Phenix Optics Co 127mm (5") Achromatic Refractor

Then we spotted the Phenix Optics 127mm Refractors being marketed on e-bay and as much as anything curiosity eventually got the better of me.

As always with these reviews, we ordered the scope though normal channels. Whilst it may be presumed that ours is a representative sample there is no guarantee of this!

Review - On the day we were expecting it the scope arrived in two large fairly heavy boxes. Despite the fact that both boxes were covered in footprints and had clearly had a tough journey the contents arrived intact - which was a good start!

The tube assembly is constructed entirely from metal, aside from the focusing knobs and is well constructed - giving the overall impression of a solid and quite imposing instrument.

The OTA is nicely finished in white, which I liked and a silver/grey Hammerite that in my opinion makes it look a bit dated. The mount, as can be seen in the picture is also finished in a silver/grey Hammerite.

As far as the OTA was concerned on initial inspection there were two main areas of concern; the first being that racking the focuser in and out revealed quite a lot of slop. The second concern and far more serious was that looking down the tube from the front, one of the internal baffles appeared as though it were stopping down the scope - subsequent tests proved inconclusive, more on this later.

Moving on to the mount, as far as first impressions are concerned there are several issues/niggles to mention; there are a considerable number of plastic parts used on this mount, far more than I would like to see. Having said that; most of the major structural parts are constructed from metal.

Our scope arrived with no instructions whatsoever - and just to throw a spanner in the works ours came with an additional thumbscrew, which had nowhere to go. The declination axis motor drive was not attached; this is something that you have to do yourself, without the aid of instructions. Being familiar with such things it didn't prove too much of a chore - but for someone unfamiliar with equatorial mounts and/or attaching motor drives to them this may prove to be a long job, especially if supplied with the extra screw!

Once assembled the mount was found to have a considerable amount of play in the RA axis. The cover for the drive mechanism had to be removed in order to trace the source of the problem, which turned out to be play in the worm gear along it's axis. Whilst fairly intuitive and easily adjusted this could cause a major headache to our novice already confronted with the extra screw.

Performance - Initial problems out of the way, the mount does make quite a solid and perfectly usable platform at least for visual use. Whilst it performs adequately the mount is borderline with this scope. On the whole, as a stand alone item it is actually quite a good mount and once set up tracks well.

Returning to the OTA; as mentioned earlier my initial concern was that the scope may be stopped down by one of the internal baffles. Measurements of exit pupil size proved inconclusive - not that I think this is a particularly precise test anyway. In the end I concluded that if this scope is stopped down then it is only by a very small amount.

There is obviously some CA with this scope, that is unavoidable in an Achromatic refractor. But it is no worse than in other Achromatic refractors of around this focal ratio and is comparable with the Meade 127mm LXD75 mentioned earlier.

Star testing failed to reveal any sign of astigmatism or coma. It did reveal that the optics on ours were perfectly aligned. There may be the tiniest hint of spherical aberration but this is by no means certain - star tests can be extremely difficult to interpret if the errors are small. Overall the results of star testing were very impressive.

The scope has produced good views of Jupiter and Saturn up to 240x magnification, although I think it performs better at around 200x and the views are altogether more pleasing at that power. Cassini division and some banding on Saturn are easy objects with this scope and nice detail can also be seen on Jupiter. With a full aperture solar filter this makes a good scope for white light solar observation and granulation is easily visible. The Moon is an obvious target, and this scope is capable of providing some wonderful views.

The initial slop found in the focuser proved to be far less troublesome than I suspected from first impressions, I also found that it could be greatly improved by fiddling with two adjustment screws either side of the focus lock screw. For visual work the scope proved quite easy to bring to sharp focus. When it came to imaging, the remaining play became more troublesome but it was still possible to obtain focus with reasonable ease.

My biggest complaint with this scope is that whilst the main tube is well baffled (possibly a little too well) the drawtube is not. To make matters worse the inside of the drawtube is quite reflective and this really needs to be dealt with!

In summary - With a few adjustments the mount has proved to be very good. With the legs fully retracted this mount provides a pretty solid platform. Bearing in mind the mount came with Dual-Axis D.C. Motor Drives and a polar alignment scope it is probably worth the money on it's own. The biggest negative is that the scope really requires a heavier duty mount!

Optically the scope itself is good and the OTA well constructed and nicely finished. The only issues being with the focuser and drawtube. Overall the scope performs as well as equivalent scopes from some of the better-known manufactures but at a fraction of the cost.

Other SVO sites

Emma's Candle Emporium
See View Observatory AstroShop
 The Haunted Natterbox Discussion Forums