APM 152mm F/7.9 APO DOUBLET WITH 3.7" ZTA

I've had this 'scope for just a month now, and with east coast NSW spending most of that time under cloud cover, I've had only a couple of opportunities to test it, and this has been limited to just astrophotography. If this review is editable, I will add further comments as time and usage permits.

There are not all that many refractor manufacturers who produce a 150mm/6" aperture 'scope. Of them, the APM is one of the cheapest, being a doublet rather than the usual triplet (or quartet). I checked fairly thoroughly its astrophotography results in galleries, like Astrobin, and found quite decent imaging being done. It is also one of the physically lightest, this being a significant consideration for one like myself who has to take his mount down when the weather turns poor. Note that the pricing shown by Testar does not include shipping costs, which make a large addition to its total cost.

The build quality of the 'scope is high, the draw-tube works smoothly with only a small amount of backlash, and the dew shield slides smoothly and locks positively. I was able to install a ZWO EAF to the draw-tube's focuser, and have provided Testar with information on how this can be done. One early problem I found was that, with its weight, it is difficult to catch the 'scope when sliding it out of the mount's saddle, with the result that the dew shield or upper lens barrel hits the mount, and in my case, chipped the barrel's coating. Another issue I had was that the clamping thumb screws that hold the entire draw-tube to the main barrel slip easily and required me to use significant force to tighten them to prevent accidental rotation of my attached camera. It comes in a very sturdy padded carrying case. Unfortunately, the case is fitted with carrying handles at each end, requiring you to be a 2m tall person to be able to stretch your arms wide enough to use them. A central, lid-mounted handle for us lesser folk would be a very welcome improvement.

Of the two targets I have imaged in average seeing conditions (for my coastal location), I have been able to get quite pleasing results (see attached example of NGC3324+IC2599). The stars are nicely round right out to the corners of the frame, and I could detect no chromatic aberration. Features in nebulae are resolvable, and are sharp where they need to be. At long exposures (300sec) the less-than-decent seeing caused the stars to bloat somewhat (guiding was in the 0.5-1.0 arcsec error range), but <60sec exposures showed them nicely sharp-edged with just a hint of haziness. I did have some initial difficulty getting the automatic focuser to work consistently, but think this might be a result of the indifferent seeing conditions.

Overall, I am well pleased with my first results and hope to improve on them with experience. If you are looking for a long f/l refractor, then this 'scope is well worth its price, and will give its much more expensive brothers/sisters a good run for it. Recommended.