Infrared photography with a TC

Willie Jan

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Hello,

i want to start making infrared pictures with a Crown Graphics (roll film).

I know that i need to set it out of focus to focus sharp for the picture, but i do not know how to do this with a tc camera. My pentax mf lenses have red indicators for this, but how to deal with this with a tc?

thanks.
 

Ole

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The easiest thing is to ignore it. Different lenses have different IR offsets, and you don't know how much it is for yours.

Which film will you be using, BTW? The IR markings are for "far IR", the far end of the sensitivity of Kodak HIE. So if you're sin Konica or Maco, the correction is much less.

Ignoring it and stopping down a couple of stops works just fine.
 

Ole

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No problem then - I've used that in 4x5" without correction. I tried a slight correction too - extended about 2mm for a 210mm lens. That might be more accurate, but again it depends on the lens.

A Tessar-type 210 was slightly sharper with 2mm extra, a 150 APO lens was sharpest without correction. Another, a 135 Planar, again was best without correction - and this was the only one I tried at full opening. Stop down to f:16 or so and I don't think you'll notice any big difference.
 

Ole

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Willie Jan said:
i use a schneider 135mm 4.7 lens..
Click to expand...
That will be a Xenar? Try both - "normal" focus and a slight nudge up to 1% out. That's 1.35mm, or in practical terms "a gnat's whisker".
 

Dave Miller

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Willie Jan said:
im will be using the:
Infrarot 820c 120 Maco
Click to expand...

I'm with Ole here - ignore the focusing error. Your choice of film is good if you use the deep red opaque infrared filter. As a guide I rate the this film at ISO 6 in bright sunlight.
 

colrehogan

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Willie Jan said:
you are right, it's a Xenar. I just found a heliopan Infrared 715 filter with 40.5 mm thread that mounts this lens. Got it very cheap because nobody uses this kind of mm thread anymore....
Click to expand...

You'll have to let us know how it works for you.
 

colrehogan

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Yes. Stick with the Heliopan 715 (which is equivalent to an 88A, I believe) I have also used a Wratten 87 successfully, but I like the results I get with the 88A better. You should be able to get good results with it. I shot this picture back in May with my 6x7 and an 88A filter.

http://dianemaher.fotopic.net/p5199700.html

And though this isn't a stellar example, I shot this with my 8x10 and an 88A filter just before Thanksgiving on a day where it was nearly sunset and there truly wasn't much light left (and it was overcast in the first place). It was simply one of those days that I had to get out of the house and take some pictures.

http://dianemaher.fotopic.net/p9564485.html
 

Ole

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I used MACO IR 820c and a Lee 87 filter (and a 210mm Xenar) for this one:
 

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TPPhotog

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Ole you guys are a bad influence it's a beautiful capture, now I'll have to stock up on some I.R. film.
 

rbarker

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Willie Jan said:
Is the bw 093 (087c) filter to high as i read somewhere on the internet to use for maco 820?
Click to expand...
Yes. As others have noted, the cutoff of the 87c (850nm) is too high for Maco 820C. You'll want the cutoff point of the filter to be lower than the sensitivity point of the film - in this case 820 nanometers.

Personally, I like the look of this film combined with a Wratten 89b filter (B+W 092), which has a cutoff point of 720nm.
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colrehogan

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TPPhotog said:
Ole you guys are a bad influence it's a beautiful capture, now I'll have to stock up on some I.R. film.
Click to expand...



I hear that a lot when I take an IR pic into my camera club meetings. They always say they'll give it a try, but they never do. Oh well. More fun for me!

I've also tried the Lee 87 filter and it works fine.
 
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