When are zoom eyepieces a good option?

[DanielC]

What are your thoughts on zoom eyepieces? In what situations do you think they're a good option vs fixed eyepieces? For example, I know that zoom eyepieces typically have a smaller AFOV than fixed eyepieces. Is that their main disadvantage? I read online that zoom eyepieces can be great for planets because there's usually one particular magnification that really works a lot better than the others in terms of making features large enough while still having enough contrast, and that.

Looking at prices, I'm thinking that if you just get a zoom eyepiece you can spend more money on it than if you buy several fixed ones. For example, for a $200-$250 budget I could either buy...

• Four Orion Expanse Wide-Field 1.25" Eyepieces, OR
• Three Orion EF Widefield 1.25" Eyepieces, OR
• One Orion 8-24mm Pro Lanthanum Zoom Eyepiece, OR
• One Celestron 8-24mm Deluxe Zoom Eyepiece.

To my inexperienced eyes, it looks to me like I can a cool and fancy zoom eyepiece for the price of 3-4 regular eyepieces and I'm trying to figure out if that's a good trade.

Thanks for the help!

[Aramcheck]

I'm mostly attempting imaging these days, but in the past we've found that the zoom eyepiece (a Baader Hyperion) useful as it saves having to keep swapping over eyepieces and filters. The main disadvantage, being rather short sighted, is that I have to keep removing my glasses to get the full FOV & my wife and I have to then refocus whenever we take turns at the eyepiece...

Cheers
Ivor

[Second Time Around]

Fixed focal length eyepieces may be slightly better corrected when compared with a zoom at the same magnification.   But that's not always a fair comparison as that magnification may not be the optimum for a given object.  This is because one of the many advantages of a zoom is to be able to dial in precisely the best focal length.  For instance, this may be 13mm or even 13.1mm, which may actually show more detail than shorter or longer fixed focal length eyepieces.  

I'm a great fan of zooms and the 8-24mm Baader zoom is easily my most used eyepiece.  I use it with the matching 2.25x Barlow.  That plus a wide field eyepiece as a finder does me for most of my sessions.

I particularly like the ability to increase the magnification to make use of brief moments of good seeing.  It takes more time to swap out an eyepiece, and the opportunity may then be missed.  You can't see anything if you haven't got an eyepiece in the focusser!

Zooms also enable the field of view to be varied to frame an object to get the prettiest view.  For this reason I particularly like them for clusters.

Many of those who post here and advocate fixed focal lengths are experienced observers.  It's so easy to forget what it was like as a beginner!  A zoom eyepiece enables beginners to easily learn what difference a change of magnification makes on all the various classes of object.  It also shows them what focal lengths would be most useful to their eyes, their telescope, and their observing conditions.  They then have the option of buying/not buying the most appropriate fixed focal length eyepieces for them.  For these reasons I'd always recommend that beginners buy a zoom as their first eyepiece.

[Jiggy 67]

Completely agree with @Second Time Around. I love my Baader zoom, easily the most used ep. I use mine a lot on double stars as you can zoom in to watch the double actual split, and fov is not really an issue with objects like stars, planets and planetary nebula. The Baader is a particularly good zoom and will save a lot of money in the 8-24 range. I've acquired fixed focal length eps since but the zoom is still, and always will be used extensively

[John]

I use a zoom eyepiece often but I would not want it as my only eyepiece. I would also want a 25mm - 32mm fixed focal length eyepiece for low power observing with a wide angle of view. The zooms have their narrowest field of view at their longer ends. Depending on the scope I would be using (you have not said what you will be using) I would also want either a good quality barlow lens or a fixed focal length eyepiece of 6mm or shorter to give high magnifications.

Of the zooms I've owned (at reasonable prices) I've found the Baader 8mm - 24mm and the Hyperflex 7.2mm - 21.5mm better quality than others I've used. The best quality zooms of all are Leica, Pentax and the Tele Vue Nagler zooms which do match the optical quality of excellent fixed focal length eyepieces but those cost a lot more money.

 

 

 

 

[RT65CB-SWL]

Having tried the Baader 8-24mm zoom at the end of February [2020] from a member at my local astro. soc./club for one hour, I was very impressed with it. Though nothing compares to using eyepieces of a 'fixed' focal length... unless it is the TeleVue Nagler zoom.

[DanielC]

Thanks for all the help guys! This is very helpful. I'll follow @Second Time Around's advice and get a zoom eyepiece, and I'll follow @John's advice and add a low power eyepiece for wide angle. I haven't bought the telescope yet because it's out of stock, but I'm planning to get a Celestron NexStar 6SE. So if the zoom shows a good image at 8mm and it looks stable enough, I could add a 6mm later. But I'll first wait and see how the zoom works out.

Thanks again!

[Pixies]

Don't forget @Second Time Around's advice on a Barlow too. That would give you down to around 3.5mm focal length with the x2.25 Baader Barlow

[Owmuchonomy]

For dealing with our local variable seeing conditions a zoom eyepiece is essential for Solar and to some extent planetary viewing.  Sometimes one just doesn't have the right fixed focal length for a comfortable view.  I have owned a Baader as described above but for me I found the (lack of) eye relief very difficult so I now prefer the better comfort of my Lunt 7 to 21.5mm zoom EP.