10D and R72 Infrared filter

[tomasil]

I took shots on my Canon 10D with a Hoya R72 filter and a 50mm 1.4. It took a long (20 sec f/5.6) to get a decent exposure. When I used brought it into Photoshop, the center of the image had a bright spot in the middle of it.
I had Rube Goldberg'ed the setup using a 49mm R72 inset and masked in a 58mm UV filter. Wanted to see if the 10D sensed enough IR before investing in a larger size IR filter. Maybe that caused the bright spot.
Any ideas?
Thanks,
Tony

[perfectpixel]

post your result for us to see.
I tried the same thing with an onld Kodack P&S digital and had exactly the same problem. Never fihgured it out, thought it was the cheap lens maybe (not to say this is your case).
Would be informative to diagnose this

[chris maddock]

It's not the camera, the 50/1.4 does give a hot spot. Some lenses do and some don't, unfortunately that one does.

KRs
Chris

[tomasil]

It's not the camera, the 50/1.4 does give a hot spot. Some lenses do and some don't, unfortunately that one does.

KRs
Chris

That's interesting, Chris. :o
I read a recent post in this forum by Matt Chase who suggested an IR procedure using a 10D, a 50mm 1.4 and R72. He didn't mention the hot spot.
I'll try another lens, a 100mm macro, and see what happens.
Thanks,
Tony

[tomasil]

post your result for us to see.
I tried the same thing with an onld Kodack P&S digital and had exactly the same problem. Never fihgured it out, thought it was the cheap lens maybe (not to say this is your case).
Would be informative to diagnose this

Sorry, PP, but I don't yet know how to post an image on this forum.
Tony

[Deckyon]

This has nothing to do with the lens. As a general rule, newer digital cameras have an IR blocking filter on the chip itself. The blooming is the result of trying to force IR onto the chip. This will happen with almost all digital cameras.

I have an article on what I had to do to have limited success with a G3. The G2, with a modification (see the G2/3/5/6 Forum for this one) and the G1 make excellent IR cameras.

The Article - Shooting with an Infrared Filter (http://www.sturm.org/modules.php?op=modload&name=News&file=article&sid= 22&mode=thread&order=0&thold=0)
Pleae note in the article, a Photoshop action is required to make the photos look "somewhat" correct. At this point, consider the photo to be Near IR (NIR) rather than pure IR.

I have yet to try my filter on my new cameras, but it is on my list of things to do.

[taskerc]

On my 300d, I found the Sigma Kit Lens (18-50) to be a perfect IR lens - 50/1.4 and 85/1.8 gave centre flare, but 18-50 did not.

[Deckyon]

BTW, I have a PS action (at home, not here at work) that will help eliminate the blooming effect of the IR. It works well. I will try and remember to upload it and post it here. It is only a starting point, you will have to tweak it for your own photos.

[tomasil]

On my 300d, I found the Sigma Kit Lens (18-50) to be a perfect IR lens - 50/1.4 and 85/1.8 gave centre flare, but 18-50 did not.

Well, I went outside with a 100mm f/2.8 macro instead of the 50mm 1.4 and voila! It was the lens! It's a fairly blowy day but sunny. I shot at ISO 800, f/18 and 10 sec. No hot spot with the macro. Didn't try to get the best results, just wanted to see if the ole 10D was senstitive enough.

I had a G1 which was a dynamite IR camera (but I sold it. Duh!);
I was able to put the R72 on it and actually preview the IR scene right on the LCD even before I shot the picture...and I did it hand-held and got sharp images!! The good ole days!

Now to buy a 77mm IR filter. Harrison and Harrison sells their 89A (R72 eguivalent) for $57.45! Does anyone know if it's up to a R72 performance?

Thanks again, guys, for your continuing help.
Tony

[tomasil]

BTW, I have a PS action (at home, not here at work) that will help eliminate the blooming effect of the IR. It works well. I will try and remember to upload it and post it here. It is only a starting point, you will have to tweak it for your own photos.

I'd be glad to get the action, Brad.
Tony

[msvadi]

Some lenses have IR blocking coating applied unevenly. This produces a hot spot. A while ago I posted here a list of lenses with and without hot spot problems (I found it on dpreview). As far as I remember, 50mm 1.8 is fine, but 50mm 1.4 has this problem.

[mattchase]

Yup, different lenses do give different results. The lens I have and use is actually the 50mm 1.8, I don't remember if I mistaken called it the 1.4 previously, but in fact it is the 1.8. And it works very nicely, not to mention the fact that an R72 filter for it was pretty cheap compared to one for larger diameters (like my 77mm 70-200mm lens).

I used to have a Harrison and Harrison IR filter, and it works ok. It is not up to a Hoya or B+W IR filter quality though, it is basically nothing more than Kodak gelatin filters sandwiched between glass. Despite the much higher cost, I would buy an R72 from one of those guys next time. What I figured out to save a few bucks is to buy the Hoya RM72 67mm filter which costs only $80, compared to the 77mm filter at $280. With a 10D / D60, the 67mm filter shouldn't vignette on most normal lenses (50mm and beyond). And even if it does vignette a bit, just call it character!

Also, isn't the 100mm 2.8 macro only a 58mm thread?

[tomasil]

Yup, different lenses do give different results. The lens I have and use is actually the 50mm 1.8, I don't remember if I mistaken called it the 1.4 previously, but in fact it is the 1.8. And it works very nicely, not to mention the fact that an R72 filter for it was pretty cheap compared to one for larger diameters (like my 77mm 70-200mm lens).

I used to have a Harrison and Harrison IR filter, and it works ok. It is not up to a Hoya or B+W IR filter quality though, it is basically nothing more than Kodak gelatin filters sandwiched between glass. Despite the much higher cost, I would buy an R72 from one of those guys next time. What I figured out to save a few bucks is to buy the Hoya RM72 67mm filter which costs only $80, compared to the 77mm filter at $280. With a 10D / D60, the 67mm filter shouldn't vignette on most normal lenses (50mm and beyond). And even if it does vignette a bit, just call it character!

Also, isn't the 100mm 2.8 macro only a 58mm thread?




Thanks, Matt, for all the info.
Yes, the 100 macro is 58mm. Glad I didn't go ahead and order the Harrison and Harrison 89A (R72-ish) filter.

Sorry to read that the fine 50mm 1.4 isn't evenly coated for IR blockage. I think it's a great little lens.

Thanks to all who responded.
Tony