[Leica] Konica Infrared 750 answers

[George Huczek <ghuczek@sk.sympatico.ca>]

At 11:20 PM 11/02/2000 -0800, Jim wrote:
>I have some questions. I bought some Konica Infrared film to play with. Has
>anyone out there used this film? If so, what sort of ISO does it have? 25?
>50? and what did you soup it in? D-76 1:1? Rodinal?
>
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Reply:

 The following is part of some information I sent to a friend 
> along with a few rolls of 120 IR 750, which might help you. 
> With EKC IR film, polarizers will have some effect though 
> minimal, since sensitivity extends to 1000 nm, and the lack of 
> a anti-halation layer permits burn-outs anyway. There is some 
> effect with IR 750, since the sensitivity is closer to red, 
> especially with the 25A filter, however, I'd suggest not using 
> it... sky and cloud contrast will be very high without it, and 
> the results might be more desirable.
>  
> Focus and exposure bracketing should not be necessary. The 
> exposure times below refer to direct light... in direct sun 
> you would still open up 2 stops for a backlit subject.
>  
> Copy of note:
>  
> B&W infrared is sensitive to the blue region of the spectrum, 
> and has been sensitized to the far red and infrared regions. 
> To avoid getting a photo with nearly the same tones as Tri-X, 
> a filter should be used to block the blue region, and transmit 
> IR. The most commonly used filter is the red separation 
> filter (#25, #25A, "A" or #29 deep red)... orange doesn't work 
> as well. A slightly better filter is the nearly opaque #70 
> deep red filter, or the visually opaque IR filters of the 87 
> series (87C most common). B&W uses different designations.
>  
> Kodak IR film is very sensitive and lacks an anti-halation 
> layer, so it must be kept in the can and loaded and unloaded 
> in a darkroom or "IR-proof" changing bag, and requires IR 
> opaque bellows, film holders, developing tanks, etc. Konica IR 
> 750 is less sensitive, and can be handled like any pan film... 
> otherwise, it could not be packaged as a 120 film. Unlike 
> EKC's product, Konica has an anti-halation layer, and has fine 
> grain for IR film... about the same as Tri-X Pro.
>  
> Outdoors, the film is best used in direct sunlight. Anything 
> with chlorophyll in it is rendered near white or light gray... 
> all leaves, flowers, grass, water lilies, etc. For instance, 
> dark green lichen on trees and rocks becomes very light, and 
> has excellent contrast with the background, where none 
> existed. Skys are nearly black with brilliant clouds; the sky 
> can be made to go black with the addition of a polarizer and 
> 1.5 stop exposure compensation. Light surfaces in the sun 
> reflect IR, and become brilliant; the same is true in 
> portraits shot with IR. Water reflecting blue sky is nearly 
> black; reflecting clouds or other light tones makes 
> reflections lighter. That should be kept in mind when 
> composing photos, since it isn't apparent to the eye. IR will 
> cut through blue haze over water and in the mountains.
>  
> Metering, exposure and printing offer wide latitude... it is 
> purely interpetative... nothing is right or wrong... the same 
> negative can be printed from grade 1 to 5 with different 
> results, so it pays to experiment with small prints.
>  
> Focusing: IR focuses behind the film plane with most lenses, 
> so after the camera is focused, the distance focused upon 
> which lines up with the major mark on the lens barrel, is 
> reset to the red mark. To avoid focus errors, most photos are 
> taken at f/16 with 35mm... f/22 or f/32 is reasonable with 
> medium format.
>  
> Exposure: Regardless of the filter used, one uses the same 
> basic exposure for Konica IR film which has a safe - 1/+2 stop 
> error toleration. The IR reflectance of objects, and amount of 
> IR varies throughout the day and with weather. A hand held 
> meter can be set to EI 8 with no filter corrections (except 
> for polarizer).
>  
> Exposure with 25A, 70 or 87 series filter on lens:
>  
> Bright sunlight         f/16            1/8 sec
>  
> Light clouds or haze    f/16            1/4 sec*
>  
> Light clouds, but sun
> can be located          f/16            1/2 sec*
>  
> Complete cloud cover     f/16            1 sec*
>  
> Overcast, rain          f/11              1 sec*
>  
> Very heavy rain         f/8               2 sec*
              
>  
> * or stop down and use time exposures... there's no 
> reciprocity failure with times to 10 sec.
>  
> Also, use 1.5 stops more exposure with a polarizer.
>  
> Before developing the film, it should be presoaked in water at 
> the same temperature as the developer for 5 min with some 
> agitation to prevent air bells. This ensures even development 
> of the film. Also, the emulsions of IR films are sensitive to 
> handling... keep fingers off the emulsion before development.
>  
> I primarily use PMK pyro for 11 min at 70F. Other developers 
> include D-76 or ID-11(+)... 6 min; D-76 1:1, 11 min. If you 
> have Kodak or Ilford D+P info for other films, you can 
> interpolate to other developers such as HC 110 B. Usually, 
> times for 100 speed films will be close. I wouldn't recomend 
> dilute Rodinal or compensating developers, or the high values 
> may be too flat. Stop, fix, fixer remover and wash are the 
> same as other films... negatives should be be dense.
>
> My favorite tried and tested personal recommendation:
> Eposure based on slightly hazy day @f/16, bracket at 1/4 and
> 1/2 second, with R25 filter.  Develop in HC110(B) @21C for
> 4 1/2 min, using a 1 minute pre-wash.
>  
> The Kodak 35mm product is very grainy, and the lack of an 
> anti-halation layer adds all sorts of "flare" around objects. 
> Therefore, it has often been used for toned photos or hand 
> coloring in pastels. The Konica 120 film gives prints which 
> are closer to 4x5 Kodak IR... sharp, with high inherent 
> contrast. When considering subjects, I tend to take graphic 
> qualities into consideration rather than the "romantic" images 
> for which Kodak HSI 35 mm film is noted... architecture, 
> groups of foilage against a contrasting background, etc. Macro 
> work with plants is disappointing... practically no tonal 
> separations... pasty gray monotones.
>  
> A good book to look at, though very simplistic and geared 
> toward Kodak only, is Joseph Paduano's "The Art of Infrared 
> Photography"... don't buy it... use the library.  See also the last
> issue of Photo Techniques, with information on IR metering.
>                     
> (Note: If you are metering TTL with a 25A filter, you could set 
> the EI to 64, which should give a sunlight exposure of 1/8 @ f/16 
> which is equivalent to Konica's suggestion of 1/60 f/5.6.) 
> 

 _
[o] -GH