150/488597.jpg

[Michael Kadillak]

I wonder if something like this could substitute for a simple IR safelight after putting some opaque tape over the glowing red illuminator on the ATN Viper?

http://www.bhphotovideo.com/c/product/488597-REG/Insight_INS_SNG_001.html

http://www.bhphotovideo.com/images/images150x150/488597.jpg

Looks interesting Jerold. My only concern would be if it is powerful enough for the task at hand. The brighter the IR the better as long as it is safe.

[jeroldharter]

I decided to buy one of these instead. It has an 850 nm LED. They also have a 975 nm model.

http://www.lightstheway.com/odyssey/thumbnail.img?picture.image.url=%2Ffiles%2F1670115%2Fuploaded%2FGTL-IR875.jpg&picture.width.max=200&picture.height.max=200&picture.image.mask.apply=false&border.fill.color=668B6B&pid=1289997881276

The picture did not work too well. It is a Glo-Toob Infrared light. Have different models that are meant to be like ultralight candle lanterns and they also have IR versions that could be used as rescue beacons an so on. Curious to see if it works.

[Brian C. Miller]

What the graph shows - more alarmingly - is that panchromatic films are sensitive to (invisible) UV radiation. The spec sheets agree. Apparently, glass does not block the entire UV spectrum. What good are so-called UV or "Skylight" filters then ?

That is correct, raw glass does not block all UV light.

Yes, pan films are sensitive to UV, and so are color films. This is why quartz lenses are made, along with UV-only filters.

UV and Skylight filters block out UV. These are manufactured, like all the other filters, to pass a certain bandwidth of light. The presence and absence of UV in a color photograph is easily verified.

(Uh, like, hello? Hello, Ken? Do you need some of my home-roasted coffee?)

[rob]

can atn viper see with 940nm LED light?, like this one:
http://cgi.ebay.com/940nm-IR-Infrared-LED-LEDs-SIR-311STA49-Qty-50-/190286534827?pt=LH_DefaultDomain_0&hash=item2c4df618ab#ht_1721wt_778

[Ken Lee]

(Uh, like, hello? Hello, Ken? Do you need some of my home-roasted coffee?)

That sounds good :)

My impression - which may be wrong - is that UV and "skylight" filters are nothing more than ordinary glass. Plano-parallel, but ordinary glass.

It is also my impression that people use these filters mostly to protect SLR and rangefinder cameras, which hang from the neck with no case or cap.

Somewhere I got the idea that camera salesmen "push" them on customers, much like electronics stores like to push their customers to purchase "extended warranty" protection.

[jeroldharter]

can atn viper see with 940nm LED light?, like this one:
http://cgi.ebay.com/940nm-IR-Infrared-LED-LEDs-SIR-311STA49-Qty-50-/190286534827?pt=LH_DefaultDomain_0&hash=item2c4df618ab#ht_1721wt_778

I tried to find information about the sensitivity of the ATN Viper regarding wavelengths but could not find any. That is why I went with the 850 nm figuring that was "normal" for the IR emitter.

[Michael Roberts]

I put some batteries in my Argus IR monocle illuminator and used my Pentax digital spotmeter modified by Zone VI and in complete darkness pointed it at the "Red Glow" and got a reading of 5.

Similarly I pointed it in the direction of my IR LED light and its Red Glow and I got a digital light meter reading of 5 as well. When I point the meter at the reflected IFF that is coming off of the wall when I point the LED light bank into it I get a zero spot meter reading.

What this comes down to is this simple question.

Can a red glow of an IR illuminator be seen by the human eye and still remain outside of the film sensitivity spectrum? There are obviously considerable variables in how IR LED's are manufactured and either a test or a spectrometer are the ultimate answer. All I know for absolute certainty is what I see with my set up.

I get the same reading--5--with my Pentax analog spot meter aimed at my ATN Viper illuminator.

[Richard K.]

I get the same reading--5--with my Pentax analog spot meter aimed at my ATN Viper illuminator.

