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TimberwolfII
2-Sep-2017, 09:17
Hi everyone, first post!

Been a lurker and generally familiar, although far from competent with 6x6. I love analogue, so have ventured into LF.

I have a 'no budget' set up, scratched together off eBay and diy:
Kodak specialist 3 rail camera
Ross of London telemetric 6.8 300mm
Elgeet no.3 universal shutter
DIY brass lens to shutter converter
Weston exposure meter.
Home made film holder (camera is a half plate)

Conundrum is: Weston is "accurate" for my Mamiya 330, ie if I do what it tells me I get decent negs.

When I meter for the big Kodak I have to allow 8 stops more exposure (!) to get a decent neg.

Why?

Cheers, Rob

Leigh
2-Sep-2017, 09:24
Conundrum is: Weston is "accurate" for my Mamiya 330, ie if I do what it tells me I get decent negs.
When I meter for the big Kodak I have to allow 8 stops more exposure (!) to get a decent neg.
Why?Hi Rob, and Welcome Aboard.

That is a really odd situation.

Commonly, old shutters slow down, so you need to use a setting for a faster speed than you really want.
If you expose at the nominal marked shutter speed, negs will be OVER-exposed.

I can't envision a shutter problem that would cause under-exposure.

- Leigh

Nodda Duma
2-Sep-2017, 09:47
Start with the basics:

In sunny conditions, set lens shutter at f/16 and expose the film at 1/ISO. So if the film is ISO 100, expose for 1/100s. This should tell you if the shutter is operating properly at that setting.

Reduce the aperture and correspondingly increase the shutter speed.


Alternatively, down load the iphone app shutter speed and test your shutter that way.

Vaughn
2-Sep-2017, 09:50
Eight stops is too much for a simple problem!

What film?

Close-up photography? If so, exposure needed to be added to compensate for long bellows extension.

Is you lens marked with modern f/stop system?

Try an exposure that you time with a lens cap rather than the shutter -- a second long exposure or more. That will eliminate shutter problems.

Test your shutter by firing a known good one at the same time -- at times around 1/4 sec or slower.

Two23
2-Sep-2017, 10:56
Eight stops--do you know if your shutter is the more modern system of f-stops (i.e. the British,) or the old U.S. (Uniform System) from around 1900? On both systems, f16 is the same. On the U.S. system, I think f8 is actually f11 in modern system. As for your question, the film is the same speed so exposure should be the same. Oh, the Mamiya will definitely have the modern f-stop system. There might be several exposure scales on your meter too--a bit confusing.


Kent in SD

TimberwolfII
2-Sep-2017, 11:01
Eight stops is too much for a simple problem!

What film?

Close-up photography? If so, exposure needed to be added to compensate for long bellows extension.

Is you lens marked with modern f/stop system?

Started with a portrait, subject got bored, ended with a tree! At about 2m distance both. Same light etc.

Ok, more info:
HP5 rated at 200
Light meter set at asa 200, gives an indication of no.11 off a grey card, which cos I want the lens wide open (6.8) equates to 1/250-1/500. Via lots of trial and error I get a decent neg off the camera set at 1 sec 6.8. (Eights stops more than indicated?) Lens is 1912 so f stops are a bit funky but all there. Shutter sounds like about a second, faster speed is under exposed 4 sec bulb exposure over.

The lens is physically about the same as the Mamiya 250 mm I have, in my head I'm wondering if so much light goes in through the hole in the lens and illuminates a 6x6 then the intensity of similar light through a similar hole hitting a 5x7 INCH neg area will be so much less intense?

I can maybe just shift all the numbers along and go from there, but that's not very scientific and I'm trying to understand what's happening.

I got into LF to really dial down into the theory, analogue stops me at first hurdle!:rolleyes::)

jp
2-Sep-2017, 11:13
If the shutter wasn't meant for that lens, the f-stop calibration is useless. This is compounded by the difference in f-stop units historically.
Could your lens have an iris or studio shutter that's stopped down even though your separate shutter is wide open? Or waterhouse stop needing to be removed?

If the film stays the same, exposure for one camera and film size will be the same for another camera and film size. (assuming you doing normal photos not closeups)

Vaughn
2-Sep-2017, 11:23
No -- there is no fundamental difference in lenses/formats that should cause a one stop difference, let alone 8.

