Orion Apex Maksutov-Cassegrain 102mm Telescope

 

Orion Apex Maksutov-Cassegrain 102mm Telescope

My 114 mm Newtonian reflector telescope and my 80mm refractor do not have sufficient focal length to  magnify strongly enough to get good views of Jupiter and Saturn. I bought the Apex which has a focal length of 1,300 mm to improve matters. When the scope arrived I was, pleasantly, shocked and stunned by the quality of the optics. The scope is equally at home being used for astronomy and terrestrial observations.

Here are some of the specifications:

Maksutov-Cassegrain design,

Optical aperture -102mm , Focal length -1300mm, Focal Ratio f/12.7
f/12.7, Resolving Power - 1.14arc seconds.

Supplied eyepiece  - Sirius Plossl 25.0mm (1.25"),

Magnification with included eyepiece  - 52x,

Highest useful magnification - 204x,

Limiting stellar magnitude - 12.7,

Finder scope - 6x26 Correct-image,

Diagonal 1.25" 45° Prism Correct-image,

Optical Tube Assembly( OTA) material - Aluminium,

Length of optical tube - 27.9cm, without diagonal,

Weight, fully assembled - 2.3kg,

Carry case for OTA, eyepieces, finder scope and diagonal etc.

This is an impressive set of specifications for a telescope which you can buy for £ 245, I paid more but why worry?

Initially ,I used terrestrial observations to set up the scope. I sighted an electricity pylon 3kms away. The Apex easily resolved the the indentations on the insulators, even through poor seeing conditions; it could also resolve some thinner wiring at the top of the pylon. I lined up the finder scope with the objective lens so that I could easily find objects at an extreme distance. I then focused on a fence at 1.25 kilometres in a park: the Apex could easily resolve the 1.5 centimetre diameter shafts. At that distance I could see the glasses frames of some people sitting on a bench. I estimated that the scope was able to resolve below 1.57 arc seconds and this was through a window with less that perfect seeing conditions.

The scope itself is solidly made and reasonably light and it looks and feels good. It needs to be mounted on a substantial tripod to avoid the shakes and appreciate its resolution. The correct image finder scope is of very good quality in itself. The 45degree correcting diagonal is also of good quality, as is the supplied 1/25" 25 mm eyepiece, which provides a magnification of  x 52. For astronomical use I shall use a 90 degree mirror diagonal.

When the skies cleared, I went out to test the optics in the night sky, even though the light pollution and seeing conditions are not very good in my vicinity. The finder scope is brilliant and for me it is much better than a red dot finder as I can actually see the stars to be used as pointers. I first found the Orion Nebula, the stars of the Trapezium were pinpoint and I could not see any aberration. The Moon was astounding, there was no chromatic aberration or distortion  apparent to me. It was possible to clearly see the crater walls, mountains and rilles on the Moon's surface and some claire obscur effects. I swung the scope over to observe Sirius which was clearly resolved without aberrations. I focused on Mars but I could only see it as an orange disc without detail, as it is now getting further and further away. I was using a 32 mm lens giving 40x magnification. I can't wait to see Saturn and Jupiter when they are in favourable postions with a 9.7 or 12.4 mm eye pieces at plus 100 x magnification.

I went  to the reservoir where I observed cormorants on a tree at 500 metres distance; I could see all the detail of their feathers in natural colour. The tufted ducks on the lake also resolved in natural colour and without any chromatic aberration even with bright sunlight reflecting from the water. The scope performs well across the full diameter of the field of view.

Back at home I tested the scope for chromatic aberrations again, I focused on a radio/tv aerial which was exceptionally shiny with very bright sunlight reflecting off it, there was no aberration. None of my other optics could match this without some colour fringing.

To crown the optical performance I observed a ring-necked parakeet at the bottom of my garden. The bird came up in completely natural colour and I could see the finest detail of its feathers and its legs. The bird seemed to be perched at the end of my arm. I have never seen such a good magnified image of a bird in any other optic, be it Leica, Zeiss or Swarovski. How is this achieved? It's the design. The primary objectives which focus the image are mirrors. Mirrors perform much better than lenses at focusing light to a single point without chromatic or spherical aberrations or distortions especially when a corrector lens is fitted in the Maksutov design. Refractor lenses can only compete with this by using top quality ED glass. Your Swarovski field scope or your Explore Scientific refractor, therefore, costs very much more to achieve the same optical quality.

The Apex scope is made in China so you could easily receive a dud because, to reduce costs, the quality control is cursory, and needs to be finalised  by the buyer. My scope arrived well packaged and in perfect working order. I checked that it was well collimated or optically perfectly aligned. Had I received a dud I would have sent it back for a refund or a replacement.  This is now a fact of modern life.

 A Swarovski will be delivered in perfect condition and if  you drop it and break it, then they will send you a new one: such is their great service and one of the benefits of bygone times, so three cheers for this. But, you are paying a premium for this on top of the almost perfect optical quality.

I tested the scope thoroughly and summarise its advantages and disadvantages below.

Advantages:

Superb optical quality across the whole field of view and even at 100 plus magnification,

Extremely good value for money,

Fairly light and strongly built,

Easy to find optical targets,

Easy to focus,

Flexible and easy to use for both astronomy and bird watching etc.

Interchangeable  1 and 1/25" eyepieces, you can even by a zoom eyepiece,

Easy to transport and set up for astronomy.

Disadvantages:

Not waterproof,

Fixed focus lenses need to be used; you could buy a zoom lens but this will compromise optical quality,

No dew or sun shade, but you can make one,

Minimal practical magnification with a 32 mm lens is 40X,

Not suitable for use in the rain or under adverse conditions,

The finder scope gets in the way; however you can remove it, but then it is  more difficult to find targets,

You need to collimate it periodically or if you give it a heavy knock,

The finder scope is not in a convenient position for using astronomical mounts, so you may need to buy optical tube assemble rings,

Conclusions:

You need a very substantial photographic tripod to mount it to avoid shaking images. Don't take it up the jungle or down the desert as it is not designed for this.

This scope is perfect for beginners in astronomy especially if you want to observe the Moon, planets, double stars and the brighter deep sky objects. It is easy to transport and set up or to take outside quickly when the clouds part.

If you are prepared to treat the scope with care it will be brilliant for bird and nature watching from a sedentary and dry place such as a hide. You will also be pleased to know that the chap sitting next to you with a Leica scope has paid ten times the price for a similar quality of view. 

The optics are fantastic; it performs so well even at 100 plus magnification.