30X = best magnification ? (1 Viewer)

[wachipilotes]

Hello,
Why usually choose 30X magnification for a 80mm telescope?
I have read in this forum that there are many observers who choose this mag.
A greeting

 

[Pinewood]

Hello,
Why usually choose 30X magnification for a 80mm telescope?
I have read in this forum that there are many observers who choose this mag.
A greeting

Hello Wachipilotes,

Greetings to you, as well

I chose 30x with my 85 mm 'scope because it gave a reasonable exit pupil and would not require a heavy tripod. At 60x, one needs a substantial tripod to avoid problems with vibrations.

Happy bird watching,
Arthur Pinewood :brains:

 

[Alexis Powell]

Hello,
Why usually choose 30X magnification for a 80mm telescope?
I have read in this forum that there are many observers who choose this mag.
A greeting

Comfortable exit pupil, brightness, field of view, and stability of view on tripod. Lower powers do better with all those things, but for me 30x is the sweet spot for a magnification that is substantially better than my binoculars (~4x larger, and more stable since on tripod) but before stability becomes difficult, so it is my preferred magnification for all terrestrial scopes (50mm, 60mm, 95mm...) regardless of exit pupil. Also, where I live and bird, atmospheric effects often nullify the utility of higher magnifications. Finally, I use my scopes and bin for bird ID, not for digiscoping, so going from 30x to 60x is rarely useful (it is only twice as large). When birds are within the limits that I typically notice them with my eyes, I can usually ID them with my bins, and when they are within the distance I typically notice them in my bins, I can usually ID them in my scope at 30x. Birds that I could ID at 60x but not 30x are usually too far way for me to notice, or are too far away to punch through that much atmosphere cleanly. So I use ~30x wide angle >95% of the time.

--AP

 

[wachipilotes]

Which field have a 30X wide angle eyepiece?

 

[John Russell]

Unfortunately, fixed WA eyepieces are becoming rather scarce. Leica and Swarovski now only offer zooms and the 30/40x Zeiss eyepiece was not available a couple of years ago when I considered one of the new DiaScopes. That leaves only the 77/88 mm Kowas and the Nikon EDGs.

There are many who would disagree, but I'm with Arthur and Alexis on this one. My 30x Swarovski eyepiece has very comfortable eye relief and offers 42 m FOV @ 1000 m, which I think is more than any available zoom even at lower magnifications.

Exit pupils a little over 1 mm associated with high magnifications are going to require bright lighting conditions, but as Alexis pointed out, mirage is often a problem here, unless one is observing across water.

John

 

[Jason Bugay Reyes]

Yes 30x is excellent on the scope!

 

[Jumbo]

Which field have a 30X wide angle eyepiece?

You can still find the Swarovski 30x W eyepiece in some UK retailers, although like many manufacturers they appear to be moving towards only offering zoom EPs.

...My 30x Swarovski eyepiece has very comfortable eye relief and offers 42 m FOV @ 1000 m, which I think is more than any available zoom even at lower magnifications.

Swarovski's 25-50x W matches the 30x W's 42m at the wide end, a reasonable trade off IMO given the extra flexibility that the higher mags offer on this particular EP. Leica's 25-50x WW manages a 41m FoV at the wide end.

Most zooms are however much more heavily compromised on viewing angle when compared to their fixed mag stablemates, and it will be disappointing to see fewer fixed EPs offered for the excellent reasons given in the above replies. Additionally, fixed mag Ep's are also significantly cheaper.

From the manufacturer's perspective only offering one or two zoom EPs must be an attractive proposition compared with perhaps 4 or 5 fixed EPs?

 

[chris butterworth]

30x, particularly a wide angle, is probably, the ideally magnification for all the times you need a 'scope. It's high enough to be able to use for identifying waders, ducks, raptors and seawatching without being affected by heat haze, doesn't need to be set in concrete if there is a bit of wind blowing and seems to provide the optimum light transmission.

Chris

 

[Pinewood]

Which field have a 30X wide angle eyepiece?

