DSLR and Ha

[cosmojaydee]

As anybody tried imaging with a un modified  Dslr  using a Ha filter, what effect would this have on the image and if you have tried can you link any pics

Thanks 

[Knight of Clear Skies]

Unlikely to be very successful I'm afraid. Even modded DSLRs aren't ideal for using with Ha filters as the bayer filter (which has twice as many green pixels as red or blue) will block about 3/4 of the signal. Then the IR filter in an unmodded camera will knock out another 2/3 or so of that. 

[Nathan_Pembs]

True about unmodded dslrs, not so good for HA, but Astrobin have some good examples of HA filter use with modded cameras if you search for them. It's not as easy as using a ccd but you can do it with long subs 300+secs

[Knight of Clear Skies]

Yes, here's a good example taken with an Ha filter through a 50mm lens on a modded camera.

[ronin]

You probaly would not get much difference.

It will depend on how much Ha the Ha filter passes, the Astronomic one passes very close to 100% so the in-built one is the one that chops 80%.

On a Canon the built in filter blocks 80% of the Ha passed so if 100% through from the Ha filter then you still have 80% blocked.

On a Nikon the in-built filter blocks 90%.

You need to know the pass or block of each, the result is the product.

[laser_jock99]

There's a school of thought that suggests wider bandwidth Ha filters are better suited to DSLR use so if you can get hold of a 35nm it might give better results than the ultra narrowband 3nm filters.

Anyway here's a picture with a standard DSLR and Baader 7nm Ha filter totalling 2400 seconds

Pelican Nebula Cygnus

[Nathan_Pembs]

There's a school of thought that suggests wider bandwidth Ha filters are better suited to DSLR use so if you can get hold of a 35nm it might give better results than the ultra narrowband 3nm filters

That does make sense if you think about it, if the filter is too narrow, the longer you have to expose for to get decent signal.

Long subs are the dslr's enemy due to the sensor heating up, so a 35nm would work out to be more useable