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View Full Version : 4x5 Extended Red Films... Rollei RPX 25, RPX 400... Any 100 ASA ??



consummate_fritterer
10-Dec-2017, 17:45
I'm aware that Rollei RPX 25 and 400 ISO films have extended red sensitivity. I'm NOT looking for true infrared films. But... are there any 4x5 100 ISO films similar in spectral sensitivity to Rollei RPX 25 and RPX 400?

Someone on Photrio mentioned Rollei Retro 400s being approximately 100 ISO. Might this be a good candidate?

alexmuir
11-Dec-2017, 06:35
It does have extended red sensitivity, but I found it more like 200 ASA. I didnít realise it came in 4x5. Iíve only used 135.
Alex



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consummate_fritterer
11-Dec-2017, 08:21
Thank you, Alex. I've read that Rollei Retro 400s is even slower than 200 ISO... maybe 100 or 160. I've never used it so I don't know. Is the grain on par with typical 160-200 ISO films.

Jim Andrada
13-Dec-2017, 21:27
I've only used Rollei Retro 80s. What grain??? I scan at 4300dpi with an IQsmart 2 and I see pixels before I see anything that looks remotely like grain.

Pere Casals
14-Dec-2017, 13:49
Someone on Photrio mentioned Rollei Retro 400s being approximately 100 ISO. Might this be a good candidate?

Retro 400s is just AGFA aviphot 400s aerial photography film,

http://www.maco-photo.de/files/images/Retro400S_Infrared_aviphot_pan400S_2006_01_09_en.pdf

Those films were designed with extended red sensitivity to deal with atmospheric haze if proper color filter used, I guess.

Resolving power is good, slightly lower than TMY

Rollei 400s: TOC (target object contrast) 1,6:1 = 40.3 line pairs /mm. Granularity 14.

TMY (TOC 1.6:1) is 50 lines/mm Granularity 10

So Retro 400s is not bad at all. I made a test with it at ISO 200 in Xtol stock, nice.

ISO 200 is not that bad, in fact if you want to see the extended red sensitivity effect you may want to use color filters to lower visible light, so from ISO 200 you are still to lose more than one stop, and if you are to cut off all visible then you will end in a pretty low ISO.

For vegetables, chlorophyll normally has its reflectance peak between 750nm and 780nm, if you want to enhance vegetables you should filter out a lot of visible.


Another DIY way to obtain IR film is IR sensitizing sheets, here you have a discussion about it: http://www.largeformatphotography.info/forum/showthread.php?99271-Sensitizing-Film-for-Infrared-Photography

This is a way some IR explorers take with good results, I plan to obtain crypto to play with self made emulsion. One has to follow some safety rules to use crypto...

Regards

interneg
14-Dec-2017, 17:28
Photostudio 13 recommend 400S/Infrared/Superpan 200 (apparently all the same film) should be rated at an EI of 125 in the Scala reversal process. This is unusual as most other films that can be run in Scala generally don't lose nearly two stops of speed. Having had a look at the Aviphot 400s datasheet, it suggests that in some developers, when developed to a G-Bar/ CI of 0.6, your EI drops to 200-ish - the design G-Bar for aerial films seems to be much higher than for regular camera films, thus the 400 rating.

I'd generally not call a 20% lower resolution than TMY 'slightly lower' - it's likely to have about the same resolution relationship to TMY-II as TX/ HP5+ etc do - if the available evidence holds up.

That said, again going by the available data, it might be finer grained than Tri-X & on about a par with old Agfapan 400.

Mark Sampson
14-Dec-2017, 18:44
Aerial films are generally developed to a much higher contrast than conventional films- due to the low contrast of the Earth seen from above. Agfa's rating was probably a measurement of Aerial Film Speed (AFS), which is not the same as the ISO method we use normally. So it's no surprise that the on-earth film speed varies... as it so often does. Run your tests to find *your own* film speed, just like you would with any new film.

John Olsen
15-Dec-2017, 17:23
I use Rollei infrared 4x5 film, developed in HC110 "B"

It's my favorite for here in the Northwest because it gives me tonal differences between the greens of our forests. It also livens up shadowy overcast scenes and just about anything else. I use a deep filter on it, either Cokin 007 (6 ISO) or Kodak Wratten 89B (3 ISO).

The only problem is that the film base is very light, it can seem to float away as you handle it. Don't drink too much coffee before loading!

Here's one from last September.

172872

Pere Casals
16-Dec-2017, 16:04
Aerial films are generally developed to a much higher contrast than conventional films- due to the low contrast of the Earth seen from above. Agfa's rating was probably a measurement of Aerial Film Speed (AFS), which is not the same as the ISO method we use normally. So it's no surprise that the on-earth film speed varies... as it so often does. Run your tests to find *your own* film speed, just like you would with any new film.

You are right, Agfa gives Aviphot speed in EAFS terms (efective aerial film speed), ranging from 200 to 630, see here page 4: http://www.maco-photo.de/files/images/Retro400S_Infrared_aviphot_pan400S_2006_01_09_en.pdf

EAFS differs from AFS in that a particular development process is referenced in the AEFS case.