You are losing light due to the extension of the bellows past the focal length of the lens. Set up the camera the same way, measure the bellows and run this equation and see what factor you would need to increase your exposure: http://www.cookseytalbottgallery.com/bellows_compensation.php also:http://www.largeformatphotography.info/bellows-factor.html

Also you might want to measure your aperature and run the equation to make sure you lens in marked with the proper modern f/stop system.

https://en.wikipedia.org/wiki/F-number

Mark Sawyer
2-Sep-2017, 12:25
At 2 meters, the bellows extension wouldn't be much of a factor, and would be the same on the medium format C330 at the same distances. In daylight with HP5 at f/6.8, 1 second is way too much exposure. As you're new to LF processing, I'd suspect development first.

jp
2-Sep-2017, 13:57
It could be the film is loaded facing the wrong way.

TimberwolfII
2-Sep-2017, 14:05
If the shutter wasn't meant for that lens, the f-stop calibration is useless. This is compounded by the difference in f-stop units historically.
Could your lens have an iris or studio shutter that's stopped down even though your separate shutter is wide open? Or waterhouse stop needing to be removed?

The lens has its iris which is wide open at 6.8. The shutter also is wide open, at 1.9.

The lens focuses at what looks like around 14" (no tape measure till morning) which is way bigger than the Mamiya can open out to. I only mentioned the Mamiya cos the 6x6 must be approx 1/8th the size of the 5x7. It isn't the same lens, one is Mamiya the other on the LF is the wray

I'll measure and run the formulas in the morning.

It's not development. I can run a decent neg, it's something about the camera/lens/shutter combo.

Jim Jones
2-Sep-2017, 14:05
The U. S. system of marking apertures was invented to simplify [?] exposure calculations. The numbers double for each halving the exposure. U.S. 1 + f/4, U.S. 2 = f/5.6, U.S. 4 = f/8, U.S. 8 = f/11, U. S. 16 = f/16, U.S. 32 = f/22, U. S. 64 = f/32, U.S. 128 = f/32, and U.S. 256 = f/64.

TimberwolfII
2-Sep-2017, 14:29
It could be the film is loaded facing the wrong way.
Could be ........Ilford hp5, grooves in top right corner with film held in right hand has the emulsion facing me? Correct?

TimberwolfII
2-Sep-2017, 14:37
The U. S. system of marking apertures was invented to simplify [?] exposure calculations. The numbers double for each halving the exposure. U.S. 1 + f/4, U.S. 2 = f/5.6, U.S. 4 = f/8, U.S. 8 = f/11, U. S. 16 = f/16, U.S. 32 = f/22, U. S. 64 = f/32, U.S. 128 = f/32, and U.S. 256 = f/64.

The shutter is wide open, showing 1.9. As the English lens only opens to 6.8, this should be the limiting factor?

I started by going with what the Weston said -1/250th at 6.8 and got virtually nothing on the neg. only when I increased it in steps up to 1 sec did I get good density. Development was held the same - rodinal 1:50 at 20 degrees c for five minutes. All I did all through the 'tests' was increase the exposure time from 1/250th to 1 sec.

Chauncey Walden
2-Sep-2017, 14:43
Is it a Telemetric or Telecentric? A shutter like that marked 1.9 would probably have contained a short oscilloscope lens. It's possible that the clear area of the shutter wide open is smaller than the clear area of your lens wide open. There is also the possibility of mechanical vignetting I suppose. When you look through the front glass of the lens when it is on the shutter and measure the opening you see in mm and divide that into 300 what do you get?

Chauncey Walden
2-Sep-2017, 14:44
Also Rodinal 1 to 50 for 5 minutes for HP5 sounds kind of short. I think my time is 12 minutes.

TimberwolfII
2-Sep-2017, 15:03
Also Rodinal 1 to 50 for 5 minutes for HP5 sounds kind of short. I think my time is 12 minutes.

Oops 1:25, my mistake. 4.75mins - off the Massive development chart. Yes 1:50 would be 10-13 mins.

TimberwolfII
2-Sep-2017, 15:06
Is it a Telemetric or Telecentric? A shutter like that marked 1.9 would probably have contained a short oscilloscope lens. It's possible that the clear area of the shutter wide open is smaller than the clear area of your lens wide open. There is also the possibility of mechanical vignetting I suppose. When you look through the front glass of the lens when it is on the shutter and measure the opening you see in mm and divide that into 300 what do you get?

