IR filter disk test request

has anyone removed their IR filter on their SD 14/15 and replaced it with an IR filter on the front of the lens?

am asking to see if this fixes the green/magenta colour cast issue. if it does, i'll take the IR filter off my DP2S and put an IR filter onto my lens adapter. it's stuffing around, but so is trying to remove colour casts from (otherwise fine) photographs.

thanks for any input.

Kye Wood said:

has anyone removed their IR filter on their SD 14/15 and replaced it with an IR filter on the front of the lens?

am asking to see if this fixes the green/magenta colour cast issue. if it does, i'll take the IR filter off my DP2S and put an IR filter onto my lens adapter. it's stuffing around, but so is trying to remove colour casts from (otherwise fine) photographs.

thanks for any input.

Click to expand...

I just batch process all of my DP2s raw files through DNG converter and then CornerFix and color casts are gone. Quick and easy. See link in this thread for free download of CornerFix (Mac and PC versions):
http://forums.dpreview.com/forums/read.asp?forum=1027&message=36559300
--
Carl
Website: http://www.schophoto.com/gallery/
TheDailySnap: http://www.blipfoto.com/SchoPhoto

Kye Wood said:

has anyone removed their IR filter on their SD 14/15 and replaced it with an IR filter on the front of the lens?

Click to expand...

Yes, I have tried this. I bought an infrared blocking hot mirror to put on the front of a 20mm f/1.8.

Kye Wood said:

am asking to see if this fixes the green/magenta colour cast issue. if it does, i'll take the IR filter off my DP2S and put an IR filter onto my lens adapter. it's stuffing around, but so is trying to remove colour casts from (otherwise fine) photographs.

Click to expand...

My experience was that it did not produce normal pictures. IMO what's needed is the exact IR blocker that's in the camera which I don't believe is available in any form other than the one in the camera. Below is a shot with an SD14 with the internal dust protector/IR bloking filter/hot mirror removed, and with a maxmax IR blocker/hot mirror attached to front of lens.
This is how the image came from the camera, converted in SPP with "Auto" setting



This is the same image corrected for WB in SPP by clicking the WB eyedropper on the white area to the right of the boy's head. Better, but still no good.



This is the same image further adjusted in PS using channel mixer, best I could do but still no good.



So, unless a hot mirror/IR blocker with the same spectral sensitivity as the one in the camera, and who knows what that is, could be procured, normal looking pictures would not be possible, IMO. (not to mention big waste of money for an 82mm hot mirror, want to buy it? )

--
JohnK
Take a picture, it'll last longer.

How could I miss this? Thank you thank you thank you. Mind you, if it doesn't work, I'll be back.

http://sites.google.com/site/cornerfix/using-cornerfix/creating-a-lens-profile

Carl Schofield said:

Kye Wood said:

has anyone removed their IR filter on their SD 14/15 and replaced it with an IR filter on the front of the lens?

am asking to see if this fixes the green/magenta colour cast issue. if it does, i'll take the IR filter off my DP2S and put an IR filter onto my lens adapter. it's stuffing around, but so is trying to remove colour casts from (otherwise fine) photographs.

thanks for any input.

Click to expand...

I just batch process all of my DP2s raw files through DNG converter and then CornerFix and color casts are gone. Quick and easy. See link in this thread for free download of CornerFix (Mac and PC versions):
http://forums.dpreview.com/forums/read.asp?forum=1027&message=36559300
--
Carl
Website: http://www.schophoto.com/gallery/
TheDailySnap: http://www.blipfoto.com/SchoPhoto

Click to expand...

Hey John, thanks for the detailed reply. Very much appreciated.

I could find the specs of Sigma's IR filter using an RSAT (reverse spectrometer analysis thingie) nah, just joking, I'm stuffed there as well...

Guess I'll just have to see how cornerfix goes. http://sites.google.com/site/cornerfix/using-cornerfix/creating-a-lens-profile

JohnK said:

Kye Wood said:

has anyone removed their IR filter on their SD 14/15 and replaced it with an IR filter on the front of the lens?

Click to expand...

Yes, I have tried this. I bought an infrared blocking hot mirror to put on the front of a 20mm f/1.8.

JohnK said:

am asking to see if this fixes the green/magenta colour cast issue. if it does, i'll take the IR filter off my DP2S and put an IR filter onto my lens adapter. it's stuffing around, but so is trying to remove colour casts from (otherwise fine) photographs.

Click to expand...

My experience was that it did not produce normal pictures. IMO what's needed is the exact IR blocker that's in the camera which I don't believe is available in any form other than the one in the camera. Below is a shot with an SD14 with the internal dust protector/IR bloking filter/hot mirror removed, and with a maxmax IR blocker/hot mirror attached to front of lens.
This is how the image came from the camera, converted in SPP with "Auto" setting



This is the same image corrected for WB in SPP by clicking the WB eyedropper on the white area to the right of the boy's head. Better, but still no good.



This is the same image further adjusted in PS using channel mixer, best I could do but still no good.



So, unless a hot mirror/IR blocker with the same spectral sensitivity as the one in the camera, and who knows what that is, could be procured, normal looking pictures would not be possible, IMO. (not to mention big waste of money for an 82mm hot mirror, want to buy it? )

--
JohnK
Take a picture, it'll last longer.

Click to expand...

Hi:

I did the very same thing as JohnK, i.e. got a filter from Maxmax (at great cost) with pretty much the same results. You end up with a worse problem than you started with.

I was trying to correct for the green cast I found in numerous (if not all) of my SD14 captures and pursuant to a series of long threads on this forum. Among other things, some people had noticed that the actual ir filter/dust protector, once a replacement was ordered, was different from the original, supplied with the camera, and this led me to believe that an outside filter (like the maxmax) could be a solution.

I also got a replacement from Sigma. I could not detect any difference at the time and was quite peeved at the expenditure of time and money for actually identical or worse results.

This green cast issue has been basically solved for me. I got a new camera (SD14) from Sigma, then new versions of SPP came along and finally, better control of exposure (making sure you are never underexposed, for one). So I kind of dropped the issue altogether.

Nevertheless, I am still very interested in finding an exact replacement of the Sigma ir filter/dust protector as a filter to install in front of the lens for the reason that removing the inside ir filter opens the mirror chamber and leaves some precious extra millimeters for the back elements of some third party lenses (once set at infinity) that I would LOVE to try on the SD14, or SD15 or SD1 for that matter.

So, yes, a perfect spectral replica of the Sigma ir filter/dust protector would be very, very valuable to me.

Any help in that direction would be greatly appreciated. I just thought (reading this post) that I could send my extra Sigma filter to Maxmax and see what they say....

Thanks.

I can supply filters made to the Foveon spec that we sell to companies making industrial cameras using the F13. The filters made specifically for Sigma are available only in the size they use. If you are interested, send me an e-mail - dave at alt-vision dot com.
--
Dave Gilblom
Alternative Vision Corp.