Blue Pictures??

[Bizibilder]

I am currently imaging with an unmodded Canon 1000D and seem to have a recurring problem in that my images there seems to be a dominance of blue and a distinct lack of very much red.

Has anyone had this before or could you make any suggestions as to why it may be happening?

I must admit to being a beginner with PS etc but even using the colour channel and saturation controls I seem unable to balance my images properly.

For "regular" photographs (ie non-astro) the colour balance seems to be perfectly OK.

[lukebl]

I've noticed that your images tend toward the blue, but can't offer any advice, apart from suggesting that you post an un-edited stacked TIFF somewhere for us to download and have a go on it ourselves. I'd love to have a bash at it.

I use a 450D, and found that it has a fairly good response to the red end (for a DSLR) and wonder if it's something to do with the 1000D.

[Bizibilder]

http://dl.dropbox.com/u/19930926/NGC4631%20Direct%20DSS.TIF

The above should be a link to dropbox. It is a DSS stack of my "Whale and Hockey stick" image from last night. No processing at all - not even the usual 20% saturation that I use. (it will take a while for the file to load!!)

[lukebl]

http://dl.dropbox.com/u/19930926/NGC4631%20Direct%20DSS.TIF

The above should be a link to dropbox......

Nope. The link doesn't seem to work. I just get an error message saying the page isn't available.

[Bizibilder]

Should be there now!

[lukebl]

Hi Roger,

I had a look at your TIFF, and it certainly is distinctly blue and doesn't look right. Nothing like any of the images out of my 450D, which show a much wider spectrum. I had a play with it, but my PS skills aren't that good, and I can't really improve on the image you posted the other day. So I can't really offer any advice, except that maybe it's something to do with the camera settings, but I'm sure someone else here can help. Don't know much about histograms, but the blue band is very much wider than the R or G.

Do you use a LP filter? Not sure that would make much difference to the colour cast, though.

[steppenwolf]

Some LP filters to indeed add a colour cast - what filters if any are you using?

[Bizibilder]

No filters at all. Also the camera is set to "Auto white balance". The only thing I can think of is that I get quite a bit of orange in my 5min subs from light pollution (especially recently!!) - I'm wondering if this is masking the "red" and is being removed in processing? I must also say that the LP is not very apparent at all in my stacked TIFF's from DSS.

I've appended a single 5min sub (a reduced JPEG - I'm using RAW of course).

[lukebl]

That's a similar cast to mine, but a basic LP filter will make a huge difference. Definitely a good investment.

[Bizibilder]

Which one Luke? I'm getting one this week and assume the SW 2" LP will do - my streetlights are good old "sodium oranges". Or is there a better one?

[lukebl]

Yes, mine is the basic SW one. You should notice a big difference.

[Bizibilder]

Thanks.

[dph1nm]

I had a look at your TIFF, and it certainly is distinctly blue and doesn't look right. Nothing like any of the images out of my 450D, which show a much wider spectrum.

Looks exactly like what I get out of my 1000D. There is basically very little red response in this camera. I find all galaxies come out blue/green, even with an LP filter (although the LP helps by reducing the amount of saturation the red channel, which means you get more red dynamic range to play with).

NigelM