M1 again with VC200L @PTC from Jan 02

[LT]

Personally, I prefer guiding with a separate guiding scope aside the imaging scope. With this guiding method, I can have much freedom in choosing a guiding star. However, the differential flexure between imaging scope and guiding system will be a very big issue, especially when imaging at very long focal length and very bad seeing condition.

In the past 2 months, I am doing some experiments to see how the extreme can go. What I would say now: It is not easy to do autoguiding successfully with a separate guiding scope if photographic focal length >=800mm with some beginner-graded mounts.

Here is one of the result for your reference.

Photographic data:

Imaging scope: Vixen VC200L (200mm F9) + 0.72x reducer
Camera and setting: Modified EOS 100D + LPS-2 @iso1600 RAW
Effective photographic focal length and ratio: 1280mm F6.4
Mount: Vixen SXP goto equatorial mount controlled by Star Book Ten
Guiding: autoguiding w/Mizar GT-68 (68mm f.l.600mm) + QHY5 + PHD
Total exposure: 4 x 360s
Processing: stacking in DSS and final touch in PS-CS2
No. of DF calibrated: 4
Air temperature: 7.5C
Air quality: Transparency = 5-6/10, seeing = 3-4/10 estimated

Better result may be achieved if applying FF calibrated. But I don't take the FF yet. S/N is not good too because of insufficient exposure time. If weather cooperates, I will do it again with more exposure and FF calibrated. Keep tuned please.

LT

[cometboy]

It seems SXP mount can handle long focal length off axis guiding.

[LT]

It seems SXP mount can handle long focal length off axis guiding.

I believe it can handle focal length even up to 2000mm if using off axis guider.

But I prefer side-by-side guiding method more. So, if I can succeed in doing autoguiding with SXP @2000mm for 10 min with this method, I will stay at using a separate guiding scope. Otherwise, hand down for an off-axis guider.

In fact, it is a very good experience in learning how to minimize the system flexure.

LT

[willis]

6mins guiding with 1296mm imaging scope with such result is very good already. I guess the mount is just a part of the story. The balancing, careful arrange of imaging scope, guiding scope, all the joins and even how to fix the wires pay important roles. All these are practical experience. Would like to see a 100% crop of M1. Thanks!

[kingyo]

Good Shoot.

[Eddy So]

Good Shoot.

X2

[LT]

Thanks everyone.

Per Willis' request, here is a 100% cropped image. Tracking is a bit off.