If you can SEE it, it's not just IR that's being output...is there a (separate) indicator LED?

[Michael Roberts]

Richard, I agree; seems like a no-brainer, right? No separate indicator, the illuminator on my ATN Viper is all-in-one. I'm ordering a separate IR LED light source to try the indirect, bounce-off-the-wall method Michael Kadillak is using.

[Richard K.]

Richard, I agree; seems like a no-brainer, right? No separate indicator, the illuminator on my ATN Viper is all-in-one. I'm ordering a separate IR LED light source to try the indirect, bounce-off-the-wall method Michael Kadillak is using.

Me too...:D

[Brian C. Miller]

My impression - which may be wrong - is that UV and "skylight" filters are nothing more than ordinary glass. Plano-parallel, but ordinary glass.

B+W Clear, UV, and Skylight (https://www.schneideroptics.com/ecommerce/CatalogSubCategoryDisplay.aspx?CID=608), Technical Data (pdf) (https://www.schneideroptics.com/info/handbook/pdf/B+WHandbook56_65.pdf)
The "clear" filter has no filtering properties, and is just a piece of glass to protect the lens. The UV and Strong UV Absorbing filters block UV light. The Skylight filter blocks UV, and has a color correction factor. The Very Light Yellow (what a price for that!) filter is for B&W and has greater blocking than the UV filter.

[Bill Burk]

I'll find out tomorrow if the ATN Viper can see 940nm. I picked up a couple from Radio Shack yesterday.

I assuming LED's have a sharp bell curve output, and when you see a slight red glow you probably are seeing the decaying toe of the bell curve of a very "bright" IR light. As others have noted: Don't look into them.

I think too much IR can cause cataracts, at least I think that's what caused my grandmother's cataracts - she was a ceramicist and how much you want to bet she loved peeking in that little hole in the side of the kiln.

I found a purple filter (popped apart an IR Receiver that came with my cable decoder). If it looks transparent to the Viper, I might put that over the emitter for a test.

I'm going to do a "test strip" where I expose a piece of film under a Stouffer scale with the Viper emitter aimed at it for an hour. I assume that kind of abuse will generate a measurable image. And I expect it will give some very useful info.

[Ken Lee]

B+W Clear, UV, and Skylight (https://www.schneideroptics.com/ecommerce/CatalogSubCategoryDisplay.aspx?CID=608), Technical Data (pdf) (https://www.schneideroptics.com/info/handbook/pdf/B+WHandbook56_65.pdf)
The "clear" filter has no filtering properties, and is just a piece of glass to protect the lens. The UV and Strong UV Absorbing filters block UV light. The Skylight filter blocks UV, and has a color correction factor. The Very Light Yellow (what a price for that!) filter is for B&W and has greater blocking than the UV filter.

Wonderful - Thanks for your patient explanation. There appears to be variety of filters with the term UV in the name: skylight, haze, UV, UV blocking - even some that are nothing more than plain glass. But as I mentioned, plain glass does block some UV - often mentioned when experts discuss the perils of Skin Cancer.

camerafilters.com (http://camerafilters.com/) mentions 3 kinds:

"UV Filters - Absorbs ultraviolet rays. Gives cleaner, sharper pictures with less haze. Also serves as a permanent lens protector.

Sky Filters - Reduces blush tones in outdoor shots. Keeps skin tones natural and free of reflection from nearby objects. Also serves as a permanent lens protector.

Clear Protector Filters - Protect your valuable lenses from expensive front element damage which can be caused by dirt, scratches, and cross threading."

According to Wikipedia (http://en.wikipedia.org/wiki/Ultraviolet): "Ordinary glass is partially transparent to UVA but is opaque to shorter wavelengths, whereas Silica or quartz glass, depending on quality, can be transparent even to vacuum UV wavelengths. Ordinary window glass passes about 90% of the light above 350 nm, but blocks over 90% of the light below 300 nm"

I have never encountered any Large Format shooters with UV-blocking filters on their lenses. Is that because they already use Yellow, Orange, and Red filters when shooting outdoors ?