1.9 is the shutter iris. The lens has a 6.8 iris. I'll measure in the morning. I just get the 5x7 covered, no real room for movements.

faberryman
2-Sep-2017, 15:23
It's possible that the clear area of the shutter wide open is smaller than the clear area of your lens wide open.
I second this. Just looking a an image of the shutter, the opening looks quite small for a 300mm f6.8 lens. For example, the 300mm f5.6 Symmar-S takes a Copal No. 3. Just a guess.

Dan Fromm
2-Sep-2017, 15:48
Good point, Frank. The OP says he has a #3 Elgeet shutter. Its an Ilex #3 Universal rebadged for Elgeet, who made the lens that was originally in it. Most likely taken from an oscilloscope camera.

Normal Ilex 3s open to 35 mm. Many 'scope camera Ilex 3s for f/1.9 lenses have restricted apertures, open to around 30 mm.

OP, a shutter's aperture scale ia for the lens intended to be mounted in it. From all other lenses' points of view, totally arbitrary and incorrect numbers. Oh, and by the way, when you took y'r shots the shutter's diaphragm should have been wide open. Was it?

jp
2-Sep-2017, 15:58
Could be ........Ilford hp5, grooves in top right corner with film held in right hand has the emulsion facing me? Correct?

Correct.

TimberwolfII
3-Sep-2017, 00:09
Good point, Frank. The OP says he has a #3 Elgeet shutter. Its an Ilex #3 Universal rebadged for Elgeet, who made the lens that was originally in it. Most likely taken from an oscilloscope camera.

Normal Ilex 3s open to 35 mm. Many 'scope camera Ilex 3s for f/1.9 lenses have restricted apertures, open to around 30 mm.

OP, a shutter's aperture scale ia for the lens intended to be mounted in it. From all other lenses' points of view, totally arbitrary and incorrect numbers. Oh, and by the way, when you took y'r shots the shutter's diaphragm should have been wide open. Was it?

Awake early for a Sunday and had tape measure out. The aperture in the Ross lens is 25mm at 6.8 on the dial - wide open; the shutter is 26mm at 1.9 - wide open. Both were wide open when making all the shots, I only changed the one variable whilst searching for the neg density - shutter speed. Also no bellows extension, I left it where it was focused when I brought it in - near as makes no odds 300mm lens iris to ground glass.

So, is my lense with a circa 30mm dia overall and an iris that opens to 25mm able to transmit less light that a massive aero Ekta say which is physically five times bigger? Or do they go to 2.8, 1.9 etc and have a greater aperture to focal length ratio?

Still not much idea as to where my 8 stops of light has gone!! Lots of head scratching from all you kind folk for which I'm very grateful! :)

Is it because I have a dinky little lense with a dinky little hole that only lets in a glimmer of light for that big ol 5x7, and just live with it darn it!? :)

esearing
3-Sep-2017, 05:23
A picture of your camera and lens might be worth a thousand words. Did you ever look inside the camera to make sure there is not a color gel inside or a filter on the back of the lens? Is your subject 14 inches or your bellows length 14inches when focused? Is it possible your medium format camera shutter is off by a couple of stops too?

Try a different lens or have your lens tested, meter with a phone App to compare meter results. Does your meter have low light and daylight settings (like the leica meters) ?

You have to eliminate one variable at a time.

Dan Fromm
3-Sep-2017, 06:32
Also no bellows extension, I left it where it was focused when I brought it in - near as makes no odds 300mm lens iris to ground glass.

Arrgh!

Ross didn't make a "Telemetric." They made a telephoto lens called Telecentric.

300/6.8 = 44, not the 25 you measured.

You have a telephoto lens. The rear nodal point, from which extension is measured, is far in front of the diaphragm.

You have a telephoto lens. It has considerable pupillary magnification. The f/ number is calculated as focal length/diameter of the entrance pupil. Measure the entrance pupil, not the diaphragm.

There are books on LF photography. The two most commonly recommended here are Leslie Stroebel's View Camera Technique and Steve Simmons' Understanding the View Camera. Both available used at low prices from on-line booksellers, e.g., abebooks.com, alibris.com, amazon.com, bn.com, ... Buy one and study it. You'll learn more that way than from short random answers to random questions.

TimberwolfII
3-Sep-2017, 06:34
A picture of your camera and lens might be worth a thousand words. Did you ever look inside the camera to make sure there is not a color gel inside or a filter on the back of the lens? Is your subject 14 inches or your bellows length 14inches when focused? Is it possible your medium format camera shutter is off by a couple of stops too?

