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sagramore

Advice for a budget planetary scope.

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Hi everyone. I've got the equipment listed in my signature, which includes a NEQ6 mount. Next on my list is a low-cost guide cam and I've got my eye on the ASI120MC, but this means I would like to also be able to do some planetary imaging work with the camera too.

Currently my two little scopes only have focal lengths of 650mm and 400mm both at f/5.0. My Skyliner 200P 8" reflector can go on the NEQ6 but it is a rather flexy tube and awkward to get set up for just 1200mm at f/6. What I'm looking for is an inexpensive and easy to carry scope specifically for use with the ASI120MC for planetary video imaging and I am guessing I need to worry more about focal length and chromatic aberration than I do about aperture?

I have my eye on:
Skywatcher Skymax 102 Mak (1300mm, f/12.74) ~£160
Celestron C90 Mak (1250mm, f/13.89) ~£140

Can anyone advise for or against my reasoning or does anyone have any opinions on these scopes specifically for this purpose? 

Thanks!

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A Mak sounds like a good idea, but remember more aperture will give you more resolution, which will be important for planetary imaging. Have you considered the 127 Mak, which isn't a huge jump in price over the 102, whilst still being compact and portable? The 150 would be even better, but it's double the price and I imagine it would be significantly heavier.

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If you get a good (preferably tele-centric) Barlow for your 200P, it will get much better results than any of the scopes listed. With a 3x Barlow you get F/18 which is nearly perfect for the pixel size of the ASI120MC. Even your 130 PDS would best them. Aperture is king in planetary imaging. My best Jupiter at 8" (SCT, so larger central obstruction than your Newtonian) is this one

post-5655-0-72307500-1423604369.jpg

A 4" scope is not going to get this level of detail

 

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Thanks both for the comments. I totally forgot that while these bright objects don't need aperture for light gathering they still need it for "resolution" and detail.... thanks for reminding me.

Perhaps you're right and a good quality 3x barlow is a more efficient way to go... The mount can easily handle the 200P optical tube, it is what I planned on using before I bought the 130-PDS, it is just the dobsonian version so it's long and bendy and I have trouble locating objects because of all the tube flexure.

Thanks for the advice though - I will take a look at some barlows.

EDIT: The only barlow I have used had a T-thread already integrated in it. Does anyone know if the ASI120MC can reach focus on a reflector using the 1.25" nose piece adapter on a barlow such as the X-CEL LX 3X ? I think the tele-centric barlows are a little out of my price range :/

Edited by sagramore
Extra question at the end.

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