IR Photography

[I2P]

This is an endeavor that my wife and I are looking into. I have a Canon 7D and Rebel Xti...both UNMODIFIED! I also have the R72 filter. Now, I went out today to give it a go. However, after setting the CWB via Green foilage I am not getting the desired result. What I end up getting is some "purple" image. I have attached the photo. Please gimmie a heads up on what I may be doing wrong!

Shane

[I2P]

By the way....the EXIF data is as follows:

Canon EOS 7D
ISO 100
f/3.5
30 sec Exposure
Focal Length 28mm
Pattern metering
no flash

[Clean Gene]

Probably a stupid question, but did you set the custom white balance before or after you put the R72 filter on? I have no idea if it even makes a difference, just curious. If you did it one way, then maybe do it the other way and then see what happens? :confused:

On that note though, I'm not even sure how much that kind of stuff can be gotten rid of in-camera. I have a modified 40D. And while I think the company that did the conversion optimised some stuff to reduce color cast, I'm still often getting a very strong red color, depending on what I'm shooting. So...even witha MODIFIED camera, I still have to do some post processing to get rid of some color (though my situation isn't nearly as extreme as yours).

Anyway, what are you trying to do? Do you want black and white IR pictures? Or do you want to do that really cool false color infrared that is often seen? I've only ever tried black and white IR. And while this is probably absolutely the wrong way to go about it, I usually just desaturate the picture until all of the color is gone. That's probably not what you SHOULD do in your case. But you certainly CAN simply take the color saturation all the down to 0, and then the purple should be gone.

Alternatively, if you want to do those cool false color IR images, then I've heard that you want a color cast over the picture. I wouldn't KNOW, since I've never tried it, but that's what I've HEARD. Supposedly you take a picture that looks like yours, then reverse the color channels. Or...something like that. Maybe you could try reversing the red and green channels, and see what happens? :confused:

Or...you could wait until you get some advice from someone who actually knows what they are talking about.

In any case, the infrared certainly WORKED. I can clearly see some of the standard signatures of infrared pictures, such as the bright foliage and dark skies. A couple of quick tests you can do right now. And not necessarily because I think they are what you SHOULD do, but more because I want to see what happens when you do it.

1) Take that picture, completely remove the color, then post the image here for comparison. Probably the wrong thing to do, but that'll show in the picture, and be a textbook example for why not to do that.

2) Take that picture, then reverse the red and blue channels. Like...use Photoshop and then select the Red channel. Under the red channel selection, there should be slider bars for the red, green, and blue color channels. Slide the "red" slider all the way down to 0, then move the blue slider all the way up to its maximum value. Now select "Blue", and then do the opposite. Move the Blue slider all the way down to 0, then move the red slider all the way up to its maximum value. Again...it probably won't help. But what the hell...do it anyway and then show us what happens.

[jvz09]

Okay, IR photos are difficult to get and I don't blame anyone for getting on colored photos.

Let's get started!

Prime lenses are probably the best. Some zooms exibit IR hot spots due to their coatings.

Step 2 put the ir filter infront of the lens and go outside to see if AF still works.
In bright sun, it should. If not, prefocus.

Step 3 if using unmodified camera step ISO to at at least 1600.
Aperature must be wide open. F/1.8 or better will do.
And shutterspeed will be slow. Approx 1/50th.

[jvz09]

Step 4: how are your results? At this point just be concerned with focus and exposure.

*tip* Live view can help with focusing

5: find a grey card, a piece of white paper, or something simmilar.
And take a photo of it.

6: go to the menus and select custom WB.
It will ask you to choose a photo, select the one you just took if it's bright enough.
It should be in the middle of the histogram.

7: select custom WB from your WB choices after you exit the menus.

8: take a shot. Or try Liveview! It should look sureal.
This will require a extremely long shutter speed indoors if camera isn't converted.

[Clean Gene]

Step 3 if using unmodified camera step ISO to at at least 1600.
Aperature must be wide open. F/1.8 or better will do.
And shutterspeed will be slow. Approx 1/50th.

Just out of curiosity, to what extent do the rest of you have to make focusing compensations for IR?

Because, like, I've HEARD that infrared focuses a little bit differently. So that one ideally SHOULD focus using visible light, and then make a compensation in focusing to account for IR radiation having a slightly different focal point.

Now...don't get me wrong. I do not do that. However, my infrared pictures are often a little bit soft, and I SUSPECT that not compensating for that might be the cause. I instead simply make sure to use the smallest aperture that's appropriate for my needs, and to only shoot IR pictures when it's okay for the images to be a little bit soft.

But just since I didn't see you mention that, I'm curious as to your thoughts on adjusting focus to compensate for IR. Is that something that you (and the other IR photographers here) do? Just how MUCH of a difference does that actually make?

