to weixing : How is astrophotgraphy with the 8"?

[VinSnr]

Care to share some opinions on this? Did you make any rotating rings for the scope?

[weixing]

Hi,

Care to share some opinions on this?

The C8N is a decent scope with decent optics... value for money... especially at the price I paid for it.

The scope is a bit heavy... may be around 8kg and after mounting tube ring, dovetail, finder scope and camera, it'll weight slightly more than 10kg.... basically slightly over the capacity limit of my GPD mount.

IMHO, like all low cost scope, the 2" rack-and-pinion focuser of this scope is the weakest component of the whole telescope, but still very usable after you tighten up all the adjustment screws to reduce free play... just that fine focusing will be a bit difficult.

Anyway, I modified a bit to make it more Astrophotography friendly:
1) Change to a slightly larger secondary mirror to have a larger fully illuminated area, but not so large that it's degrade the planetary view. Basically, just change from 25% to 27%.

2) Replace the 60mm focuser adapter to a 60mm to 2" adapter, so that I don't need to use the 2" eyepiece holder and will have enough back focus to use a coma corrector.

3) Replace and standardize all the collimation screws to + screws.

Anyway, I only manage to take one image (Omage Centauri) using this scope till date... not enough clear sky. Also, I'm doing a bit more visual and quite busy "chit chatting" during observation session... ha ha ha So not enough time for imaging... Will try to allocate time for imaging next time... hee hee

Did you make any rotating rings for the scope?

No.. rotating ring are so expensive and I don't have the resource to DIY.

Have a nice day.

[VinSnr]

Thanks Weixing. Without the rotating rings, don't u find the position of the scope can be akward at times?

Actually there is a cheap way to make the "rotating rings". Just get a few large size cable ties, do a daisy chain thing and then wrap the "chain" tight allong the side of your tube rings. Maybe can try this....it might work.

Another way is to do the Wilcox rings. see this : http://www.andysshotglass.com/wilcox_ro ... rings.html

Not sure where to get the garden edging. probably a rubber hose will work as well.

[weixing]

Hi,

Thanks Weixing. Without the rotating rings, don't u find the position of the scope can be akward at times?

Ya... I just loosen the tube ring and rotate the OTA.

Actually there is a cheap way to make the "rotating rings". Just get a few large size cable ties, do a daisy chain thing and then wrap the "chain" tight allong the side of your tube rings. Maybe can try this....it might work.

Hmm... I will try it next time.

Have a nice day.

[VinSnr]

Hi,
Ya... I just loosen the tube ring and rotate the OTA.

Sometimes this can be difficult itself because if not careful, the whole tube can slip down the rings!

[weixing]

Hi,

Sometimes this can be difficult itself because if not careful, the whole tube can slip down the rings!

Yap... this'll happen if not careful.

Anyway, I always try to predict the correct tube orientation at the location I'm going to aim at and rotate the tube in horizontal position before I point to that location... work quite well.

Have a nice day.

[anat]

Sorry for my ignorance. Why do you want to rotate your OTA? Is the rotation of the focuser equivalent to the rotation of the OTA?

Thanks
Anat

[VinSnr]

Sorry for my ignorance. Why do you want to rotate your OTA? Is the rotation of the focuser equivalent to the rotation of the OTA?

Thanks
Anat

When a newtonian is on an EQ mount, the movement of the mount can put the eyepiece position at a very akward and uncomfortable angle. So you need to rotate the tube to bring it back to a comfortable viewing position.

This may also happen to a refractor, but for refractor, you can either rotate the focuser or rotate the diagonal.

For the newtonian case, although it sounds cumbersome. actually it does has its advantages. One of them is that if you have a heavy camera at the focuser. You can rotate the tube in such a way that the focuser is horizontal so that it doesn't slip with the camera behind. Of course, in most cases you would have lock down the focuser.

I am thinking of getting a 8" f/4 just for the kick of trying out with a DSLR.

[anat]

Thanks, Vincent. You will need a white OTA to match with your mount

[Meng Lee]

Hmm a white OTA 8" and f/4 Newtonian is vixen's R200SS