OAG guide camera. - Forums

Topic starter

Sep 13, 2021

Hello all,

I have the Celestron OAG and the only camera I have is the ZWO ASI120MM. I was wanting to know if this camera would work for this OAG as the guider, or do I need to get a different one.

Any help or advice would be greatly appreciated.

CS,

Chris.

Tommy Blomqvist

Sep 13, 2021 · Edited: Sep 13, 2021

The ASI120MM (as well as -S and -mini) works well with most "standard" OAGs. I have used that camera model with (skywatcher) OAG with good results.
But the 120MM-model is a bit old and isn't supported in ASIAIR PRO/PLUS, for that you need the -S och -MINI model.

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Chris

Topic starter

Sep 13, 2021

Thanks Tommy,

I look forward to using it again, I got it for the 8SE and then traded up for a refractor. It has been a real headache with the 8RC and a guide scope and I needed to make sure the camera was going top work.

CS,

Chris.

Mina B.

Sep 13, 2021 · Edited: Sep 13, 2021

With an 8“ RC even with Reducer you‘ll have a pretty narrow FOV with the 120MM Mini. I use it with an OAG, but at 451-560mm Focal lenght. You‘ll probably have difficulties finding a guide star in certain areas of the sky. 120MM Mini and Off axis guiding - it probably gets difficult over 600-700mm focal lenght. I‘d recommend the 290MM Mini (roughly same FOV, but way more sensitive) or better yet, the 174MM Mini (huge sensor, basically it‘s made for Off axis guiding with long focal lenghts) - it also makes full use of the huge Celestrom OAG prism.

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Bruce Donzanti

Sep 13, 2021

Chris

I also use the Celestron OAG. I would suggest getting the ASI174MM as the first choice. If you need to spend less, the ASI290 MM is a good choice. The ASI120MM should also work but it may give you fewer guide star options. You should test the guide cam you have first as it technically will work to see how many guide stars you get but I now use the ASI174MM as it never fails on my C11".

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Michel Makhlouta

Sep 13, 2021

I had an orion ssag and an ASI224MC, both were a nightmare with the zwo oag and the EdgeHD 8 (reduced to 1495mm FL) due to the lack of stars. I upgraded to the 290MM mini, and the difference was very noticeable, I rarely have issues finding a star nowadays.

In your case, the 174MM mini might make more sense. I was limited to 290MM because the ZWO OAG prism is 8x8 and the 174MM sensor is larger than that. A problem that you wouldn't have with the Celestron OAG.

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Jeff Ridder

Sep 13, 2021 · Edited: Sep 13, 2021

This calculator can help you size your guide cam/scope for your imaging cam/scope: astronomy.tools

Chris

Topic starter

Sep 13, 2021

I just want to thank everyone for their information and will go through all of your advice. After doing some homework, thank you Jeff for the web site I completely forgot about it. The thing is with my 8RC is that I do have the QHY183M-Cool, which is really not suitable for the 8RC unless you use Binning. In my case with the 183 is that without a FR you would have to Bin 3x3 as to not over-sample, Binning 2x2 with a FR.

According to astronomy.tools the 120mm-s will work but will be over-sampled, unless it is Binned, which is what I will be doing anyways. The 290mm mini will work for the un-binned, but until I get my new camera that will work with the 1x1 bin. Until then, I will have to do go with the binning solution.

Yuxuan

Sep 14, 2021

If you want to enhance guiding performance, get the 174mm.

Thomas

Sep 14, 2021

Kind of depend on the focal length of your scope.
The ASI 290 mini blows the 120 out of the water in every way and works well for focal length up to 1500mm.
For longer scopes I'd recomend an ASI 174mm mini or a QHY 174III, bigger chip (if the prism of the OAG is big enough) and larger pixel help a lot.

cs
Thomas

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Chris

Topic starter

Sep 14, 2021 · Edited: Sep 14, 2021

Thanks for everyone's advice and it looks like the 174 is the winner and will get it soon as I can find one.

CS,

Chris.

Found one.