[Brian C. Miller]

I have never encountered any Large Format shooters with UV-blocking filters on their lenses. Is that because they already use Yellow, Orange, and Red filters when shooting outdoors ?

Right. Yellow blocks blue, and UV is beyond blue. A "minus blue" filter is recommended by some, like a Wrattan #8 or lighter. When I shoot color, I always use some kind of UV blocking filter. Polarizers also block UV, so a seperate UV filter would be redundant.

When I am shooting something in low-lit shade with B&W, I usually don't use a filter at all. The shade is all blue light, so a yellow filter would really cause a problem. With color I would use a Skylight to warm things up just a touch.

Actually, I can't imaging anyone not wanting to protect their lens. For under $20, protecting even a $100 lens is worth it.

[Richard K.]

Richard, I agree; seems like a no-brainer, right? No separate indicator, the illuminator on my ATN Viper is all-in-one.

Would it be possible to place a Kodak Wratten IR filter (no transmittance 400 - 700 nm) over the illuminator to allow just the IR through? They cost around $90...maybe a group purchase and cut one up? :D

[Brian C. Miller]

I remember seeing a while back that unexposed and processed E6 acts as an IR filter. In fact, I made one myself, and it worked decently. I used it with a wide-angle lens and a polarizer. Do you have a strip of E6? Cut that up and try it.

[Sal Santamaura]

...I have never encountered any Large Format shooters with UV-blocking filters on their lenses. Is that because they already use Yellow, Orange, and Red filters when shooting outdoors ?It's because you've never run into me on a trail. :) Every one of my lenses has a multicoated UV filter (B+W or Heliopan) affixed. I've run tests and, at the Rocky Mountain altitudes I shoot, all black and white films I use record substantial contrast-reducing haze without filtration. UV filters eliminate that.

If I decide a colored filter is appropriate, the UV filter gets removed and replaced for that shot.

[Bill Burk]

Test results are in.

I exposed a full hour with un-modified ATN Viper at 15" with eyepiece covered so the only exposure was from IR emitter. Then I developed normally in complete darkness. For control, a standard test strip is also on the film.

There is overall fog 0.45 at this intensity, distance and time combination.

Stouffer 21-step 0.15 interval resulting density

1 - 0.45
2 - 0.39
3 - 0.34
4 - 0.27
5 - 0.21
6 - 0.16
7 - 0.11
8 - 0.09
9 - 0.07
10 - 0.06
11 - 0.05
12 - 0.04 = Base+Fog

http://www.beefalobill.com/images/testneg1.jpg

On the graph, the IR is lower-right graph and the upper-left graph is the normal test strip plot.

http://www.beefalobill.com/images/testgraph1.jpg

My interpretation of the results:

I will not develop film for an hour, more like 15 minutes.
So I can read down the list of Stouffer steps 4 steps (two stops)

My worst case density would be 0.21

I would rather have a worst case density of 0.07
So to step down the Stouffer scale 4 more steps (two more stops) I will attenuate the ATN Viper emitter with an 0.60 density piece of black and white film.

Anybody could make one of these from scrap negative by looking for any piece of film that makes your spotmeter drop two stops when you look through it.

Yes E6 black slides are clear to the Viper, but I can still see the red glow through it - and every other filter I could think of. So to play it safe, I am going to put a silver-based 0.6 scrap over the lens. It dims the output of the eyepiece about as much as adding the pinhole lenscap so is not a real problem.

I won't have to do more testing because I know it will work!

After adding the "ND Filter" I will have 0.03 density added by IR worst case - but probably will be less than that because I won't be staring at the film all the time. I'll be shuffling sheets through the tray, so some of the time they will be covered.

[Michael Kadillak]

Test results are in.

I exposed a full hour with un-modified ATN Viper at 15" with eyepiece covered so the only exposure was from IR emitter. Then I developed normally in complete darkness. For control, a standard test strip is also on the film.