Try a different lens or have your lens tested, meter with a phone App to compare meter results. Does your meter have low light and daylight settings (like the leica meters) ?

You have to eliminate one variable at a time.
The Kodak is just the usual two stages with a bellows, no gels etc, nowt on the lens either169173

This is it picked up and brought inside, haven't moved bellows etc.

Yes maybe the MF is off too, they are all the same vintage, but both MF shutters would have aged identically. But the MF and LF would still be eight stops different relative to each other. The MF works fine when set to the readings of the Weston light meter, whereas the LF MASSIVELY under exposes.

Yes the Weston has a bright/dark flip up screen, but imho the light meter and Mamiya aren't at fault I've used them fine for two decades....

It's just this darn new fangled large format! :)

TimberwolfII
3-Sep-2017, 06:49
Arrgh!

Ross didn't make a "Telemetric." They made a telephoto lens called Telecentric.

300/6.8 = 44, not the 25 you measured.

You have a telephoto lens. The rear nodal point, from which extension is measured, is far in front of the diaphragm.

You have a telephoto lens. It has considerable pupillary magnification. The f/ number is calculated as focal length/diameter of the entrance pupil. Measure the entrance pupil, not the diaphragm.

There are books on LF photography. The two most commonly recommended here are Leslie Stroebel's View Camera Technique and Steve Simmons' Using the View Camera. Both available used at low prices from on-line booksellers, e.g., abebooks.com, alibris.com, amazon.com, bn.com, ... Buy one and study it. You'll learn more that way than from short random answers to random questions.

Ok, entrance pupil is 50mm. I will look up "pupillary magnification" sounds painful.

So, 300/50 is 6, seeing as its all actually in imperial that would work out about right for f6.8.

I have lots of books and an internet, but it's much more companiable chatting to you guys. Try and find 'real' folk ready to talk about this stuff!!! Even 'photographers' just glaze over. My son just said "just take the picture with your iPhone!" Philistine.

Anyhow, it's not doing what it's supposed to! Where's my light gone!?

TimberwolfII
3-Sep-2017, 06:55
Wiki says
"The pupil magnification of an optical system is the ratio of the diameter of the exit pupil to the diameter of the entrance pupil. The pupil magnification is used in calculations of the effective f-number, which affects a number of important elements related to optics, such as exposure, diffraction, and depth of field. For all symmetric lenses, and for many conventional photographic lenses, the pupils appear the same size and so the pupil magnification is approximately 1."

Which for my lens is 50mm entrance 25mm exit. Does this effect what light hits the ground glass relative to the aperture setting then?

Dan Fromm
3-Sep-2017, 07:15
Which for my lens is 50mm entrance 25mm exit. Does this effect what light hits the ground glass relative to the aperture setting then?

No. The f/ number is all you need to know. Buy a book. Read a book.

TimberwolfII
3-Sep-2017, 07:21
I have lots of books and an internet.

it's not doing what it's supposed to! Where's my light gone!?

Books don't tell you how to trouble shoot, they tell you theory and protocol, what happens when theory and protocol don't work?

faberryman
3-Sep-2017, 07:38
I checked and an Ilex 3 has a max iris of 34.6mm. A Copal 2, for example, has a max iris of 30mm, and a Copal 3 has a max iris of 45mm. Still, eight stops light loss is a lot.

Maybe the OP could measure the diameter of the rear element of his lens.

TimberwolfII
3-Sep-2017, 08:01
Maybe the OP could measure the diameter of the rear element of his lens.

Iris at max opening = now I look very closely the iris opens up to maybe 30mm - it's in the centre of the lens half way down so hard to gauge with the optics
169175
There is a mask near the rear element that is 25mm dia.
169176
You can just see a glint of its edge above, its close to the rear element, but is NOT the iris.

Rear element is 50mm dia

Sheesh, plenty of crud in that lense! :rolleyes:

169177

34.6mm of shutter aperture. Plenty of holes for light to tumble in!

faberryman
3-Sep-2017, 09:49
Well if the rear lens element is 50mm, and the shutter opening is 34.6mm, then I would think that you are suffering light loss, though hard to say if it is eight stops.

Tim Meisburger
3-Sep-2017, 10:16
I think, as someone else mentioned, that you are loading the film backwards. Are you sure you have the emulsion side facing the lens on your homemade holder? Looking through the lens at the film in the holder the notch should be in the upper right corner.

Exposure on LF is exactly the same as MF and 35mm. Exposure doesn't change with format.

