Filters for a modded dslr?

[scoobymike]

Hi,

I have just bought a 1000d canon and am going to mod it

My question is whether Ha and OIII filters are usable/necessary with it? I understand filters only let through a certain wavelength, which must mean that the raw image contains all data. So is it possible to extract that data in software, or is it just swamped and made indescernible by the rest of the spectrum?

They're kind of expensive in 2" format, so I'd like to know if its worthwhile investing?

Thanks!

[Darth Takahashi]

DSLR already have a Bayer mask in them which cannot be removed. This gives you the colour images RGB, but there are 2x G and B than R so filters will not help, that is unless we are talking about light pollution filter?

[nag]

Hi,

Usable yes, necessary no.

You can use those filter with a DSLR, but you gonna need a lot of exposure time.

Nuno

[swag72]

I have an Ha 12nm clip in filter that I used to use with my modded DSLR. Makes for some great mono images, but you are looking at 15-20 minute exposures to get much worthwhile data.

I also had a clip in LP filter (also an Astronomik) which meant I was able to get 8-10 min exposures without having an orange-out!!

I would absolutely recommend the Astronomik clip in filter range. If you are going to use a normal camera lens with them though, perhaps use the camera on a tripod for wide field, you can not use EF-S lens's with them though.

[scoobymike]

Hi,

And thanks! 15 - 20 mins seems like a very long exposure - maybe I need to play with my new guiding set up and get used to using that with the canon (when it arrives!) first...

Sara, as you obviously have some experience in this, in your opinion are the results worth the extra effort and expense, or if you had the chance to do it all again would you stick with plain old 'broad' band? I have no lenses for the canon ( I have a nikon for everyday use) yet, is it worth getting one for some decent wide angled shots?

Thanks again

[Stephen]

swag72 is more of an authority on this than me, but am I not correct in thinking 5 mins and 10 mins can produce reasonable results too?

Obviously not as much as 20 mins, but sure there's plenty of samples on here of shorter Ha DSLR shots?

[swag72]

Maybe I always just went for the hard stuff!!

Actually, just looked through my Flickr stuff at the Ha DSLR images.

IC1805 - Heart and Soul Nebula | Flickr - Photo Sharing! - These were 10 min exposures

NGC7380 (Wizard) in Ha | Flickr - Photo Sharing! - This was 20 min exposures

@Mike - I loved using the Ha filter and it was definitely worth having to be able to image when the moon was bright. However, there was a real knack to it, it was a devil to focus for example. The wider field was even more difficult than the 300mm stuff. I found noise to be a big problem for me with the DSLR full stop, but it was very noticeable in Ha to my mind. Also, seemed you needed loads of subs!! Glad I did it though and yes, I'd do it again.