Stacking the mix

[Mickoid (Michael)]

I'm trying to work out the best way of combining filtered and unfiltered subs to achieve the best star colours. This shot of a section of the Milky Way I shot from suburban Melbourne the other night. It consisted of 5 x 30secs with a CLS clip in filter on a full spectrum modded DSLR and 5 x 30 secs with an unmodded DSLR. The same 50mm lens was used on both cameras at f2.8 1600 iso.

I just chucked the 10 subs into DSS and this is what it came up with after a little contrast and levels adjustment in PS. The question is: Should I have processed the filtered and unfiltered subs separately in DSS and combined the resulting Tiff files in PS or is what I did the way to go?

Any comments welcome.

[sil (Steve)]

I always found setting daylight white balance gave me more accurate star colours. This shot they all look cast to me rather than accurate. Personally I don't use either DSS or PS for any astro processing at all. but try chucking a single raw into photoshop and use ACR to set white balance to different options and a little stretching, ignore milky way detail, just look at the star colours and see for yourself. My DSLR is not modded so I dont know what effect that has on a good white balance setting for you, but its the way I work anyway.

[Mickoid (Michael)]

Thanks for the advice sil. My version of PS doesn't support ACR, in fact it's so old it won't even open RAW files so I may have to update the software. I have to convert the RAW to TIF files and take it from there. I've heard DSS is not the best application to use for astro processing, you get what you pay for and DSS is free, so I can't really complain. It's good to use when you're starting out but I now see it's limitations so I might have to invest in something a little better such as PI and Star Tools. I was just wondering how others process their filtered and unfiltered subs. My unmodded subs usually hold fairly good star colours but of course you miss a lot of the Ha and OII that I can capture with the modded. There are many things to learn so experimenting with different techniques can help find the best option.

[rcheshire (Rowland)]

Perhaps try StarTools demo version. It's fully functional except for saving images. A basic work-flow should answer your colour questions.

[raymo]

DSS is fine for its intended purpose, which is stacking and very basic processing.
raymo