TimberwolfII
3-Sep-2017, 12:10
Well if the rear lens element is 50mm, and the shutter opening is 34.6mm, then I would think that you are suffering light loss, though hard to say if it is eight stops worth.

As the picture above shows the light actually has to get through a 25mm hole [I]after[I]the lens aperture, which is part of the lense design, maybe that's an issue?

All I can say about the emulsion is: grooves in top right corner held in the right hand makes the emulsion face towards you, left hand holds the carrier facing upwards and the right hand holds the film with emulsion also facing upwards. Slot the two together and voila!

I'm still not clear how an amount of light going through a hole of say 25mm and hitting say 36 square centimetres (6x6) has the same intensity per unit area as the same amount of light going through a 25mm hole and dispersing itself over 234 square centimetres (13x18cm or 5x8")?

Pfsor
3-Sep-2017, 12:30
Buy one and study it. You'll learn more that way than from short random answers to random questions.


Books don't tell you how to trouble shoot, they tell you theory and protocol, what happens when theory and protocol don't work?

I hold with Dan on this one, I have to say. Books will teach you to ask correctly, to look correctly for questions. You start to be cocky on people who give their time to help. I want to be helped as I say, not as you want to help me is selfish and childish.
You cannot learn to cook just asking your nose how it smells.

TimberwolfII
3-Sep-2017, 12:57
I'm really really not trying to be cocky; I've been shooting b&w on and off for thirty years 35mm then MF. I have books and I use them. I'm trying to improve my craft. Because LF facilitates craft it was my next move. I've never come across this phenomenon where the kit seems to be doing something weird. I thought it might be something peculiar to LF so I came here.

But in four pages of dialogue there doesn't seem to be an answer. I have responded as thoughtfully and thoroughly as I know. I can't go to a book and find the answer to this, I've tried. I thought that was the purpose of a forum and a community, to ask respectfully of ones peers?

It wasn't a 'random' question.

Maybe I just go and ask elsewhere.

Newbies may seem childish because of their ignorance, we all have to start somewhere.

faberryman
3-Sep-2017, 13:04
You could always just meter, add eight stops, and expose. If that consistently works for you, then you have solved your problem.

TimberwolfII
3-Sep-2017, 13:33
Thanks Faberryman. Looks like I'm gonna have to.

Maris Rusis
3-Sep-2017, 14:09
Why dance around the problem?

If the shutter has an iris in it always leave that iris fully open. That iris is not used in the operation of the lens and the aperture numbers engraved on it are irrelevant.

Measure the entrance pupil of the lens with the lens iris fully open. The entrance pupil size is the diameter of the aperture as seen through the front glass of the lens. Measure this appearance. This can be tricky, avoid parallax error.

Measure the actual focal length of the lens. It's not the distance between the front and rear standards of your view camera if the lens is a telephoto. It's not the focal length engraved on the lens if the lens has some missing or extra glass and you don't know about it. There are a number of ways of measuring focal length. Study. Pick the one most convenient.

Divide the focal length you measured by the entrance pupil you measured and the number you get is the maximum relative aperture, or f-stop, of the lens. That's optical law and it hasn't been repealed. Compare the number you got with the number engraved on the lens. If there is a difference then the f-stop markings of the lens needs recalibration.

Check the shutter speeds for obvious errors.

Emulsion side of the film? Hold the film in portrait orientation, short edges top and bottom, long edges left and right. If the film is notched in the top edge and the notches are toward the right corner the the emulsion is facing you.

The rest is just the usual subject brightness, film speed, f-stop, shutter speed equation.

koraks
3-Sep-2017, 15:35
If the 8 stop underexposure would be due to an iris issue, then the iris would have to be quite tiny. 8 stops is a difference in light intensity of roughly 1:500 (1:512 in fact), so an iris that is even only half the diameter it should be, would not amount to this effect (that would only make for an underexposure of 2 stops, not 8).

Exposing through the wrong side of the film generally makes for an underexposure of 3 to 5 stops, in my experience.

If you were to add a very significantly smaller iris to film loaded the wrong way round, one would get in the neighborhood of the observed 8 stop underexposure. Either of these effects separately would in my opinion not result in this huge issue.

Aperture and focal length in principle have nothing to do with film format; think of he image as a cone of light casting a circular image, part of which you capture and the size of that part depends on the film format chosen. The light cone doesn't change in brightness depending if you capture only a small or a large part of it. Hence, it doesn't make a difference if you measure for 8x10" or 35mm; if a measurement says e.g. 1/100 @ f/5.6, then that isn't dependent on film format.

