orthochromatic film?

[h2oman]

I might be interested in using orthochromatic film for a particular sort of image, in 4x5. Any advice? Where to get it, developer to use, etc? I know nothing about it... I've only found some FPP xray film (Freestyle and B&H) and Ilford Ortho Plus (B&H).

[maltfalc]

https://www.largeformatphotography.info/forum/showthread.php?48099-Use-of-X-ray-film-technical-discussion-with-example-images

https://www.ebay.ca/itm/324489774359?epid=24033154017&hash=item4b8d190517:g:-tQAAOSwkRpZl1CF

[letchhausen]

What's wrong with the Ilford Ortho? I've shot that and developed in HC110. Rollei makes an ortho film that you can get at B&H. I'd use one of those before I'd mess around with X-Ray film.

[Eric Woodbury]

Ilford Ortho is very good. Lots of contrast to be had. Fine grain.

[Steve Goldstein]

And if you have a supply of Ortho film you can also use it for unsharp masks. It allows you to work under a dim red safelight, much easier (for me, at least) than doing it all by feel in total darkness.

[maltfalc]

What's wrong with the Ilford Ortho? I've shot that and developed in HC110. Rollei makes an ortho film that you can get at B&H. I'd use one of those before I'd mess around with X-Ray film.

ilford's 29 times more expensive than the fujifilm x-ray film i linked to.

[Michael R]

I might be interested in using orthochromatic film for a particular sort of image, in 4x5. Any advice? Where to get it, developer to use, etc? I know nothing about it... I've only found some FPP xray film (Freestyle and B&H) and Ilford Ortho Plus (B&H).

The Ilford film is excellent and easy to use.

[h2oman]

Pardon me if this is an ignorant question: Could a person get an effect similar to using ortho film by using a blue filter with panchromatic film?

[letchhausen]

ilford's 29 times more expensive than the fujifilm x-ray film i linked to.

You mean twice as much? Since the Ilford:

https://www.bhphotovideo.com/c/product/24605-REG/Ilford_1813157_Ortho_Plus_4x5_B_W.html

is $57 for 25 sheets and the Fuji:

https://www.freestylephoto.biz/11083-FPP-X-Ray-Film-4x5-25

is $25 for 25 sheets. The Rollie is more expensive at $84. If I was using ortho for a project as opposed to experimentation, I'd pay extra for Ilford.

[letchhausen]

Pardon me if this is an ignorant question: Could a person get an effect similar to using ortho film by using a blue filter with panchromatic film?

I think you'd have to use a cyan filter since that's the opposite of red. But there's probably someone here that's actually done it as opposed to my speculation.

[Mark Sampson]

The Wratten #44 is a "minus-red" filter. When used with pan film in daylight, it will give you a tonal rendition like an ortho film. A blue filter, like a #47, will give more extreme effects.

[maltfalc]

You mean twice as much? Since the Ilford:

https://www.bhphotovideo.com/c/product/24605-REG/Ilford_1813157_Ortho_Plus_4x5_B_W.html

is $57 for 25 sheets and the Fuji:

https://www.freestylephoto.biz/11083-FPP-X-Ray-Film-4x5-25

is $25 for 25 sheets. The Rollie is more expensive at $84. If I was using ortho for a project as opposed to experimentation, I'd pay extra for Ilford.

i have no idea what brand the fpp stuff actually is and would never recommend it to anyone. the FUJIFILM is $49 USD for 600 sheets once you cut it down to 4x5. one box saves you literally thousands of dollars compared to the ilford.

[Drew Wiley]

Helps to be specific, Steve. Ortho would be useless for masking color film. As far as sensitivity for other purposes, it's product specific, so you need to study the tech sheet. For example, Arista ortho litho is about 3 times more sensitive to blue than to green, but without red sensitivity. Classic Ortho sheet films for shooting purposes, a niche the current Ilford product allegedly fills, can be vaguely simulated using a medium-deep green filter over the lens; but that will block some blue too, along with red. It's hard to find good glass deep cyan filters; and it's a filter hue category that tends to fade. But since pan films themselves differ somewhat in specific spectral sensitivity, there can be no solid generic answer. Experiment.