Hello Wachipilotes,

My Zeiss 30X is so old, that I cannot find the specs for field of view. I suspect that my eyepiece is a rarity. Certainly, it is wider than a zoom set for 30X. The current 30/40 eyepiece gives a 40 metre field of view at 1000 metres with the 65 mm Diascope; 30 metres with the 85 mm Diascope.

Happy bird watching,
Arthur Pinewood :hi:

 

[Torview]

I can`t decide, currently use a wide 20x on an 80mm scope, very rarely do I need more power.

 

[Pinewood]

Hello Wachipilotes,

I searched my cupboard and found the instruction sheet for my 85 mm Diascope. The old 30x eyepiece does have a 40 m. field of view at 1000 m.

Happy bird watching,
Arthur :hi:

 

[Robert Wallace]

My first decent scope which I still use is the Nikon 60mm Fieldscope 11 which I purchased in 1991 with the 20x and 20-45x, zoom eyepieces. When some years later, the 30x WA became available I have rarely use my old eyepieces.
In practice I have found 30x pretty adequate.
I currently use a Swarovski 30x75 drawtube which I bought about 4 years ago out of pure indulgence and I love it.

 

[Hermann]

Well, after all this praise I've got to add a dissenting voice. I find 30x is too much magnification on sunny days with a lot of heat haze or in woodland. I much prefer something like 25x on those days.

And 30x often doesn't cut it at the coast when the distances are large. In many places higher magnifications mean you can get a bird you just wouldn't be able to identify at 30x.That's where I almost always use a zoom nowadays.

Hermann

 

[janvangastel]

It depends. I very often use a 50 x magnification on my Swarovski 80 mm, with good results. If birds are far away 30 x mis not enough.

 

[kabsetz]

In the Swarovski ATX 95 I currently have, 30x is the minimum magnification of its wide-angle zoom. Max is about 72x. I cannot say precisely what percentage of my viewing time is done with the zoom set at 30x, but it is not very large - certainly less than 20%. There have been zero times I have hoped for a smaller minimum magnification, but many where I would not have minded to be able to go up to about 85-90x. Granted, this is a scope with a large objective lens, whereby the image at 30x has an exit pupil (and hence brightness and contrast) roughly equal to that of an 82mm scope at 25x or a 60mm scope at about 20x.

But perhaps a better answer is that there is no fixed magnification that is the best magnification. Every fixed magnification is a compromise, and it depends on the user which compromise they find least detrimental. In the past, when zooms invariably had narrow fields of view and poor eye-reliefs, sometimes combined with mediocre optical quality, there were good reasons to choose the sort of compromise a fixed wide-field offered. Now, when you can get zooms such as the Leica/Swarovski 25-50x wide or the more recent Swaro X-series 25-60x/30-72x and Kowa 25-60x wide zoom, fixed wide-angle eyepieces are becoming redundant.

Kimmo

 

[looksharp65]

This post reflects my personal opinions only! YMMV.

As a general rule, as low magnification as possible should be used. Larger exit pupil, less shake and more light never hurts. BUT:

I believe, based on my personal experience, that the use of two eyes (if you have and regularly use both) corresponds to using a 2.5x monocular. To create a stronger impression it takes about 3x magnification. Anything less is largely useless.

Correspondingly, to obtain a significantly greater impression of magnification, the scope magnification should be at least 3x the magnification of the binoculars.
When I use my Nikon ED50A w/ 27x I use 8x binoculars, and when I use 10x binoculars, it's with my ED82A with the 30x Wide eyepiece.

I have tried 21x magnification, albeit not with top optics, and I find that a good pair of 8x binoculars provides the same level of detail and a lot more viewing satisfaction.

//L

 

[Alexis Powell]

...I believe, based on my personal experience, that the use of two eyes (if you have and regularly use both) corresponds to using a 2.5x monocular. To create a stronger impression it takes about 3x magnification...

