Wide Angle vs. Standard Eyepiece (1 Viewer)

Hello All,

I’m new to birding and realized that for seabirds the use of a scope would make identifying them a lot easier! I can’t quite grasp the idea behind the wide angle versus regular eyepiece choices. With wide angle it seems you get constant apparent FOV across the zoom range, while the regular ones it decreases with increasing power. I’m not sure how the wind angled can keep a constant apparent FOV.

Anyway, what are the pros and cons of the two approaches. Any assistance would be most appreciated. Thanks!

Tsutomu

By 'regular' or 'standard' eyepiece, I assume from your description that you mean zoom? A fixed power, wide-angle eyepiece offers a wide, bright FOV which makes the acquisition and following of seabirds, raptors etc much easier, the trade off being that it may not give you the magnification required to make an identification. A zoom eyepiece will offer a fairly wide FOV at lowest magnification aiding acquisition, which reduces markedly as the magnification is increased. The smaller FOV/higher available magnification makes following a flying bird much more difficult and, even though the extra magnification is useful, identification is made more difficult by more frequent adjustments to focus/oscillation of tripod due to reduced depth of field. Basically its all about physics; you pays your money and takes your chance. Decide what matters most to you and make your purchase based on that. Hope this is helpful?

RB

Thanks, RB for your reply. What you said makes sense. But, I was for referring to a zoom eyepiece for both types. Specifically, for the Meopta MeoStar these two eyepieces are available (pasted below). I’m not sure how a constant apparent (subjective) FOV is possible? What do they mean by that?

Variable eyepiece 20-70x

Specifically designed for the MeoStar S2 82 HD spotting scope. Provides a 45˚ subjective field of view at 20x and a 63˚ subjective field of view at 70x magnification. Optimized for extra magnification range and sharp to the edge image. Push button, quick release bayonet mount. Twist-up eyecup. Nitrogen purged and waterproof.

MeoStar S2 eyepiece 30-60x WA
Specifically designed for the MeoStar S2 82 HD spotting scope. Provides a constant 66˚ subjective field of view through the entire magnification range. Optimized for the absolute widest field of view and sharp to the edge image. Push button, quick release bayonet mount. Twist-up eyecup. Nitrogen purged and waterproof.

The 30x-60x eyepiece has only a 2x zoom range, so making a constant apparent field is easier.

The 20x-70x has a 3.5x zoom range. The same AFOV would be possible but at a low value.

B.

The left two images correspond to result from zoom eyepiece with a (severely) reduced apparent FOV at the lower magnification. The righthand two shows the benefit of having the wider apparent FOV maintained at the lower magnification; easier to find target and more view to look at.
https://www.popastro.com/main_spa1/field-of-view/

Hi,

most wide angle zooms don't have a constant afov over the zoom range... but still they get a lot less narrow at the low magnification end than normal zoom EPs.

They trade less zoom range and/or a larger and heavier EP for this...

Joachim

I prefer fixed power eyepieces so I can a wider Field of view to make finding and observing things easier, though I then need to bring several around. Zooms are almost always a compromises I do have a zoom, which is reckoned to be a pretty good one, but I still find it claustrophobic vs fixed power eyepieces. Wider fields of view can be more costly to provide with high quality. Constant apparent field might mean that it effectively uses less of the scope aper to re at low powers,.. I believe the zeiss plays this trick. I’d probably take the latter, but then you lose the lowest and possibly higher powers.... that you might occasionally might want.
The powers I have available are spread across a factor of 3.4x from low to high, though I mainly sit in the middle.

Peter

wllmspd said:

I prefer fixed power eyepieces so I can a wider Field of view to make finding and observing things easier, though I then need to bring several around. Zooms are almost always a compromises I do have a zoom, which is reckoned to be a pretty good one, but I still find it claustrophobic vs fixed power eyepieces. Wider fields of view can be more costly to provide with high quality. Constant apparent field might mean that it effectively uses less of the scope aper to re at low powers,.. I believe the zeiss plays this trick. I’d probably take the latter, but then you lose the lowest and possibly higher powers.... that you might occasionally might want.
The powers I have available are spread across a factor of 3.4x from low to high, though I mainly sit in the middle.

Peter

Click to expand...

Modern wide-angled zooms avoid what you describe and that's the reason why there is no new fixed eps from Swarovski, Zeiss (before the Harpia...), Kowa (at least on the 77/88), Leica and Meopta!...

Tsutomu,
In the case of the Meopta, it depends on what you want and your expected birding - both should be great eps.
The non wide-angled has the advantage of allowing lower mags (might be useful when there is lowlight and for some digiscopy) and higher mags - for more detail - is a 3.5x zoom!!!
The wide angled is more comfortable due to the larger AFOV. Some might think 30x is too much for minimum mag but the 60x is ok, compared to competition.

I use a fairly wide zoom.. The Baader hyperion mk IV.. Starting at 57degrees, jumping to 60 most of the range and up to something close to 70° at the highest power setting.This is a 3x zoom. For pretty much all of its range compares very well with all the high quality wide fixed eyepieces I have used over the years.. The trend on super high quality, 2x or 2.5x zooms might be better in all respects, I don't know, I think most of these offer an even wider field. I personally don't need more,but a wider AFOV would probably be welcomed. In the case of the Meopta and the Kowa series, they offer two zoom models,one being the wider model we just discussed with a shorter zoom range, and a standard AFOV model with more zoom range, delivering higher power, and probably(or maybe not) better eye relief.. Another possible trade off of wide angle zoom designs..although my excellent baader doesn't really suffer of such limitations. It is a matter of knowing what you need.Probably trying both side by side would clarify the issue,all I can say it's that for me a wide angle zoom is a must from now on. I could do with a fixed wide eyepiece just fine, but I don't think I would be happy with a, standard field zoom in the long term

Thanks to everyone for responding, much appreciated.

I realize this is an old thread but here’s another illustration illustrating AFOV‘s between a 50 degree and a 82 degree, 10mm eyepieces at 50x mag on a 80mm scope.
Of course, you won’t get 82*AFOV from a zoom eyepiece, but 50* or less is typical of most zoom eyepieces.
Wide angle, fixed astro eyepieces are not that expensive. You can find a couple or three eyepieces for the price of one zoom eyepiece for a spotter.