OAG Question

[SB (Chris)]

Hi everyone,
I have been using a ZWO OAG with the Esprit 100 and get good guiding with ASI 120mm-s. Main cameras are the 183 mm/mc. My frustration is twofold:

1. Connectivity to the OAG is not always rock solid and it can slip sometimes
2. When I rotate the main camera the guiding needs recalibration which eats valuable time.

I went back to using a guide scope using the FMA180 which gave excellent sharp stars but now there is an imaging/ guide ratio of 1:4 this could be reduced marginally with the ASI 290 guide cam

Is point 2 above just something I have to live with? Any suggestions how to make the OAG connection more solid?

Thanks

SB

[Sunfish (Ray)]

Getting a solid focussed connection with the OAG guide camera in the day time can be good. I focus on ships on the horizon. A little out of focus on the guide camera stars can be ok.

A quality OAG with a solid round dovetail which allows rotation of the main camera should not disturb the OAG connection.

Originally Posted by SB

Hi everyone,
I have been using a ZWO OAG with the Esprit 100 and get good guiding with ASI 120mm-s. Main cameras are the 183 mm/mc. My frustration is twofold:

1. Connectivity to the OAG is not always rock solid and it can slip sometimes
2. When I rotate the main camera the guiding needs recalibration which eats valuable time.

I went back to using a guide scope using the FMA180 which gave excellent sharp stars but now there is an imaging/ guide ratio of 1:4 this could be reduced marginally with the ASI 290 guide cam

Is point 2 above just something I have to live with? Any suggestions how to make the OAG connection more solid?

Thanks

SB

[evltoy (Wayne)]

To answer your question. Yes you do need to recalibrate the guide camera every time you move the OAG to find a star. - What software are you using? I use an OAG on my C8 with the 120mm through the ASIair plus and it takes 60-90sec to recalibrate.

To make a physical item more solid? I gather that’s just the quality of the product. Have a look at the Celestron OAG

[Craig_]

Can't say I've had any issues with the connection not being solid enough with the ZWO OAG and an Esprit 120.

[The_bluester (Paul)]

Any time you rotate the OAG (Or the entire scope) you do need to calibrate whatever guide software you are using, but as mentioned above, it should only take a minute or so. If you are messing around looking for the best framing, just take short unguided subs until you like the framing and rotation, then cal the guider and go.

Rigidity wise I have no idea about the standard ZWO guider, the ones designed for the current cameras and filter wheels are very rigid but in other brands I have had good ones (A QHY OAG-M) and really floppy ones that I binned rather than sell on to someone else (An Orion thin OAG) useful for a specific purpose which is using an OAG when backfocus is very tight but not very rigid if you are trying to hang a decent sized camera on the end of it, tilt was different every time it was put together.