Zoom eyepieces

[impactcrater]

Oh great knowledge...What are the musings on 'zoom eyepieces' vs dedicated ones ? eg celestron 8-24 vs celestron Omni....or any others the gurus would consider....regards impactcrater...

[rowan46]

Their only benefits are convenience and not having to carry lots of eyepieces around. the better ones cost a lot, cheaper ones are not as good as fixed length eyepieces. They could be useful in a portable grab and go kit but I wouldn't have them as my main eyepieces. the usual field of view is 40 degrees at the 24mm end to 60 degrees at the 8mm. the tv nagler zooms get a very good report as do the pentax xl, leica aspheric (see the theme developing) hyperion zooms come in the next tier with celestron, vixen seben in the next tier. There are a few new zooms coming on stream and zooms are getting better but the cheap ones are not really there yet

[ronin]

In its simplest form you could take one zoom eyepiece out and do all your viewing with that by just altering the apparent focal length.

The disadvantage is usually that the zoom will not perform as well in things like sharpness across the whole field - more of the edge bits could lose sharpness. Not sure if the field of view would be as wide - could be reduced to mask the less sharp bits. Also more glass and more chance of flare and scatter, however we look at fairly dim objects so that would not be greatly apparent.

We tend look at something in the centre of the scope/eyepiece not normally the edge section. Most likely what you are observing will be a factor, double stars in the centre being OK - you really only view the centre of the image, lunar observing not OK - out of focus edges could well be annoying.

Some people will not mind others will object.

Scope could be a factor, a tracking scope will maintain centered objects for longer an manual dob will have drift across the field so edge definition and size is more relevant - less nudging.

I am not sure about the "ease" of one as I would have thought that gripping the eyepiece to alter focal length would be as long in time and move the scope more then undoing one eyepiece and dropping another in. So not sure of the advantage in that respect.

Suppose if you are going out for an hour or two just to look round sort of informally then they are great, if going to locate something more difficult and specific then they may not be the best.

They will get better, look at camera lens. Always used to be prime lens now zooms are the main thing. And as with most things cost is a factor. Someone saying my £5000 zoom is as good as your 6 BST's I would expect, but my 6 BST's only cost £250 (bought them before then went to £47).

At present I will stick to a few fixed focal length EP's - I have put together an additional half set of BST's for my "informal" viewing periods - 5mm, 8mm, 25mm, however as the scope is simple and fairly short but I suspect that at some time I will try a zoom when one appears that has (for me) good performance for the cost.

[rwilkey]

Although I have tried the Sky Watcher 8-24 ep, this helped me make up my mind that zooms are not for me, I prefer the widefields of a fixed focal length ep. It is no trouble to swap between ep's in my view and quality of view is important to me.

[CSM]

Zoom eyepieces can be quite useful when you are starting out. They will give you an idea of what is suitable for different conditions. The Skywatcher 7 - 21mm has 5 focal lengths, 7, 9, 11, 15 and 21 - cheaper than buying 5 separate eyepieces. I found the 15mm to be just as good as my 15mm Televue, which was a bit of a disappointment!

[RT65CB-SWL]

If you are referring to the 8-24mm & 7-21mm ones, then there are differences of quality. Earlier this week I was reading a post and one member said that the Seben zoom was a better performer than those 'badged' by some of the 'big' manufacturers out there. The only downside with a zoom eyepiece is that the field of view can be narrower than a plossl eyepiece if they are the only eyepieces you are currently using.

If you are looking at the TeleVue 3-6mm & 2-4mm Naglar zoom eyepieces, then I don't think there is any competition!

I have the 3-6mm zoom and 'she' is a stunning piece of kit.

[impactcrater]

thank you all for your comprehensive replies...impactcrater

[LukeSkywatcher]

As stated above, the only real advantage to a zoom EP is the ability to take a single EP out with you and not have to swap over EP's and filters (if you have any attached). I have the Baader Hyperion Mk III (as many other do). Mine works great and suits my needs for carrying less gear. The Mk III is not without its problems though and many people complain that theirs have locked up on them and simply wont zoom. Other members have bought and tried the Seben 8-24mm zoom and are very pleased with it. The Seben costs a fraction of the Hyperion. Seben is usually a brand to avoid, but they seem to have done something right with their zoom EP.

[edjrgibbs]

I'd get rid of your eyepieces and image instead;-)

[Moonshane]

an advantage of zooms that's not often realised, especially at the top end of magnification is that most have infinite range between click stops so you can tune the magnification to the seeing conditions.

In terms of zoom eyepieces, I have only got the nagler 6-3mm zoom and it's truly amazing.

[estwing]

an advantage of zooms that's not often realised, especially at the top end of magnification is that most have infinite range between click stops so you can tune the magnification to the seeing conditions.

In terms of zoom eyepieces, I have only got the nagler 6-3mm zoom and it's truly amazing.

+1 for said EP.

[LukeSkywatcher]

an advantage of zooms that's not often realised, especially at the top end of magnification is that most have infinite range between click stops so you can tune the magnification to the seeing conditions.

In terms of zoom eyepieces, I have only got the nagler 6-3mm zoom and it's truly amazing.

This is true. Very early on when i bought my Hyperion 8-24mm zoom i discovered that you can actually use the magnifications in between every click stop. So an 8-24mm zoom is in essence an:8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23 and a 24mm.

Pretty much all you would ever need.

[Steve_meg]

I really get on with my celestron 8-24 ep, especially when I was using a manual dob as a first telescope. Made it really easy to find an object then zoom to a higher magnification without changing ep and losing the object.

that said, now I have a tracking telescope I may well invest in more fixed ones as the field of view is pretty small at high magnification.

[peroni]

This is true. Very early on when i bought my Hyperion 8-24mm zoom i discovered that you can actually use the magnifications in between every click stop. So an 8-24mm zoom is in essence an:8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23 and a 24mm.

Pretty much all you would ever need.

and don't forget you can get a Baader 2.25 barlow for the Hyperion zoom that gives you even more flexibility

[mitchelln]

and don't forget you can get a Baader 2.25 barlow for the Hyperion zoom that gives you even more flexibility

+1 for this. I've got the Hyperion MKIII and barlow which gives me a total range of 3.5-24mm. I've no issues with image quality when used in my 2" focuser. It's a very solid bit of kit. I can even hang my DSLR off it.

[Jules Tohpipi]

It's horses for courses, but I found that the Baader Zoom wasn't really for me. It was a bit soft at the edges which meant more frequent DOB nudging. Also, FOV was too narrow for me at the wider end. For example, the Maxvision 24mm has much wider FOV and sharper across more of it.

Of course, it's likely to work out more expensive going the separates route.

But it has certainly been useful for getting used to telescope and understanding which EPs might work best for me. Plus I'll probably get most of my money back on selling because I bought a used version.

[mitchelln]

For wide FOV I swap out the zoom for my Baader 2" 31mm aspheric. These are the main two lenses I use now.

Sent from my GT-N7105 using Tapatalk 2