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Modern Zooms vs Fixed EPs? (1 Viewer)

G

giosblue

Well-known member
If modern zooms are that good, why do they still make fixed EP's?
Some people say they are, others say, they're not.

I've just fitted a Baader zoom to my Optolyth, and to very good effect, it really has transformed the scope. I was going to fit a fixed 13mm which would have given me about 35x which is about right for the birding I do.
Unfortunately I can fit the 13mm Baader, Well, I could with a modification, but would it be worth it over zoom?

Would love to hear from anyone who has both and what they think.

thank you

Ron
 
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I've got both a zoom (MCII) and several wideangles for die Nikon Fieldscopes. Optically (resolution, contrast and so on) the zoom is at least as good as the wideangles. However, in the case of the Nikon Fieldscopes the zoom (MCII) has got a fairly narrow field of view and not a lot of eyerelief. Still, the zoom is so good that I much prefer to use it over the wideangles, simply because I can change the magnification so quickly.

With modern zooms (like the current ones by Zeiss, Leica, Swarovski and Kowa) the field of view is wide. And they're as good as really good wideangles.

Hermann
 
I'm happy with the sharpness of the Baader I've fitted, Ideally I want it to be brighter when I'm zoomed in.
I know the exit pupil is much smaller at max mag, I think with my scope it's 4.36@ 18x and 1.45@ 55x.
So I am right to assume my scope would be about the same brightness has any other scope with a zoom that gives the same magnification and exit pupil? It's an 80mm ED Optolyth.
Maybe I'm jumping the gun, because the weathers been poor in the UK since I fitted it and due to that, and work commitments, I haven't tried it in sunny clear conditions.
I have a windfall coming to me soon which would just about buy me Kowa 883 with 25x60 zoom.
unfortunately there is no way I can try one before I buy.

I don't want to shell out over £2000 and be disappointed.

Ron


Ron
 
Field of view is the main reason. Zooms have the wider apparent field of view at the lowest setting (such as 8mm). So you need at least one additional wide (65-72 degrees) 20-24mm eyepiece for wide true field of view.
There aint no 100 degrees zooms and there is only one zoom with 82 degrees at ~9mm (Leica Aspheric) and only a fiew zooms with 68 degrees at ~8mm, such as the Baader, as far as I know. Most generic 24-8mm zooms are 40-60 degrees and 21-7mm are even narrower, 35-55. Sodastraw. They also have lower transmission and may add false color.
For astronomy there are reasons to use a 100 degrees eyepiece, or an Ortho for planets etc. For terrestrial, as I said elsewhere, a low power fixed and a zoom is a very good tactic. Say, a 24mm Baader Hyperion (excellent transmission) and a Baader Zoom, used as a 20-8mm (its 24mm is the only thing I don't like on the Baader).
Otherwise, you might prefer a fixed eyepiece for a fixed magnification, say a 20mm Pentax for 20x and that's it.
 
giosblue said:
I'm happy with the sharpness of the Baader I've fitted, Ideally I want it to be brighter when I'm zoomed in.
I know the exit pupil is much smaller at max mag, I think with my scope it's 4.36@ 18x and 1.45@ 55x.
So I am right to assume my scope would be about the same brightness has any other scope with a zoom that gives the same magnification and exit pupil? It's an 80mm ED Optolyth.
Maybe I'm jumping the gun, because the weathers been poor in the UK since I fitted it and due to that, and work commitments, I haven't tried it in sunny clear conditions.
I have a windfall coming to me soon which would just about buy me Kowa 883 with 25x60 zoom.
unfortunately there is no way I can try one before I buy.

I don't want to shell out over £2000 and be disappointed.



Ron


Ron
Click to expand...

RSPB optics have the Kowa at £1999 though out of stock online. There may be some in their reserve shops where you can try it out if you are near one.
 
The reason I've asked this is because reading scope reviews of the Kowa 833, which is one of the best scopes, if not thee best for birding. the consensus is, it gives a very bright image. If you go off the specs, the Optolyth has the same exit pupil at 55x that the Kowa has at 60x. So if the two scopes where side by side at max magnification, would the Kowa be much brighter than the Optolyth? Everybody says the Baader is an excellent Ep, but how far behind say the Kowa zoom is it. Baader £189 Kowa is around £650. I'm a great believer in you get what you pay for, I know the Baaders made in China, which keep the price low, and potentially offers better value fore money. But I can't help thinking that the Kowa must be far superior in build and optically.
I understand that Kowa scope if better and you have to look at both the EP and the scope together.
Is the Kowa really that good compared to the Optolyth with the Baader zoom?

