Advice needed on reflector for AP

[Shelldrake]

To date I have been using a 80mm F6 apochromatic refractor (FL 480mm) and ASI183MC CMOS camera for imaging but would like a scope with more focal length for imaging smaller DSOs. I have tried using my Celestron C8 SCT with 0.63 focal reducer (FL 1280mm) but issues with fine focus, mirror flop and guiding have been frustrating to say the least.

I am therefore considering a Newtonian with coma corrector, either a 200mm Orion/SkyWatcher F4 astrograph (FL 800mm) or 150mm SkyWatcher F5 Newtonian (FL 750mm) that is optimized for AP (150PDS). The 200mm scope is faster but will be more demanding in terms of accurate collimation, heavier and a potential "wind sail". The 150mm scope is a bit slower but should be somewhat less demanding in terms of accurate collimation and will definitely be easier to handle and less of a "wind sail".

I am undecided on which option to go for and need advice. Thanks!
David

[JayTee]

My next step up from my 80 mm f/6 APO was the GSO 6" RC. It has a long enough focal length for the small targets and with a focal reducer short enough focal length to be the next step from 480 mm fl APO. Besides, it was very inexpensive.

Cheers,
JT

[Shelldrake]

My next step up from my 80 mm f/6 APO was the GSO 6" RC. It has a long enough focal length for the small targets and with a focal reducer short enough focal length to be the next step from 480 mm fl APO. Besides, it was very inexpensive.

Cheers,
JT

Thanks JT. I hadn't considered a RC so now I have another option! What focal reducer are you using? Will the Meade 0.63 focal reducer for my SCT also work on a RC?
David

[bobharmony]

I have been using a Celestron C6N (150mm diameter, 750mm focal length) for the past few years and I enjoy working it. A lot will depend on just how small the objects you want to shoot are. I find the scope to be forgiving for guiding, not affected by winds of 10-15 mph, and I like the results I get with it. It won't do much for the Ring Nebula but it is great for the larger nebulae and galaxies that are out there. Some of that will depend on the camera you pair it with as well. I use a DSLR with and APS-C sensor.

You can check out the photos in my gallery for some of the objects I have imaged with it. Good luck with whatever you decide to go with!

Bob

[KathyNS]

The 200mm f/4 is a great scope. I have had mine for 10 years, and I love it. The stock focuser is decent, but a bit limited in its capacity. I recently upgraded mine.

I like the fast optics. The f/4 really grabs those photons! My image scale 1.2 "/px is right around what people say is the optimum for DSO AP. There are a few objects that are too big for it, and quite a few that are too small, but there are a huge number that fit beautifully.

It is a wind sail. And you need a fairly hefty mount for it.

[Shelldrake]

The 200mm f/4 is a great scope. I have had mine for 10 years, and I love it. The stock focuser is decent, but a bit limited in its capacity. I recently upgraded mine.

I like the fast optics. The f/4 really grabs those photons! My image scale 1.2 "/px is right around what people say is the optimum for DSO AP. There are a few objects that are too big for it, and quite a few that are too small, but there are a huge number that fit beautifully.

It is a wind sail. And you need a fairly hefty mount for it.

Thanks Kathy. I have an EQ6R which I think is borderline for the 200mm f/4 especially if the wind is blowing! That is the main reason that I am considering the 150mm f/5.

[JayTee]

Thanks JT. I hadn't considered a RC so now I have another option! What focal reducer are you using? Will the Meade 0.63 focal reducer for my SCT also work on a RC?
David

Hi David,

I use the ASTRO-PHYSICS CCDT67 FOCAL REDUCER FOR F/9-F/18 TELESCOPES (https://optcorp.com/products/astro-phys ... QsQAvD_BwE). It gets my FL down from 1370mm to 917mm, or f/9 down to f/6. I don't know if your Meade FR will work in an RC scope. The easiest way to tell is to try it and see what happens.

Cheers,
JT

[DMouse]

Hey Shelldrake, I had a Skywatcher 200mm F5 Newt on a HEQ5 for a long time and even though it pushed the mount to its limit I got plenty of great images. So an f4 200mm Newt should be fine on a EQ6-R. Working at F4 does have its collimation issues, you have to collimate a lot more accurately than at F5. I would highly recommend the Catseye collimation tools, and putting a new center spot on the primary. I would also say that if you do plan to do planetary imaging as well then the F5 would give sharper more contrasty images.
Good luck with your choices and clear skies

Paul