Sky rover 115mm works with ASI2600MC?

[MarkInSpace (Mark)]

Hi
I have a skyrover 115mm refractor and the sky rover flattener. I’ve just installed a brand new asi2600m camera and I am having lots of difficulty achieving a flat field and focus.
I have attached a photo taken at 55mm back focus and the photo looks like it needs more back focus, however I am at the lower limit of the focuser and when I add extra back focus the camera will not focus.
What can I do?
Does anyone have experience with this telescope? Is there a way of bringing the focuser closer to the front lens?
I am really stuck! I didn’t have the same problem with my old asi294mc, maybe because of the smaller chip size?
Any suggestions who could help me with this?
Cheers
Mark

[MarkInSpace (Mark)]

I should also mention I have a Baader 7.5nm Ha filter in the image train.
Cheers

[AdamJL]

Hi Mark

That's odd. You can't move the focuser into the tube any further, correct? Normally for your elongated starfield, you could just add spacers like this to fix it, but that sounds like it would push you back and you can't then get focus.
https://www.testar.com.au/collection...8-spacer-0-5mm
https://www.testar.com.au/collection...m48-spacer-1mm

I've not heard of an issue where you can't get closer to the objective... hope someone here can help you (or I'd be talking to the manufacturer about it!)

[pmrid (Peter)]

I take it that the reducer/flattener is taking up a fair bit of your available back focus. From the images I have seen, the drawtube only has 50mm of travel (or is it more). That begs the question how far back is the “normal” point of focus?

Perhaps some pics of your setup would help. Is this the product you have?
https://www.astronomyalive.com.au/pr...cer-flattener/

[JA]

Originally Posted by MarkInSpace

Hi
I have a skyrover 115mm refractor and the sky rover flattener. I’ve just installed a brand new asi2600m camera and I am having lots of difficulty achieving a flat field and focus. ....

Hi Mark,

I had a look at your image and my first thought is that it seemed like a reducer type issue, but you mentioned a flattener only, but looking at the image seemed it was too wide a field of view for your 805mm (115mm f/7) focal length, since you have a flattener fitted. I checked on Stellarium and it's more consistent with something around 600mm, suggesting maybe you have a combination flattener and reducer fitted (???). If that's the case, then the reducer will see closer to the edges of the image circle than just a flattener AND coupled with the larger sensor diagonal of the 2600mm (28.3mm) compared with the 294 (23mm) will show more of the outer image circle a lot further outward (~22% more).

If it really is a flattener & reducer fitted then, maybe its position in the image train needs to be fine tuned for optimum results. Also in reading I noticed somewhere a backfocus of 54.8mm recommended

Best
JA