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All in wonder ??


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 I never have in the past considered Zoom eyepieces. When I purchase my scope some day prob mid summer, probably a Sky watcher flex tube 10 inch Dob or 12 inch Dob  ?? I want to try a zoom eyepiece and see what all the rave is about. I definitely will be doing public outreach stuff in my home town.  In the past I made astronomy so difficult I just want simple fun under that stars.  What are your feelings on zoom eyepieces . Are the zoom eyepieces worth it? If you have experience with zoom eyepieces which one would you buy and why ?? I have looked at the offerings here in the USA they seem to go from sub -$100.00 to well over $350.00+ are they all the same or is it worth spending the extra money on a really expensive one. As usual with this incredible hobby you get what you pay for so is the crazy expensive ones worth the extra money.  Or would 350.00 on up be better spent on a small collection of Mid Grade eyepieces. Thank you so much ! Clear Skies!  

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Some people like zoom eyepieces, some people do not.

Advantages;

Convenience - and that’s for a few reasons; not having to change eyepieces in the dark, convenience of having a range of focal lengths, less to carry about etc.

Disadvantages -

field of view at longer focal lengths; they are generally limited by a narrower field of view at the longer end of the focal length so you see less of the sky.

Size and weight - they can be a bit big and bulky.

Changing focal lengths can be a bit fiddly in the dark, sometimes it needs two hands.

Generally (and only generally) fixed single eyepieces offer a slightly better view all else being equal.


As with all eyepieces, there is a massive difference in quality between eyepieces. At the upper end of the scale Baader Hyperion zoom is nearly universally liked but is quite expensive.

Generally there are two choices 8-24mm and 7-21.5mm. I think there are some good cheaper ones but each one is different

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I went for the Baader Hyperion IV zoom with matching 2.25x Barlow. Not cheap, but very good. Focal length goes 24-8mm, barlowed it goes 10.6-3.5mm. Probably my most used eyepiece until recently. 

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You'll have to wait for the eyepiece gurus to come along and help with this one!

I'd imagine, that in a 10" or 12" 'scope a zoom lens would need to be well corrected.

You'd be looking at the more expensive offerings from the off.

We've a cheap version for use in school, and in terms of versatility, flexibility and ease of use it's fab.

But then this isn't high end observing. ;)

 

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A zoom has several advantages in addition to those mentioned: 

 - you can focus on a target and decide how high you want the mag. If you happen to have a high quality EP at that mag, you can switch to it. If not, the zoom will still hopefully be good enough.

- if you're using a filter, it saves faff and time, as you can attach it to the zoom without having to change EPs and thus the filter too. The same is true with a Barlow.

Personally, I use an OVL Hyperflex 7.1-21.5mm. it's a pretty good one, though I have fixed-focus EPs with better resolutions.

Edited by cajen2
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The minimalist approach suits me and I am a fan https://astro.catshill.com/the-zoom-eyepiece/

Going for the BHZ and Barlow was a fair investment but it was totally the right one for me. I decided on it after reading so many positive comments here and on Cloudy Nights. It’s not just the convenience. Very often I use the zoom function to find out what the ideal magnification is for an object. The nearest analogy I can think of is having an automatic rather than manual transmission car. Racing pros will opt for the manual (fixed), whereas I like my automatic (zoom).

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Another pro for a zoom is for hunting out faint objects - nebulae, galaxies, etc.  Their visibility is determined by contrast, conditions, the observer, the object, etc. But contrast varies depending on magnification, so having a zoom means you can quickly adjust the focal length and find which magnification works best for getting  the most contrast of an object. 

If you are spending an evening on the hunt for faint fuzzies - and galaxy season is nearly upon us - zooms are a really useful tool.

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The 10" and 12" Dobs you mention are quite fast at f/5, and even the mighty Leica ASPH will suffer at the edges from astigmatism.  If you put your Dob on an EQ platform or get a goto version, this may not matter all that much to you.

The Tele Vue Ethos line quickly became very popular among the fast Dob crowd because they are very well corrected even at low f-ratios and have a very wide field allowing for long dwell times on objects in nontracking scopes.  In other words, as the object drifts from edge to edge, it remains quite sharp and observable for a longer time than in a narrower, more poorly corrected eyepiece.  No zoom eyepiece comes close to this capability.

I like zoom eyepieces best in binoviewers because changing out a pair of eyepieces and making sure they're correctly seated so they'll merge views is a royal pain.  Also, because I use a 2x Barlow nosepiece operating at 3x to reach focus, the zooms are insulated from the fast f-ratio of the scope and perform perfectly from edge to edge.

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I've got the Celestron 8-24mm zoom mostly for convenience but more so for the machined thread so I can attach a DSLR to it. It offers good views but dedicated power eyepieces are better overall.

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  • 3 weeks later...
On 24/01/2022 at 00:03, Elp said:

I've got the Celestron 8-24mm zoom mostly for convenience but more so for the machined thread so I can attach a DSLR to it. It offers good views but dedicated power eyepieces are better overall.

Hi @Elp, total newb question, I have the Celestron 8-24 zoom and access to a Canon D60, is it as simple as attaching a t-ring to get started in astro or do I need to worry about adding spacers or the likes? Visual is difficult enough for me, so I'm nervous about going down this rabbit hole.

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I haven't used it enough to get a clear experience with it but when I tested it with my Coronado PST it was a case of just mounting the Tring to the dslr, and then that to the eyepiece.

You shouldn't worry too much about spacers, it's quite easy. What scope have you got? You can attach the Tring/dslr combo directly onto a field flattener or threaded focus tube adaptor to image, no eyepiece needed. I've done this both on my refractor and Newtonian though the Newtonian I have been advised probably needs a 20mm spacer to get the right focal distance (via the use of a gso coma corrector), on my refractor it's fine without. A typical Canon DSLR requires a backfocus of approximately 55mm.

Edited by Elp
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