[maltfalc]

Pardon me if this is an ignorant question: Could a person get an effect similar to using ortho film by using a blue filter with panchromatic film?a cyan dichroic filter would give the best result. https://www.bhphotovideo.com/c/search?Ntt=permacolor%20cyan&N=0&InitialSearch=yes&sts=ma

[Jim Noel]

pardon me if this is an ignorant question: Could a person get an effect similar to using ortho film by using a blue filter with panchromatic film?

no

[Jim Noel]

I have been using orthochromatic film since 1938.
Some of my answers to various questions here are:
1. It is naturally more contrasty than panchromatic film.
2. There is NO filter which will give you the same film sensitivity and color response as orthochromatic film ,or vice versa. There are many suggestions from workers with little or no experience with ortho film.
3. Ilford is probably the best ortho film available today for most people. The primary reason for this is that it is single sided and all current x-ray films that I can find are 2-sided. That is, there is an emulsion on both sides. I use probably 10 times as many sheets of x-ray as any other film because I am used to handling the delicate emulsion without scratching either side.
4. I normally use D-23 or Pyrocat HD developers because they give me the highest speed, and are not in themselves so active as to increase contrast. The produce beautiful mid-tone contrast. Such is not true of HC110, or other "modern" developers.
5. I grew up developing by inspection, and continue to prefer that method, although I no longer attempt to teach it because most people today are unable to learn to see the correct contrast. It takes lots of time and lots of practice. My estimate is development 100-150 sheets of ortho is necessary to get efficient.
6. There is no better emulsion for portraits of older men, images made in Utah of red cliffs, Autumn leaves, etc.
I could go on, but that is enough. I do not and will not argue with newcomers, those with under 75 years experience. BUT - if you consider what I have said, your appreciation of ortho film will improve.

[Drew Wiley]

Actually, the effect of a blue filter all depends of just how deep a blue is involved. Sometimes I carry an ordinary medium-light blue tungsten conversion filter, which still lets some red and green through, but not as much as ordinarily. On the other hand, a deep blue separation filter like a 47 or especially 47B will block not only all the red, but all the green too. So that gives a very different look than ortho film. But foliage itself is rather complex, because certain wavelengths are reflected which we might not ordinarily associate with natural "greens".

As far as controlling reddish Southwestern rock or clay goes, I prefer to use a medium green Hoya X1 filter for pan films. I'm not going to carry a completely different film for that purpose alone.

[h2oman]

You all can carry on, but I think I'm good at this point. If I try it, I'll use the Ilford ortho film and D-23, which is my current developer anyway. Thanks to everyone, and in particular to Jim.

[Roberto Nania]

I started using Rollei's Ortho 25 few time ago. At the moment I was able just to make few shots to test a suitable speed/developing time with HC110. The expiration date was at 2016, so not too old.
I'm currently using it at iso 16.

I have two reasons for choosing ortho film: higher contrast and shorter tonal range for the images I have in mind and the easier developing procedure in open tray allowed by working under red safety light.

Unfortunately, it is quite expensive, both Rollei and Ilford.

[Jim Fitzgerald]

I would go with what Jim said, after all 83 years of experience kind of counts a lot in my book.

[Doremus Scudder]

Pardon me if this is an ignorant question: Could a person get an effect similar to using ortho film by using a blue filter with panchromatic film?


The Wratten #44 is a "minus-red" filter. When used with pan film in daylight, it will give you a tonal rendition like an ortho film. A blue filter, like a #47, will give more extreme effects.


...
2. There is NO filter which will give you the same film sensitivity and color response as orthochromatic film ,or vice versa. There are many suggestions from workers with little or no experience with ortho film.
...

Let's be a bit more specific here.

Ortho film almost certainly has different characteristics than filtered panchromatic film, which make it unique. (I'm sure different ortho films have characteristics slightly different from one another too; it's just that these days, the choices are rather limited...)

That said, one can approximate the spectral sensitivity of orthochromatic film by using red-blocking filters with pan film. The end result, i.e., the exact spectral sensitivity, of the filtered pan film will, of course, depend on the exact filter used and the spectral sensitivity of the film used. Still, the effects obtained by using red-blocking filters on pan film can be gratifying and one doesn't have to carry extra film, just some filters.

And, let's differentiate between older blue-sensitive emulsions and orthochromatic emulsions. The former are the "original" photographic materials, the silver halides alone, which are only sensitive to blue light, not green or red. Later, emulsion formulators learned to add sensitizing dyes to the emulsion to make it sensitive to green as well as blue. These blue-green sensitive emulsions were named orthochromatic. Even later, when components were found to make film sensitive to blue, green and red, thus better approximating the visual spectrum, panchromatic emulsions became common.