[jvz09]

Yes it is a bit different, try using live view if your camera has it, if not some lenses have IR markings. Or small aperatures. But I have had good results with just putting the IR filter on and focusing. I use a hoya r72 or 720nm filter that lets in a bit of red. But then....speedlites use IR beams, so I bet either the little bit of red light going thru works or the AF sensor works with IR as well.

Hope this helps, and send me a PM because I probs wont check back here again due to checking out other threads.

[weemannie]

A colour cast is quite normal.
Custom WB should be done with the filter on. Grass is a good subject.
Set the camera to use the Custom WB!
Shoot Raw and use a tripod.
Often when using Camera raw to process the temperature slider won't go down far enough to match your custom WB (only 2000k). You can Canon's own Digital Photo Professional as it will use your WB. Alternatively you can download Adobe DNG Profile Editor and create a custom profile. Its easy to do. Firstly, you need to create a DNG file from one of your original Raw images (Adobe DNG Converter or Lightroom). The profile editor does not need to be installed, just double click the .exe file. Choose File>Open and locate the DNG file you created. To keep it simple, just choose 6500k from the Colour Tables dropdown list on the Color Tables tab. Finally go File>Export Profile and give it a meaningful name.
When you go to Adobe Camera Raw after this the profile will be available to you from the Camera Calibration tab. Click on the Name dropdown and your profile should be on the list.
There are numerous tutorials on the web for both B&W and false colour processing - just take your pick.:)

[AbPho]

Just out of curiosity, to what extent do the rest of you have to make focusing compensations for IR?I think each lens is different. Older (I think film) lenses had markings for focusing at infinity when using IR film. From what I find, newer lenses do not provide those markings anymore. Your best bet is live view.

I just got IR camera. Life pixel can only calibrate the camera to properly focus with one lens. I chose to stick with the default 50mm f/1.8 mark II lens. If I want to use something else I will need to use live view to ensure proper focus.

In the day that I have had my camera I have found that the images look a little soft. And trying to nail focus, either in automatic or manual mode, or via live view, is a little difficult.

[ralff]

So if you use live view you can focus with any lens? Sending in a lens only helps if you do NOT have live view and you want auto focus, is that correct?

[Clean Gene]

Yes it is a bit different, try using live view if your camera has it, if not some lenses have IR markings. Or small aperatures. But I have had good results with just putting the IR filter on and focusing. I use a hoya r72 or 720nm filter that lets in a bit of red. But then....speedlites use IR beams, so I bet either the little bit of red light going thru works or the AF sensor works with IR as well.

Hope this helps, and send me a PM because I probs wont check back here again due to checking out other threads.


Yeah, it's just that...I also have done infrared using 35mm film and 4x5 film. And while even those pictures ended up usually being just a little bit soft, it usually wasn't detrimental. And in some cases, it actually helped by giving the picture sort of slightly surreal dreamlike quality. But in any case, looking at those pictures, the descriptive term that came to mind was always "a little bit soft" rather than "holy ****, that's horribly out of focus".

Meanwhile, on my converted DSLR (using the same lenses that gave acceptable pictures using 35mm film), more often than not I ended up saying "holy ****, these pictures are just horribly out of focus." On my DSLR, it was far less likely for the pictures to have a pleasingly soft focus, and more likely for the pictures to just look ugly.

And let me clarify that in NONE of those cases did I actually try to compensate focus for infrared. I simply focused without the filter, then took the picture with the filter on. No compensations made whatsoever. In 35mm and 4x5, it still usually looked pretty damn good regardless. But once I start doing that with my converted DSLR, I just get UGLY pictures that are horribly out of focus.

So, here's my issue. I suspect that the exact same thing is happening in all cases. That the "pleasing softness" I was getting in 35mm and 4x5 is also indeed due to infrared photography requiring a focus compensation, with me totally not even bothering to make that compensation. My question is, why is my DSLR producing pictures that are just so much uglier?

1) Is that due to the size of the "sensor". Is it that deviations from proper exposure are more noticeable with a smaller sensor? And that when I go to my DSLR, I pass the threshhold where the sensor is small enough that it makes my pictures look ugly if I don't compensate for focusing in infrared?

2) Or is this a digital vs film issue? Because in 35mm and 4x5, I was using FILM and getting good results. The bad results are primarily coming from the DIGITAL camera. Is that the problem? I sort of doubt that. I mean, I know that there are various differences between film and digital, but I don't see that focusing should be one of them (in visible or infrared). So...I sort of doubt that it has to do with digital vs film, but I'm gonna ask that anyway.

