Focusing with infrared

Checkergirl · Mar 2, 2005

OK: slightly freaking out. Think I might have messed up my roll of infrared. Won't be able to develop it until next Tuesday, so thought I would ask. Shot my first roll of infrared with a Nikon N65. I covered up that little square inside that you're supposed to cover up and loaded and unloaded in the dark.
My question is: did I mess up the roll by: 1) manually focusing and not "back focusing" and/or 2) not covering up the little viewing line that shows you what roll of film you have loaded in the camera.
Someone, calm my nerves, please. Compositionally, it turned out to be a great session. Hopefully all won't be lost.

Thanks! Lisa

kaiyen · Mar 2, 2005

Checkergirl said:
My question is: did I mess up the roll by: 1) manually focusing and not "back focusing"

Depends on which filter you used. A red 25 lets enough visible light through that you don't need to make any focusing correction. with an opaque "IR" filter like a wratten 87 or a Hoya RG72, you do need to make some correction.

I once read an interesting argument that folks incorrectly compensating for focus may in fact aid the common perception of the difficulty of IR focusing. They in fact make their images _less_ sharp by compensating too much, and then get even more worked up about how hard it is to focus (having trouble saying that - does that make sense).

regardless, develop it and see what happens.

2) not covering up the little viewing line that shows you what roll of film you have loaded in the camera.

I have never covered up that little window on my n70 and I have not had a problem with a couple dozen rolls of HIE.

allan

colrehogan · Mar 2, 2005

Checkergirl said:
OK: slightly freaking out. Think I might have messed up my roll of infrared. Won't be able to develop it until next Tuesday, so thought I would ask. Shot my first roll of infrared with a Nikon N65. I covered up that little square inside that you're supposed to cover up and loaded and unloaded in the dark.
My question is: did I mess up the roll by: 1) manually focusing and not "back focusing" and/or 2) not covering up the little viewing line that shows you what roll of film you have loaded in the camera.
Someone, calm my nerves, please. Compositionally, it turned out to be a great session. Hopefully all won't be lost.

Thanks! Lisa

No, you won't mess up by not making that minor focusing adjustment. And no, you probably will be okay for not covering up the viewing window. There's really no way to tell until you develop the film. Be sure to let us know how it came out and feel free to ask any questions you might have.

rbarker · Mar 2, 2005

(Insert your favorite calm, soothing music here ) I wouldn't worry too much about the focus compensation, Lisa. Unless you were shooting at fairly wide apertures, and fairly close, it shouldn't be much of an issue. Some IRophiles shoot at f8 or smaller, just to avoid the issue altogether.

Checkergirl · Mar 2, 2005

Ahhhh.....thanks, everyone. Yes, I am definitely going to develop it next week, and will keep my fingers crossed. I used a 25 red filter, so it seems that all might be ok. But, I was using a large aperture (I wasn't using a tripod, so I using pretty open settings). We'll see . . . thanks for the nerve calming!
Lisa

kaiyen · Mar 2, 2005

I shot this sunflower at, I think, f4 with a red 25. You should be fine.

allan

geraldatwork · Mar 2, 2005

Your biggest concern based on my one roll of experience and from what I've read is exposure. From what I understand the film "sees" light differently than that of a meter. Also I've heard many different opinions as to what ISO to use. You didn't mention if you bracketed your exposures. Sorry to give you something else to worry about. Maybe someone else can make you feel more comfortable.

Checkergirl · Mar 2, 2005

Yes, I thought about the bracketing issue, too. I believe my camera meters at 100 ISO if it can't "read" what's in the camera. And, no, I didn't bracket . . . the truth will be in the developin'!

Checkergirl · Mar 2, 2005

Wow . . . very cool pic. Thanks! Will let everyone know how the roll comes out. And, if any of them are worthy, I'll be sure to post 'em!

kaiyen · Mar 2, 2005

Checkergirl said:
Yes, I thought about the bracketing issue, too. I believe my camera meters at 100 ISO if it can't "read" what's in the camera. And, no, I didn't bracket . . . the truth will be in the developin'!

I had forgotten that the N65 defaults to 100 with nonDX film.

