Choices for IR film?

[Athiril]

Are you sure that the 645N's meter is within its sensitivity range when you stich an R72 filter on the front of the lens?
That filter is substantially opaque to a lot of visible light.

Most electronics are sensitive to IR like silver halide is sensitive to UV/blue intrinsically. Often the peak of their sensitivity is in IR. Youd have to know the particular detector being used in your camera.

CdS LDR

Photodiode
https://www.ti.com/lit/ds/symlink/opt101.pdf?HQS=TI-null-null-alldatasheets-df-pf-SEP-wwe

 

[MattKing]

Most hand meters have little or no IR sensitivity. Are in camera meters different?

 

[Athiril]

Most hand meters have little or no IR sensitivity. Are in camera meters different?

Youd have to take your meter and put an R72 in front of the meter and check how many stops it drops by in metering the scene. CdS are common for meters, and silicon photodiodes also common and are the second type with more sensitivity in IR than anywhere else, that type may employ an IR-cut filter over the sensor, like digital cameras do

 

[pentaxuser]

I wonder how we find out what the P65N or even I suspect the older P645 in-camera meter is in terms of the graphs. Do the graphs indicate that any of the three sets of spectral sensitivities will do the job of giving the four stops required for extended red sensitivity films?

You would also think that such in-camera meters would not be confined to Pentax and thus you'd expect other camera users to report that R72 give them the right the exposure as well. Maybe they just have bothered to report this. The problem is that we get almost no threads which report good news in an exchange of information. By this I mean most users who find that that there is no problem with their in-camera meters for IR photography are unlikely to share this information. We tend to be a "problem" forum only and any exchange of information stems for a problem not a desire to exchange information for its own sake

Anyway there are probably too few of us here on Photrio who have P645n or P645s and a R72 filter to test and report on this but it would certainly be helpful if those who can report do so

Unfortunately as I reported i do not have a R72 to test.

pentaxuser

 

[Helge]

I bought some expired Konica IR from someone on this forum, really great film. This is with a red filter.
Bishop Hall by Bryan Chernick, on Flickr

Kinkaku-ji by Bryan Chernick, on Flickr

How did you get such a strong effect with just a normal filter?
In my experience the difference between regular film and IR with a standard 25A red filter is negligible.
Did you use a polarizer on top?

 

[pentaxuser]

Looking at Laurie White Hayball's book on IR photography the spectral response of Konica 750 would appear to extend further than Ilford SFX So for instance and in a comparison of pictures, Konica with an orange filter already appears to exhibit the start of the "wood effect on tree foliage With a red filter this extends into the grass area but the sky still hasn't gone as dark as in the same picture with an IR filter. In the pictures in the book hardly any of the Konica skies are as dark as in BAC1967 even with an IR filter but this may be accounted for by reproduction in a book and presumably where in terms of clear air and at what height the picture including the sky was taken. I have seen some pics in high clear mountainous area with an non IR film and a mid yellow that in the U.K. at near sea level I would have had difficulty matching it with a red and polariser combined.

pentaxuser

 

[Wallendo]

Konica's IR spectral response is as per this document: http://photo-element.ru/book/pseudo_ir/ir_films/KONICA_inf_750.pdf
As a "true" IR film, it shows the basic silver halide reponse to blue light and then is sensitized to IR radiation. There is essentially no response between 500 and 650 nm so there is no need to filter out light in that range. Konica recommended only a red or orange filter. Its peak response is at 750nm. A R72 filter should enhance the Wood effect, but shouldn't really effect the sky much.

 

[Athiril]

I wonder how we find out what the P65N or even I suspect the older P645 in-camera meter is in terms of the graphs. Do the graphs indicate that any of the three sets of spectral sensitivities will do the job of giving the four stops required for extended red sensitivity films?