Something odd certainly seems to be going on and I can't really come up with a good hypothesis on what's going on, apart from that it looks like a pretty significant error somewhere in the process.

Dan Fromm
3-Sep-2017, 16:00
Maris, koraks, the OP seems to have hung a 300 mm telephoto lens in front of an Ilex #3. This puts the lens' rear node a good distance in front of the lens' diaphragm and farther in front of the shutter's aperture. It might act as a stop.

TimberwolfII
3-Sep-2017, 22:55
Why dance around the problem?

If the shutter has an iris in it always leave that iris fully open. That iris is not used in the operation of the lens and the aperture numbers engraved on it are irrelevant.

Measure the entrance pupil of the lens with the lens iris fully open. The entrance pupil size is the diameter of the aperture as seen through the front glass of the lens. Measure this appearance. This can be tricky, avoid parallax error.

Measure the actual focal length of the lens. It's not the distance between the front and rear standards of your view camera if the lens is a telephoto. It's not the focal length engraved on the lens if the lens has some missing or extra glass and you don't know about it. There are a number of ways of measuring focal length. Study. Pick the one most convenient.

Divide the focal length you measured by the entrance pupil you measured and the number you get is the maximum relative aperture, or f-stop, of the lens. That's optical law and it hasn't been repealed. Compare the number you got with the number engraved on the lens. If there is a difference then the f-stop markings of the lens needs recalibration.

Check the shutter speeds for obvious errors.

Emulsion side of the film? Hold the film in portrait orientation, short edges top and bottom, long edges left and right. If the film is notched in the top edge and the notches are toward the right corner the the emulsion is facing you.

The rest is just the usual subject brightness, film speed, f-stop, shutter speed equation.

Thank you for the comprehensive answer it is appreciated.
I'll do the math and see whether the lens is doing what it should. I will study.
I believe I am putting the film in correctly, but obviously I will be very conscious to be aware when loading.

TimberwolfII
3-Sep-2017, 23:01
Aperture and focal length in principle have nothing to do with film format; think of he image as a cone of light casting a circular image, part of which you capture and the size of that part depends on the film format chosen. The light cone doesn't change in brightness depending if you capture only a small or a large part of it. Hence, it doesn't make a difference if you measure for 8x10" or 35mm; if a measurement says e.g. 1/100 @ f/5.6, then that isn't dependent on film format.
.

Now I understand why the light intensity doesn't change between formats. Thank you koraks succinctly and clearly described.

TimberwolfII
3-Sep-2017, 23:09
169234
This is the lens/adapter/shutter configuration. The lens has the mount thread just behind the iris, about a third the way along the barrel, hence the long adapter otherwise the lense would clash the shutter.

Sorry bout the dark image, it's early morning and I don't want to disturb my significant other turning on lights...:)

koraks
4-Sep-2017, 00:51
Maris, koraks, the OP seems to have hung a 300 mm telephoto lens in front of an Ilex #3. This puts the lens' rear node a good distance in front of the lens' diaphragm and farther in front of the shutter's aperture. It might act as a stop.
I understand, but how could that amount to an 8 stop difference? 2 or 3 stops, sure, and maybe even 4. But 8? Even quite far from the nodal point, the iris would have to be quite tiny to get even close to 8 stops!

Tim Meisburger
4-Sep-2017, 05:52
Right. The eight stop difference is huge, and the reason I though the OP was shooting through the film base (although I'm not even sure that would give you eight stops).

Dan Fromm
4-Sep-2017, 05:55
I understand, but how could that amount to an 8 stop difference? 2 or 3 stops, sure, and maybe even 4. But 8? Even quite far from the nodal point, the iris would have to be quite tiny to get even close to 8 stops!

Fair question. I too have trouble with 8 stops.

Here's a test for the OP. Hold the lens/shutter at arm's length with the shutter open and its and the lens' diaphragms both fully open. Looking through the lens from the rear, slowly close the lens' diaphragm until the blades just become visible from the rear. What's the marked aperture at that point?

TimberwolfII
4-Sep-2017, 11:11
Immediately. I can see them start to move off max 6.8. I can see them past the 'mask' near the rear element. It's like an uninterrupted tunnel, all the projections - lens iris, mask, shutter iris all look the same diameter.

I'm hoping I can get time to contact print the under-ok-over negs in next couple of days so I can post them with accompanying data. Maybe they will shed some light, if you'll excuse the pun.

