Jump to content

Narrowband

Maksutov Focus Failure - Help!


Recommended Posts

Barry, no the scope certainly wasn't fully cooled. My decision to go out for a test was rather last minute, so it had about an hour of cool down time. Initially the diffraction pattern was a real mess, with a couple of huge dark blobs spoiling the rings. So definitely not an ideal test...

When I took the mirror cell out of the tube and took it apart I was very careful to not overtighten the retaining collar that holds the primary in place. That's the only thing holding it. The primary sits snuggly over the central obstruction tube section, and then a second part of the central obstruction screws down onto it to clamp it down. But perhaps it is still too tight? But would a circular clamp on the centre of the primary lead to the slightly triangular shapes? I could understand it if it were held by 3 bolts spaced at 120 degrees, but it's not.

I'm not too keen on taking it apart again now, as it's getting close to working well for me...

I've definitely sorted out a lot of small issues, and the performance of the scope is now greatly improved. I'm starting to get to the point of thinking that what I'm left with now are external factors i.e. not enough cooling time, bad seeing, and my lack of skill at planetary imaging :)

Thanks for the advice about exposure, I'll try and go more steady next time out. Focusing is also something I find hard to judge, with the constant washing of the seeing it's hard to know when I've nailed it. I was considering using a bahtinov mask whilst aimed at a bright star, and then moving to Saturn. Am I right in thinking that the focus point for the two will be the same?

Link to comment
Share on other sites

  • Replies 82
  • Created
  • Last Reply

Looks to me as tho it 's almost mission complete Sam.

Nowt you can do about seeing but yup let it cool :) as for the mask yup that would work or think about a SCT crayford/motor-focuser set up or just a motor focuser.

Look fwd to seeing more test results !:eek:

Link to comment
Share on other sites

Oh yeah, we're getting there! :eek:

post-16299-133877596655_thumb.png

Vastly improved results compared to last time. I used a bahtinov mask to focus up on Arcturus, and then left well alone. The colour image is taken with my Microsoft HD Lifecam, and to be honest I think the camera might be the weak link here... As you can see the mono picture taken with the modded SPC900 (with a 2x barlow) is much sharper.

I reckon I'm about there now... More down to practice and conditions than Mak now. I must admit there were times when I didn't think I'd get the scope on song, but I'm very happy that I have! :)

post-16299-133877596652_thumb.png

Link to comment
Share on other sites

nice one sam, glad you stuck with it and sorted it, just need to get my one sorted now, really need to clean the main mirror but cant for the life of me get to it, cant seem to seperate the ota tube from the mirror cell, was gonna send it to orion but when they found out it was second hand to me they more than doubled the price for doing job and gave me some attitude over it

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.