There is overall fog 0.45 at this intensity, distance and time combination.

Stouffer 21-step 0.15 interval resulting density

1 - 0.45
2 - 0.39
3 - 0.34
4 - 0.27
5 - 0.21
6 - 0.16
7 - 0.11
8 - 0.09
9 - 0.07
10 - 0.06
11 - 0.05
12 - 0.04 = Base+Fog

http://www.beefalobill.com/images/testneg1.jpg

On the graph, the IR is lower-right graph and the upper-left graph is the normal test strip plot.

http://www.beefalobill.com/images/testgraph1.jpg

My interpretation of the results:

I will not develop film for an hour, more like 15 minutes.
So I can read down the list of Stouffer steps 4 steps (two stops)

My worst case density would be 0.21

I would rather have a worst case density of 0.07
So to step down the Stouffer scale 4 more steps (two more stops) I will attenuate the ATN Viper emitter with an 0.60 density piece of black and white film.

Anybody could make one of these from scrap negative by looking for any piece of film that makes your spotmeter drop two stops when you look through it.

Yes E6 black slides are clear to the Viper, but I can still see the red glow through it - and every other filter I could think of. So to play it safe, I am going to put a silver-based 0.6 scrap over the lens. It dims the output of the eyepiece about as much as adding the pinhole lenscap so is not a real problem.

I won't have to do more testing because I know it will work!

After adding the "ND Filter" I will have 0.03 density added by IR worst case - but probably will be less than that because I won't be staring at the film all the time. I'll be shuffling sheets through the tray, so some of the time they will be covered.

I want to thank you Bill for taking the time to do your testing and detailing your procedures and results.

If I am not mistaken a previous contributor mentioned that the manufacturer listed the IR light source emitted by the Viper was technically outside of the visible range of T Max 400 and Ilford FP4+. If that was the case it should not matter how long the film was exposed to the IR light source. Clearly, some level of FB+F is being contributed to the film and some "filter" seems advisable to keep the adverse consequences to a minimum as Bill concluded.

This is the conclusion that my testing arrived at two years ago although I was not able did not test each IR monocle that has come to the market. I feel that technical specifications are only as good as their practical application in the real world.

Don't tell me - show me.

Whoever came up with that statement is right on.

[jeroldharter]

...
If I am not mistaken a previous contributor mentioned that the manufacturer listed the IR light source emitted by the Viper was technically outside of the visible range of T Max 400 and Ilford FP4+. If that was the case it should not matter how long the film was exposed to the IR light source. Clearly, some level of FB+F is being contributed to the film and some "filter" seems advisable to keep the adverse consequences to a minimum as Bill concluded...

I assume that any fogging is not from the IR emitter but from the auxiliary, visible, red LED indicating that the unit is on. At least that is my hope. So if I use an invisible IR "safe"light and cover up the ATN Viper emitter I should be fine with no fogging.

[Ken Lee]

Thanks for the test !!!

For those of us who are sensitometrically challenged: How much fog is there, in percentage terms ? If 0% = black IE normal base + fog, and 100% = white, then to what % level did the fog raise the deepest obtainable black ?

Another way of looking at this, is that fog decreases effective film speed. How much was the film speed reduced ?

One hour at 15 inches is a lot of exposure. Given that the film is in pre-soak + developer + stop bath for no longer than 15 minutes, and at 2+ feet away, the actual exposure my film would receive, is much less. Doubling the distance equates to 1/4 exposure. Cutting the duration to 1/4, brings the total to 1/16 or roughly 7% of Bill's test exposure.

I routinely develop 10-20 sheets at a time, so any one sheet is likely to get its corresponding fraction of exposure to the lamp. Unless I'm mistaken, this brings us down to less than 1 % of the Bill's test exposure.

In percentage terms, how much fogging would we see with only 1% of the test exposure ?

Might that explain why I have never noticed any fogging ?

