IR again? Little help!

[Skipper]

Ok I got my Hoya R72 an set up the tri-pod and took several in my frount yard.

Well when I changed them to black and white the trees did not look like others do, not white, so what am I doing wrong.

Had a little blur but I can figure that out.

There just got to be more to this, I did however get talked into a red filter the cost was so little I did not mind.

They told me that the red filter was the same as the IR, I was able to get a nice clear shot but when same problem as above.

Can some one help in this new toy I am playing with?

I am off work tomorrow so will go out and play again.


Thanks much

Skip :lol:

[Jon]

Examples?

The Wood effect (after the definer, not the trees) that makes IR so distinctive is because leaf cells reflect strongly not only in green but in near IR. If there's not a strong source of IR (i.e. bright sunny day) the effect will be seriously muted.

[Skipper]

Hello Jon,

Thanks much, we have a very sunny day today will go out and play.
One question will the Red filter do the same as the IR as I was told by a camera store?

Skip

[Jon]

It'll let some of the visible spectrum (red light) through, but the effect won't be too far off. It'll make it easier for you to see what you're framing too, although not the final effect, and may reduce any problems with focussing due to the IR focus shift (back in the old days, when men were men and lenses were focussed manually :{)# lenses had an IR focussing mark in addition to the regular one).

[Skipper]

Ok Jon,

This B the first one but the sky ran into the house so thought I would us PS and mess with it.

Forget the tree and the sky what do you think of the IR?

I can see there is a lot to learn about IR.


Thanks

Skip :lol:

http://www.cv-access.com/twilight/ir.tif

[Jon]

Sorta hard to say without a little more to go on.
First, as a favour to people who are using dial-up (some of us do, from some sites), could you post JPGs, which can be smaller, and which most browsers understand without loading helper apps.
Second, has it been rather dry, or do you have a less-than luxurious lawn? I ask because it looks kinda grey. Vegetation reflects IR most strongly when it's in good health. That's one reason the USDA, among others, now does aerial photography work in CIR or multispectral. That lovely bright magenta's a sure cue to a healthy crop, and even quite small variations will show up strongly. Unhealthy stuff tends toward the cyan, as does pavement. In film BWIR, healthy vegetation would be almost white. There should be some classic aerial examples over on NASA's site, (LANDSAT, Skylab among others).

Third, if you were shooting in straight IR, the shadows would normally be very pronounced. If there's much big water droplets (moisture does a wonderful job of soaking up IR) it'll bounce the IR all over, reducing the contrast. Very dry air, even with fine haze, should be better. Back, not side, lighting helps, as that's when the incident light scatter isn't being bounced back as strongly to you. So part of using IR for peak effect is struggling with the light and weather conditions. I can't say what effect various atmospheric pollutants would have, but CO2 in the Venusian atmosphere is considered a major contributor to a runaway green-house effect, bouncing the IR radiation back in, instead of letting it radiate out into the upper atmosphere and space.

I'd suggest wandering over into the trees on the horizon and shooting some there. Good source of high-reflectivity IR, and also of contrasty lighting if you're on the edge or in a glade.

My D60 has an anti-IR filter in place. Don't know about the 10D and DR, bur I assume not if you can photograph the light from a remote control. As a result, my IR experience is not with Canon digitals, but mostly the good old-fashioned way with Kodak BW & (E-4) Ektachrome IR. I'll try pulling out the old gels and an IR-capable digital when it clears up here.

[Jon]

Here's (http://www.mo.nrcs.usda.gov/technical/geo_tech/out/CIRvsBW.pdf) an article that talks a bit about viewing classic "false-color" IR imagery as either "natural color" or black-and-white. They use ArcView, a GIS tool, but you may find it helpful both for seeing what colour IR normally looks like and for the concepts of post-processing on IR imagery.