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Infrared help!

PostPosted: Sun May 15, 2005 8:23 am
by mateo
Hey this is an emergency!!!!!! I just got my gosu uber l337 infrared filter today! and... it doesn't appear to be working as I wanted it to. here are some samples:

Image

Image

How do I fix this to get the WB correct so that the grass/tree. etc are white? I tried taking the red out in in photoshop along with blue, green and many combos. The images I've seen have all been nice and white for the green from the get-go. What do you use for infrared?

mateo

PostPosted: Sun May 15, 2005 10:44 am
by sirhc55
Mateo - what wavelength does this filter work at? Any info on the filter could help in working out the problem.

PostPosted: Sun May 15, 2005 10:50 am
by Nnnnsic
Is this one of those IR filters that looks orange or green?

PostPosted: Sun May 15, 2005 11:31 am
by mateo
http://www.adorama.com/BW67IR093.html

That's the filter! It filters out the visible spectrum, i.e. 750nm +... I don't get it. I was under the impression it was something wrong with my White Balance, thus why the purple is showing up. Hope you can help!

mateo

PostPosted: Sun May 15, 2005 11:39 am
by sirhc55
Mateo - try converting to black and white! The 093 filter is basically for B&W film and as such will give results in color that might not be expected.

This is the filter that you have to set your scene before exposure due to not being able to see anything when the filter is attached.

PostPosted: Sun May 15, 2005 1:31 pm
by brembo
Have you tried taking a white balance reading off of a patch of green grass, if not, give it a go.

PostPosted: Sun May 15, 2005 1:49 pm
by mateo
I'll try converting it to B&W... but the ones I have seen have been (like http://www.pbase.com/catson/infrared_world). Those are the images I want! I know that person used a Hoya 72 etc, but the Hoya filters out all color too, as far as I understand it (I think it's 730nm? something like that, which is all of the visible).

I tried to do WB on the grass... that's what the problem was, it wasn't turning.. white :x

mateo[/url]

PostPosted: Sun May 15, 2005 3:10 pm
by sirhc55
Not sure as WB will be of any use in this situation because you are dealing with IR.

PostPosted: Sun May 15, 2005 3:20 pm
by sirhc55
Mateo - I do not know if your pics have had any PP but I took both of your pics into PSCS and played around in colour balance (roughly). I think you will need to do some experimenting - but here are the results:

Colour balance - midtones - +24 red; +100 Green; -64 yellow

Image

Colour balance - midtones - -45 cyan; +100 green; -16 yellow

Image

As you can see there is a difference. Shoot RAW and play :D

PostPosted: Sun May 15, 2005 5:00 pm
by Greg B
The BW conversion is important to the outcome with IR.

Try splitting the image into RG and B channels and check out the differences bewteen them. I generally use the red channel to get my BW image, then start tweaking. Good luck.

infrared

PostPosted: Tue Jun 14, 2005 6:02 pm
by olrac
I just figured out how to get my hoya r72 filter to not give a red color cast on every photo.

You need to take a white balance reading off some grass that is in some sunshine.....

i like to use preset and measure instead of using a photo but this is personal preference.

Make sure that the filter is on the camera when you take the reading, as obvious as it seems i spent hours thinking i was not measuring my white balance correctly.....

well have fun i may post some of my photos at some stage.

My wife thinks the IR photos look like an early ninties video clip. You know you have succeded when you are channeling the essence of MC hammer in a photograph :)