So, filtering the red out of the light reaching a panchromatic emulsion gives a similar spectral response as orthochromatic film (Jim, note I'm saying "similar," not exact :) ). The classic minus red filters are the Wratten #44 and #44A, which were originally used in color separation work. Ansel Adams recommended those filters for approximating the effects of ortho film with panchromatic emulsions. Optical-quality cyan filters will block red and can be used for the same purpose as well. The effects will vary depending on exact spectral characteristics of the filter and film. And, I've had pretty good luck getting an ortho effect on pan film using the 80A and 80B color-conversion filters. They look blue, but pass quite a bit of green and a bit of red (they were originally intended to convert tungsten light into something better approximating daylight when using daylight-balanced films, especially transparency materials, with tungsten lighting, which is much redder).

Using a Wratten #47 filter or similar, that passes only blue light, will give an effect more similar to the old blue-sensitive emulsions, as they don't pass any green light. They are also a useful tool, but will not, strictly-speaking, give the "orthochromatic effect" that other filters that pass green as well as blue do.

An interesting read on the specific application of using filters to obtain an "ortho look" would be to find the thread over at Photrio started by Jarin Blaschke here: He was the cinematographer for the award-winning film "The Lighthouse" and had filters specially made for his cine film (Plus X?). He eventually had filters specially made to suit his needs.

Best,

Doremus

[Roberto Nania]

I have been using orthochromatic film since 1938.
Some of my answers to various questions here are:
1. It is naturally more contrasty than panchromatic film.
2. There is NO filter which will give you the same film sensitivity and color response as orthochromatic film ,or vice versa. There are many suggestions from workers with little or no experience with ortho film.
3. Ilford is probably the best ortho film available today for most people. The primary reason for this is that it is single sided and all current x-ray films that I can find are 2-sided. That is, there is an emulsion on both sides. I use probably 10 times as many sheets of x-ray as any other film because I am used to handling the delicate emulsion without scratching either side.
4. I normally use D-23 or Pyrocat HD developers because they give me the highest speed, and are not in themselves so active as to increase contrast. The produce beautiful mid-tone contrast. Such is not true of HC110, or other "modern" developers.
5. I grew up developing by inspection, and continue to prefer that method, although I no longer attempt to teach it because most people today are unable to learn to see the correct contrast. It takes lots of time and lots of practice. My estimate is development 100-150 sheets of ortho is necessary to get efficient.
6. There is no better emulsion for portraits of older men, images made in Utah of red cliffs, Autumn leaves, etc.
I could go on, but that is enough. I do not and will not argue with newcomers, those with under 75 years experience. BUT - if you consider what I have said, your appreciation of ortho film will improve.


I would go with what Jim said, after all 83 years of experience kind of counts a lot in my book.

Yes, I was thinking of made a test on D23. Thank you

[Drew Wiley]

It all depends on what you're priority is - development by inspection, or a certain kind of look in the scene? You need real ortho film for the former, but can skin the cat any number of ways in the latter instance. But why not experiment with real ortho while it happens to be around? It's not going to blow up like a 1950's chemistry set.

[Nodda Duma]

Doremus, I think what you’re missing, and perhaps what Jim has in mind, is that the response of classic Orthochromatic film continues down in to the ultraviolet. Modern panchromatic film has been designed to block ultraviolet to stabilize the speed of the film throughout a year’s variation in UV. A red filter will cut out the red, yes, but will not add the ultraviolet sensitivity of a classic ortho emulsion to a panchromatic film. Hence an insurmountable difference.

[Drew Wiley]

In the case of the current Ilford Ortho product, the sensitivity falls off rather quickly below 400nm, so I wouldn't personally consider it particularly UV responsive, just marginally so. And the light-scattering tendency of UV with respect to atmospheric haze would seem to lead to less sharp images in certain instances. But I suppose it depends on just how UV much gets through the lens elements to begin with.

I'd be curious just how far Fuji Acros can be tweaked into a general Ortho look, sensitometrically. It's orthopan, and already in effect more green responsive than pan films, due to being distinctly less red sensitive. And its sensitivity extends into the UV range. From a practical standpoint, it seems pretty easy to leverage the Ortho direction with very modest filtration tweaks. I have a lot of experience with it. But in sheet film version, sadly it is no more; so this becomes a hypothetical.

[h2oman]

It's funny how threads often outlast the attention span of the OP, but I'm still following!

Maybe I should be more specific about what I'm looking for. I'd like to get sort of a Watkins/O'Sullivan look when photographing high desert landscapes in mid-dayish light under clear skies. If I can get there using a filter with panchromatic film, that would be great - the simpler the better. I'll probably start by trying a filter and see if I can get the effect I'd like.

