Guide scope FOV smaller than imaging scope?!

[labtech1122]

Hi, I was just curious at the field of view of my guide scope and when putting the numbers in I realised the FOV is smaller than my imaging scope. Is this a problem? Should the FOV be the same or maybe bigger than the imaging scope

[vlaiv]

That is quite normal since guide sensor is very small.

You won't have any problems because of that as sole purpose of guide system is to find and lock onto a star/stars (and there are plenty of stars out there - even on small FOVs).

People using OAG (off axis guiders) - always have smaller guide FOV then their imaging FOV as same focal length is used for both and guide sensors are smaller.

[labtech1122]

Ah ok, thank you very much I was just concerned because someone said you can use your guide scope as a finder because the FOV is wider than the imaging but that clearly isn't the case

[vlaiv]

6 minutes ago, labtech1122 said:

Ah ok, thank you very much I was just concerned because someone said you can use your guide scope as a finder because the FOV is wider than the imaging but that clearly isn't the case

Well, you can - but if you plate solve - you don't need to - computer will figure out where the scope is pointing and point it to the right place automatically.

Even if you don't plate solve - use main imaging system to figure out where the scope is aiming - take frame and focus exposure and check out star patterns to orient yourself. Guide scope can be be offset to the main scope - so they don't necessarily point to the same place in the sky (won't affect guiding) - so it is better to use main camera as it will do the imaging after all and where it's pointing is what counts in the end.