[Michael Kadillak]

There are still a numbers of variables left in this iteration. I have noticed that the IR light source is stronger when I have fresh batteries and diminishes in power as the unit is used. My unit takes two AAA batteries that only have several hours of life in them.

Maybe I am alone in the assertion that the acceptable tolerance of added FB+F from any photographic related activity in the darkroom with film and paper is zero but that is where I stand on this issue. That being said I recognize that there are acceptable gives and gets in the real world. The engineer in me feels compelled to completely understand and qualify the price of admission.

[Bill Burk]

I tried the 940nm LED, it is too far into IR for the ATN Viper. I could see it glow through the Viper but it didn't light anything much up.

I don't think the ATN Viper has a secondary emitter. I think it is near IR which excites the human eye as red.
Through 3 layers of E6 black slides the red appearance did not diminish.
In nature the only other light that appeared with the same red brightness through 3 slides was the sun.
My eye is still twitching, I won't repeat that test.

Michael,

I figure the problem of safelight exposure is like finding the safe level of x-rays to use on humans, there is no safe dose but you can always get away with a little.

Each step on the Stouffer scale represents a half-stop less exposure.

Step 12 meets your requirements: Absolutely no measurable effect.

In other words, you need to restrict the dose of IR from the ATN Viper.

For zero tolerance you need 6 stops less exposure than 1 hour at 15 inches.

Step 6 results in 0.10 over Base plus Fog. This is what many people use as a speed point.

In terms of zone system, you could imagine this is about where zone 0 ends and zone I begins.

I would say it is intolerable to destroy all of zone 0.

So I would say it is intolerable to give a dose on the order of 3 stops less exposure than 1 hour at 15 inches.

So the solution in percentages:

Percent of zone 0 destroyed:

100% = 3 stops reduction
66% = 4 stops reduction
33% = 5 stops reduction
0% = 6 stops reduction

Here is how I am going reduce my dose

Cut the time down - two stops (15 min)
Cut the brightness - two and a half stops (0.70 silver developed film ND filter)

-Now I am already 4 1/2 stops down, only destroying 50% of zone 0

Anything further that I do to improve the situation will help save zone 0.

This includes not staring directly at the tray!

Weaker batteries would help.

Shuffling would help.

Turning it on and off would help.

Setting up a "safelight" in a distant corner of the darkroom would help.

[John Berry]

I have used it for Fp-4 and looked at the neg close range for a long time with no problems. I have however had it fog with t-max2 400. Develpoer was Pyrocat-P. Ian covered the main problem people have and that is not keeping the unit close to the eye. Raise your whole head not just lift the lens to lookup higher.

[Brian C. Miller]

What if you got a small mirror, say from a dental mirror, and taped it in front of the emitter so that it reflected the light up to the ceiling? Then you would have a diffuse light.

[Ken Lee]

I have used it for Fp-4 and looked at the neg close range for a long time with no problems. I have however had it fog with t-max2 400. Develpoer was Pyrocat-P. Ian covered the main problem people have and that is not keeping the unit close to the eye. Raise your whole head not just lift the lens to lookup higher.

May I ask, do you presoak your film ? As I recall, Ilford films have a differently colored dye than TMY. These dyes could also interfere with the transmission of IR. Even if the presoak water appears clear to the viewing device (as it does for me), what the film sees is not necessarily the same.

Another factor to consider is the developer itself. I use Pyrocat HD, which starts out looking fairly transparent to the IR device, but becomes cloudier as development proceeds. I presume this cloudiness blocks the IR, but again, it's merely blocking what the device sees, not necessarily the film. It could be blocking more or less, or not at all.

[Ken Lee]

For zero tolerance you need 6 stops less exposure than 1 hour at 15 inches.

Step 6 results in 0.10 over Base plus Fog. This is what many people use as a speed point.

You meant 6 steps less exposure, no ?

Six steps = 3 f/stops. 3 f/stops = 1/8 the exposure.

It seems to me that if we develop 8 sheets or more - and shuffle - we automatically meet the requirement.

