[MortonH]

So I bought the Orion 7.2mm-21.5mm zoom from Bintel this afternoon. I did a quick test in the shop with a short tube 80mm, mainly because I wanted to see if the image got mushy at the short end as some 8-24mm zooms do. It was fine. I also tested the zoom mechanism as there have been reports of excessive stiffness in the Orion model. Again, no apparent issue in the shop, and none later either.

My main reason for buying is to have a dedicated solar setup consisting of my William Optics ZS66, Lunt solar wedge (1.25") and zoom eyepiece. I also have a 1.25" star diagonal and a 1.25" erecting prism, so this small package will cover solar, astro and terrestrial viewing.

I went back and forward between the Orion zoom and the Lunt zoom. Outwardly they appear the same, as do many other versions in Europe, although the Lunt's maximum FOV at 7.2mm is 53° while Orion's is 60°. I figured that even if the edge performance of the Orion isn't perfect, it would still "feel" nicer, especially for terrestrial viewing.

I didn't get home in time to view the sun so I waited for darkness and looked at Mars and Saturn in the ZS66 from my balcony, plus a few star fields. OK, maximum magnification in this scope is only 54x, so not a harsh test, although the scope's focal ratio is relatively fast at f/5.9.

The views were crisp and clear, with no image degradation visible at 7.2mm. A good start. Stars near the edge were pretty sharp - certainly no seagulls!

I found it very comfortable to use. Eye relief is listed at 15mm. While I didn't measure the eye relief, it seemed to me that 15mm is probably about right. With some eyepieces (Explore Scientific, for example) the eye lens is recessed and so the true eye relief is less than the spec.

I thought I might as well give it the stiffest test I could, so I got out my 200mm f/5 Newtonian. I'd lost Mars over the roof by this time but Saturn was nicely placed. After lining up the scope through the finder, I returned to the eyepiece expecting to see a tiny, featureless Saturn. However, I hadn't realised that I'd left the zoom set at 7.2mm. The view was excellent. No ghosting, excellent sharpness and good contrast. Plenty of surface detail was visible. I'd call it very good performance, reminiscent of a Baader Hyperion zoom I had a few years ago.

EDIT: I also viewed the Moon in the ZS66 and the performance remained the same.

So, what about downsides? Well, there are a couple.

Edge performance in the f/5 Newt wasn't great, but it certainly wasn't terrible. While viewing Saturn, I found the planet stayed sharp until around 75-80% from the centre of the field of view. For star fields I didn't really notice the edges being a bit soft unless I really looked for it. In normal viewing, with your chosen object in the centre of the field, I don't think the edges will be an issue at all.

In viewing the Moon with the ZS66, you can see some softness at the edges of the field if you let the Moon drift there. Craters became slightly fuzzy and less well defined. Again, this is in a f/5.9 scope.

This eyepiece is not parfocal (nor does it claim to be). However, as long as you don't zoom too quickly (as I did at first!) the object remains well focused as you make subtle adjustments to the zoom setting. In my ZS66, I measured approximately 1mm of focus adjustment required between the opposite ends of the zoom range.

Overall impression? A very good eyepiece and good value for money. It looks like it'll fulfil its intended purpose and a bit more.