Best camera for use with OAG?

mcgillca

Hi - I have Williams Optics Star 71 which has a focal length of 350mm and a 1600MC for my imaging camera.

I'm considering either the ASI120MM-S or the ASI178MM as a guider to use with the ZWO OAG.

With the 178MM, I'd have double the real estate (about a square degree vs 0.5 square degree for the 120MM) so increasing the chance of finding a good guide star, but at the expense of a little more weight, and from the photos, looks like the 178 is a little longer ,and of course the additional cost.

Any advice?

Thank you,

Colin

tgmorris99

I too have a WO Star71 + ASI1600MC-C and just purchased the ZWO OAG. I already had an ASI224MC so that's what I'll be using for guiding.

A word of caution though. I attached the OAG to the Star71 using the native M48 thread on the Star71. It seemed to attach fine but when going through the motions of getting everything focused I discovered that the depth of the M48 thread on the Star71 is too long for the OAG and it bottomed out against the stalk of the prism. No damage but it did mean that I had to switch to the M42 plate on the OAG and use an M48-M42 reducer on the Star71.

I could have also used a spacer ring on the Star71 to change the depth but since my other use is on an AT130EDT and the FR/FF has an M42 connection it's OK using the M42 adapter plate.

rockstarbill

mcgillca wrote:
Hi - I have Williams Optics Star 71 which has a focal length of 350mm and a 1600MC for my imaging camera.

I'm considering either the ASI120MM-S or the ASI178MM as a guider to use with the ZWO OAG.

With the 178MM, I'd have double the real estate (about a square degree vs 0.5 square degree for the 120MM) so increasing the chance of finding a good guide star, but at the expense of a little more weight, and from the photos, looks like the 178 is a little longer ,and of course the additional cost.

Any advice?

Thank you,

Colin

The ASI120MM is a staple guide cam. Tested, tried, proven, and very reliable. Its footprint is very small (smaller than the SSAG from Orion) and the sensor picks up tons of stars.

mcgillca

rockstarbill wrote:

The ASI120MM is a staple guide cam. Tested, tried, proven, and very reliable. Its footprint is very small (smaller than the SSAG from Orion) and the sensor picks up tons of stars.

That's very good advice - thank you!

I'll go with the smaller guide camera.

Colin

mcgillca

tgmorris99 wrote:
I too have a WO Star71 + ASI1600MC-C and just purchased the ZWO OAG. I already had an ASI224MC so that's what I'll be using for guiding.

A word of caution though. I attached the OAG to the Star71 using the native M48 thread on the Star71. It seemed to attach fine but when going through the motions of getting everything focused I discovered that the depth of the M48 thread on the Star71 is too long for the OAG and it bottomed out against the stalk of the prism. No damage but it did mean that I had to switch to the M42 plate on the OAG and use an M48-M42 reducer on the Star71.

I could have also used a spacer ring on the Star71 to change the depth but since my other use is on an AT130EDT and the FR/FF has an M42 connection it's OK using the M42 adapter plate.

That's great to know - I have a 5mm M48 extension - I'll check the thread length when the OAG arrives.

Thank you,

Colin