(Waiting until we have that many sheets to develop, saves time and chemistry. Affordable plastic containers (http://www.kenleegallery.com/html/tech/devtray.html) are deep rather than wide, and cause less oxidation than conventional developing trays, so it's easy to handle up to 20 sheets at a time.)

Thanks again for your most helpful research !

[Bill Burk]

I wrote it right but I know I didn't write it clearly.

Step 6 on the Stouffer scale is 3 stops less and it ruined zone 0. You need to do less damage than that.

Step 12 on the Stouffer scale shows 0.04 - same as baseline B+F - so that is where you want to be. That's 6 stops.

In practice you could go somewhere in-between, closer to 6 stops the better.

I'm going to test with E6 dark slides, see if they help. Because if they do reduce the exposure to the film they are "clear" to the Viper so they won't darken your view.

[jeroldharter]

I received my Glo-Toob 875nm infrared light today. It is completely invisible to my eyes when turned on. I can see it brightly with the ATN Viper. The light has several flashing beacon modes, but I turned it to the 100% power, always on mode for its brightest continuous infrared light. It is still rather dim and certainly does not light up the room like a typical safelight. However, it does light up the immediate area. It is quite small, not much bigger than my thumb. I did not need to turn the power on the ATN as I could see the same either with ATN power on or off. The Glo-Toob uses the same battery as the ATN so that is a happy coincidence. It comes with a lanyard. so you could hang it in close proximity to the working area. The light itself is quite bright but the reflected light it casts on other objects is a bit dim so I did not use the light attenuator on the ATN lens. I have not tested it for fogging, but it must be considerably less than the red light on the ATN.

http://www.amazon.com/Glo-Toob-Lithium-Infrared-IR875-Multi-Purpose/dp/B001G45YGY/ref=sr_1_1?ie=UTF8&s=hi&qid=1290886377&sr=8-1

http://ecx.images-amazon.com/images/I/41T6TYKpWxL._SL500_AA300_.jpg

[Ken Lee]

Please let us know what you find. It' funny that the ATN will see IR with the power off or on. I wonder why.

I guess you could mount it on the top of the ATN with a small reflector - that way you'd illuminate wherever you look.

[jeroldharter]

I think the ATN is a passive IR device, so it will see whatever IR is there but will not amplify the signal like expensive, newer generation, active IR devices.

I don't think that attaching the Glo-Toob to the ATN would work because its IR source is too weak and diffuse to reflect a signal off objects at a distance. I think it is going to work better placing or dangling the Go-Toob close to the objects I am working with.

I am taking some portraits tomorrow. I will expose some doubles and then leave the exposed film near the Glo-Toob for a reasonable period of time to see if I can tell a difference. Not a solid test, but I'm curious. If I have time, I might do do a real "safelight" test. Would be best to do with film pre-flashed with visible light to Zone 0 I think.

[Michael Kadillak]

My Argus C3 monocle is passive as well and does not need to be turned on to register IR illumination.

This is just my opinion but weak IR illumination can be terribly counterproductive to the process. When you have difficulty seeing what you are doing, the objective becomes compromised IMHO. That said there is no question that this is a valuable darkroom tool.

I mentioned to one of the technical sales reps that I purchased my IR monocle from that I was going to use it in a photographic darkroom and it just about blew his mind.

Can you imagine if darkroom safelights as we know them were not designed to be used in the darkroom? This is precisely the situation we are dealing with as we speak.

[Bill Burk]

I put two blackslides of E6 in front of the illuminator and found that it reduced the exposure to my film by a few steps.

It did this without appreciably dimming the view through the Viper.

Still wet so I don't have the numbers but it looks good for taking a few old slides and gluing them to the Viper emitter.

[Brian C. Miller]

It' funny that the ATN will see IR with the power off or on. I wonder why.

Well, these devices are "light amplifiers." The cheap ones are Generation 1. The Generation 1 tubes require either constructing a unit with multiple tubes end-to-end (which is what I used in the Army to see by starlight), or else pairing it with a nice, bright light. The cheap Gen 1 tubes really aren't better than a scope with an illuminated reticle. The light amplification tubes can "see" into near infrared like a video camera, so that's why they come with IR illuminators.

