A question on Filters

Exfso (Peter) · #1 26-07-2009, 01:39 PM

I was wondering if I could get some feedback on what filter is necessary to get more out of nebula's. I am using a modified 40D that is cooled and seem to remember having read somewhere that the UHC filter should do the job. However, all I read is that they are good for visual. I was wondering how this translates into results for imaging on a DSLR.
All suggestions welcome.

Mike21 (Michael) · #2 30-07-2009, 07:28 PM

Hi Exfso,

I'm definitely no expert at imaging, but I thought the logic went something like this. A UHC filter reduces the amount of extraneous light, therefore, in a proportional sense, you're getting more of your nebula light - that'd be good for photography. There is also an important distinction to be made between emission and reflection nebulae though; one goes well with a UHC the other not so well. Don't quote me but I think UHC's perform better on reflection nebulae. Of course in absolute terms ANY impedence will reduce the rate at which your 40D gathers light and therefore increases your exposure time.

The little I know came from this site:

http://www.company7.com/baader/options/uhc-s.html

Hope I've finally helped someone else.

Mike.

Bassnut (Fred) · #3 30-07-2009, 07:38 PM

For a cooled modded 40D, an Ha filter is the go for nebulas IMO, a screw on or clip in. You can then image with moon up too.

Hagar (Doug) · #4 30-07-2009, 10:33 PM

G'Day Pete. Ha is the way to go but be prepared for some strange processing. The ha will gather so much more from emmission nebulas but will require a lot longer exposures and will require some new Photoshop skills to get the best results. A UHC will darken the background and highlight the nebula but will also add some colour casting to the image.

My choice would be a Ha which allows you to take your Ha /lum images during bright moonlight nights then gather your RGB during the dark nights.

Exfso (Peter) · #5 31-07-2009, 01:36 PM

Thanks chaps, all makes sense. With the cost of filters, I just did not want to go out and spend a fortune, must admit I was thinking of an O111 as well. Trying to see if I can get the effect commonly known as the Hubble Pallet. Nothing like wishful thinking hey