Rob

TimberwolfII
4-Sep-2017, 11:33
Ok, lets go back to check the film base way round. Maybe I can put it to bed yes I've put it in right or no I've screwed up. I've looked at the negs and I know the subject was looking to MY left when I took one of the images. My brain is hurting trying to juggle which way the notches/emulsion/head direction is cos everything turns upside down and back to front.

Greg Davis
4-Sep-2017, 11:46
If your subject on the negative is looking the same direction as in real life with her head at the top of the image, the notches should be in the top left while held vertical.

Mark Sawyer
4-Sep-2017, 13:21
If your subject on the negative is looking the same direction as in real life with her head at the top of the image, the notches should be in the top left while held vertical.

Only if he loaded the film with the notches at the bottom of the holder, or put the holder in the camera from the bottom.

TimberwolfII
4-Sep-2017, 13:37
169274

She was looking to my left in real life. Neg is in right way round then?

Holder goes in from top of camera. I believe I put the film in so the notches are at the bottom hinge portion of the holder i.e. Notches end up at the bottom of the camera.

Mark Sawyer
4-Sep-2017, 15:14
Oh, sorry, I got turned around by everything being reversed, upside-down and inside-out...

cowanw
4-Sep-2017, 15:49
169274

She was looking to my left in real life. Neg is in right way round then?

Holder goes in from top of camera. I believe I put the film in so the notches are at the bottom hinge portion of the holder i.e. Notches end up at the bottom of the camera.

Assuming the shiny side is facing us in the photo, yes.

Leigh
4-Sep-2017, 16:27
My brain is hurting trying to juggle which way the notches/emulsion/head direction is cos everything turns upside down and back to front.
The emulsion is ALWAYS toward the subject (in camera), or toward the paper (in enlarger/contact).

When you load film into a filmholder, the notches are at upper-right so the emulsion is toward you, and toward the opening at the front of the filmholder, thus facing the subject when in-camera.

- Leigh

Tim Meisburger
4-Sep-2017, 19:20
If she was looking left, then the film was loaded correctly, and I'm stumped. Strange....

TimberwolfII
4-Sep-2017, 23:23
Assuming the shiny side is facing us in the photo, yes.

169303

Obviously same neg. Held the same, shiney. She was looking north, to my left, up the garden. Not me loading film backwards. One down.

"Once you illuminate the impossible, whatever remains, however improbable, is the truth" Arthur Conan Doyle

I'll contact print the three negs with attendant data, see if that throws owt up. Might be a blind alley and I just make a conversion chart for this set up; but it's niggling me.

koraks
5-Sep-2017, 00:13
Maybe it's just me, but that negative looks unbelievably dense and it may even be fogged as well. Are the edges completely clear, or is there density running towards the outer edges of the film, at least in some places?

Hypothesizing a bit: if the film was fogged (severely), then it would take a huge additional exposure to get any separation between the fog and the image. That could explain the 8 stop overexposure necessary to get an image at all. The underexposed images should still show density (fog) if this is the case. And the 'correctly' exposed images would be low in contrast and rather grainy as the entire image would be compressed onto the shoulder of the curve.

It would greatly help to see these negatives (photographed) on some kind of light box.

TimberwolfII
5-Sep-2017, 10:39
Ok, best try. No light box so improvised with a bowl and an led floodlight...:p
#1 First one, imho underexposed
169331
BIG light leak from bottom flap of holder (its cobbled together from laminate and ply) in fact light leaks on all negs; hope to improve in film holder mkII.
Data:
Film HP5 rated 200 5x7
Weston lightmeter said asa200, no.8, 5.6 1/30th. This was taken INDOORS.
Camera 6.8 1/5th (because I've had under exposure issues previous so I was guessing)
Dev rodinal 1:25@20 c 5mins 30 sec initial agitation the 10sec per min.

#2 Second try no model, so a tree, looking for more light so came outside.
169333
In person looks 'okish' Defoe not good or great, but printable with effort. Vignette is mostly the bowl acting as lightbox.
Same film.
Meter set asa 200, no.11, says f8-5.6 and 1/250th
Camera set f6.8 for 1 sec (shutter)
#3
169334

Wife comes back!:)
All settings the same as#2 again maybe a 'useable' negative.

#4
169335

Everything the same as #2 & #3 but 4 seconds manually timed with B on shutter. Looks 'overexposed' in person.

