Correct colour using a modded DSLR

[Aenima]

Thats good to know, thanks.

The white balance is taken very good care of when stacking raw in deepskystacker so its more of an issue when doing other types of photography - the person I advised to use custom white balance was doing widefield with lens + B/W - Uv/ IR filter and getting pale pink results.

I had to stop taking normal pics after the camera was filter removed, the focus was all out - but when out taking long exposures on the scope its very handy to use CWB so the little thumbnail on the preview screen gives you a better idea of how your imaging is going.

Anyway, thanks for the info - will remember 18% grey.

Regards

Aenima

[Photosbykev]

A white card will give you a white balance. I use an 18% grey card because it gives me the white balance and a standard exposure reference. i.e for general photography the metering in a camera is designed to try to make everything the equivalent of 18% grey. Which is why if you photograph a white card using auto exposure it turns out grey and also black turns out less black.

[lensman57]

So I take it the white card is ok. and only 18% off?

Aenima

Hi,

The 18% refers to the card's reflectivity not grayness as the card is "specterally flat " anyway. For raw imaging colour balancing is not necessary but helpful. Standard Graycard reference, Kodak R27 has two surfaces, one gray of 18% reflectivity and one white of 90% reflectivity and both could be used for primarily determining correct exposure and for colour balancing under different illuminations sources.

Regards,

A.G

[Astrosurf]

I was assuming you had light pollution filters in your optical train?

Oh yes, I do! Sorry for being a dunce!

[Astrosurf]

Alex, are we getting there yet?

Yes we are!

[todd8137]

I would buy a cheap ebay one for astro work if thats possible

[andyboy1970]

I took a series of pictures of a white card in the midday Sun then used the INFO function in Photoshop and noted down the white point i.e. 255 for R,G & B.

I got something like R=255 G=222 B=238

When processing moving the White (right) slider to these values for the R, G & B levels gives a better colour balance.

Thats my method.