Jacob.Of.Olympus avatar
My first post on Astrobin! I was wondering if others have experience or thoughts that may be helpful.

I have been using the Starsense Autoguider on my Celestron 8SE for a couple of months now. So far it has worked well-ish. For the 8SE, it has a small image circle and I was worried an off-axis guider would not work well.

The guiding graphs on it are typically +/- 0.5 arcseconds.  Depending on the target I can often get exposes up to 5 minutes with mediocre looking stars. I have not pushed it past 5 minute exposers.

With a lot of targets, I have to go down to 2 or 3 minute exposures to make the stars not be bean shaped. My conclusion so far is that the issue is mirror flop.

My solution so far has been to shorten exposure time and then add a slew and center command in N.I.N.A. every 30 minutes. That has worked well so far, but I would love to push exposure times up. Processing data from longer exposures just generally seems faster and easier.

Are there any other thoughts on how to improve this?

Thank you!
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andrea tasselli avatar
The Starsense gizmo is an on-axis guider not an off-axis guider. And, yes, mirror flop is certainly a possibility with SCTs. You need an off-axis guider i.e., an OAG to avoid the issue you are seeing. Something like this: ZWO Off Axis Guider (OAG) v2 | First Light Optics
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Jacob.Of.Olympus avatar
Thank you for the reply!

My OTA is a Celestron 8SE. Others online seemed to have an issue where the small image circle degraded the ability to use an off axis guider.

Do you have a sense for if the 8SE is able handle an OAG?
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andrea tasselli avatar
Thank you for the reply!

My OTA is a Celestron 8SE. Others online seemed to have an issue where the small image circle degraded the ability to use an off axis guider.

Do you have a sense for if the 8SE is able handle an OAG?

*Yes, of course, it can handle that just as well as any other ordinary SCTs.
Jacob.Of.Olympus avatar
Thank you,

I will give it a shot!
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