You will actually probably end up with underexposed film, which is maybe not terrible (I tend to blow the heck out of HIE more often than not, especially the first several rolls I shot. I was saved only through bracketing). If you're camera was defaulting to 100, then with metering through the red 25 you're effectively down to 12.

Usually, the "starting point" is to set your meter to 400, then meter through a red 25 to get to an effective 50 (red 25 == 3 stop loss, which takes you from 400 to 50). Many people will actually set the meter to 50 and meter without the filter on to help with composition, etc. I hope that makes sense.

so...what you can do next time is to meter without the filter with a +1 exposure compensation (or just do it manually by 1 stop over). This will give you an exposure that is equivalent to if it were 50 speed film. Or, you can do it through the filter with a -2 compensation - its' the same thing (taking you from 12 to 50).

Again, I hope that makes sense. I can try again if it doesn't

allan

Ed Sukach · Mar 2, 2005

Which Infra Red film did you use?

THe more I think of it, the more convinced I am that, using the R25 filter, there does not need to be any "compensation". Considering the cut-off characteristics of the filter, the only light that will get through will be the light that is seen while focusing - directly.

I notice that on the newest Hasselblad lenses, the IR reference mark is missing ... and I think the reason behind that was it was causing focusing errors with films like Konica IR, Ilford SFX (? was that the "extended" color sensitivity film?), MACO 750 and 820 and a #25 filter.

I can see where it might be of use with Kodak HIE, and a filter with a high cutoff point like the #87 or #89 - the use of these precludes direct focusing anyway.

Checkergirl · Mar 3, 2005

Hey Ed,
I used Kodak HIE and a red #25. Metered through the camera lens. Will get to developing this Tuesday and will let everyone know.
Thanks to everyone that has responded with their words of advice! This was my first post. I'm very excited to be a part of this group. I'm in the process of following my heart of becoming a photographer (from being a scientist).
Lisa

colrehogan · Mar 3, 2005

Checkergirl said:
Hey Ed,
I used Kodak HIE and a red #25. Metered through the camera lens. Will get to developing this Tuesday and will let everyone know.
Thanks to everyone that has responded with their words of advice! This was my first post. I'm very excited to be a part of this group. I'm in the process of following my heart of becoming a photographer (from being a scientist).
Lisa

Welcome from another photographer/scientist. Though the latter pays the bills for the former at the moment.

rbarker · Mar 3, 2005

Checkergirl said:
. . . I'm in the process of following my heart of becoming a photographer (from being a scientist).

Aren't most photographers just artistic scientists at heart?

Checkergirl · Mar 8, 2005

Hey everyone!

Developed the roll of infrared and, if I may say, I think it pretty much rocks for a first roll. The other consideration is the ISO setting. My negatives were a bit dark, so if I stop down next time to comensate for my camera thinking its 100 ISO, I'll be good. I'll try my hardest to post some pics tomorrow (I have limited computer toys and need to go to another location to scan).
Thanks again for all your support!

And, I definitely agree with Ralph's last e-mail!!!!!!! I feel like a geeky artist!

Lisa

rbarker · Mar 9, 2005

Using a 25 red with HIE, most of the actual exposure is coming from visible-spectrum light, so no focus compensation is required. Once the visible light is filtered out by a "real" IR filter, the difference in wave length becomes more of an issue.

Glad the first roll came out close, Lisa. If you use the in-camera meter, I'd just adjust the ISO setting on the camera to a higher setting to reduce the density of the negs. If you shift to an opaque IR filter, however, you'll need to use a different ISO setting, and compensate manually. The meter in the camera won't see any more than you do through the opaque filter.

Here's a chart of various IR Filters & Films

ras351 · Mar 9, 2005

Hi Lisa,

Glad it worked. I've been messing around with the Maco IR films which are a bit slower (but are available in 120 and 4x5) and have been getting some pleasing results. If you want to try a cheap IR filter a piece of unexposed but processed E6 film works well but you might need to go to 120 or 4x5 size to get something big enough to cover the lens. I often forget to reset the focus when I slip the filter into the holder but as someone else mentioned if you stop down enough it doesn't matter.

Regards,
Roger.
PS I'm also one of those scientist/photographers.

Focusing with infrared

Privacy & Transparency

Privacy & Transparency