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Old 10-02-2020, 06:28 PM
smifx3 (JOHN)
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Eyepieces .. zoom vs. individual

Hi everyone
Wondering which way to go ... should I go for a good quality zoom or go with individual eyepieces.. using a Meade LX65 on a Skywatcher HEQ5PRO Mount
Cheers
John
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Old 10-02-2020, 08:23 PM
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ngcles
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Hi John,

I'd suggest high-quality fixed focal length eyepieces over a zoom.

All zooms (including camera lenses) are a compromise and rarely deliver the same degree of image sharpness as a single fl eyepiece can. The only one I thought pretty good was a Baader Hyperion 24-8mm zoom I had on loan for a test report. But it isn't a cheapie either ($500- AUD)!

The limitation even on such an expensive unit is that at low powers, the FOV is about that of a plossl (~50deg) and wider fields (60-68 deg) only comes with higher powers. It was pretty to quite sharp at all focal lengths, though sometimes the field stop went out of focus or became "soft". Cheap zooms are generally, really somewhere between awful and catastrophic. Zoom eyepieces will generally work better on longer focal length telescopes that impose fewer demands on the eyepiece optics.

The Baader was by far the best zoom I've experienced, but in the end, I prefer a wide range of Televue Naglers. Yes, I know they're very expensive too -- but a great eyepiece is a jewel forever and if you change 'scopes you can use them with another 'scope. You can buy 'em (like I did) one at a time over a number of years. I think it took me ten years to get the suite of eyepieces I currently use (eight) -- all Naglers (bar-one).

Best,

L.
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Old 11-02-2020, 02:11 AM
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Ukastronomer (Jeremy)
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Quote:
Originally Posted by smifx3 View Post
Hi everyone
Wondering which way to go ... should I go for a good quality zoom or go with individual eyepieces.. using a Meade LX65 on a Skywatcher HEQ5PRO Mount
Cheers
John
I have both, Axiom, LVW Vixen, William Optics, and Baader mainly 2" BUT also the Baader MK4 Hyperion.

Apart from the terrible FOV as compared to my 2" ones the Baader is a very well respected and good eyepiece, I use it on the 72mm ED Skywatcher

Only buy 2" where you can



.
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Old 11-02-2020, 01:30 PM
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OICURMT
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Like others, I'd also stay with fixed focal length for most/all my collection.


The *only* exception would be the Hyperion zoom, which I have and use for lunar and solar observation only, as it makes it easy to scan and zoom-in when/where required.
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Old 11-02-2020, 03:38 PM
Rainmaker (Matt)
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I also prefer single focal length eyepieces although having owned the Swarovski and used the Zeiss zooms I found that they lost nothing in sharpness to my other eyepieces.
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Old 11-02-2020, 08:51 PM
ausastronomer (John Bambury)
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Hi John,

I pretty much concur with all the preceding comments. Like Matt (Rainmaker) I own cases full of premium eyepieces predominantly from Pentax and Televue. I don't have a zoom amongst the 25+ premium eyepieces I own.

As Les mentioned it is very rare that a zoom eyepiece / lens will optically equal a fixed focal length unit of the same quality. That applies to Camera Lenses, Eyepieces, Binoculars and Rifle Scopes. Some of the very high end German Zooms are exceptional but just a fraction behind an equivalent fixed focal length product IMO for a couple of reasons. They are also very expensive.

The Leica 8.9-17.8 is excellent as is the Leica 7.3 to 22. The Swarozski 9.4 to 18.2 is also very good. These are all well North of $1,000. The best astronomical zoom would be the Zeiss Diascope 20 - 75X (6.9mm to 25.1mm) which optically in terms of sharpness, contrast and light throughput, will equal the best fixed focal length eyepieces from Pentax or Televue and at about $2,000 it would want to. The thing with the zooms is I find they have some -ve's; the biggest one of which is that the AFOV narrows as the eyepiece focal length is increased.

To me the very best eyepiece experience combines many factors including optical quality (sharpness, contrast, light throughput and a lack of aberrations), build quality, The FOV for me and enough eye relief to use with eyeglasses. I find that satisfaction with fixed focal length eyepieces from Pentax, Televue, Nikon NAV HW and Docter Optics.

Cheers
John B
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Old 16-02-2020, 07:02 PM
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JimsShed (Jim)
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Hi John,
The LX65 has a 2032mm focal length which means big magnification already as compared to a sub 1000mm FL scope. I have a Baader Hyperion Zoom and use it often in my refractors, but not much in my 9.25 SCT because the field of view is too small for many targets.
In selecting eyepieces, you might like to look at this https://www.skyandtelescope.com/obse...pe-calculator/ and in particular pay attention to the exit pupil values.

Jim
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