You would also think that such in-camera meters would not be confined to Pentax and thus you'd expect other camera users to report that R72 give them the right the exposure as well. Maybe they just have bothered to report this. The problem is that we get almost no threads which report good news in an exchange of information. By this I mean most users who find that that there is no problem with their in-camera meters for IR photography are unlikely to share this information. We tend to be a "problem" forum only and any exchange of information stems for a problem not a desire to exchange information for its own sake

Anyway there are probably too few of us here on Photrio who have P645n or P645s and a R72 filter to test and report on this but it would certainly be helpful if those who can report do so

Unfortunately as I reported i do not have a R72 to test.

pentaxuser

I think CdS is likely to be the most common photo resistor used. A lot of Sekonics use a silicon photodiode though. It depends on the maker, they might filter it, or buy parts that have a spectral response suppressed for the visisble spectrum.

I can only imagine the more IR sensitive the detector is, the more it would need an IR-cut filter in front of it in order to get accurate visible spectrum metering. I attached an example from a cheap action camera, which I removed the lens and put another lens on (the IR cut filter in these cameras is usually on the back of the lens, not on the sensor, the new lens didnt have one), without a filter to cut IR you get a lot of IR mixed with visisle spectrum. After that I made a lens adapter both with and without an IR cut filter.



The IR cut filters can be very strong too, in this case I am getting a lot of IR at exposure thats maybe like 1 stop faster than normal. On my old 30D I was able to capture IR with the cut filter in place, in the middle of the day at ISO 1600 for a 30 second exposure if I recall correctly by using IR filtration (I used 2 pieces of black developed slide film at the time). On my A7s with a 680nm filter I just get red without IR.

 

[Klaus_H]

For R80S with RG715 or R72 filter I use 1/1° ISO.
I develop in ATOMAL 49 by ADOX.
This combination allows even details in the shadow, which are not a strength of R80.

 

[pentaxuser]

Athiril so if most camera makers of say relatively modern build cameras such as the P645N use CDS will these meters actually meter correctly for near IR film? Assuming that is the case then you'd expect a range of cameras such as Canon and Nikon to do an equally good job of metering for near IR film. This being the case then isn't it likely that if these meters are OK for near IR then is it likely that the same makers would not want to sacrifice the metering abilities for non IR films and non IR filters so it sounds as if each maker would fit an IR cut filter as well

So we are no nearer working out why the P645N is so accurate at metering near IR films, are we, unless there is something deliberately built in to P645N meters that other cameras do not have ?

pentaxuser

 

[Helge]

Wow! Can we have something like this back?

You really don’t need anything but a 25 or 29 filter.
It even says so in the data sheet.

Of course a real IR filter will “improve” things (depends on what you’re after) but only slightly.

You could shoot this handheld no problem.

 

[Athiril]

Athiril so if most camera makers of say relatively modern build cameras such as the P645N use CDS will these meters actually meter correctly for near IR film? Assuming that is the case then you'd expect a range of cameras such as Canon and Nikon to do an equally good job of metering for near IR film. This being the case then isn't it likely that if these meters are OK for near IR then is it likely that the same makers would not want to sacrifice the metering abilities for non IR films and non IR filters so it sounds as if each maker would fit an IR cut filter as well

So we are no nearer working out why the P645N is so accurate at metering near IR films, are we, unless there is something deliberately built in to P645N meters that other cameras do not have ?

pentaxuser

I think photodiodes are more likely to be used in modern SLRs than a light dependent resistor.

 

[Sirius Glass]

I measured all my filters through light meters and the denser ones seem to be off. Therefore for IR I meter with the filter off, use the manufacturers rating to adjust the lens. I have never had a miss even with IR film. But hey I have had only sixty years of experience doing this.

 

[reddesert]

Athiril so if most camera makers of say relatively modern build cameras such as the P645N use CDS will these meters actually meter correctly for near IR film? Assuming that is the case then you'd expect a range of cameras such as Canon and Nikon to do an equally good job of metering for near IR film. This being the case then isn't it likely that if these meters are OK for near IR then is it likely that the same makers would not want to sacrifice the metering abilities for non IR films and non IR filters so it sounds as if each maker would fit an IR cut filter as well

So we are no nearer working out why the P645N is so accurate at metering near IR films, are we, unless there is something deliberately built in to P645N meters that other cameras do not have ?