[maltfalc]

It's funny how threads often outlast the attention span of the OP, but I'm still following!

Maybe I should be more specific about what I'm looking for. I'd like to get sort of a Watkins/O'Sullivan look when photographing high desert landscapes in mid-dayish light under clear skies. If I can get there using a filter with panchromatic film, that would be great - the simpler the better. I'll probably start by trying a filter and see if I can get the effect I'd like. if you want "a Watkins/O'Sullivan look" then you don't want an ortho look, you want the look of plates that were mostly sensitive to blue and violet. with pan film a blue dichroic short pass filter is your best bet.

[Drew Wiley]

I already gave the clue : a medium light blue filter like an ordinary 82A or 82B will get you somewhat there, without going overboard or drastically lengthening exposure times. But a 47 deep blue will give more of the authentic blue-sensitive-only look of antique films; even greens will go very dark, and blue skies will end up essentially white. The even stronger 47B filter is essentially overkill, and will require even longer exposures. A filter factor of 6X or three stops of compensation is required for a 47 filter when using most pan films; 8X or four stops is characteristic of 47B. Sometimes all that extra exposure time is an advantage, like when using the lenscap exposure method with barrel lenses.

And yes, I've achieved the feel of mid-day glare and sheer overwhelming light in the desert in this manner. And if blacks can be blocked out for optional graphic effect, so can whites, as a kind of reverse silhouette, something O'Sullivan was a master at.

[Doremus Scudder]

if you want "a Watkins/O'Sullivan look" then you don't want an ortho look, you want the look of plates that were mostly sensitive to blue and violet. with pan film a blue dichroic short pass filter is your best bet.

+1

You'll be needing to approximate a blue-sensitive emulsion. Try a Wratten #47 to start. You may have to use a gel filter; glass may be harder to find. Possibly Tiffen still offers them in glass.

I'm not sure where you can get the dichroic filters maltfalc is referring to. Maybe "dichroic" in this sense refers to blocking two of the primary colors, passing only one (blue in this case). Maltfalc, can you elaborate?

But, the one need not exclude the other. Take out your trusty camera and filters and make shots with a #47, a #44, an 80A and whatever else you want to experiment with and see what gives you the results you want.

@Nodda Duma

Yeah, I'm aware that using filters on panchromatic film is just an approximation. Still, I've had results I like using filters, even though they may be (markedly) different than real ortho film. Still, I wonder how much UV gets through modern lenses anyway...

I have been getting more interested in the ortho rendering of tones lately; maybe I'll have to order some Ilford Ortho and do some work with it.

Best,

Doremus

[Drew Wiley]

I think dichroic is a totally wrong designation in this case. Glass filters of this type are either tinted glass, with or without supplemental coatings relative to reflection control, or sandwich-style, with the filter material between sheets of glass, the Tiffen method. 47's are still easy to get, although I strangely notice that the current Tiffen version is weaker than the older ones. I still have the older 47B's too, so haven't searched for any of those lately. I sometimes use the denser 47B version for actual color separation work; but viewing through the groundglass to evaluate the effect is difficult with a filter that dense, so the slight weaker, but one full stop brighter, 47 makes more sense in the field for black and white shooting applications.

[abruzzi]

Not remotely my area of expertise, but there was a discussion on Photrio where a cinematographer was trying to get an "ortho look" out of Kodak Double X film. He ended up using a short pass filter--SP570, IIRC. If you want to see the results the film came out a couple of years ago called "The Lighthouse".

[maltfalc]

+1

You'll be needing to approximate a blue-sensitive emulsion. Try a Wratten #47 to start. You may have to use a gel filter; glass may be harder to find. Possibly Tiffen still offers them in glass.

I'm not sure where you can get the dichroic filters maltfalc is referring to. Maybe "dichroic" in this sense refers to blocking two of the primary colors, passing only one (blue in this case). Maltfalc, can you elaborate?

But, the one need not exclude the other. Take out your trusty camera and filters and make shots with a #47, a #44, an 80A and whatever else you want to experiment with and see what gives you the results you want.

@Nodda Duma

Yeah, I'm aware that using filters on panchromatic film is just an approximation. Still, I've had results I like using filters, even though they may be (markedly) different than real ortho film. Still, I wonder how much UV gets through modern lenses anyway...

I have been getting more interested in the ortho rendering of tones lately; maybe I'll have to order some Ilford Ortho and do some work with it.

