Rollei Infrared IR400 focus index.

[habsphoto]

I have been shooting HIE for 19 years and am testing Rollei IR 400 for an IR workshop that

I am teaching. I have not seen any specifications that explain the exact focus shift of the

film, and after years of shooting IR I have grown accustomed to shifting focus

automatically. I have read some threads for beginners that suggest not worrying about the

shift, and using the DOF of lenses at f16 or f22. That isn't applicable to my style, no

tripod, wide-open, indoors. Nowhere in the Rollei literature does it mention focus. Since

HIE is sensitive at and around 950 and Rollei is sensitive to 850, my gut reaction is to split

the

difference and use a focus compensation point between the visible and IR index mark.

My

HIE technique is 50mm 1.4 lens wide open, shoot at 200ASA TTL, with 25 or 29 deep red

filter, I religiously shift the focus to the IR index, because of the f1.4 aperture. Then I have

the local pro lab machine dip-dunk-process in T-max RS developer the same time temp

as Tmax 100. 95 percent of the shots are correctly exposed with no bracketing, 1 percent

of the shots are worth printing and hanging on the wall if I'm lucky, so I use a fair bit of

film. Rollei might be a possible backup if HIE goes out of production, which wouldn't

surprise me after the Kodak Paper discontinuance (is that a real word?). And I just don't

get the same joy & satisfaction out of digital IR, and that's the whole point, no? Any

thoughts or similar test results would be appreciated. www.schafphoto.com<div></div>

[Fotohuis RoVo]

Rollei IR-400 is sensible till 820nm but in the graphics you can see that above 750nm it's going down fast.

Most IR index on the distance scale are compensated for 800nm. You can use it also for this film.

 

Due to the less sensitivity of the Rollei film it's also much less critical to load and unload. You can do it in subdue light with this film.

Some tests with this film and a Heliopan RG715nm filter brings it around E.I. 25.

 

Rollei IR-400 is available in 35mm, 120 rollfilm and 4X5".

 

Best regards,

 

Robert

[wickedmartini]

The shift recommendation for Kodak's IR used to be an adjustment that worked out to be 1/4 of 1% of the focal length of the lens. Most modern lens coatings will generally eliminate the need to make any adjustments. The emulsions sensitivity to IR and the filters that you use will also have bearing. I hope that helps.

[michael_briggs2]

I think Robert's advice is good. The spectral sensitivity graph in the datasheet of the Rollei IR film shows much less IR response than Kodak HIE or the Maco IR820c. The y-axis is a log scale, so the response is falling off very rapidly above 725 nm. With both a 25 and 29 filter, a rather large fraction of the exposure will be from 600 (or 620) to 725 nm. So the exposure will be heavily weighted to the visual red. With a well achromatized modern lens, probably the regular focus mark will work well. If you shift the focus, I'd bias it towards the regular mark.

 

Color correction to make a lens achromatic is mostly a result of glass selection and usage in the lens design and not of the coatings. With the wide variety of modern glasses (index, dispersion) and lens designs, I don't think the old simple rule of a shift of 1/4% of the focal length will always work.

[bruce_karnopp1]

This is always a question and a problem. There is another related question. Suppose one is using an APO lens.

 

My solution is to always use the hyperfocal distance when shooting landscapes. There is a very easy way to do this for prime lenses. Soi one way or another, the shift is taken care of.

[habsphoto]

Thanks for your answers, I'm inclined to use an imaginary focus index point between

visible

and IR focus index, because (as was mentioned), this film with a 29 filter is really

extended-

red photography. My first roll was shot with a 25A at 200 ASA and seems to be correctly

exposed, perhaps I would try 160ASA next time. Then my second roll was

shot with a 29 filter at 125 ASA and also seems to be correctly exposed. (Automated

process normal T-

max RS developer at Tmax 100 time, the lab I use runs Tmax process control strips every

morning so whatever the Time/temp it should be a factory spec) I shot a roll

of HIE along side the R-IR400 and even though I was using a 23 light red filter on the HIE

camera, the negs are MUCH more infrared typical... especially in the area of blue sky which

is a mid-gray on R-IR400 and almost clear on the HIE negs. Nothing too surprising, but

since the 29 filter is about as dark as you can go and still practically view through the lens,

it seems the R-IR400 really needs a tripod and a IR cutoff filter to clearly give that good-

ole IR feeling I've been used to. As far as the question of APO lenses, I was told by

someone smarter than me, that APO lenses do not need to have focus compensated for IR

because of the optical design, I would surmise that any APO lens of high quality would

have a IR focus index mark if this was not the case.

[Fotohuis RoVo]

APO lenses doesn't have any correction for I.R. photography, most are corrected till 900nm so far over the I.R., area normally used. I was told some time ago by a Leica engineer in Solms.

 

Another thing is that the regular (non-APO) Leica M designs do not have any I.R. mark either but for an Elmarit-M 2,8/28mm the correction is in the DOF, so neglectible. No problem to have any view through the 715nm black IR filter: It's a range finder.

[FilmPhotography-DuaneHorne]

More of a question than a reply. I shoot HIE at 100 or 200 with an opaque IR filter (87). Can I use the 87 filter with Rollei IR film? I will be using a Mamaya TLR.

[Fotohuis RoVo]

For the Rollei IR-400 you need at least an 665nm IR filter, 695 or 715nm is even better to get a full 'wood' effect with this film but 780nm is out of the sensitivity range of this film.

 

The Rollei has an anti-halo layer, HIE has not and with HIE you will get already a wood effect with a (dark) red filter.

HIE is sensitive over 900nm, the Rollei IR-400 not and you can see on the spec it's going down fast in sensitivity over 750nm wavelenght. That's why you can load and unload this film in subdue light while the HIE must be loaded and unloaded in total darkness.

 

Here is the Rollei IR-spec:

http://www.fotohuisrovo.nl/documentatie/RolleiIR-400.pdf

 

and here you find the right development table:

http://www.fotohuisrovo.nl/documentatie/Development_Rollei%20films.pdf

 

Some more info about the RLS developer:

http://www.fotohuisrovo.nl/documentatie/CG-512%20ontwikkeltabel.pdf

 

best regards,

 

Robert

[FilmPhotography-DuaneHorne]

Robert, Thanks for your very informative reply.

 

Duane

[gerry_hopkins1]

<p>I to have been acustomed to shooting with Kodak Infrared film - now its gone sadly so i have bought some of the Rollei stuff to try in 35mm and 120, I have also bought a Hoya deep red R72 filter. the question is what would you guys recomend as an ASA Meter setting? its rated at 400 but I guess thats without a filter, any sugestions greatly recieved!<br>

Gerry Hopkins</p>

 

[Fotohuis RoVo]

E.I. 12 is recommended with the Hoya 72R filter. And without filter the film can be rated for E.I. 250-400.

Here some examples from my gallery with the Hoya filter:

http://gallery.fotohuisrovo.nl/thumbnails.php?album=10