The Gen 2 tubes and Gen 3 tubes have successively better light amplification characteristics. The current Gen 3 tubes allow you to see by starlight, but in a nice, compact package.

[Bill Burk]

Tested with two sheets of E6 dark slide over the ATN Viper emitter.

Test exposure at 15 inches for one hour, developed in total darkness.

Stouffer Step ... Density
1. 0.20
2. 0.16
3. 0.14
4. 0.11
5. 0.09
6. 0.08
7. 0.07
8. 0.05
9.0.05
10. 0.05
11 0.04

---

Interpretation: Four steps improvement = Two stops improvement over previous test.

I had intended to use an 0.7 ND silver piece of film over the emitter to achieve this same end result, but the view in the ATN Viper eyepiece was diminished substantially.

Now I believe that darkslides (unexposed, developed E6 film) make an effective IR filter, test results appear to show that you get one stop of safety improvement for each sheet of E6 film placed over the emitter.

There is some diminished brightness in the ATN Viper eyepiece, however this is a small penalty for a significant gain in safety.

If two sheets of E6 film provide sufficient safety. Three sheets of E6 film will provide an extra measure of safety.

The next run of film I did, I used the Viper. I found that it was hard to resist looking at the film the whole time at a working distance about 22 inches for 14 minutes development time. I did shuffle 8 pieces of film, the edges tended to always show.

I measured negatives from this darkroom session, half developed in total darkness and half developed with the ATN Viper and saw 0.04 to 0.06 density in the rebate from both groups. My gut tells me that the ATN Viper could have contributed to fog but my instinct is not confirmed by density readings.

All my negatives from the session are acceptable, but to honor my gut instinct I plan to glue 3 sheets of E6 darkslide to the ATN Viper emitter.
---
I also noticed that the ATN Viper continues to operate for a time after power is turned off, but I believe it is a residual charge because it eventually does turn off.

[Bill Burk]

ps Thanks to Ken Lee and Michael Kadillak for spurring me on and special thanks to Brian Miller for suggesting E6 dark slides. I knew I collected those for a reason.

[Michael Kadillak]

It is my understanding that companies that cut and/or repackage sheet film use IR technology to assist them in these processes. Surely, they have some form technical standards for acceptable working conditions so that the film they sell is not adversely affected along the way. I will make a couple of calls.

[George W.]

It is my understanding that companies that cut and/or repackage sheet film use IR technology to assist them in these processes. Surely, they have some form technical standards for acceptable working conditions so that the film they sell is not adversely affected along the way. I will make a couple of calls.

That is a good idea to get more information!

Another possibility might be to contact one of the remaining E6/C41 labs,
they have used for years IR goggles to handle colour film in the dark.

They surely can indicare what they used in order not to harm the colour film.

[jeroldharter]

I decided to test my own processes using the ATN Viper plus an 850nm IR Glo-Tube that I used as a potential "safelight."

I was concerned about comments that the red glowing "on" indicator for the ATN's IR emitter could fog film. So just to be safe, I bought the 850nm Glo-Tube. That emits a much dimmer "light" than the ATN, but I am able to see OK by using the ATN turned off and with the Glo-Tube as the light source.

Coincidentally, I just went on a trip and due to a baggage foul-up I was worried that 60 sheets of 8x10 inch TMY were fogged. So I processed a blank sheet of film and found no fog. I was happy about that. Then I took a second sheet and exposed segments of it to the Glo-Tube for 2,4, and 6 minutes. Then I exposed on top of the 6 minute Go-Tube exposure with 2, 4, and 6 minutes of ATN Viper with the red light on at close working distance to the film. Then I flashed the edge of the film just to confirm that I could develop some density. The Glo-Tube was suspended by its lanyard very close the the sheet of film.