Best,

Doremus


I think dichroic is a totally wrong designation in this case. Glass filters of this type are either tinted glass, with or without supplemental coatings relative to reflection control, or sandwich-style, with the filter material between sheets of glass, the Tiffen method. 47's are still easy to get, although I strangely notice that the current Tiffen version is weaker than the older ones. I still have the older 47B's too, so haven't searched for any of those lately. I sometimes use the denser 47B version for actual color separation work; but viewing through the groundglass to evaluate the effect is difficult with a filter that dense, so the slight weaker, but one full stop brighter, 47 makes more sense in the field for black and white shooting applications.

dichroic filters are essentially mirrors that are transparent to some colours but reflect others with nearly 100% efficiency, which is why they're used in colour enlargers, dlp projection tvs, rgb lasers, three-ccd video cameras, hot mirrors for digital cameras, etc.. you can get them at b&h and a bunch of other places. a short pass dichroic filter reflects all light above a certain wavelength, so a blue short pass dichroic filter will cleanly chop off anything pre-ortho film or plates weren't sensitive to while giving you near 100% transmission of blue, violet and whatever uv can penetrate the glass. standard filters won't let through nearly as much of the light you want or block all of the light you don't want.

215383

215384

[Tin Can]

Gonna watch that again


Not remotely my area of expertise, but there was a discussion on Photrio where a cinematographer was trying to get an "ortho look" out of Kodak Double X film. He ended up using a short pass filter--SP570, IIRC. If you want to see the results the film came out a couple of years ago called "The Lighthouse".

[Nodda Duma]

if you want "a Watkins/O'Sullivan look" then you don't want an ortho look, you want the look of plates that were mostly sensitive to blue and violet. with pan film a blue dichroic short pass filter is your best bet.

Of course, if you want the look of plates, then you can just shoot plates.

[Michael R]

You blew my mind a little, Doremus. I either forgot, or never knew specifically what movie Jarin was preparing for, and when I saw The Lighthouse I didn’t pay enough attention during the credits (actually I was pretty disappointed with the movie) so I never made this connection. I remember exchanging a lot of PMs with him at that time because I think he was trying to figure something out with pyro.

Wow.


Let's be a bit more specific here.

Ortho film almost certainly has different characteristics than filtered panchromatic film, which make it unique. (I'm sure different ortho films have characteristics slightly different from one another too; it's just that these days, the choices are rather limited...)

That said, one can approximate the spectral sensitivity of orthochromatic film by using red-blocking filters with pan film. The end result, i.e., the exact spectral sensitivity, of the filtered pan film will, of course, depend on the exact filter used and the spectral sensitivity of the film used. Still, the effects obtained by using red-blocking filters on pan film can be gratifying and one doesn't have to carry extra film, just some filters.

And, let's differentiate between older blue-sensitive emulsions and orthochromatic emulsions. The former are the "original" photographic materials, the silver halides alone, which are only sensitive to blue light, not green or red. Later, emulsion formulators learned to add sensitizing dyes to the emulsion to make it sensitive to green as well as blue. These blue-green sensitive emulsions were named orthochromatic. Even later, when components were found to make film sensitive to blue, green and red, thus better approximating the visual spectrum, panchromatic emulsions became common.

So, filtering the red out of the light reaching a panchromatic emulsion gives a similar spectral response as orthochromatic film (Jim, note I'm saying "similar," not exact :) ). The classic minus red filters are the Wratten #44 and #44A, which were originally used in color separation work. Ansel Adams recommended those filters for approximating the effects of ortho film with panchromatic emulsions. Optical-quality cyan filters will block red and can be used for the same purpose as well. The effects will vary depending on exact spectral characteristics of the filter and film. And, I've had pretty good luck getting an ortho effect on pan film using the 80A and 80B color-conversion filters. They look blue, but pass quite a bit of green and a bit of red (they were originally intended to convert tungsten light into something better approximating daylight when using daylight-balanced films, especially transparency materials, with tungsten lighting, which is much redder).

Using a Wratten #47 filter or similar, that passes only blue light, will give an effect more similar to the old blue-sensitive emulsions, as they don't pass any green light. They are also a useful tool, but will not, strictly-speaking, give the "orthochromatic effect" that other filters that pass green as well as blue do.

An interesting read on the specific application of using filters to obtain an "ortho look" would be to find the thread over at Photrio started by Jarin Blaschke here: He was the cinematographer for the award-winning film "The Lighthouse" and had filters specially made for his cine film (Plus X?). He eventually had filters specially made to suit his needs.

