I have the zoom, should I buy a 20X fixed? (1 Viewer)

I have a Swarovski ATS80HD with the 20-60X zoom eyepiece. Just now I've started thinking about buying a 20X fixed eyepiece to supplement it. Will I get any benefit from that?

Looking at Swarovski's specifications, I see that the exit pupil diameter is 4.0 mm - i.e., the same as the zoom at 20X. For interest, the 30X is 2.7 mm, the 45X 1.8 mm, and the zoom at 60X is 1.3 mm. I would have thought that that was a key factor, but I haven't noticed any particular difference in this regard using the zoom at higher settings - if it affects vignetting, it doesn't do so very noticably with the Swarovski adaptor and the CP4500.

The thing that attracts me is the wider field of view. At 1000m, Swarovski quote 60m for the 20X fixed (42 for the 30X, 28 for the 45X, and 36 to 20m for the zoom). That suggests to me that at a sensible distance, let's say 50 metres, I can currently see 1.8 metres worth of bird (with the zoom at 20X), but with the 20X fixed lens, I could see 3 metres worth (before allowing for the bit of the round picture that the camera chops off). If that difference translates into reality, it would give me an extra 35% or so worth of picture. Looking at my swans taking off from last weekend, for example, I'd have got that left-hand bird into the picture instead of chopping it off.

(OK, OK, I'd have got another nice picture of my bootlaces, but a perfect me would have got that second swan. You know what I mean.)

So, if I bought a 20X fixed eye piece, would there be a noticable benefit?

I can live with the idea of having to swap e/ps from time to time, as when I find a good spot I'm mostly using the 20X60 in the 20 to 25X range anyway, and one more bit of kit to carry is not the end of the world.

One last question - I see that the 20X is a few MM shorter than the zoom: am I safe in assuming that it wil fit with the Swarovski camera adaptor jus the same?

Thanks in advance to anyone who can answer these questions for me.

Tony

PS: as an afterthought, here is the original, uncropped swan picture I had in mind as an example of why I think a wider field of view would help.

Anyone?

I'd go for a fixed magnification wide-angle lens every time. Zoom lenses don't have such good optical quality - they can't, as you need a slightly different lens shape for each different magnification, and a lens which gives a perfect sharp image at one magnification won't at another.

Wide angle lenses are much better, as locating birds with them is so much easier and faster - with a fly-by bird this can make all the difference between seeing it for long enough to identify it, or not.

Michael

Thankyou, Michael. The big question (from my point of view) is does this still apply for digiscoping? Will the camera see that wider view?

Maybe it's a dumb question. I'm new to all this - before I bought the Swarovski my only experience with optics was a cheap pair of binoculars I bought which were so poor that I took to leaving them in the car and just using the old-fashioned Mark One Eyeball instead. So, from a watching point of view (as opposed to for photography) the 20X60 is far, far better than anything I ever used before and I'm happy with it. Photography is my aim here. (But, of course, if a 20X fixed happens to improve my "just-watching" experience as well, then so much the better!)

I have the Swarovski ST80HD, the original 20-60 zoom and the X15 and X30 wide eyepieces. So first, the adapter for the 20-60 will not fit the other eyepieces as they are narrower. Optically, the fixed eyepieces are somewhat better. The X15 is very usefull as sometimes the 20-60 provides too much magnification. The X30 is a little sharper than the zoom @X30. I use the CP4500 with the scope (although I tried the D100 as well), and the "wide" is not that wide. It doesn't allow you to go all the way to the wide setting zoom of the camera. The X30 is even worse in this aspect. The 20-60 is very good, up to X40 at least, therefore, I leave the X30 at home and take the X15 and the 20-60 along. Sometimes, in tight places I use the Scopetronics Maxview 40, which is about X10-12 and leaves a larger zoom headroom.
The bottom line - if I would have to make the choice again, I'd go for the 20-60 and the Maxview.

Thanks Yossi. (And some very nice results you have been getting with them too.)

As I understand it, Swarovski changed all their e/ps over at about the time they replaced the ST with the TS series scopes. I think that the Swarovski adaptor I have will fit OK onto the 20X fixed e/p - but I can check that with the shop before I buy it, so I'm not too worried about that side of it.

According to Swarovski's web site, they don't make an X15 anymore, just 20, 30 and 45X. If they had a 15X then I'd go for it. I'm happy with the sharpness of the 20X60 - all else aside, I don't have anything to compare it to - but I can't believe how good the Swaro is already and struggle to imagine that it's possible to get even better!

Despite your very helpful answer, I'm still not quite sure if I'll get a wider field of view out of the 20X fixed or if it will be the same as the 20X60 at 20X. (Note that I'm not really interested in the eye's field of view here: it's a question of whether the camera will get a wider field of view. (I can't just try it out in the shop, as the shop is in Sydney and I'm 700 kilometres away from there.)

