IR on the CHEAP

[Don Hoey]

D2X polarised false colour infrared.

Well this one is a bit of a surprise. On the D100 most of the false colour would have gone, particularly in the sky. Processing was the same as in my gallery shot of The Swaffham Turbine taken on the D100. I have attatched that for comparison.

Adding a polariser has taken the exposure out to 15secs. In this situation an eyepiece blind of some sort is absolutely critical to prevent visible light contamination.

Don

[Don Hoey]

I have just tried the B+W 091 Dark Red filter, and that just lets too much visible light through. So it is a no go way of getting round the long exposure times required with a proper IR filter.

Don

[Don Hoey]

Originally Posted by postcardcv

Well I ordered a screw in filter to have a go on the cheap, unfortunately the 30D clearly has a very strong internal IR filter - without the filter I was getting 1/400th at f8, with the filter on I needed to push the shutter speed out to a ridiculous 25 seconds to anything. Even then the files don't have that IR feel, I think with the long shutter speed I'm also getting some visable light contamination. I think I now have two choices, get the camera converted or forget about IR for now...

What filter did you get then Peter.
Looking back at the 30D test with a Hoya R72, that chap was getting 4 secs at f2.8 at ISO800. So say 16 secs at f5.6 ISO800 puts you in the same ballpark as my D2X with polariser. Stronger IR filters than the R72, example the B+W 093 that cuts at 800nm, would probably require far longer exposure times.

My tests show that the only possible source of IR contamination if you use a screw in IR filter, is stray light through the viewfinder. Eliminate that, and exposure duration is not a prob until sensor heat creates its own set of problems.

Don

[andy153]

Hi all, I have just posted a couple to the Gallery. Full processes explained and EXIF preserved. Don these are my first Manual WB - set to the surrounding grass. PS, I chose to convert the D100, rather than a D2x, because several people mention its very strong anti-aliasing (?) filter, which makes it quite insensitive to IR.

[Don Hoey]

Originally Posted by andy153

......... Don these are my first Manual WB - set to the surrounding grass. PS,

Now Andy I suggest you check out the shooting banks.
The D100 has two available. This would allow a set up similar to mine, where I have Bank A on Auto WB, and Bank B on Custom WB taken from sunlit grass. Depending on the effect you want you can just go to menu (1st line) and pick your preference without redoing WB for each session.

Next up if you do not have one, is a polariser.

Don

[andy153]

Thanks Don - done the shooting banks and have the polarizer

[Don Hoey]

Checking the net for various IR processing methods I found a blog with some info that is quite useful, particularly for any Canon 40D users fancying a go with an unmodified camera.
It is a two parter with quite a few relevant responses in each part.
Part 1
http://stevencastle.wordpress.com/20...ng-on-a-d-slr/
Part 2
http://stevencastle.wordpress.com/20...-false-colour/

Don

[postcardcv]

after much messing around I've come to the conclussion that either the Canon's aren't great for IR, or my cheap filter isn't a true IR one... or most likely I just don't know what I'm doing! Anyway I picked up an IR converted compact to have a play with and it really does make things simple.

[Don Hoey]

Interesting result Peter.
A couple of questions for you. How much processing did you have to do, and is this taken with auto or custom WB ?

Don

[andy153]

Very interesting Peter, another question, do you know what filter is in it?