M13 Again...

[Stub Mandrel]

This would have been a pretty massive (for a globular) three hour's data but as I forgot to remove my Bahtinov mask it's something over 1 1/2 hours of 2-minute subs.

At least I can be sure focus was spot on - I have over 40 otherwise useless subs that prove it...

[Kev M]

A stunning example....

[bobro]

Nice colourful and sharp cluster Neil.

Interesting contrast with my M13 - a recent first light B/W image ( 30 min) with an Altair 183M (non-cooled) and coma corrector not yet installed. Your larger DSLR sensor (I guess that is what you used) provides smaller and sharper brighter stars.

Bob

[Adam J]

14 minutes ago, bobro said:

Nice colourful and sharp cluster Neil.

Interesting contrast with my M13 - a recent first light B/W image ( 30 min) with an Altair 183M (non-cooled) and coma corrector not yet installed. Your larger DSLR sensor (I guess that is what you used) provides smaller and sharper brighter stars.

Bob

 

I am not sure that a camera can provide smaller or sharper stars that is down to the optics. Its difficult to compare unless you are sure the image is presented at the same scale, also i suspect your coma corrector has a large part to play here. 

[bobro]

5 minutes ago, Adam J said:

I am not sure that a camera can provide smaller or sharper stars that is down to the optics. Its difficult to compare unless you are sure the image is presented at the same scale

In essence that's what I meant Adam. I've been comparing images taken with my Canon 1000D (on 650/130 and 150PL reflectors) and new 183M on the 650/130 reflector. The smaller sensor/lower resolution of the 183M (in conjunction with the scope optics) seems to show brighter stars as larger for the same image fov. So yes, the image scale is very important and a good CC may make a useful difference. I'm pondering how an M13 will look with the 150PL (skies allowing).  I think that brighter stars will look large but with the image scale M13 will also be larger. Then there are the aspects of arcsecs/pixel and slower scope to consider, so it may not be worthwhile.

[Adam J]

7 minutes ago, bobro said:

In essence that's what I meant Adam. I've been comparing images taken with my Canon 1000D (on 650/130 and 150PL reflectors) and new 183M on the 650/130 reflector. The smaller sensor/lower resolution of the 183M (in conjunction with the scope optics) seems to show brighter stars as larger for the same image fov. So yes, the image scale is very important and a good CC may make a useful difference. I'm pondering how an M13 will look with the 150PL (skies allowing).  I think that brighter stars will look large but with the image scale M13 will also be larger. Then there are the aspects of arcsecs/pixel and slower scope to consider, so it may not be worthwhile.

Honestly I would think about a 130PDS and a 2 inch corrector to go with it. Either that or a 500mm or shorter refactor, its always going to be difficult to get good results out of a scope made for visual use.

[Seanelly]

A pleasing example of this massive cluster.

[Stub Mandrel]

13 hours ago, bobro said:

Nice colourful and sharp cluster Neil.

Interesting contrast with my M13 - a recent first light B/W image ( 30 min) with an Altair 183M (non-cooled) and coma corrector not yet installed. Your larger DSLR sensor (I guess that is what you used) provides smaller and sharper brighter stars.

Bob

The Canon 450D and 130P-ds with comam corrector give a scale of 1.83" per pixel, my guiding is about 1.0"  - I need to tweak, but clearly it is good enough to give sharp stars.