Infra-Red Film

[Ted]

I was wondering whether any of you have experimented with Infra Red film (other than Kodak) in the Studio. I am trying to get high key movement pictures and although reasonably successful in my first attempts using Konica 120 wonder whether anyone else has tried and had success with this combination or any other.

 

[Sean]

There is a filter for infrared that is almost opaque, and I have seen very high key results from this filter. Sorry, can't remember the exact filter name...

 

[Aggie]

..

 

[fhovie]

Shooting people with an 89c will be interesting "can you please hold perfectly still for 2 full seconds??" I would love to see the results though. Maybe do like the pioneers did and make sure everyone is posed with a brace.
Frank

 

[Ole]

Can you use the 89c with Konica IR? That film only goes to 720nm, which is about the cutoff for the filter...

 

[fhovie]

I think I ran out of that film before I got my 89c filter - I had been using the red25 with very nice effects on the konica - I bet it would work though - the response of those films are not that exact and I don't think the filters are that tight either. Make it a loooong exposure. Konica doesn't list that as a filter to be used - They only list a Red 25.

 

[Ed Sukach]

Can you use the 89c with Konica IR? That film only goes to 720nm, which is about the cutoff for the filter...

Not quite true. Konica 750 has a "bi-modal" sesitivity curve with one "peak" at something like 550um, and the other "IR" peak at 750um. Both peaks are uniform (they look like semi-circles) so there is an amount of sensitivity out to ~ i don't know .... 850um or so.

A "Red 25" filter cuts off (attenuates) light below abut 690um rather effectively, so there is no intense gain from an 87 0r 89 filter - and they both have the disadvantage of removing a great deal of the visible light - therefore they are "opaque" - to normal vision.

 

[Aggie]

..

 

[Ole]

Funny...

MACO only mentions 12(yellow), 22(orange), 25(red), 29(dark red), 70(very dark red), 88A, 87, and 87C (Black, IR transmitting) on their website...

No mention of 89C on mahn.net, nor in my "filter bible": CRC Handbook of Chemistry and Physics, 62nd edition. There is an 89B, with 50% transmittance at 720nm, however...

The 50% point are (roughly):

25: 600nm
29: 620nm
70: 680nm - narrow band filter
87: 795nm
87C: 860nm
88A: 750mn
89B: 720nm

So 87 and 87C would be very dark for MACO 820, almost totally black for Konica IR750. 89B looks more promising, and is equivalent to what is sold as "R72". 70 would give about the same results as 89B with IR films - except Kodak HIE, where it would cut off some of the far infrared.

 

[Nige]

Ole, does your book mention unexposed, processed E6 film? Works great with Maco 820n

 

[Ed Sukach]

[Not quite true. Konica 750 has a "bi-modal" sesitivity curve with one "peak" at something like 550um, and the other "IR" peak at 750um. Both peaks are uniform (they look like semi-circles) so there is an amount of sensitivity out to ~ i don't know .... 850um or so.]

You guys are slipping. I mistakenly labeled the wavelengths as "um" - or "micrometers".... Ooops!! Should have been "nM" or "nanometers". Not much of an error ... only one thousand times (1000X).
:roll:

 

[Ole]

You guys are slipping. I mistakenly labeled the wavelengths as "um" - or "micrometers".... Ooops!! Should have been "nM" or "nanometers". Not much of an error ... only one thousand times (1000X).
:roll:

I was not slipping - I slipped out to test MACO IR820c instead. With 89B filter. May post results, if I find them worth it

 

[dr bob]

I exposed close landscape scenes with Konica IR at EI=12 through a Wratten #29 (deep red filter -I wanted no colors other than far red and infra recorded). I might have used 8 except my spot meter won't set that low. I will admit some trepidation in focus due to the shift, but I used the setting on the KO 90mm Hexanon and a wag as to the foreground/ background dof. A tripod was essential (as usual). I'll admit to doing a little bracketing. Development was in D76 1:1, 8-1/2 minutes, 20 deg. C., (according to data found in the Massive Development Chart).
Everything is in relatively sharp focus. The dream-like feeling
is there without that fuzzy-wuzzy pictorialistic "look" which I find
disturbing. I am also surprised at Konica's tonal range. The negative is a
bit harder to print than I first believed. The tonal range (11+ zones?)
exceeds the ability of the VC paper to produce a "straight" print of
"normal" values. I had to use a Kodak #3 filter and then do a bit of
dodging and burning. I gotta get a web site to show these things. I have
put some prints on APUG and maybe I'll post one of these prints in the Technical Gallery soon - if the computer doesn't die and the scanner and.... Boy chemical photography is GREAT!

Truly, dr bob

 

[sparx]

I have just aquired a roll of Konica IR750 35mm for my course project. I am rating it at iso 100 (approx f5.6 @1/60th according to my camera) but am a bit concerned about this focus shift as my lenses (Olympus OM) don't have a IR mark.

My 28mm probably won't be too much of a problem because of its large depth of field but i was hoping to take some shots using a 70mm and a 200mm as well. Does the shift pull the focal point towards the camera or away?

 

[Ole]

IR "bends" less in the lenses, so it isn't focused as much. That means that you have to pretend the subject is closer to your camera - so you focus closer. Fortunately you don't have to force your lens helical past infinity...

 

[Ed Sukach]

IR "bends" less in the lenses, so it isn't focused as much. That means that you have to pretend the subject is closer to your camera - so you focus closer. Fortunately you don't have to force your lens helical past infinity...

This is true, at least in theory. Lately I have been experiencing trouble with IR focusing ... I religiously focus and reset to the IR (red line) on the Hasselblad lenses (the older ones) --- and ... I'm obviously "out of focus".

I've been thinking ... with films that are primarily sensitive to "far" (comparatively) Infra - Red (i.e., Kodak HIE) and filters that cut off light in the visible spectrum - this IR index probably made sense - but with the "near" IR films - Konica 750, Maco 820, Ilford SFX, and what was Agfa's -- and the use of mild filtration ... R25 ... I don't think there is that much of a "shift". Seems to me, the focus of the image we see through the viewfinder (filtered) is probably *very close* to what will be recorded on the film.

I notice that there is *no* IR Index on the new Hasselblad lenses - which would seem to bear this out.

"Next" technical task - to "wring this out".

 

[Ole]

Ed, you are perfectly right.

The IR index mark is fo "real" IR, while most of "us" use "deep red" which behaves about like ordinary red light. Even with an 89C filter on MACO IR820 I could see no sign of focus shift using a 150mm APO-Lanthar lens, and very, very little with a 150mm Symmar.

With any film except Kodak HIE and the very darkest filters, ignore the focus mark - except if it is very far from the infinity mark. Lenses are different, some are better corrected than others. APOs should be very close to no correction even in the worst-case scenario.