Full Spectrum Photographic Film

[ph0toni]

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Contrary to popular belief, Rollei Infrared film has an extended sensitivity from infrared ... to deep ultraviolet
It is basically Full Spectrum

Rollei recommends using "at least" a light red filter 590 nm, or dark red or infrared 720 nm
Looking at the sensitivity curve, you can see that it is sensitive up to 400 nm, I tried to go further.

1 - photo with deep UV filter -350 > 400 nm
2 - photo with orthochromatic film emulation filter 350 > 510 nm
3 - light green filter
4 - light red filter (A25) 390 nm
5 - dark red filter 670 nm
6 - IR filter (Hoya R72) 720 nm

I used an old 6x6 Agfa Isola II camera, which has a simple lens, a triplet, without anti-reflection coating, to be able to "see" also in the UV spectrum
Modern lenses with multiple lenses, or glued groups, with anti-reflection coating, stop the frequency at about 400 nm.

As I wrote in my first post (Monochrome Full Spectrum - UV - VIS - IR) ,

I would like to have a modified M246 F.S. to do this test.

Thanks
Toni

 

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Edited March 6 by ph0toni

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[250swb]

1 hour ago, ph0toni said:

Contrary to popular belief, Rollei Infrared film has an extended sensitivity from infrared ... to deep ultraviolet
It is basically Full Spectrum

 

'Popular belief' already knows this, you can use Rollei IR as a normal film. IR films do not come already filtered, they are simply more sensitive to that spectrum but require a filter to work. And modern lenses do not stop the IR effect at 400nm, I use modern lenses much of the time and if I put a 718nm filter on the lens the image is rendered in infrared.

There are other films that render in infrared without shouting about it, put an IR filter on the lens for Adox HR-50 and it becomes an infrared film, take the filter of and it reverts to a normal tonal range film. I'm not sure what you are trying to get at, these things are known.

You can use an IR filter on the lens with an M10 and get pretty decent infrared images. 

Edited March 6 by 250swb

[ph0toni]

21 hours ago, 250swb said:

Popular belief' already knows this, you can use Rollei IR as a normal film

The "popular belief" most likely does not know that infrared film is also sensitive to deep ultraviolet, that is below 400 nm

The filter I used in photo 1 cuts all visible human and infrared, it covers only UV from 350 to 400 nm

21 hours ago, 250swb said:

And modern lenses do not stop the IR effect at 400nm

And modern lenses stop the UV effect at 350 to 400nm ...
Modern and ancient lenses see well IR, if they are not apochromatic they have a shift in focus.
(remember the red dot on lenses that marks infinity with IR film?)

 

21 hours ago, 250swb said:

You can use an IR filter on the lens with an M10 and get pretty decent infrared images.

 exposure difference between IR film and M246 - M10 - M11 is about 6 > 10 stops.
Only the M9 saw IR well

 

You are right, Adox HR-50 is very good

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Edited March 7 by ph0toni