www.astrocafe.hk

I've been planning on this setup for months and today I finally have the time to set it up to show everyone the idea.

As you can see the most important element is the SG4 which is mounted under the objective of the scope. This can highly lower the torque and in some way lessen the demand of the amount of counterweight. The setup in the photo is perfectly balanced, so you can see the counterweight is only half-way down the shaft.

A T-mount camera lens of 135mm F3.5 is attached to SG4 (i bid it on Ebay).

There are still some hardware issues like wiring and initial setup of SG4 to test and deal with, but all in all I'm quite pleased with the fact that the idea finally worked out. I no longer need to deal with the flexture and cumbersome side-by-side guidescope setup, and when compared to my original setup this thing is at least 5kgs lighter (and I haven't taken into consideration that the amount of counterweight can be further reduced.)

Hello Paul, thanks for the sharing, a very nice and portable setup indeed.

some details wish to check with your experience on,

- achieving critical focus with this setup

- the damping performance of photo tripod

1) Do you mean the guiding lens focus or the imaging scope?

2) It should be no problem as I've known many people putting their setup (even much heavier ones) on Gitzo tripod, and produced very good results.
It may be because of the photography angle that makes the tripod looks slim...

PaulNg 寫:1) Do you mean the guiding lens focus or the imaging scope?

2) It should be no problem as I've known many people putting their setup (even much heavier ones) on Gitzo tripod, and produced very good results.
It may be because of the photography angle that makes the tripod looks slim...

thanks Paul for the sharing, may be the tripod I tried before is not as good, those are inexpensive ones for few hundred dollars anyway....

What I mean critical focusing is the imaging scope, my personal experience with Epsilon 180ED is not very successul even a Takahashi reduction knob is used, part of the reason is the extraordinary high speed at f2.8, and I don't have any electronics or quantifiable aids. So wish to learn more about your experience on this. Of course, SKy 90 is more forgiving due to the lower speed.

thanks....

Thanks for sharing. I have little knowledge in guiding and so I cannot give any suggestion. I am also looking for a good mini set up for deep sky photography and yours certainly provides good inspiration for my thoughts.

Yeah the focuser does not even have a micro control. I just have to be very patient when dealing with that~

I may try the Batimov mask later if i have the hardware support, but now the liveview is working fine for me...

Dear Paul,
Thanks for sharing. Is it a Sky90? It has a focal length of 500mm or 407mm with reducer. Which mean u are using a 135mm guiding scope to guide a 407mm scope. How's the performance? Have u ever tried even longer focal length scopes with this guiding system?
Regards,
Willis

I just set it up to try the balancing issue...

In fact i've never tried autoguiding before =P

yup It is 407mm with reducer. But as SG4 has a theoretical guiding ratio of 1:10 this shouldn't be a problem.

WIsh u clear skies & wait for ur photos!

PaulNg 寫:Yeah the focuser does not even have a micro control. I just have to be very patient when dealing with that~

I may try the Batimov mask later if i have the hardware support, but now the liveview is working fine for me...

Paul, Bahtinov focus mask is a must for critical focusing, "strange enough" Live View is not as long as focuser have digital focusing.

It's interesting that I found Canon 350D is sometimes marginally more sensitive to critical focus then my 5D Mark II, with focus motor with digital position display, I can easily reach +/-3.6um with my telescope.

Now I am on the way to airport back to Hong Kong, from this Taiwan astrophotography trip, I learn more about focusing, temperature compensation... etc. Will share more later on.

期望你的相片.

唔通我真的要買個Autoguiding... 好貧窮...

我之前都用manual guide 用左 7年而家先轉autoguide...

有心影既一定影得好既~~

PaulNg 寫:我之前都用manual guide 用左 7年而家先轉autoguide...

有心影既一定影得好既~~

Originally I think manual guide is kind of training. But the weather in HK is too bad. We don't have much clear skies and therefore lack of polar alignment practice. Every clear sky is treasure. I don't want to waste time so I go for autoguiding. The other reason is that autoguiding is not expensive now, the price of LVI I is $3000 only.

willis 寫:Originally I think manual guide is kind of training. But the weather in HK is too bad. We don't have much clear skies and therefore lack of polar alignment practice. Every clear sky is treasure. I don't want to waste time so I go for autoguiding. The other reason is that autoguiding is not expensive now, the price of LVI I is $3000 only.

This is exactly what I think as well.