You can't tell how any given camera or handheld meter is going to meter with a red or IR filter unless you know both the spectral sensitivity of the sensor and what filtration the manufacturer put in front of the sensor. Both of these vary and there is no way to know them. Even knowing whether the sensor is CdS or silicon photodiode doesn't help, and there are lots of different silicon photodiodes with different sensitivities, plus the filtration; the meter makers add filtration so that normal metering isn't thrown off by excess IR light.

You just have to measure it. Or you can meter without the filter and apply a filter factor (eg 3 stops for a red 25 and normal B&W film often works, but IR film is different).

 

[BAC1967]

How did you get such a strong effect with just a normal filter?
In my experience the difference between regular film and IR with a standard 25A red filter is negligible.
Did you use a polarizer on top?

Just the red filter. The camera was a Ricoh Diacord L.

 

[Helge]

What we lack in this thread is a clear concise list of all of the IR films currently available and the characteristics, pros and cons.
Let me try a first wee step.

SFX 200

Rollei Superpan 200 (not sure if this is the current curve. This is for the Aviphot Pan 200 which Superpan 200 was derived from).

Rollei Infrared 400

Rollei Retro S400

Rollei Retro S80

Is this all of the NIR/IR films currently fresh and on sale?

What are filter options?
Real IR filters are expensive and one trick ponies, even old Wratten gels.
But they might be the only sensible thing in the end?

25 and 29 filters seems to be used often with pretty good results. Perhaps with a polarizer for the sky outside noon sun hours.
Any thoughts on this (yes it’s been done to death elsewhere, but I’d like to hear it again and with new data)?

What are the options for DIY?
Both WRT lens and flash filters.
You hear a lot about Congo Blue gels combined with red filters as a good DIY option, when you dig a bit into the matter.

 

[Athiril]

What are filter options?
Real IR filters are expensive and one trick ponies, even old Wratten gels.
But they might be the only sensible thing in the end?



What are the options for DIY?

Zomei IR filters are inexpensive, I have a 680nm one.

You can use 2 layers of developed unexposed slide film. Thats why I used when I had a 12-24mm lens that took rear gel slot filters.

 

[Anon Ymous]

What we lack in this thread is a clear concise list of all of the IR films currently available and the characteristics, pros and cons.
Let me try a first wee step.

SFX 200
View attachment 256180

Rollei Infrared 400
View attachment 256181

Rollei Retro S400
View attachment 256182

Rollei Retro S80
View attachment 256183

Is this all of the NIR/IR films currently fresh and on sale?

You forgot Rollei Superpan 200. But keep in mind that Agfa doesn't produce Avophot Pan 400 for some time now and Rollei IR, 400S and Superpan 200 are likely the same film. The only difference is who does the conversion.[/QUOTE]

 

[pentaxuser]

It would look as if we may never get to the bottom of why the P45N in-camera meter works correctly for at least Rollei 80S but I assume this might be the case for all near IR films on which an IR filter has been used. I found that for ordinary yellow, yellow-green, orange and red 25 filters my 35mm Pentax in-camera meter gives the same readings as my P645N as they are probably of a similar vintage so hopefully with near IR film and an IR filter I have two cameras where I can leave it to the in-camera meter to do the job

Any else with Nikon, Canon etc know how their cameras behave with IR filter and near IR films such as Rollei or SFX?

Thanks

pentaxuser

 

[MattKing]

It would look as if we may never get to the bottom of why the P45N in-camera meter works correctly for at least Rollei 80S but I assume this might be the case for all near IR films on which an IR filter has been used.

All we know is that in a particular set of circumstances the meter reading from that camera did the job.
My experience indicates that meter readings only provide some useful evidence, because they never match exactly how the film sees the mixture of visible and IR light.
I've always had to apply some judgment on top of the reading.
All of that experience is with the near IR films. I never used HIE.