Best,

Doremus

[maltfalc]

Of course, if you want the look of plates, then you can just shoot plates.

well yeah. i was just answering his question specifically about filtering pan film. blue sensitive x-ray film would also be a dirt cheap and easy option that can be developed under most safelights.

[Drew Wiley]

maltfalc - I'm very familiar with dichroic coatings. The biggest manufacturer of these in the world was once nearby, and their former catalog would stun you. No, you don't get them at places like B&H, unless its just a mild or "colorless" UV filter (I'm wearing coated "computer glasses" right now). Nor are these kinds of coatings used for ordinary taking contrast filters. Vacuum deposition techniques apply to both categories, but for different reasons. With camera filters, it's mainly to fine-tune only tiny transmission characteristics and control reflections, just like multicoatings on modern lenses. The kind used in enlarger colorheads are incidence-angle specific in terms of transmission/reflection characteristics, so would not be dependable in an ordinary photographic application where a lens accepts light from a range of angles. I built what is probably the only privately-owned true simultaneous additive halogen enlarger in the world using dichroic "sandwich" trimmer filters, which cut off the bandwidth on both sides of the desired RGB peaks. But I'm no optical engineer. I merely consulted with them.

There is a real engineer responding to this thread, if he wishes to describe the distinctions more precisely than I can, or correct me as per my own definition of "dichroic". But as I already noted, contrast filters for black and white photography, which are the kernel of this aspect of the discussion, are primarily made of either dyed-in-mass glass, or via the colored thermo-foil sandwich method that Tiffen uses. Any optical coatings are secondary. As far as laser applications go, I once sold certain industrial lasers, which doesn't make me an expert in that field either, but knowledgable enough to understand a number of basis issues.

[PRJ]

About a year or so ago i picked up some Ortho film from Photowarehouse on a whim and it was pretty dang cheap. Just an FYI. Still haven't used any of it yet.

I just checked and they still have it. 100 sheets of 4x5 is only $29.

[h2oman]

Of course, if you want the look of plates, then you can just shoot plates.

I was just waiting for someone to suggest this! :cool:

[Drew Wiley]

I dropped enough plates already this week. (One is too many, especially in the kitchen.)

[maltfalc]

maltfalc - I'm very familiar with dichroic coatings. The biggest manufacturer of these in the world was once nearby, and their former catalog would stun you. No, you don't get them at places like B&H, unless its just a mild or "colorless" UV filter (I'm wearing coated "computer glasses" right now). Nor are these kinds of coatings used for ordinary taking contrast filters. Vacuum deposition techniques apply to both categories, but for different reasons. With camera filters, it's mainly to fine-tune only tiny transmission characteristics and control reflections, just like multicoatings on modern lenses. The kind used in enlarger colorheads are incidence-angle specific in terms of transmission/reflection characteristics, so would not be dependable in an ordinary photographic application where a lens accepts light from a range of angles. I built what is probably the only privately-owned true simultaneous additive halogen enlarger in the world using dichroic "sandwich" trimmer filters, which cut off the bandwidth on both sides of the desired RGB peaks. But I'm no optical engineer. I merely consulted with them.

There is a real engineer responding to this thread, if he wishes to describe the distinctions more precisely than I can, or correct me as per my own definition of "dichroic". But as I already noted, contrast filters for black and white photography, which are the kernel of this aspect of the discussion, are primarily made of either dyed-in-mass glass, or via the colored thermo-foil sandwich method that Tiffen uses. Any optical coatings are secondary. As far as laser applications go, I once sold certain industrial lasers, which doesn't make me an expert in that field either, but knowledgable enough to understand a number of basis issues.

i'm seeing lots of talking yourself up and going off on condescending tangents without refuting anything i actually said. "No, you don't get them at places like B&H" https://www.bhphotovideo.com/c/product/614956-REG/Rosco_120310807000_Permacolor_3180_Primary_Blue.html/specs "Nor are these kinds of coatings used for ordinary taking contrast filters." never said they were, but they are used for separating colours in various cameras. "The kind used in enlarger colorheads are incidence-angle specific in terms of transmission/reflection characteristics, so would not be dependable in an ordinary photographic application where a lens accepts light from a range of angles." have you tried it? yes, the cutoff point shifts as you get further from the center of the image, but you need a pretty wide lens for the shift to even be noticeable on the ground glass, and since it's just shifting to a deeper blue, the only significant effect in the final black and white image is going to be a little extra vignetting. if you really want to be picky, there are options other than rigid, flat filters.