I largely agree--using both eyes is advantageous--but I don't get such a big improvement as the equivalent of 2.5x. Stabilizing the view is also quite advantageous, so I get at least as much benefit from tripod use, but since I rarely stabilize my binoculars, I only enjoy that with a scope. So for me, the greater stability more than compensates for the loss of binocular vision.

--AP

 

[looksharp65]

I largely agree--using both eyes is advantageous--but I don't get such a big improvement as the equivalent of 2.5x. Stabilizing the view is also quite advantageous, so I get at least as much benefit from tripod use, but since I rarely stabilize my binoculars, I only enjoy that with a scope. So for me, the greater stability more than compensates for the loss of binocular vision.

--AP

First I thought I'm with you but now I'm increasingly confused about what you really mean. Would you prefer using a tripod-mounted 10x monocular over 10x handheld binoculars?

Larger magnifications require stabilisation. Assume that a handheld 16x scope provides the same perceived detail recognition as a pair of 10x binoculars (well, for me it's 25x, but anyway) if you can hold them both steady.

Then assume that you increase the magnification to 20x. The shake is now so distracting that there's no perceived advantage over the 16x until you put it on a tripod.
Once there you experience an increased detail recognition over the handheld 10x binoculars.

But if you have very steady hands or regularly support the elbows while watching, you may find that the 10x binoculars provide a similar impression as the 20x scope, and you must have at least 25x (tripod mounted, of course) to see any detail advantage over the binoculars.

So what's my point? A steady view is vital and has to be obtained with suitable means for the user and the level of magnification. Using lower magnifications is a safe bet, tripods and IS systems are helpful too.

//L

 

[Alexis Powell]

First I thought I'm with you but now I'm increasingly confused about what you really mean. Would you prefer using a tripod-mounted 10x monocular over 10x handheld binoculars? ...

My answer is maybe. If I can place my bins on a fence post, I gain a significant advantage in stability, even compared to resting my elbows on car top, knees, and in other stability promoting stances. I find small vibrations very destructive when using an optic to the limits of my visual acuity, and I think that in practice stability is more important to me than delivering info from 2 eyes to my brain even though I know that the latter is helpful (especially as the light gets low). A 30x scope is a major improvement over my 8x bins in part because of its higher magnification and in part because I have it on a stable tripod (unlike the bins). You seem to notice a considerable gain with the use of two eyes. For me, the gain is more subtle in comparison to stability and magnification.

--AP

 

[looksharp65]

My answer is maybe. If I can place my bins on a fence post, I gain a significant advantage in stability, even compared to resting my elbows on car top, knees, and in other stability promoting stances. I find small vibrations very destructive when using an optic to the limits of my visual acuity, and I think that in practice stability is more important to me than delivering info from 2 eyes to my brain even though I know that the latter is helpful (especially as the light gets low). A 30x scope is a major improvement over my 8x bins in part because of its higher magnification and in part because I have it on a stable tripod (unlike the bins). You seem to notice a considerable gain with the use of two eyes. For me, the gain is more subtle in comparison to stability and magnification.

--AP

I see. But stability is a prerequisite under any circumstances so I didn't consider leaving it out. Of course an unsteady view is destructive for the detail recognition.
Most people can handhold 8x binoculars without getting disturbed by shake, but handholding a 30x scope is a challenge for most of us.

I'm thinking that any comparison between binocular use and supported use has to be made with the same magnification. In my (admittedly subjective) opinion, where it takes 2.5x more monocular magnification to match the view through binoculars, a stable view is implicit.
Without that, there would be no possible way to compare binoculars vs. a scope.

Also remember that magnification magnifies not only desirable image details but also the length of the blur caused by shake. Therefore the size relation between details and blur remains the same regardless of magnification.

A low magnification will mean lower resolution down to the point where the smallest and most distant details won't be seen. High magnification will show the details accompanied with blur streaks. Somewhere in between there will exist a feasible compromise where details are recognisable and the blur streaks are moderate enough to neglect.

Another problem with image shake with too high magnification (i.e. too high for the viewing distance) is the large-scale movement of large details.
It is easier for the eyes to compensate for image movements with short eye movements than with large ditto.

//L