I made my own Cheshire eyepiece by drilling a 1.5 mm hole in the center of a 1.25" focuser end plug.
I post the picture of what I found.
I can see the 3 mirror holding clips so you'd think it would be OK as is?
How important is offset and collimation?
I'm like that.
if someone posts a picture I go straight to the 4 corners and start pixel peeping.
Can I find any out of round stars or stars with comet tails on them?
I've looked through Carl Zeiss eyepieces and there was a large difference
compared to ordinary eyepieces especially when looking at planets.
Even when looking at Orion - you could see more nebulosity.
cheers
Allan
Yeah your right Alan, You do get what you pay for. My wife saw my post and said " Richard tell the truth. You're just too tight to pay for the good stuff"
I made my own Cheshire eyepiece by drilling a 1.5 mm hole in the center of a 1.25" focuser end plug.
I post the picture of what I found.
I can see the 3 mirror holding clips so you'd think it would be OK as is?
How important is offset and collimation?
cheers
Allan
Looks good to me Alan. Just need a cheshire or well collimated laser to check the cross hairs or laser dot are centred on the primary spot and you're all good I reckon, though I cant see that well but looks like your secondary holder not quite centred in focuser draw tube so could do better but probably not crucial
Cheers, Richard
Last edited by croweater; 05-03-2023 at 09:48 AM.
Reason: add info
Yeah your right Alan, You do get what you pay for. My wife saw my post and said " Richard tell the truth. You're just too tight to pay for the good stuff"
Looks good to me Alan. Just need a cheshire or well collimated laser to check the cross hairs or laser dot are centred on the primary spot and you're all good I reckon, though I cant see that well but looks like your secondary holder not quite centred in focuser draw tube so could do better but probably not crucial
Cheers, Richard
That picture was taken when the telescope was a bit out of alignment.
I should have re-collimated it first.
I don't see how I can get a proper collimation without offsetting the
secondary mirror downwards.
That picture was taken when the telescope was a bit out of alignment.
I should have re-collimated it first.
I don't see how I can get a proper collimation without offsetting the
secondary mirror downwards.
cheers
Allan
Do you have enough movement of your secondary holder(by using threaded rod that holds it, swivel movement and tilt screws to center the holder in the draw tube? If you can do that first. then adjust your tilt to center the primary in the secondary mirror. Sorry if I am teaching you to suck eggs Alan
Do you have enough movement of your secondary holder(by using threaded rod that holds it, swivel movement and tilt screws to center the holder in the draw tube? If you can do that first. then adjust your tilt to center the primary in the secondary mirror. Sorry if I am teaching you to suck eggs Alan
Hi Richard,
I don't know yet.
I haven't dared to touch it until experts had advised me first.
The information contained in the faulty setup is valuable to know what happened.
It also helps others.
Hi Richard,
I don't know yet.
I haven't dared to touch it until experts had advised me first.
The information contained in the faulty setup is valuable to know what happened.
It also helps others.
cheers
Allan
No worries mate. Good luck with it all. All said and done if all else fails you cant go wrong if you follow astrobaby's excellent instructions.
I re-collimated the scope and -
took a clearer image using my mobile phone through a Cheshire cap.
and a person on another forum made this image and agrees that there is an offset problem.
he says - The current secondary mirror (dashed green circle) needs to be moved to the solid green circle (about 1/6 of the secondary mirror diameter, so ~15mm).
I am about to pull the secondary out for a closer look.
What should I do about the dimple plate for the 3 adjustment screws?
So - the dimples didn't line up so they just reversed the plate -
or is that the normal setup?
What should I do about the dimple plate for the 3 adjustment screws?
So - the dimples didn't line up so they just reversed the plate -
or is that the normal setup?
Doesn't look normal to me Al. my plate has no dimples so never seen that before, but you'd think it was the wrong way around. But the dimples too widely spaced to line up with the screws so I don't know what they're for. Maybe try just centering the plate under the three screws and see where you end up.
Your secondary looks miles out. Should be centered under focuser drawtube as the other forum guy indicates.
Also, just a suggestion maybe start new thread with name like "secondary mirror collimation offset problem, help needed" as then this will alert many of the experienced guys on this site of your problem. (your current title maybe not asking for the help you want)
Cheers, Richard
Last edited by croweater; 07-03-2023 at 08:05 AM.
Reason: add info
Doesn't look normal to me Al. my plate has no dimples so never seen that before, but you'd think it was the wrong way around. But the dimples too widely spaced to line up with the screws so I don't know what they're for. Maybe try just centering the plate under the three screws and see where you end up.
Your secondary looks miles out. Should be centered under focuser drawtube as the other forum guy indicates.
Also, just a suggestion maybe start new thread with name like "secondary mirror collimation offset problem, help needed" as then this will alert many of the experienced guys on this site of your problem. (your current title maybe not asking for the help you want)
Cheers, Richard
Thanks Richard,
I'm OK - I'm getting plenty of help.
It looks like that dimple plate is for another telescope secondary mirror hub.
The screws should have been rounded to fit into the dimples
but when it didn't line up they just reversed it and didn't care.
I am making a 15mm thick round spacer for the 3 adjustment screws -
and I'll get a longer 6mm thread - M6 Allen head bolt for the center part.
Thanks Richard,
I'm OK - I'm getting plenty of help.
It looks like that dimple plate is for another telescope secondary mirror hub.
The screws should have been rounded to fit into the dimples
but when it didn't line up they just reversed it and didn't care.
I am making a 15mm thick round spacer for the 3 adjustment screws -
and I'll get a longer 6mm thread - M6 Allen head bolt for the center part.
Latest news,
I fitted a 15 mm spacer and used a longer central socket head bolt -
I also rounded the 3 screw ends a little bit.
After a lot of collimation help from another forum I achieved a better result.
Once you get it all working, would also suggest reviewing software - NINA has great support for native QHY9M drivers now, and the download speeds much faster than I ever could get from ASCOM support. Rapidly developing into a very powerful free solution.
Once you get it all working, would also suggest reviewing software - NINA has great support for native QHY9M drivers now, and the download speeds much faster than I ever could get from ASCOM support. Rapidly developing into a very powerful free solution.
Hi Rob,
thanks for your reply.
I will need to review software at some stage.
Beware of the high speed download on a QHY9-M.
See the picture which shows dark frames.
The high speed readout has a noise level 4 times higher than
the low speed download which is about equivalent to the sky noise
in Melbourne - an average of 4,225 bits out of 65K bits.
High speed is the default readout so it needs to be unticked.
For the record I attach the before and after image via
the Cheshire eyepiece with added circles.
I am now ready to take some pictures outside when the weather is clear.
see pic.
I used part of a new shoe lace.
It's glued on at 2 spots just for extra security.
The lace could not be glued to the paint on the back of the mirror as
the glue would attach to the paint and silicone remnants and be easily ripped off.
It had to be glued directly to the glass.
I gently scraped off the paint with a fine chisel and used metho but
finished off with Acetone for a super clean surface.
I used 5 minute epoxy resin.
When I touched up some areas on the inside of the tube using a tiny brush -
with Krylon 1602 Ultra Flat Black they show up against the
TS "Black" anti-reflective paint.
Which is better?
The Krylon looks darker.
The next time the spider is out I might need to spray paint
as much of the inside of the tube as possible especially opposite the focuser.