3) Additionally, is it possibly also just that the viewfinder on my DSLR freaking SUCKS? Because...the ground glass plate on a 4x5 camera is a big ol' "viewfinder". The viewfinder on my 35mm SLR is a lot smaller (though significantly brighter), but at least I can generally tell when I've got the focus right. Meanwhile, on my DSLR, I have a hard time focusing anyway, because of the tiny-ass viewfinder. Focusing is sort of a pain in the ass anyway, and even my non-infrared pictures have a greater tendency to be soft or completely out of focus when I'm using my DSLR. So...is it simply that my problem is caused primarily by the fact that I have a hard time focusing correctly through such a small-ass viewfinder?


Overall, I suspect that it's a combination of 1 and 3. I suspect that it's a combination of the size of the film/sensor, and my ability to focus correctly anyway due to the quality of the viewfinder. That's my suspicion, but I don't know if that's really the cause. So it'd be cool if someone could weigh in on that.

Also another question regarding lens "hot spots". On my DSLR, my lenses give me hot spots. How noticeable they are seems to primarily depend on aperture (and to a lesser extent, lighting condistions and the placement of light/dark values within a scene). I am USUALLY okay stopping down to f/8, and can SOMETIMES get away with stopping down to f/11. Meanwhile, I can take the exact same lenses, put them on my 35mm film SLR, then stop down to the smallest aperture. And in NONE of the pictures taken using my 35mm SLR have I ever seen a hint of a "hot spot". Which...doesn't make sense to me. Because hot spots seems like something that should be ENTIRELY dependant on the lens. And if I'm using the same lens, then...shouldn't I also get hot spots regardless of which camera I use? Again, the only thing that seems remotely plausible is that the difference in format size is what is making the difference. But even then, my DSLR usually allows my a minimum aperture of f/8 for infrared (using that lens), and even at that aperture I still usually have to discard SOME pictures because of a noticeable hot spot. Same lens on a 35mm film SLR lets me get away with going all the way down to f/36 without any hint of a hot spot whatsoever. So even if it IS an issue of sensor size, does a "1.6 crop factor" really make THAT much of a difference between f/8 and f/36?

EDIT: I also use a Hoya R72 filter. And while I can see through it, that's not nearly enough light to allow me to focus with the lens on. One thing I'll do is to hold it over my spot meter in order to get better exposure and not have to do so much bracketting. And even then, I'm only barely able to see the scene well enough to tell what I'm supposed to be metering on. Actually FOCUSING with an R72 filter on the lens is something that I absolutely positively cannot do. My eyes just plain aren't good enough to focus properly in such diminished light.

[jblaschke]

What lenses are you using, Gene? Most conversion shops calibrate to basic 50mm 1.8 lenses when they make the conversion. I used to use the Canon 28-135 IS all the time for IR with thread-in filters, and got fine results. But once I tried to use it on my converted camera, the images were horribly soft. The IR focal adjustment marks are all over the place along its focal length. It's just not going to focus sharply unless I use a really narrow aperture like f/16 or higher. So I don't use that lens anymore. I get excellent results with the EF 50mm 1.8 mk I and the EF 85mm 1.8, which have very similar focus compensation adjustments, which fall within the calibration on the camera. The only zoom I use is the EF-S 10-22, but this one is pretty much restricted to landscapes and the like, and I only shoot with it at f/8 and above, mitigating the focus shift issues.

[gt1cm2]

Custom WB should be done with the filter on. Grass is a good subject.


Sorry to bring up an old topic but I'm new to playing with IR so I'm quite interested in this comment. When doing the custom WB and using grass as the subject, do you take the photo using a long shutter speed like what you plan to be using for the photo session?

[jblaschke]

Sorry to bring up an old topic but I'm new to playing with IR so I'm quite interested in this comment. When doing the custom WB and using grass as the subject, do you take the photo using a long shutter speed like what you plan to be using for the photo session?

Yes. Shutter speed for the CWB image should be similar to the expected exposure times, ie 10-20 seconds (at least, that's what I got with my pre-conversion XTi). And remember, you have to put the filter on before taking the CWB shot. A visible light photo of grass or leaves won't work.

[gt1cm2]

Great thank you, shall have a bit of a play :)

[john5189]

Try focus bracketing as well as Exposure bracketing.
You will always need to IR compensate the white light focus point. But easily just infinitey focus to the IR mark on the lense.

You do need to know what aperture you can close down to without getting diffraction, f/16 should be OK, this makes life easier too.

I tend to find reliable results form just using the red channel from the final image and any major contribution from other channels.
Coloured IR can sometimes look a bit pointless Though when it works it looks great.

Directly converting the full colour image to B&W is not always the most vivid result. So experiment with your recorded image.

I haven't got a converted camera these images wer taken with R72 taped to lense after composing on tripod and I think they were multi seconds exposures.
http://www.photoduet.co.uk/images/cotswolds/cottage%20on%20main%20road%20ir%20L.jpg
http://www.photoduet.co.uk/images/gothic/gothic%20ball%20post%20gate%20ir%20L.jpg