Filters

[PeterBolt]

Does it matter where in the imaging train you place a filter? 

I have a DSLR and and a coma corrector.  As far as I can see my options are:

1)  a 2" filter to go on the nose of the coma corrector.

Or 

2) a clip in style to go in my camera so that it is as close as possible to the sensor?

Does it make any difference?  

Any help and advice appreciated.

[AstronomyUkraine]

Posted by: @petedevon

Does it matter where in the imaging train you place a filter? 

I have a DSLR and and a coma corrector.  As far as I can see my options are:

1)  a 2" filter to go on the nose of the coma corrector.

Or 

2) a clip in style to go in my camera so that it is as close as possible to the sensor?

Does it make any difference?  

Any help and advice appreciated.

The closer your filter is to the sensor, the less chance of vignetting. A clip in filter, or a filter drawer would be the best choice for a dslr. TS make a filter drawer for canon cameras, it accepts 36mm unmounted filters, or 2" filters. The backfocus from your coma corrector to your sensor has to be near perfect to achieve optimium focus, usually around 55mm for dslr's, but may vary according to different manufacturers.

Brian

[PeterBolt]

@AstronomyUkraine - that's great thank you.  So if I went for the clip in filter would that have any effect on the backfocus requirements for the coma corrector?

[AstronomyUkraine]

Posted by: @petedevon

So if I went for the clip in filter would that have any effect on the backfocus requirements for the coma corrector?

None at all. The back focus would still remain the same.

Brian

[PeterBolt]

@AstronomyUkraine really appreciate your advice thank you???