help with focusing with ...

[StrifeYun]

Hi guys,

anyone has experience with focusing a

DSLR + orion t-ring adaptor(adjustable one that can inset eye piece) + 25mm eye piece + 1200mm, f13.9 telescope ?

have tried last night but cannot seem to get focus, help help !
will be trying out this wkend again when i have more time.

thanks in advance.

hope u gurus can share your experiences

or is there a related thread i can look up ?

[weixing]

Originally Posted by StrifeYun Hi guys, anyone has experience with focusing a DSLR + orion t-ring adaptor(adjustable one that can inset eye piece) + 25mm eye piece + 1200mm, f13.9 telescope ? have tried last night but cannot seem to get focus, help help ! will be trying out this wkend again when i have more time. thanks in advance. hope u gurus can share your experiences or is there a related thread i can look up ?

Hi,
You need to be patient when focusing as Maksutov-Cassegrain Telescope got a huge focusing range. I suggest you try out on the day on a terrestrial object first. You can try this long method if you don't have a tracking mount:
1) First make sure you align your finder scope (or red dot finder) to your scope.
2) Aim at a far away non moving terrestrial object such as traffic light (at night) and make sure you can see the object in the center using the eyepiece only (visual mode).
3) Now took out the eyepiece and put in your eyepiece projection adapter (with eyepiece), T-Ring and DSLR.
4) Now turn the focusing knob in one direction until it hit the end and start focusing slowly at the opposite direction until it reach focus... remember not to turn too fast as you might miss the focus zone.
5) Now it'll be quite near to the focus, so aim at your target such as the Moon and focus again (in either direction).

Anyway, there are also other short-cut method, but you need to know your telescope well and experiment it in the day... such as finding the focusing different and direction to focus between visual and eyepiece projection mode with your DSLR.

Good luck and happy imaging.

Have a nice day.

[StrifeYun]

Originally Posted by weixing Hi, You need to be patient when focusing as Maksutov-Cassegrain Telescope got a huge focusing range. I suggest you try out on the day on a terrestrial object first. You can try this long method if you don't have a tracking mount: 1) First make sure you align your finder scope (or red dot finder) to your scope. 2) Aim at a far away non moving terrestrial object such as traffic light (at night) and make sure you can see the object in the center using the eyepiece only (visual mode). 3) Now took out the eyepiece and put in your eyepiece projection adapter (with eyepiece), T-Ring and DSLR. 4) Now turn the focusing knob in one direction until it hit the end and start focusing slowly at the opposite direction until it reach focus... remember not to turn too fast as you might miss the focus zone. 5) Now it'll be quite near to the focus, so aim at your target such as the Moon and focus again (in either direction). Anyway, there are also other short-cut method, but you need to know your telescope well and experiment it in the day... such as finding the focusing different and direction to focus between visual and eyepiece projection mode with your DSLR. Good luck and happy imaging. Have a nice day.

Thanks weixing,

BTW weixing, is a tracking mount worth getting, cause i got the mini tripod which can mount the tracking, but did not buy.


look like i have to find more time to try out, bz bz bz sighz... (IPPT, work, study, hahaha... ippt lucky just passed, 2nite exam) this wkend should be free 2 play liao

[weixing]

Hi,

Quote: BTW weixing, is a tracking mount worth getting, cause i got the mini tripod which can mount the tracking, but did not buy.

You mean the Min-EQ™ Tabletop Equatorial Mount?? IMHO, you can only use that mount for your 90mm Mak for visual (or webcam imaging) or mount your DSLR with may be up to 100mm telephoto lens for wide field Astrophotography (with good polar alignment), but not both your 90mm Mak and DSLR... the mount is just too small.

Anyway, if you want to take decent Astro image, a decent EQ mount with tracking is basically a must.

Have a nice day.

[cantaresg]

I think the latest (or the previous) issue of Sky and Telescope has an article on building a tracking mount. Perhaps you can take a look?

[StrifeYun]

wah , okie okie guys, thanks.

now must save save save , shot shot shot , practice practice practice.

i got the 90mm Mak to bring overseas for portability hee. now a days lazy 2 set up liao , waiting to retire 1 day and full time astro and CSer !!

[jmmtn4aj]

Not infinity focus?