ASi178mm vs ASI290mm

bruceaust

I am setting up an OAG on my imaging scope and would like some advice on which camera to purchase.

My setup:

LX200 Classic 10" F10 FL 2500mm , pier mounted in observatory.

ASI294MC imaging Camera.

OAG (less camera!)

I have set up the OAG system using an ASI120mc to make sure both cameras reach focus together.

I now wish to purchase a sensitive mono camera to complete the system.

My question:

Am I better off with the 290MM OR the 178MM ?

Comparing the specs, the 178MM has much higher resolution, smaller pixels. and larger sensor than the 290MM. Is this more suitable for the long FL of the LX200 ?......and would i be better off using the 178MM which will give a wider FOV and more pixels?. The 178 looks to be slightly more sensitive also.

The primary use for the camera will be OAG. However, sometimes the camera may also be used for some imaging on another portable mount with a 1500FL SCT and 280mm standard zwo guide scope system.

Thanks in advance,

Bruce.

riklaunim

For OAG guider I would use a camera with as big pixels as possible - to supply it with as best signal as possible. Guiding is already subpixel so high resolution is not needed (even small external finderguidescope could work) plus seeing on very high resolution per pixel may give false movement for the guide app.

bruceaust

Thanks for the reply.

What I am concerned about is the large difference in the FL . My normal guide scope is FL 280 mm (using an SSAG or 120mc) my SCT is FL 2500mm. At the moment the guiding "looks ok" but am I really getting optimum guiding with the difference in FL? A small movement calculated by PHD2, effectively amplified by the ratio of the FL's.

This iis why a am exploring the OAG route.

I know there is a point of diminishing returns, but I would like to get the best system possible within my budget.

bruceaust

In addition . If the 178mm was Binned 2x2 , effectively 4 times the pixel size while keeping the the same chip size ----- both good for guiding?

Support@ZWO

Well, they both good. 178mm will have biger FOV to find a guiding star.