| beejaybee |
| (Marvin) |
| 08/07/2008 14:13 |
|
Re: Digital Infrared Part 2
|
Quote:
After having read around the web, everyone was saying to expect longer exposure times (and judging from the darkness of the glass, I was expecting this as well) but was surprised when it didn't take any longer to capture an image.
So, now I'm got this great (ha!) image, what the heck do I do with it? It's a very wine dark colour throughout. Fair enough, I also expected that, but I was expecting, I dunno, some IR image...where did I go wrong?
The light meter doesn't react the same way as the sensor ... you're going to have to apply loads of exposure compensation or (more probably) manual mode with "guesstimated" metering. Start at about 2 stops over what the meter says and increase in 1/2 or 2/3 stop increments until the sensor starts to saturate, then back off a bit. Once you've found out what correction needs to be made, that will serve as a reasonable starting point in future. You may need less correction when the light is reddish anyway (dusk & dawn) and more when the light is bluer (midday sun, cloud, deep twilight etc).
Your image is red because only the red sensitive photosites on the sensor have any sensitivity at all to the IR transmitted by the filter. You will need to convert to monochrome; perhaps the camera's built in "monochrome picture style" conversion will do, but doing the conversion in external software (Photoshop) and setting the ratios to 100:0:0 R:G:B will almost certainly work better.