Could A 6 Inch F8 Reflector Best A 6 Inch Apo On The Planets And Moon?

[refractordude]

Hello there

I am thinking it would be at least close due to the focal ratio of the reflector being F8. Thanks to you all

[N1 (Mirko)]

A good 6" f/8 reflector will get close, but if the apo is worth its salt it should not be "bested" (what do you mean by that specifically?) by an obstructed design of equal aperture - with the exception of UV/IR imaging.

[refractordude]

N1


Sorry but I do not understand your question. My question to the forum is on contrast and resolution between a 6inch an Apo vs a 6 inch reflector with a focal ratio of (F8).

[Nikolas (Nik)]

Apo should have better contrast

[N1 (Mirko)]

Originally Posted by refractordude

N1
Sorry but I do not understand your question. My question to the forum is on contrast and resolution between a 6inch an Apo vs a 6 inch reflector with a focal ratio of (F8).

Yep the apo will be better on those fronts. The picture, as it were, becomes less clear when imaging, but I didn't think of the subforum name when I replied. So yes - for visual and ignoring ergonomics and mounting requirements, apo all the way.

[refractordude]

I am asking the question because I put a chip in the lens of my 1200 F8 achromatic. The chip is covered by a 4 inch aperture mask which I always use for the moon and planets. I need another full aperture scope for my dark site. The 1200mm refractor is a beast to break down at 2:00am in 30 degree weather. So I am thinking for my two hour drive away dark site I would use a Dob and the large refractor at home. One of the scopes I am considering is the Skywatcher 150mm Heritage. Not a lot of aperture but very much within my budget. Besides my dark site is most likely a Bortle 3.5 which is very dark. I have an AZ4 mount with a lite tripod that I could put the Heritage Dob on. Your thoughts on the 150mm Heritage. Thanks to you all.

https://www.skywatcherusa.com/produc...etop-dobsonian


Here is a good deal https://agenaastro.com/sky-watcher-6...pe-s11600.html

[The Mekon (John Briggs)]

Hard to follow your reason for the question when you start talking about F8 achromats which are quite different to Apo's.

Some years back S&T did a comparo between F8 6" reflectors of known wave error. To finish the test they tested the best, a 1/10 wave scope against an AstroPhysics refractor. The refractor was better.

[refractordude]

The Mekon


Yes my mistake and thanks for the correction.

[N1 (Mirko)]

The Heritage's strong points are its low weight, portability, decent optics and small demands on mounts and storage space. It's in an entirely different league from the hassle that comes with a 6" refractor. Weak points are ergonomics, and the need to manage stray light. Possible weak points are the helical focuser, the short-ish focal length (resulting in coma and field curvature which may or may not be objectionable), 1.25"-only and the lack of an optical finder. Optically, it will outperform an achromat of equal aperture on almost everything. Note - it's f/5 not f/8. It's a good scope overall.

Any particular reason why you're wanting to stick with 150mm of aperture? I think the best visual reflector to replace a 6" f/8 achro is a standard 8" dob. Same FoV but better (sometimes vastly) at absolutely everything, incl portability.

How big is lens chip in the achromat? Maybe just mask that and leave the rest of the aperture open?

[refractordude]

N1


Thanks for you response/advise. The mask leaves me four inches of aperture which I already use for the planets/moon. After a stargazing session I am very tired. Really need a quick and easy to breakdown six inch aperture scope. Thinking an eight inch dob would be way more of a hassle at the end of the evening than a six inch dob. I am satisfied with what a six aperture scope could do at my dark site. Never own an eight inch dob. Will an eight inch be a greater hassle at the end of the evening than a six? I also have my 20x80 and 7x50 each on their own parallagram mount. Something has to give.

[gregbradley]

The best views I have seen have always been APO refractors. TEC 180mm
140mm AP, 130mm AP, CFF 105 F6, Tak FS152, FSQ106N and ED, Tak FS102 F8.

Reflectors in similar size have been Vixen RS200 (very widefield and not engaging visually).

Visually and for imaging nothing beats an APO of high quality, hence the high prices and huge demand for them. Reflectors generally speaking, have large star sizes. A good APO shows stars as tiny pinpoints.

I find my AP130 GT F6 to be a mesmerising visual instrument, especially on open clusters where the stars are pinpoints and often have different coloured stars.

But APOs are not that great for galaxies as they need aperture. A good SCT is better for them.

A 6 inch APO is probably at least $10,000 and up from there depending on the maker.

But for imaging there is a considerable gap between APOs and reflectors.
The reflectors that come closest that comes to mind are the Tak Epsilon 130 and 160ED Newts.

Greg.

[refractordude]

gregbradley


Nice reply and thanks. I actually do most of my observations with my 20x80 binoculars. I use the telescope for greater magnification. My 20x80 binoculars are just as bright as my six inch scope at low power. Using the Meade 56mm plossl with the scope the brightness is the same. Perhaps it is an illusion of some kind. I have tested them against each other on several kinds of objects and the brightness is the same. I will most likely end up with 150mm aperture apo binoculars. I play the lottery every week.