Which refractor for viewing planets?

[Star Struck]

I am thinking of buying a refractor primarily for viewing the moon and planets. I want one that I can use at high magnification e.g. up to 200x or maybe beyond.

Would I be better buying a modern F10 or F11 achromat or should I hold out for a 100ED?

I have an EQ5 mount, so it would have to be comfortable on that.

I am sure this has been covered before, but I would appreciate your views

[nightfisher]

whats your budget?

The only decent achromat these days is the altair astro starwave 102 f11, i would have said the Tal 100rs but you just cant get them now

or the skywatcher ED100

[PeterCPC]

You can get the Tal here http://www.harrisontelescopes.co.uk/acatalog/TAL-100RS_100mm_Refractor_Optical_Tube_Assembly.html

Peter

[Star Struck]

The budget is a max of £400 (or thereabouts).

[John]

If you could afford one, personally I reckon the Skywatcher ED120 is a great refractor for planetary viewing. Mine will comfortably exceed 200x under decent conditions and 250x is regularly useful on Saturn and Mars.

On the used market they can be picked up for under £500.

If your budget is more constrained the ED100 would be the one I'd go for although the TAL and Lyra / Altair achromats are very good as well.

[damnut]

Whilst the benefits of APO's are well known, there are good achro's. There are other achromatic scopes,  Bresser 127'l s are well corrected for their cost as are the Phenix and long focal length evo's.

[Moonshane]

My 120ed is the first refractor I have had that is even close to my dobs on planets

[Peter Drew]

For a £400 budget I would go for a 8" F6 Dobsonian. More resolution, brighter image at high magnification and a good allrounder. 

[russ.will]

My Bresser AR127L was very good on planets and regularly punched through poor seeing that left the 12" Dob floundering. This and the Opticstar ARC127, are basically a Meade AR-5, with the few issues that scope had sorted out. It's build quality is a notch above the Synta Achros, with a aluminium OTA and a metal, fully collimatable lens cell, that even offers up lateral shift of the lens elements. At F9.5, CA is minimal and at 1200mm focal length, 200x is possible, depending on your tolerance of floaters.

It's comfortable on an EQ5 (or clone thereof) but I wouldn't want to go a lot longer or heavier. Bear in mind you may need an extra counter weight.

Russell

[damnut]

see review :--- http://stargazerslounge.com/topic/114507-bresser-messier-127mm-achromat/

[ronin]

I would go (wait) for a 100ED, you want detail and the ED should supply that better then an achro.

The Skywatcher seems a bit unavailable, there is the Altair 102ED at £600, cannot see an ED (doublet) on ES, and nothing on the TS site.

They do appear on ABSUK, but nothing specific at present.

[Roy Challen]

Yes, an ED scope may be 'better' but the Tal 100rs is a fine scope (Tal fans are justifiably biased:D) and if you are prepared to wait they come up for sale s/h every now and again for not very much money. They can also handle x200 with decent eps

[Peter Drew]

Double your resolution, quadruple your light grasp and halve the cost with a 8" Dob.    

[Caldwell14]

The ED100 is a fantastic planetary scope. Like John and Shane say the 120 is the one to go for if you can afford one. If not the 100 will not disappoint, I have owned both.

[Rainmaker]

For a £400 budget I would go for a 8" F6 Dobsonian. More resolution, brighter image at high magnification and a good allrounder. 

How would you mount that onto the OP's EQ5 mount?  Might need a few extra counterweights .........  

[Rainmaker]

Double your resolution, quadruple your light grasp and halve the cost with a 8" Dob.  

I've just checked all my refractor databases and I can't find an 8" Dob refractor anywhere ............ I must update my database !!! 

Now in answer to the original question, for an EQ5 mount I would be looking for a 100mm F9 scope.  

[Peter Drew]

The OP specified viewing the Moon and planets, an EQ5 would be up to that task, photography would be a different matter. I only labour the 8" Newt as for the budget suggested there is nothing in the refractor line that would match its overall capabilities.

[russ.will]

How would you mount that onto the OP's EQ5 mount?  Might need a few extra counterweights .........  

Traditionally, tube rings and a dovetail. Just putting it out there....

Russell

[Chris]

I've just checked all my refractor databases and I can't find an 8" Dob refractor anywhere ............ I must update my database !!! 

Now in answer to the original question, for an EQ5 mount I would be looking for a 100mm F9 scope.  

I'm going to suggest an 8" SCT, after all, the front corrector plate does refract  

[Rainmaker]

Please note my comments about the 8" Dob were said in jest. !!!

If however the OP is after a refractor, as he indicated, a large newt at the maximum capacity of the the EQ5 is not really answering his question.

Without knowing the price of used equipment on that side of the globe, I would be looking for a reasonably long focal length 4"-5" refractor that is not too heavy so as not to create too large a moment arm for the little mount to handle.  One of the best in this size is the Vixen/Celestron FL102S but may be outside his price.

If the OP is open to other designs such as the Newtonian or SCT there are many good options for planetary viewing. 

[John]

Sometimes I think it is worth posting an alternative solution / option. The original poster can simply ignore the suggestion if it does not appeal. Often though I see folks saying something along the lines of "oh, I hadn't thought of that ...."

[Chris]

Please note my comments about the 8" Dob were said in jest. !!!

If however the OP is after a refractor, as he indicated, a large newt at the maximum capacity of the the EQ5 is not really answering his question.

Without knowing the price of used equipment on that side of the globe, I would be looking for a reasonably long focal length 4"-5" refractor that is not too heavy so as not to create too large a moment arm for the little mount to handle.  One of the best in this size is the Vixen/Celestron FL102S but may be outside his price.

If the OP is open to other designs such as the Newtonian or SCT there are many good options for planetary viewing. 

I'm just going along with the banter

BUT! I do think an 8" SCT would fit the OP needs well:

i.e it would sit nicely on an EQ5 without having to crouch down like you do with a long frac. Also the large aperture and long focal length of an SCT are perfect for planets.

This might be contraversial to say, but I've owned a 120ED and my current SCT has it beat on planets. I used BCO's with the ED120 and I now use ES100's with the C8 so both very good EP's.

[Moonshane]

I'd expect most 8" scopes to beat a 120ED on planets. My 6" f11 beats my 120ED once cooled but the 120ED cools a lot quicker.

[dweller25]

Hello Starstruck

For £400 you can get very high performing scopes, mount included that will give no chromatic aberration, good planetary and deepsky views and cool down quickly.

They are the Newtonian design which in a dobsonian mount work very well and have the best price/ aperture combination

For your money you could have a 8 or 10" scope

No 4" refractor will come close to the performance of a 8/10" dobsonian

[ollypenrice]

Double your resolution, quadruple your light grasp and halve the cost with a 8" Dob.  

I agree optically but the nudging on planets does become an issue for me. It's nice to settle down and relax while waiting for the seeing to improve with a tracking mount - a personal view.

Olly