Ron
 
Thanks, Martin Mere's the only one I can get to at the moment. In-Focus have a shop there, but they don't stock Kowa, they used to.
 
the only reason for a fixed eye piece would be longer ER (when it comes to the the top alpha scopes),
modern zooms are good enough and even better than fixed, since fixed ep:s usually are of an older design,
less different items in stock means less costs for manufacturers, and fixed EP:s probably don't sell much anymore,
I also prefer having the opportunity of lower mag in a 25-NNx zoom before a 30x fixed EP.
 
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giosblue said:
I'm happy with the sharpness of the Baader I've fitted, Ideally I want it to be brighter when I'm zoomed in.
I know the exit pupil is much smaller at max mag, I think with my scope it's 4.36@ 18x and 1.45@ 55x.
So I am right to assume my scope would be about the same brightness has any other scope with a zoom that gives the same magnification and exit pupil? It's an 80mm ED Optolyth.
Maybe I'm jumping the gun, because the weathers been poor in the UK since I fitted it and due to that, and work commitments, I haven't tried it in sunny clear conditions.
Click to expand...

Hi Ron,

the exit pupil diameter will be the most important factor contributing to perceived image brightness in situations where the exit pupil is smaller than the pupil of your eye - for scopes at higher magnifications that is the normal case.

Given the same exit pupil diameter and lighting situation on different scopes you might see small differences due to coatings and scope or eyepiece construction but the dominant factor is exit pupil size.

So I'd first wait to have a closer look at your scope in better light and maybe get a look through the scopes of fellow birders before deciding anything.

I am inclined to say that the comparison will show your combination to be quite good and the upgrade not really worth the money - at least that was the result for me comparing my Kowa/Opticron Frankenscope to some current Zeiss, Leicas and Swaros - haven't seen a Kowa 883 yet, though...

Joachim
 
Thanks, yes, this upgrade to the scope has acted like a cloud magnet,LOL
I'm not going to rush out and buy a Kowa 883 (it would be nice though)
I did a comparison a few weeks ago with the Opto at a Wildlife reserve, there was an Opticron a Swarovski and mine. The Opto held it's own with the fixed EPs, but was sadly lacking in the zoom dep.
I've fitted the Baader and that is a big improvement, it's like looking through a different scope. so like you say, the best bet would be to wait for some decent weather and make a further comparison with the Baader fitted.

Anyway, it looks like whatever the limitation of the scope, it's not down to the Baader zoom, so I'll be sticking with that and returning the fixed eyepiece.

Ron
 
I still think there's a definite advantage to a good fixed ep in certain situations such as seawatching, where I wouldn't tend to ever use zoom, and where the extra fov would come in useful.
 
Grando said:
I still think there's a definite advantage to a good fixed ep in certain situations such as seawatching, where I wouldn't tend to ever use zoom, and where the extra fov would come in useful.
Click to expand...

Perhaps. Or maybe not. Because modern zooms tend to have large fields of view as well, not quite as much as some of the top fixed wideangles, but a far cry from the narrow field of yesteryear's zooms. And they've got one huge advantage: If you come across something interesting, you just switch to as much magnification as possible under the circumstances.

Hermann
 
It takes time to change eyepieces. Sometimes they get stuck (those that have the notorious groove especially). Many are not parfocal with each other, so you have to refocus, often far more than 1, 2 or even more turns of the focus knob. If you are an optophiliac (and who isn't here?) you might get distracted comparing different eyepieces and miss the view. Stars don't move fast, 15 arcmins per 1' - although at high magnifications with undriven scopes they will most probably not be in the field of view after changing eyepieces, it happens all the time with my 1500-1800mm telescopes- but most surely, while birding, after changing eyepieces you'll see that the bird it has flown, to a place on it's own, somewhere all alone!
 
And dont forget that these new zooms are also waterproof,so the weather consideration or the use near then sea/sand is not a big problem..and yet the only possible advantage ,for me,of a fixed simple wide angle eyepiece is durability...zooms are more susceptible of getting debris ( not necessarily from outside,if they are sealed,but from its own flocking or internal paint)and internal debris can spoil,or even ruin a view .And there is also the possibility of breaking ,freezing ( literally,in cold weather )or getting stuck somehow by mechanical failure in the midst of the action
 
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Interestingly I got the chance to compare the new Kowa 25-60x eyepiece with the 30x wide on an 883 at the weekend, and if I was going to buy one my personal preference would still be for the 30x fixed. It had that lttle bit more fov at the equivalent zoom and just seemed to me to hit the sweet spot. Saying that, the zoom is a fantastic eyepiece, though I didn't think it was very much better than the old 20-60x zoom. I will be buying a fixed 30x while they're still available to future proof me in case I do every get to upgrade from my 663 to an 883 in future.
 
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