More IR on sunny days?

[Jemapela]

Hi all IR experts,

I've taken an interest into IR photography, and bought a Hoya R72 filter.

I already read the guide on IR photography and noticed it says "sunny day".

Am I right to assume that there's more IR on sunny days for better IR photography? How about cloudy days? Or at night?

I'm gonna try on my Canon EOS 20D and the kit lens. Any tips?

Anyone tried with the Wratten 89 filter?

[Reno]

it is definitely better to do it on the sunny day...... remember to get your tripod and do your WB with the filter on.!!

no no for nite....

[teerex]

Best IR effect - Bright sunny day, mornings or late afternoons. Shoot with the sun behind you where the most sunlight fall on the scene you're shooting.

Shooting on overcast, cloudy day you will still be able to get IR effect. But without the sun shining on the foliage, you will not be able to get the foliage very white with post processing.

Like Reno mentioned, don't forget to set your White Balance with the filter on first.

[Jemapela]

With the IR filter on, I need to take a shot to do custom WB. Does this shot have to be "properly" or "adequately" exposed with the partial metering circle aimed at green grass or blue sky?

Since the filter is so dark, I have to aim and focus without it first, then put it on to do the custom WB shot. Do you guys go through the same hassle?

Also, what's the reason for adjusting the channel mixer as stated in the sticky thread?

I would prefer to understand than just memorise without knowing why.

Actually, I have tried it out earlier today. Using ISO 800, at f/6.7, my exposure times took 120-180 seconds. I suspect its because it was a very cloudy day. At the widest focal length, I had the central hotspot in every image.

Anyone shot using the EFS18-55mm lens without the hotspot?

[PandaOng]

i notice that you exposure is rather long with ISO 800. I usually shot at ISO 100 f8 for 30s

yes, the kit lens will produce bad hotspot. try opening up your aperture. (Tips by Max2.8, have not tried it myself)

try the EF 50mm f1.8 (rather cheap and good piece of glass) it does not produce hotspot. only downside, you have to zoom with your legs. good luck!!

[deadpixel]

Originally Posted by Jemapela Also, what's the reason for adjusting the channel mixer as stated in the sticky thread? I would prefer to understand than just memorise without knowing why.

When you shoot in IR, and depending on the filter you use, most of the visible spectrum from mid-red downwards is blocked. This results in shots that are slightly tinted with red and where blue skies appear "black". You would have noticed by now that if you do not do a "brightly-lit-grass" CWB your photos would turn out completely red, and even if you did, the photos would look orangey or brownish with very dark skies.

When you do a Red/Blue Channel switch, you are actually changing colors originally recorded as shades of red to shades of blue and anything originally recorded as shades of blue to shades of red. Since the skies of IR shots are tinted with residual red that are not completely filtered out, this would turn them to blue, giving your photos the desired effect of deep blue skys with everything else having a slightly blue tint.

To test out what I just said, just draw two circles or boxes in Photoshop, one blue and the other red. After you flatten the image, open the channel mixer, do a R/B switch and watch the red turn to blue and vise versa.

Cheers,
Matt

[Jemapela]

I have read that opening the aperture helps reduce the occurence of the central hotspot. That was the reason why I used f/6.7. With the kit lens, there isn't really much more to open up.

Has anyone else here used the kit lens and found it hopelessly incompatible with IR? Or could it still be used (as long as not at the widest focal length and opened fully)?