C9.25 OTA exchange for a SW EVOSTAR 100DS-PRO

[merlinxlm]

Hello everyone, I'm about to return my C9.25 as part exchange for these items. First Light Optics - Skywatcher Evostar 100ED DS-Pro Outfit

Plus First Light Optics - DMK 21AU04.AS Mono

I'll be using this set up mainly for lunar and planetary imaging and viewing. The reason that I've decided on the 100DS instead of the 120DS is because of its longer focal length of 900mm and f9. Am I correct at assuming this? I will also be buying a smaller retractor to mount on top of the 100DS for wide field imaging/viewing, maybe a 70mm to 80mm f6. Would I be able to use the 100DS and the dmk to guide with? How will the 100DS compare with the C9.25 that I'm returning, I understand that Its smaller but I've heard that the 100DS is a very good scope with very good colour correction. Any advice or comment very appreciated.

Thank you.

[Merlin66]

You don't really need a guide scope when imaging the moon or planets.

If your mount is well aligned and your tracking is OK then the camera will sort out the rest.

For DSO, then yes - the DMK will guide under PHD.

[Peter Drew]

From what I've seen in the past, I would have thought that the C9.25 would be a far superior telescope for lunar and planetary imaging. .

[neilmack]

A 100mm telescope is decidedly easier to handle and mount, but apart from that the advantage lies with the 120mm. They both seem to be the same focal length according to the FLO website, and at 900mm are short for planetary imaging. For observing the moon and planets the 120mm scope looks the more interesting; if your main focus is on imaging then stick with the SCT. Have a look at the planetary images of Damian Peach Welcome to Views of the Solar System! and Christopher Go Saturn and see what can be achieved when imaging with SCTs only a bit bigger than your C9.25. Any five inch refractor, even a Takahashi or an Astro-Physics, won't be able to compete on planetary imaging, even though they're decisively better in other respects.

best of luck,

Neil