But you introduce a whole new idea with the Maxview. I hadn't considered that. Is their optical quality good? Is it easy to switch betwen the Maxview and the 20X60? Do you think I might be better off forgetting about the 20X fixed (I'd prefer about 15X anway - I already have 20X at the low end of the 20X60) and getting a Maxview instead?

Thanks again,

Tony

Hi Tannin,
The Maxview is optically very good. I have two versions of it - the one with the Plossl mount (you need the adapter for the Swarovski) and one with a special fit for the Leica 62 Apo I have. The Plossl version, albeit needing an additional piece for mounting, can suit other scopes as well. They now have also a version for Swarovski - with the right mount. What you need is a T to 28 mm ring adapter - which they carry in their line too. Somehwere in this site I've described a very interesting solution - using a Pentax eyepiece of the XL series. They have a huge front element, which allows you to fully zoom the camera. You need a Plossl adapter, and to "shave-off" a piece from this eyepiece. With a 21mm eyepiece - you can practically zoom from 830mm to about 3300mm. I have in addition the 7mm eyepiece, which triples this range. At about 8000mm and upwards, it is quite difficult to get a good image due to vibrations and optical limitations. I got those eyepieces at Adorama for slightly over $200.
Scopetronics has two "wide" eyepieces too - of 14 and 18mm, which will allow you full zooming, but they are not very much suitable for the Swarovski, as they have too much CA under harsh light conditions (what we have here).

Hi Tannin, this maybe a little late on the subject. For months I was in limbo on what type of eyepiece(s) I was going get for my Swarovski 65mm telescope. I ended up ordering the 20-60X zoom. The convenience of not having to change eyepieces was what appealed to me. I also use a good quality binocular as well. So I felt that I had all angles covered and did not really need to add another lense. But like yourself, I got interested when I noticed that the FOV of the fixed 20X was nearly twice that of same power on the zoom. So if you have decided to use the fixed 20X as well, your opinions would be most welcome.

Thanks.
Danny

Stick with the zoom, Tannin.
I've got the same scope and eyepiece and wouldn't even consider buying the fixed eyepiece.

Chris

Like Michael I wouldn't consider a zoom. Recently tried a couple out and thought they were pretty poor compared to the fixed mag....guess you'll just have to try some out and see what you think. I have noticed people often plump for a zoom as their first eyepiece but often end up using a fixed mag

The 30xW would be my choice - far wider than the zoom (which will look tunnel like after you have used it). The Swaro zoom is slighgtly wider than some but still can't approach a fixed wide angle for width of view, overall brightness and clarity in my view. Surely the extra brightness and width will be a boon to your digiscoping?

It's interesting that some contributors reckon zooms are always inferior to single-magnification eyepieces. When I compare my old-model Swarovski zoom to wide angles at lower magnifications the zoom is often better (brighter, sharper). Yes, it's a narrow field of view and the wide-angle lenses are more aesthetically appealing, but I think the very best zooms have caught up with fixed mags.

There's another point,; I'm no expert on the technical side, but isn't it true that when it comes to fixed magnification eyepieces, the non-wide angles are optically better than the wides? At least a man in infocus told me this a while ago.

I understand that it is technically impossible to create a zoom that is objectively better than a fixed magnification eyepiece like for like. This, I believe, is because a zoom lens requires several more lens elements in its construction when compared to a fixed magnification lens, each of which by definition introduces a) an unwanted abberation to the path of light, which needs to be corrected - often by the use of another lens element and b) unwanted reflection and dispersion / absorption of the light passing through which leads to, at the least, darkening of the final image. A compromise always has to be reached with any lens and much more of a compromise when there are more elements to deal with as in a zoom.

What you describe, however, might not be wrong for you - the fixed eyepieces you have looked through might be of a generally overall poorer quality than was the zoom you used. In the case of Swarovski that would truly surprise me. I have looked through many fixed wide and zoom eyepieces on Kowa, Opticron, Swarovski, Leica, Nikon and Zeiss and have never yet been as impressed with the zoom as I am with the fixed wide angle - again, on a like for like basis. Even 40-60x fixed eyepieces give far wider and brighter views than a zoom. The widest zooms are Zeiss, Swarovski and Leica; the most faithful colours are given by the Nikon.

Well, by now we all know that because of their wider field of view, the fixed eyepieces have it over the zooms. But something I've noticed in the technical comparisons is that anything over 40X power, both types of lenses tend to even out the FOV (maybe that's why only the zooms go up 60X)? Also, because zooms have more glass for the light to travel through, the less brighter the view becomes. But due to the advances in computer assisted optical engineering, this distinction has changed, and high quality very bright variable lenses are now on the market. So, why not get the best of both worlds; have a 20X (or 30X) fixed eyepiece for general viewing, and for the flexibility and long range closeups, grab a zoom as well! I am sure the scope manufacturers would also agree.

I bet they would - and that's what many on this forum do. It's the brightness of the high power fixed that make them better than a zoom, I should think.