Orion zoom 7.2mm-21.5mm (now with first light review)

[MortonH]

I'm thinking of a zoom eyepiece for solar viewing with my ZS66. I quite like the look of the Lunt Solar zoom 7.2-21.5mm, although the maximum AFOV is only 53° at 7.2mm.

The Orion zoom appears to be pretty much identical to the Lunt except that the maximum AFOV is 60°.

In a small scope like my ZS66 the difference in AFOV isn't very significant, but if I was to use the zoom in a larger scope it might be, so I'm wondering if the Orion is a better option. The Lunt seems to be sharp but I can't find much information on the Orion version.

The zoom would also be used for occasional terrestrial viewing in the ZS66.

Any owners out there?

[casstony]

I've used both eyepieces and they seemed the same. The only noticeable difference was the Orion was much stiffer to turn, but I've only used one sample.

[MortonH]

The stiffness is one of the few comments I've found on the Orion. Someone speculated that the internal grease doesn't like winter temperatures in the US, but if it's stiff here as well...!

As zooms go, how were they? I've used a few in the past, including the old Tele Vue 8-24mm and the Baader Hyperion Mark III 8-24mm, so they are my reference points.

[Renato1 (Renato)]

Is there any difference between the Orion 8-24mm and the cheaper Seben MZ 8-24mm (with the exact same fields of view)?

Or the Lunt 7.2-21.5mm and the cheaper Seben Orbinar 7.2-21.5mm (with the exact same fields of view)?

Regards,
Renato

[MortonH]

Originally Posted by Renato1

Is there any difference between the Orion 8-24mm and the cheaper Seben MZ 8-24mm (with the exact same fields of view)?

Or the Lunt 7.2-21.5mm and the cheaper Seben Orbinar 7.2-21.5mm (with the exact same fields of view)?

Regards,
Renato

Even though the specs appear the same there definitely are differences between different models based on what I've read. For example, apparently one cheap zoom (possibly Seben, I can't remember now) has plastic lenses and is awful.

However, my impression is that once you reach a certain price point the quality is the same or similar, and paying more might not be worth it. I'm trying to figure out that point!

[casstony]

Originally Posted by MortonH

As zooms go, how were they? I've used a few in the past, including the old Tele Vue 8-24mm and the Baader Hyperion Mark III 8-24mm, so they are my reference points.

Compared to the Televue (I owned a Vixen 8-24mm), the Baader and Lunt should be a lot sharper in the short focal lengths. The Baader has a bit less eye relief than the Televue and the Lunt has a little less again.

If the zoom will be used at night the Baader is my preference due to it's larger FOV. For solar or planets where the FOV doesn't matter the Lunt very good.

[Renato1 (Renato)]

Originally Posted by MortonH

Even though the specs appear the same there definitely are differences between different models based on what I've read. For example, apparently one cheap zoom (possibly Seben, I can't remember now) has plastic lenses and is awful.

However, my impression is that once you reach a certain price point the quality is the same or similar, and paying more might not be worth it. I'm trying to figure out that point!

Yes, it's tricky. I have one cheap 7-21mm zoom which isn't anywhere near as good as the Seben 8-24mm that I bought 5 or 6 years ago, when all up it cost around $60. My Seben was so good for the price, that I bought another one to use in my binoviewer.

Cheers,
Renato

[julianh72 (Julian)]

Originally Posted by MortonH

Even though the specs appear the same there definitely are differences between different models based on what I've read. For example, apparently one cheap zoom (possibly Seben, I can't remember now) has plastic lenses and is awful.

However, my impression is that once you reach a certain price point the quality is the same or similar, and paying more might not be worth it. I'm trying to figure out that point!

There may be zooms out there with plastic lenses; I have the cheap Seben 7.5 - 22.5 mm zoom, and it has glass, not plastic. While it may not suit enthusiasts, it's a great eyepiece for beginners; optical quality is certainly comparable to my SkyWatcher and Seben Orbinar fixed-FL Plossls. (And I'm not the only one who thinks it is great value - check out this thread for example: http://stargazerslounge.com/topic/19...zoom-eyepiece/ )

[EDIT: According to this post http://stargazerslounge.com/topic/19...ece/?p=2126037 the Seben 7.5 - 22.5 uses both glass and plastic elements. This may be the case - but I'm still very impressed with the optical image quality for the asking price.]

[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.

[omegacrux (David)]

There a handy thing , lately with my MZT? 7-21No name zoom I have barlow'ed it 2x and had good results with the ed80 on Mars .
Need a good night though.

David

[Astro_Bot]

Originally Posted by Renato1

Is there any difference between the Orion 8-24mm and the cheaper Seben MZ 8-24mm (with the exact same fields of view)?

They might be the same. I used to have the MZT 8-24mm, which is also sold as Seben and Celestron (possibly others) and allegedly a Chinese clone of the Vixen 8-24mm. It wasn't bad, but I prefer my Baader MkIII 8-24mm, especially for solar viewing, due to fewer reflections (better coatings, I expect) and slightly wider FOV.

Come to think of it, didn't I sell my MZT zoom to David (omegacrux)? It was someone in Tassie, anyway.

[omegacrux (David)]

Don't know why I thought it was 7-21 and not 8-24
So that's who I got it from couldn't remember !

David

[MortonH]

Have used the zoom a couple of times now for white light solar viewing with my ZS66 and Lunt solar wedge. The zoom range is perfect for the ZS66 (388mm focal length). Performance for solar was just as good as noted above.

It's a keeper!

[MortonH]

Further update on edge performance. Had a brief chance to try it out in my SV80ED f/7 refractor tonight.

At 7.2mm, I let Saturn drift out of the field and the image was reasonably sharp until Saturn's leading edge reached the field stop. There was a small amount of lateral CA visible from around the 90% mark, and a minor loss of sharpness, e.g. the Cassini division was difficult to pick out. Casual observers would likely not notice, as the effect is similar to moments of poor seeing.

[LightningNZ (Cam)]

I have a Seben 8-24mm and while it has a rather scary rattle going on the quality seems very reasonable. I consider it very good value considering its versatility and the measly $60 I paid.

Not having to constantly change eyepieces with each object if I just want a slightly more magnified view is a pleasant time saver. It's not parfocal but not far out either.

Cheers,
Cam