Astronomic CLS CCD exposure times?

[Axeldude]

I've been looking to get me an Astronomik CLS CCD filter for my modded 1100D, but I've read it will increase my exposure times "significantly".

Can someone tell me what "significantly" is?

I mostly shoot unguided subs of about 1.5 to 2 mins at ISO 1600 as this is the farthest I can go without trailing with an ED80 f/7.5.

If I use my "nifty fifty" I can certainly get longer exposures.

Is it worth getting the clip filter for this set up?

My guess it won't be of much help with the ED80 as my exposures are not long enough, but it might be good for the widefield shots with the 50mil?

[StuartJPP]

I have got an Astronomik CLS CCD filter, however I haven't really done a side-by-side comparison with and without it (for some reason).

If the weather stays clear this weekend I might be able to try it for you, although it really needs to be tested at a dark site since the image with the filter will appear a lot darker because it is doing its job by removing LP. There is of course some loss and I'd say I have experienced no more than 1/2 a stop difference.

Remember that the clip filter is not compatible with EF-S lenses (your 50mm should be okay).

[jgs001]

I use a cls clip filter with my ef 50mm and have used it with the nifty fifty. I have used it at f5 on my st80, but on the ED80 prefer to use the sw lpr filter. It cuts out that bit leas light than the cls, and at f/7.5 that makes a difference.

[Axeldude]

Thanks Stuart and jsg!

Awesome, that comparison would be great!

I think I'm going to skip buying the cls for now and use the money to buy more EF lenses as I!'ve only got the nifty.

i'll keep using my baader skyglow filter for now