Review of SkyWatcher 70×700 Telescope

At the same time as I purchased a new portable astrophotography mount I decided to add a guide scope to it. This would allow prime focus photography through the Megrez 80 when out in the field. The guide scope would also double for use on the LX200 as a longer focal length alternative to the Megrez 80 for guiding.

In early 2005 I purchased a new portable astrophotography mount – a Losmandy GM-8. For this I intended to use my William Optics Megrez 80 side-by-side with another similarly sized guide scope to perform long exposure astrophotography. The setup was to be my long awaited upgrade from the portable mount I had been performing long exposure astrophotography with for the last 4 years (an EQ2 equivalent with RA motor only).

For the guide scope I chose to buy the OTA of the SkyWatcher 70×700 AZ2 setup. This is a simple refractor with the following basic statistics:

  • Focal Length: 700mm
  • Aperture: 70mm
  • F-stop: F/10
  • Tube Outside Diameter: 80mm
  • Construction: Metal tube with plastic due/sun shield, metal rack and pinion focusser with outside focusser housing being plastic.
  • Included accessories: 1x 25mm eyepiece, 1x10mm eyepiece, 2x barlow lens, 5×24 finder scope

The complete package cost me $179 plus $30 postage from the eastern states of Australia.

There are a few things I really like about this telescope as a guide scope:

  • Weight: 1.2kg including 90 degree mirror and a small guiding eyepiece.
  • Length: about 77cm depending on focus position.
  • Focal Length: 700mm is a bit more suitable for guiding than 500mm often used.
  • Cost: An affordable AU$179
  • It has a focus lock.
  • The eyepiece holders (1.25″ of course) have two lock screws, good for holding heavier items like bigger eyepieces and CCD cameras.
  • The focus tube has a threaded end for directly attaching a T-thread adapter (directly attach CCD or film camera, very useful for using a CCD for autoguiding).
  • Stars are sharp.

The telescope is of course an entry level OTA and don’t ever expect more than that. But for what it is I believe it’s great value for money. It feels nicely constructed for what it is with rough threads on screw locks and the like being a main “cheap feeling” characteristic (of course construction is nothing compared to the WO Megrez 80 of course, but that was AU$1500!).

The finder scope functions fine although is of course very small. This suits me OK as I have never had a finder scope at all on my portable setup before, simply using a green laser for finding my targets (held pressed against the telescope mount). The finder scope mount does feel cheap (it is plastic) and is probably the cheapest feeling aspect of the telescope.

The eyepieces are light weight so can’t have much in them, but they seem to function fine and it’s nice to have some included anyway. They do introduce false colour. Using Meade Super Plossle eyepieces removed about 1/2 the false colour visible with these eyepieces and sharpened the image. Using the supplied eyepieces the Cassini division on Saturn was clearly visible on a good night of viewing. The rest of this review assumes the use of higher quality eyepieces such as the Meade Super Plossle.

Optically the view is crisp and sharp. There is a fair amount of false colour especially surrounding bright objects such as Jupiter but this didn’t inhibit my view of Saturn which clearly showed the Cassini division on a good night of viewing. This was possible using most combinations of the eyepieces supplied but best viewed using a higher quality 6mm eyepiece with no 2x barlow. The false colour is also not a problem for guiding on a star for astro photography. If I were a beginner I would be quite please with the optical quality of this instrument for the price but would choose to purchase 2 higher quality eyepieces.

I have tried using my WO Megrez 80 with a 2x barlow and the CCD as a guide scope for prime focus astrophotography on my 12″ LX200 (at F/6.3) with limited success. It works but the focal length is really pushing it. I am hoping that the 700mm while F/10 rather than F/6 of the Megrez will be an easier focal length to use.

The dew shield/sun shield can be removed but unfortunately a lens cap is not supplied which fits the remaining tube diameter. This is a shame because without the shield the length is cut by about 15cm which if there were a second cap to fit, would make packaging that much more effective.

Ring sets are easily available to clamp this telescope to the top of your existing telescope/mount. Simple clamp style rings are available for as little as AU$35 and are very effective. Also available from a few manufacturers are 3 point adjustable ring sets. has a low cost set available which is suitable for a scope as light as this one for about AU$75. Losmandy sells much higher quality rings with much higher weight capacity which would be more suitable if attaching heavy equipment such as large CCD camera’s for auto guiding. The Losmandy ring sets are of course much more expensive and heavy, and for my purposes overkill. The 80mm tube fits within 80mm clamp rings.

If you are looking for a guide scope I can highly recommend this. It’s extremely light weight and short length, combined with slightly longer focal length than the usual 500mm guide scope make it very well suited. Focus lock is an added very useful (almost required) feature.

I think the only improvement upon this for a guide scope would be a larger aperture to keep the exposure times down. It would be nice to be at about F/6 at 700mm. Of course the problem with that is requiring a larger, heavier tube which simply isn’t practical on the 12″ LX200, the extra weight of a 4″ refractor I feel would be too much for stability.