(https://i.imgur.com/gvxMsg5.jpg)
Last night was my first try with autofocussing, it seems to be a lot better than I have been able to manage so far. There were other tweaks, I changed the separation between the reducer and the camera and added an Ha filter.
I do feel this is my best effort so far (but that isn't claiming a great deal!)
The Sharpstar 15028 is incredibly fast, this was one evening's data. I feel I overexposed the L frames at 20 seconds. I was too inconsistent with the RGB times and I have a lot to learn about guiding. This is the result of running the frames through APP on the preset values and then tinkering in Photoshop. I always just want to see what I have got. I will now have a more leisurely go with PI.
Info:
Sharpstar 15028 HNT on iOptron CEM 25P mount
Imaging camera: ZWO 1600 MM Pro, ZWO Mini Filter Wheel and Electronic Focusser.
ZWO miniguidescope with ASI 120mm
Lum: 20 seconds * 100
Red: 40 seconds * 30
Green: 90 seconds * 20
Blue: 120 seconds * 20
H Alpha: 300 seconds * 10
Temperature: -15
Gain: 143
John
That's come out pretty well, especially considering what stage you are in the learning process.
How fast is your Sharpstar? i.e. what F ratio is it?
Guiding and coping with autofocus, you really are coming on.
Carole
The Sharpstar 15028 is f2.8 (150 mm aperture). That really makes focus critical which is why autofocus is such a help.
John
I wonder whether you have darkened the sky background a bit too much and have lost some of the outer faint nebulosity, might be worth checking.
Carole
Thanks Carol.
I will settle down and do a proper processing run with PI soon.
I was interested to read your comments about reducers. I think someone tinkered with the telescope and moved the reducer backwards into the telescope before it was sold.
Unfortunately, the two pronged tool required to unscrew it was missing when I received it. This means I cannot remove it for the purpose of collimation (which the Google Translate manual suggests).
Also, I am not sure that the eyepiece holder is perfectly perpendicular to the reducer. I have a very pronounced dark arc on one side of all images (flats cure it but it does make imaging and deciding on exposure times more tricky).
John
John
Very nice, and a good target for that setup.
I see you are falling deep into the money pit!
I opened your image in ASTAP to take a quick look at the star diameters:
(https://cdn.astrobin.com/thumbs/w2BKpPCqC0-H_1824x0_YU5xgF4r.jpg)
Which indicates there may be a collimation / focal plane issue (not that it's noticeable on the image).
Have you tried firing a laser down it?
Noel
Hi Noel,
Yes, if you mean a laser collimator.
Looking at out of focus stars collimation is not perfect although the laser hits the middle of the main mirror and returns centrally.
I think that I need to rotate the focuser and see what happens? If I look at a flat the brightest part is quite a way off centre.
Thanks,
John