A Beginner's Lesson in IR

[raymondluo]

Hello all,

I have been reading up on IR and am considering getting a GF-1 converted to IR for B+W and I have a few questions.

I understand that the higher the wavelength (specified) in the camera body less colors will pass through. at 750nm and beyond it will pass red, and only B+W images will be produced. Since the higher the wavelength the more colors will be blocked, will that affect low light sensitivity?

And what's this I hear about an IR-pass filter in front of the lens? Will there be a need for a lens IR filter if I already have the IR-modded body at a high wavelength? I am assuming that the resources I've read are rather dated and require additional filtering of visible light since they may be referring to usage on film cameras.

The last question would be on flash photography. I understand that the purpose of IR photography is to capture objects at 'a different light', so will a normal flash work in the same fashion at 750nm ++? Also, a little bird told me that tungsten light is a good producer of invisible light.

Okay so that isn't the last question, but I would like to hear the process and difficulty of replicating the consistency of the look between image to image and if shooting beyond 750mm will help since I've heard of color balance issues.

This resource has been very informative for me so far. http://www.ayton.id.au/gary/photo/photo_infrared.htm

 

[Vivek]

Whatever you do, please scratch those "suggested subjects" in that link.

With the Panasonic NMOS sensor, false colors are feeble in IR. 700nm or 750nm would make little difference. Light sensitivity isn't affected.
Since metering and focus is off the imager itself, pretty much nothing changes- one of the strengths of liveview.

It is either muted colors (two tones) or monochrome. There are no color balance issues to worry as there are very little colors to deal with!

Regular flash would work for IR.

You do not need additional filters on the lens with a dedicated IR cam.

Tungsten works well.

 

[raymondluo]

Ah, that's great then. So I can actually do something like an incognito flash photography without the visible light flash if i wanted to?

 

[raymondluo]

So anyway I called the guy at my local store and he said that the GF-1 body can only take up to 7##nm filters. Apparently 800nm and above are too big. Real bummer there. Anyone knows what's the highest filter the GF-1 can take? Thank you for your patience.

 

[Vivek]

Ah, that's great then. So I can actually do something like an incognito flash photography without the visible light flash if i wanted to?

Yes, you can.


Untitled by Vivek Iyer, on Flickr

while flashing


Untitled by Vivek Iyer, on Flickr

Wratten 87 on the pop-up. This works accurately (within its range).

You can put any IR filter over the sensor as long as the filter with the right thickness (all available or can be custom ordered) and dimensions. There may be more out there than your local store.

 

[raymondluo]

Thank you Vivek, you've been a blessing to the forum indeed, and your G1 is looking very spy type!

 

[Vivek]

You are most welcome, Raymond Luo!

These folks will cut up any bandpass filters (thickness, size).

http://www.galvoptics.fsnet.co.uk/Index.htm

Pricey but very reliable.