[Nodda Duma]

TBH if I wanted to accurately replicate ortho look with panchromatic film, I wouldn’t limit myself to photo filters. I would look somewhere like Edmund Optics or Thorlabs which has a wider selection, and I don’t really care by what process the filter does its job. Dichroic filters have sharp cutoffs, but that doesn’t replicate the spectral roll off of ortho sensitizing dyes well. Blaschke ended up going to just such a supplier for his Lighthouse filter. I forget which but do recall the choice made perfect sense.

For that level of OCD, however, you also need to know exactly what spectral response the various orthochromatic and panchromatic sensitizing dyes provide. “Orthochromatic” is of course not an industry standard anymore than “Panchromatic” is. In any case, at some point you realize this is just an academic question, as cheap ortho film is readily available.

[maltfalc]

Dichroic filters have sharp cutoffs, but that doesn’t replicate the spectral roll off of ortho sensitizing dyes well. the actual change in brightness of say green to yellow leaves would still have a gradual taper to it because the colour of the leaves includes a wide range of frequencies. not as gradual as with actual ortho film, but not anything you'd notice in a photo. you could also get a more gradual cutoff by mounting the filter behind the lens, ideally in combination with a wider aperture.

[Drew Wiley]

maltfac - you simply do not seem to understand how dichroic filters work. That's quite apparent. So you might want to do a little serious homework before arguing either with me or someone with an actual optical engineering background. As far a B&H goes, they have any number of links to exotic odds n ends some of their regular suppliers might catalog list; but that does not mean they stock these things themselves, or that their own link, in this case, to Rosco, even made it themselves. Camera stores are not where one looks for that category of item, or for application information. And if you missed what I stated, I outright built a big SIMULTANEOUS additive enlarger, you'd understand why colored sheets of any type in a filter drawer would not convert an enlarger head into that purpose. That would hypothetically work for SEQUENTIAL additive printing, but so would a basic set of decent 29, 61, and 47B glass filters right over the lens. And even if I hypothetically wanted something dichroic for a filter drawer, I wouldn't pay hundreds of bucks apiece from a tertiary supplier either, but just make a phone call directly to the manufacturer five minutes away and ask what random scraps they have, and what they'd charge to trim it down to requested size. It was many years ago that I did just that, in early stages of my own project experimentation, and it was only about five bucks apiece - they had barrels of random dichroic scrap glass laying around! But anything like that would be worthless over a camera lens for taking pictures.

[Michael R]

Hi Jason, slightly off topic but since you brought up EO and Thorlabs, do you know if their products are generally of equal quality? I might need a BBAR-coated optical window so I’ve been looking around. Some years ago I was able to buy some custom glass like this from Schneider Optics (the U.S. arm) but I think it is more complicated to do that now (if still possible) and both EO and Thorlabs are likely less expensive. I’m looking at a few other places as well but figured I’d ask.


TBH if I wanted to accurately replicate ortho look with panchromatic film, I wouldn’t limit myself to photo filters. I would look somewhere like Edmund Optics or Thorlabs which has a wider selection, and I don’t really care by what process the filter does its job. Dichroic filters have sharp cutoffs, but that doesn’t replicate the spectral roll off of ortho sensitizing dyes well. Blaschke ended up going to just such a supplier for his Lighthouse filter. I forget which but do recall the choice made perfect sense.

For that level of OCD, however, you also need to know exactly what spectral response the various orthochromatic and panchromatic sensitizing dyes provide. “Orthochromatic” is of course not an industry standard anymore than “Panchromatic” is. In any case, at some point you realize this is just an academic question, as cheap ortho film is readily available.

[Drew Wiley]

Michael, it's often difficult to tell just when Edmund makes something themselves, and when they order it from someone else. They can be pricey for individual quantities, but send me each issue of their Scientific/Industrial catalog, which I always fun to peruse. I don't know what happened to the coatings division of OCLI when that split apart. My boss at that time lived near them, invested in their stock, and within three years cashed in and made enough profit to pay all of his son's ongoing college tuition. But only about six weeks later, OCLI announced their invention of vac deposition transoxide pigments, which soon became far more profitable than their optical products themselves; and my boss would have probably made millions if he had stuck with them a little longer. Now there are alternate paths for making transoxides. But back then I was early into the game, as a distributor, of vac deposition of clear titanium coatings for metal protective purposes. Being in a marine climate, we were selling tremendous amounts of door and marine hardware subject to discoloring. Some people like the naturally oxidized brass or bronze look, but other's like keeping their brass shiny. Another significant re-adaptation of lens coating technology!

