Captures from 19.03.22

[PatG]

A selection of captures from last night. Variable success. Seem to have some distorted star shapes, particularly in on the left. Not sure of cause, maybe to do with focal reduction (using a MFR5 from Mallincam) which is fitted to the front of the camera or simply a little out of focus or a combination of both. Struggled with focus quite a bit last night. Windy gusts also contributed to the challenge.  Another aspect I found difficult last night was the adjustment of histogram, in order to bring out some detail this was either making images dark round the edges or too light, images seemed to lack contract. All done with basic mean stack in starlight live. Need to gain better understanding of the stacking options. Any feedback, comments, suggestions welcome and appreciated.

 

 

[catburglar]

Pat

 

It looks like you had a good session. I think the issues with your start shapes are probably a combination of coma (exacerbated by too much distance between the reducer and the ccd chip) and tilt.

I'm not sure if your using an 8 inch LX90, but this is the sort of field of view you should get if your using a 0.5x reducer at the correct spacing. Looking at your image of M51 compared to the one below, it looks to me that you're probably operating at a reduction of about 0.3- and that makes the coma and the vignetting around the edge of the image much worse. So if you can, I'd try to get the reducer a bit closer to the CCD - you'll probably still get some coma in the corner of the image, but if you can get the reduction factor to 0.5 or 0.6 I suspect you'll get better looking stars., and your images will be more evenly illuminated which makes manipulating the histogram a bit easier. The tilt is may be a bit more difficult to correct- are you using an eyepice clamp with just a single set screw...They can often introduce tilt. If you can get a compression fitting that has two or three screws and then tighten them up equally to hold the camera and that might help get your CCD plane parallel to the image plane.

 

I'm afraid I've never used SLL, so I can't help much with that one- sorry.

[PatG]

Thank you for the feedback / advice Catburglar.
 

Yes it’s a 200mm SCT. Now that you mention it I think I had two spacers (total 15mm) between the FR units and the camera last night which i think is different to previous configurations, albeit this was some time ago. I will reduce spacing and lower FR. The comment about tilt is also a potential weak point. I do have a single screw type clamp, I will swap out with a better clamp, that achieves a more uniform compression - Thanks once again, really helpful.

Pat