IR Question

doenoe · Aug 8, 2006

Ok, i always read (and now tell other people) that with Digital IR, you have to set an custom whitebalance. For the whitebalance, you have to take a picture of grass (just grass) and use that for your whitebalance.
But i was shooting some IR some days ago and just shot a pic with the filter on it (no custom whitebalance yet), so the pic looked all red and pink and whatever and then used that pic as my whitebalance.
So with my non-grass white-balance i took a couple of pics and they turned out fine. Below you will find an example. I worked the levels on the pic, but i always do that.
So i dont think it is really nescesary to take a pic of grass which fills the whole frame. You can just take a pic with the filter on and use that for whitebalnce. Or am i making a mistake thinking that and something is still terribly wrong?
Here is the pic:

Greetz Daan

Arch · Aug 8, 2006

yea im pretty sure if your shooting RAW, you dont necessarily need any preset custom WB...... i do anyway.... the same method as you (shoot grass to get a green WB)..... but i think you only REALLY need to do this if your shooting TIFF or Jpeg.......
I think its possible (although i'v never tried) to shoot with Auto WB and then do the usual WB adjustments in the RAW software to get the same result.

doenoe · Aug 8, 2006

ok, thanks for the answer.
And this was a jpeg shot. Still have to confince myself to shoot in RAW.
But i also heard that you can shoot in Auto WB in RAW and then to set the right temp, you click on the leafy bit in the picture with the eyedropper thingie in the RAW software stuff (you get it?) Have to try that sometime.

rmh159 · Aug 9, 2006

What type of filter did you use? I'm looking into IR filters but I'm not sure of any others besides the Hoya.

Digital Matt · Aug 9, 2006

I shoot everything in RAW, infrared and otherwise, so I only worry about WB in post.

AluminumStudios · Aug 11, 2006

RAW IS the way to go with infrared. I shoot in RAW with my D50, take the horribly red images and use the whitebalance tool in Rawshooter to bring the images to life. I get a lot of control and different results by clicking on grass or clouds for my whitebalance rather than being locked into whitebalance provided by a photo of grass.

I can't praise RAW enough for IR. I'll never shoot .jpg again ...

fotogenik · Aug 12, 2006

Archangel said:
yea im pretty sure if your shooting RAW, you dont necessarily need any preset custom WB...... i do anyway.... the same method as you (shoot grass to get a green WB)..... but i think you only REALLY need to do this if your shooting TIFF or Jpeg.......
I think its possible (although i'v never tried) to shoot with Auto WB and then do the usual WB adjustments in the RAW software to get the same result.

Curious, does this method also work if you shoot dead (i.e. brown) grass? I mean it is (I think) the chlorphyll in the grass giving off the reflected green color. Dead grass has no chlorphyll and therefore doesn't reflect the same way. Any opinion on this?

Cheers,

rmh159 · Aug 12, 2006

Can't tell if this is a joke or not but I'll give the benefit of the doubt. I believe (and I'm a complete noob at IR) the entire point of shooting the green grass is for the <drum roll> green color. If you shot dead grass... you'd kind of be defeating the purpose of getting a frame filled with green color.

Why don't you give it a try though and report back to us how it works. :wink:

Rashadan said:
Curious, does this method also work if you shoot dead (i.e. brown) grass? I mean it is (I think) the chlorphyll in the grass giving off the reflected green color. Dead grass has no chlorphyll and therefore doesn't reflect the same way. Any opinion on this?

Cheers,

fotogenik · Aug 12, 2006

No, wasn't really a joke, just an experimentation sort of question really. I don't particularly expect the answer to be yes it would be ok to do that, but then I am not sure what the ir reflective properties of dead grass is.

Your not shooting the white balance fro green, your shooting the white balance for full IR reflection of light. How much IR does brown dead grass reflect? Is it the Chlorphyll that reflects the IR? Is the Chlorophyll present in dead grass? Something can be present but dead and still possibly reflect the IR light.

Just curiosity so to speak.

I don't particularly do in camera white balance when I shoot IR because I find it much easier to do it in camera raw post.

Cheers,

doenoe · Aug 13, 2006

i dont think it will work of you shoot dead grass. I know that of you shot trees in fall (with dead leaves on it) it wont look white. I read somewhere that if the tree is healthy it will look nice and white. If it is an old tree which is dieing, the leaves wont reflect alot of IR and so wont look white. I think its the same with grass. You can better use the young and still green looking grass for the whitebalance in stead of the dead stuff (which probably wont reflect the IR)
Have to try it someday though.

Arch · Aug 13, 2006

Hmm.... im not sure about the dead grass thing.... its worth trying out one day....
I just did a quick experiment with the WB on auto, shooting in RAW..... and the same shot with the custom WB i'v been sticking with.....
There's no difference in the final conversion at all...... the camera preview is harder to make out on auto because everything is red, so parts of the image are harder to see, rather than the blue/greys and browns you get with using the custom WB. So maybe for compositional purposes out in the field, it may be better to stick with the custom WB...... but it wont effect the final image in any way if you choose to shoot on auto.

AluminumStudios · Aug 16, 2006

I've shot dead, brown, leaves before and they still showed up as fairly bright in IR, not as vividly white as living leaves, but I don't suspect it's the chlorophyl that is reflecting all of the IR that gives plant's their white appearance.

I've also shot areas where patches of grass were dying, and once againt it looked similar (fairly light) but not as vivid (I could easily distinguish it in the IR photo.)

That being said, dead grass is still somewhat neutral gray'ish/white'ish in IR and would probably work to WB off of.

But still, I'm all into shooting RAW then whitebalancing in rawshooter. I find that clicking on different leaves or even the clouds can give me slightly different results (sometimes more blueish or reddish vegitation.) I like being able to choose which is right for each photo after I take it.

fotogenik · Aug 16, 2006

yep, totally agree. I like being able to custom white balance in software by clicking different spots to acheive the wb I want for a particular shot.

ksmattfish · Aug 16, 2006

rmh159 said:
Can't tell if this is a joke or not but I'll give the benefit of the doubt. I believe (and I'm a complete noob at IR) the entire point of shooting the green grass is for the <drum roll> green color. If you shot dead grass... you'd kind of be defeating the purpose of getting a frame filled with green color.

It's not about the green color. It's about the way chlorophyll affects the reflection of infrared wavelengths. When you shoot green grass/foliage it reflects more IR, but a green building doesn't necessarily do the same.

One thing to keep in mind about white balancing IR is that IR is invisible, and by converting it to visible, you (or the sensor or film you are using) are making up a color for it. There is no right visible color for IR. Make it pink, make it green, make it orange, whatever you want.