TimberwolfII
5-Sep-2017, 13:35
#2169341


#3169340

Not okish. Nightmare. Low contrast, and the lens obviously isn't covering the neg.
but there is still summut else. And yes absolutely, fog sounds right but what causes it? Never experienced this sort of thing before.

Vaughn
5-Sep-2017, 14:05
My advice -- take care of the light leaks before trying to determine exposure and development times. Sort of like testing one's car's gas milage with flat tires. Use photopaper if you want to go cheap and easy.

Nodda Duma
5-Sep-2017, 16:33
If you measured 25mm wide open shutter, then your f/# is

300 / 25 = f/12

Which is ~2 stops down from what you metered for right there. That's not quite the working f/#. Magnification due to object distance plays a role as well. Additionally, positioning the shutter as-is will cause a change in magnification of the entrance pupil and changing the f/# as well. Going back through, pupil magnification sounds like 2x. Those effects could add up to an additional stop or two.

Working f/# ~ (1 + m/P) * f/#

m = d(object) / d(image)
P = 2

For object 2m distant, f/# will be about 1.1 x 12 ~ 13.2

There's also a vignetting effect due to the shutter position so far behind. Sort of like a T-stop effect but in reverse. If I'm calculating correctly, that could be 2-4 stops depending on what the original f/# is.

So you could be 4-6 stops down from all those effects.

That negative also looks very dense, as in it looks very overexposed. However, closer inspection of the edges indicate significant fogging. To overcome that fogging requires additional exposure..conversely exposing as you did will not get the image very out of the fog and it will look underexposed. Maybe another stop or two from that effect? Veiling glare due to light leaks could account for another stop. 2-3 stops from those effects.

Also, developing HP5+ at 200 (N-1) in Rodinal 1:50 at 20C should be more like 7:00 with 30s agitation. N-2 is about 5 minutes, so you're 1 stop underdeveloped as well. Rodinal 1:25 would be about 6:15.

So I'm estimating 6-9 stops down!

Conclusion: death by 1000 cuts. I agree with Vaughn..You need to refine your "no budget" camera, verify developing times, and probably buy fresh film! :)

TimberwolfII
5-Sep-2017, 23:08
Wow, you guys. Just wow. I see all that.

Don't understand the calcs but get the principles.

In my tiredness last night I took the white round the image to be a vignette, but probably its light leak fogging. Loads. It's white not dark. The dark slide aperture is pouring light in! Likewise the loading flap joints.

So, mkII film holder and try again.

I'll run a thread on the build. Having folk watching makes me up my game and I'm sure I'll get some help.

Many thanks, I think we got somewhere.

Photography like nothing else makes me giddy with interest and excitement and crashes me into pits of frustration and despair. I need to attenuate, get more zen. (Man). It's had me hooked for years and just gets more and more of a hold!!:)

TimberwolfII
22-Sep-2017, 23:34
I have revisited all the advice, especially the light leaks; I concluded that I could fight another 5x7 holder together or, seeing as I was near the end of the pack of film, go to 4x5.

I had one fidelity elite 4x5 holder so I've made an adapter to the Kodak rear stage.

Cheaper, less variables and hopefully no light leaks. Some Foma film landed yesterday so I'm good to go.

Also I can use my de vere enlarger direct too now with no adapters.

I'll work on nodda's calcs and assumptions and see if 4-6 stops without leaks and accurate processing time gets me anywhere.

That, and a mental shift of a bit less giddy with enthusiasm and excitement and a bit more calm and deliberate.☺️

Leigh
23-Sep-2017, 05:08
Given that this is a very old shutter, failures are to be expected.

One that would cause the observed symptoms is if the aperture closed fully during exposure, regardless of the aperture control setting. Such a failure could be caused by a broken part inside the shutter.

Have you observed the light through the shutter during an exposure (cells removed, obviously)?

- Leigh

TimberwolfII
23-Sep-2017, 12:49
Fair point, I'll bear it in mind.

I managed to squeeze some time together today to make two images. I took a meter reading and added four stops for one image and six for another, based on nodda's theorem. Both of the same subject - the bark, lichen and moss of the tree above.

I processed the neg of the f+4 normal, it looked good. So I took a risky punt and decided that the f+6 could be dense and did a semi stand development. Initial result kind of confirms.

I'll print them in due course and post for some feedback.

Suffice to say they are a massive step forward. It gives a datum to now work from.

One Very Happy Bunny. Thanks team!