These are my readings from an X-Rite 810 densitometer:

B+F 0.05
2 min Glo-Tube 0.05
4 min Glo-Tube 0.05
6 min Glo-Tube 0.05
6 min Glo-Tube + 2 min ATN 0.05
6 min Glo-Tube + 4 min ATN 0.05
6 min Glo-Tube + 6 min ATN 0.05
Flash 1.31

So my conclusion is that for my work with the ATN, which includes loading film holders, film reels, Jobo tanks (but not tray development) I will experience no fog with the ATN Viper and its red-glowing emitter in close quarters with my film.

[George W.]

Many thanks for all the feedback from the real world.

If I remember correctly, safelight testing is sometimes difficult,
as you are in the curve toe, just below the threshold when something
will be measurable by the densitometer, above b+f.

By preexposing the negative before making a safelight test, this
test will get much more sensitive.
Through the preexposure small effects by fogging can be detected
by the densitometer.

I will try to find back in the literature where such a procedure for safelight
testing is described.

[George W.]

reference:
"Way Beyond Monochrome"
Ralph W. Lambrecht
second edition

pages 428...432
Chapter: "How Safe is Your Safelight?"

happy reading!

[Bill Burk]

Vindication (at least partial) for the ATN Viper.

In an earlier report, I concluded that the ATN Viper fogged TMY-2 to 0.20 after 1 hour exposure with 2 pieces of E6 slide film taped over the emitter.

Under the same conditions, I left a piece of film half-uncovered for an hour, with no IR.

The result was a significant .10 to .15 fog of the uncovered film (developed to CI 0.6).

Much (but not all) of the fog reported was environmental. My darkroom apparently isn't sufficiently dark to leave film out for an hour.

[John Bowen]

Has anybody else experienced the light intensity varying? My viper atn has a nasty habit of going dim at the most inopertune times. Any thoughts?

[Bill Burk]

I had the battery die when my kids got ahold of it. But do you know the front of the emitter twists so you can turn the emitter on and off that way. Check that's not loose.

I still do time and temperature development. But now when a shot needs more time, I can give it all it needs. Here's an example where inspection helped.

http://www.beefalobill.com/imgs/_MG_7028crop.JPG

To clarify the change in my conclusion: My initial tests have to be thrown out because the background fogging seriously degrades the data. But I think my first tests support the hypothesis that two sheets of E6 (dark slide) over the emitter make the ATN Viper safe for TMY-2 for 30 minutes of handling.

[John Bowen]

Thanks Bill, I'll give it a try. My first thought was a bad battery, but with a fresh battery installed the problem remained.

[Ken Lee]

Mine has started to do that also (change intensity at the most inopportune moments).

I'll see if the emitter is screwed on tight.

Thanks !!!!!

[buggz]

Any updates to this?
IS anyone still using this device?

[Ken Lee]

"IS anyone still using this device?"

Yes. I've changed the battery once in X years. It's still working fine, although it does get brighter and darker now and then. I missed the earlier post about making sure the emitter is tight. I'll be using it this weekend, so we'll see if that helps.

It has paid for itself many times over.

[Bob Mann]

Any updates to this?
IS anyone still using this device?

Yes, for loading and unloading film holders it is great - makes the job a lot easier and quicker. I use dip tanks with hangers, so it helps a lot in getting the hangers moved from one tank to another and I can't resist taking a look at what is happening during agitation. While I am using a time/temp routine for developing, I guess you could say I am also developing by inspection because if I see something that needs more or less time, I can make the adjustment as I am working.

My unit is about 3 years old, changed the battery once - otherwise it works just like new.

[Ken Lee]

Well stated :cool:

The term Development By Inspection is a bit of a misnomer: perhaps a more accurate description would be Development With Inspection.

[Bill Burk]

Yes! Like Bob and Ken, I develop by time and temperature but when it looks like a shot needs more developing, I take out the sheets that are done, reset the timer and give the thin neg a few more minutes. I also know when the film clears so it is easy to give twice that time in the fix.