 

[Pentode]

View attachment 256129
Wow! Can we have something like this back?

You really don’t need anything but a 25 or 29 filter.
It even says so in the data sheet.

Of course a real IR filter will “improve” things (depends on what you’re after) but only slightly.

You could shoot this handheld no problem.

Back when I used this stuff (mid 1990s) I didn't yet own a real IR filter and I got very nice results with a regular old R25, and, yes, I shot handheld. I suspect an R72 would have been better, though, and that probably would have required a tripod.
If I remember correctly HIE also has a distinct drop in green sensitivity but I get much better HIE results with a real IR filter than I do with an R25.

....But hey I have had only sixty years of experience doing this.

Well, you might get the hang of it eventually....

 

[Helge]

You forgot Rollei Superpan 200. But keep in mind that Agfa doesn't produce Avophot Pan 400 for some time now and Rollei IR, 400S and Superpan 200 are likely the same film. The only difference is who does the conversion.

Fixed.
Not sure about the datasheet since it appears the A/G stock it was derived from (Aviphot Pan 200) is not produced anymore.

I understand that Superpan 200 is especially good with the Scala reversal process, because of it’s clear base.

Is that something that’s true for the other “Rollei” films?

 

[markjwyatt]

Here are a few from 1978-1980, Kodak HIE. Was really fun stuff. (Zeiss Icarex 35S TM Pro; CZ 50mm f1.8 Ultron)


curve by Mark Wyatt, on Flickr


mystical man by Mark Wyatt, on Flickr

Mariah by Mark Wyatt, on Flickr

Seeing the conversation develop here (no pun intended, or was it?), thought I would add that these images were shot with a Zeiss R filter (basically 25A). If I recall, I just guess exposed treating HIE as around 100 ASA.

 

[Helge]

Zomei IR filters are inexpensive, I have a 680nm one.

You can use 2 layers of developed unexposed slide film. Thats why I used when I had a 12-24mm lens that took rear gel slot filters.

There appears to be some good eBay package deals with a stack for the same price as one IR.

Here’s some interesting reviews/writing on the Zomei filters:

https://www.davidkennardphotography.com/blog/990-zomei-ir-filters-review-comparison.xhtml

https://www.photoartfromscience.com...ared-filter-comparisons-hoya-bci-neewer-zomei

I’m thinking I might as well go with a vintage Cokin and not have to bother with screwing in and out and separate stepdown rings.

Might really be better in some ways, because you can compose and click the filter into place with a free hand and take the photo.
Anyone know of hinged filter holders for regular screw-in filters?
Edit: https://petapixel.com/2019/05/29/alter-rfs-a-hinged-lens-filter-adapter-that-swings-out-of-the-way/
Other similar solutions?

Using colour film for filter doesn’t seem like a good idea.
Film was never made for its transmissive abilities. I haven’t heard of using colourfilm as anything but a quick and dirty/toy IR filter.
Even for IR flash filters you might be able to do better with a stack of the aforementioned Congo Blue filters.

680 is barely more effective as an IR filter than a 29 filter.
It’s doesn’t appear to work too well at least with SFX.
https://tweecatphotography.com/ilford-sfx-filtration-test/

 

[Anon Ymous]

Fixed.
Not sure about the datasheet since it appears the A/G stock it was derived from (Aviphot Pan 200) is not produced anymore.

I understand that Superpan 200 is especially good with the Scala reversal process, because of it’s clear base.

Is that something that’s true for the other “Rollei” films?

Aviphot Pan 200 seems to be a current product according to Agfa's website. Over the years, Rollei's repurposed films from Agfa's stocks may have changed. Aviphot Pan 400 might have been used in the past, but it's no longer available, so Rollei IR could have been the 400 variant, whereas today it's converted from the 200. Generally speaking, Maco aren't very upfront about the source of their films, but nevertheless, I'm glad that they make the effort to make some interesting aerial films available to us. And yes, all repurposed Agfa film stocks with the clear polyester base make spectacular slides. They also dry dead flat, which is another bonus.