[maltfalc]

maltfac - you simply do not seem to understand how dichroic filters work. That's quite apparent. So you might want to do a little serious homework before arguing either with me or someone with an actual optical engineering background. As far a B&H goes, they have any number of links to exotic odds n ends some of their regular suppliers might catalog list; but that does not mean they stock these things themselves, or that their own link, in this case, to Rosco, even made it themselves. Camera stores are not where one looks for that category of item, or for application information. And if you missed what I stated, I outright built a big SIMULTANEOUS additive enlarger, you'd understand why colored sheets of any type in a filter drawer would not convert an enlarger head into that purpose. That would hypothetically work for SEQUENTIAL additive printing, but so would a basic set of decent 29, 61, and 47B glass filters right over the lens. And even if I hypothetically wanted something dichroic for a filter drawer, I wouldn't pay hundreds of bucks apiece from a tertiary supplier either, but just make a phone call directly to the manufacturer five minutes away and ask what random scraps they have, and what they'd charge to trim it down to requested size. It was many years ago that I did just that, in early stages of my own project experimentation, and it was only about five bucks apiece - they had barrels of random dichroic scrap glass laying around! But anything like that would be worthless over a camera lens for taking pictures.

i know exactly how dichroic filters work. i've clearly explained how in great detail in this thread. you said you can't buy them from b&h, you can, you're wrong, get over it. i don't know why you obsessed over b&h in the first place since i mentioned there are a ton of places to get dichroic filters. b&h was just one example. "And if you missed what I stated, I outright built a big SIMULTANEOUS additive enlarger, you'd understand why colored sheets of any type in a filter drawer would not convert an enlarger head into that purpose. That would hypothetically work for SEQUENTIAL additive printing, but so would a basic set of decent 29, 61, and 47B glass filters right over the lens. " what the hell are you talking about? i never claimed anything like that. i said dichroic filters are used in colour enlargers. they are, i'm sitting 6 feet from a dichro colorhead right now. "anything like that would be worthless over a camera lens for taking pictures" i asked you if you'd tried using dichro filters on a camera. you're dodging the question just like you've dodged or strawmanned everything else i've said, so i assume you haven't. my claims about how a dichroic filter will act in the specific use being discussed in this thread are based on first-hand real world experience. you are completely full of it, incapable of having an honest discussion and not worth wasting another second on. put me on ignore and don't ever speak to me again.

[Drew Wiley]

Indeed. Welcome to my ignore list, temporarily at least. A waste of time. Assume and accuse whatever you wish. It doesn't in the least affect what I already know, and have already done.

[maltfalc]

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[Nodda Duma]

Hi Jason, slightly off topic but since you brought up EO and Thorlabs, do you know if their products are generally of equal quality? I might need a BBAR-coated optical window so I’ve been looking around. Some years ago I was able to buy some custom glass like this from Schneider Optics (the U.S. arm) but I think it is more complicated to do that now (if still possible) and both EO and Thorlabs are likely less expensive. I’m looking at a few other places as well but figured I’d ask.

I would use them professionally without question, if they had what I needed. They often don’t (as you may guess), so other sources of a wider variety of stock and custom windows/filters are Rainbow Research Optics, Omega Optical, Semrock. I have used them all.

There are others, but more expensive and specialized. Coincidentally was just talking to a supplier about feasibility of a very challenging filter which will likely cost — no joke — $30k+ for a 7/8” diameter filter. Hoping I don’t need it but I probably will.

As a fun side note, when it comes to technically challenging filters, I talk to certain suppliers not because of the company, but because of the individual coating designer who works there. Coating design isn’t something everyone can do. The companies I mention all have good coating designers, and BBAR vis coatings are almost trivial anyways.

-Jason

[Michael R]

Thanks Jason!


I would use them professionally without question, if they had what I needed. They often don’t (as you may guess), so other sources of a wider variety of stock and custom windows/filters are Rainbow Research Optics, Omega Optical, Semrock. I have used them all.

There are others, but more expensive and specialized. Coincidentally was just talking to a supplier about feasibility of a very challenging filter which will likely cost — no joke — $30k+ for a 7/8” diameter filter. Hoping I don’t need it but I probably will.

As a fun side note, when it comes to technically challenging filters, I talk to certain suppliers not because of the company, but because of the individual coating designer who works there. Coating design isn’t something everyone can do. The companies I mention all have good coating designers, and BBAR vis coatings are almost trivial anyways.

-Jason