ATX 115 Data Wanted (1 Viewer)

[Will K]

I wonder if any ATX 115 owners can answer these questions for me?

What is the AFOV for the full spread of magnification? (in the two digit format, e.g., "65-80 degrees at 30-70x", or whatever it might be)
What is the AFOV for the full spread of magnification, with the 1.7 extender?

It would be great to have these verified by users. I'm trying to track down a model to try myself, but its not easy.

Thanks!

 

[wllmspd]

I expect all the ATX will have the same AFOV as it’s an eyepiece thing, found specs for the 85mm giving 57-71degrees across the range. Would expect the same with the extender, but am more than happy to be corrected by someone who’s got one! Not bad for a zoom, but can get wider for a fixed focal length.

Peter

 

[Will K]

Thanks, Peter!

I'd be surprised if there wasn't at least some variation in AFOV, considering the impact it would have on exit pupil, etc. Not that I'm basing that assumption on any particular understanding of how these things work. I've only looked through an 85, so far, but I should be examining a 95 in a shop in London tomorrow, alongside a Zeiss Harpia 95.

Where did you get those figures from? The "57-71" for the 85?

 

[wllmspd]

Swarovski webpage list that too for all the ATC models. https://www.swarovskioptik.com/gb/e...x-stx-btx/tech-spec/atx-spotting-scope-system
The AFOV is a function of the eyepiece design, it’s doesn’t change with the scope you put it on… though the magnification, exit pupil and physical ft at 1000yds field of view will all change.

Peter

 

[Will K]

That’s interesting! I didn’t know these figures were given in that section; I’d been looking for variables on the individual pages of each modular component.

So I guess the basic AFOV is 57-71 on all the modules, from 65mm to the 115. Possibly with the extender, too.

The BTX figure is also given as 60 constant. I wonder what that means?

 

[Will K]

Ah, ignore me.

I completely forgot that the BTX has a limited mag range.

 

[wllmspd]

It’s AFOV is narrower (doesn’t change as it’s not a zoom), but being a binocular it will probably feel a little wider, alpha binoculars seem to have upto 70degrees AFOV now, so it’ll be a little narrower than them, but with a significantly closer view from the much higher magnification.

Be interesting to see what your experiences are tomorrow.

Peter

 

[Will K]

I very much enjoy the 71 degree AFOV on my NL 12x42, and I’m looking for a similar panoramic view with my next scope upgrade.

If the bigger objective modules do not make any substantial difference to AFOV, then I think I’m leaning toward the Harpia again, which boasts an amazing 72 degree constant AFOV all the way through its mag range of 23-70x. Sounds fantastic! The only downside with the Zeiss (on paper) is the lack of integrated booster or extender options, and I do love a high mag option, too (+90x). And then there’s the whole business of individual aberrations, requiring star tests, etc.

I’m also interested in checking out the Leica APO Televid, but I guess my in-person demo comparison tomorrow will be decisive in some way. But I hope I don’t love one of them too much. I can’t really afford it yet 😆

Thanks!

 

[kimmik]

Eyepiece determines AFOV.

Eyepiece focal length, divide by objective focal ratio, gives the pupil size.

Objective focal length, divide by eyepiece focal length, gives magnification.

I also like the harpia over swaro. But havent seen leica

 

[Will K]

Eyepiece determines AFOV

Good to know, thanks!

I wondered if Swaro had used some kind of optical wizardry to give themselves an extra edge with the big objectives, playing to the NL AFOV fans. Guess not 🙂

 

[kabsetz]

Zeiss Harpia does not have a booster available yet, but it does have exchangeable eyepieces so there is nothing preventing Zeiss from introducing higher magnification options. They haven't yet, though, but I'd be surprised if none are introduced in the future.

Since the zoom is in the scope body, AFOV will stay the same throughout the range also with potential future eyepieces. The problem with the Zeiss design that may limit the usefulness of higher magnification eyepieces is that the zoom vignettes the objective at lower magnifications. This does not matter much at 23x, where the objective is effectively just under 60 mm, but if the eyepiece would have a range starting at 40x or more, image at the lowest settings of the zoom would look considerably dimmer than in Swaro or Kowa scopes at the same mag. But the bigger problem is that such eyepieces are not yet available.

 

[Will K]

Zeiss Harpia does not have a booster available yet, but it does have exchangeable eyepieces so there is nothing preventing Zeiss from introducing higher magnification options. They haven't yet, though, but I'd be surprised if none are introduced in the future.

Since the zoom is in the scope body, AFOV will stay the same throughout the range also with potential future eyepieces. The problem with the Zeiss design that may limit the usefulness of higher magnification eyepieces is that the zoom vignettes the objective at lower magnifications. This does not matter much at 23x, where the objective is effectively just under 60 mm, but if the eyepiece would have a range starting at 40x or more, image at the lowest settings of the zoom would look considerably dimmer than in Swaro or Kowa scopes at the same mag. But the bigger problem is that such eyepieces are not yet available.

Thanks for this explanation.

I’d be very happy to go with the Harpia if that was the case. I’m guessing they’ll come up with some solution to the problem you anticipate, even if it’s just reducing the price to compensate for the negative effect (wishful thinking, perhaps?)

There’s always the option of using a 3x or 4x mono (like the Zeiss 3x12) to boost the image manually. But I’d like to see what a properly machined setup can do.

 

[wllmspd]

At lower powers your eye pupil is probably the limiting aperture (unless it’s a specially dark). The ability to use holiday powers depends on the light available and the lack of heat haze which will negate any benefit, especially at long distances.

Peter

 

[Brummie]

As mentioned above, the ATX eyepiece has the same AFOV of 57-71 on all the objectives (the ATC also has the same AFOV). I therefore don't think the Extender makes any difference to the AFOV either (I certainly don't recall noticing it).

The BTX has a fixed 30 / 35x magnification, and a fixed AFOV. IIRC, the BTX without the extender stops the 115 objective down to an effective diameter of 105mm. With the BTX + Extender, this isn't an issue.

 

[wllmspd]

The older ATS models could use a 1.25” adapter, so you could use wider field (non zoom) eyepieces if you like very wide AFOV, though you’d only have 65 and 80mm option a then.

Peter

 

[Will K]

I do like a flexible zoom at high mags, because it’s easier (and fun!) to scan for birds and then get closer.

Out of curiosity, though, what might the AFOV be on such a setup? (Old ATS w/ wide field eyepiece).

 

[Brummie]

Out of curiosity, though, what might the AFOV be on such a setup? (Old ATS w/ wide field eyepiece).

Depends on the eyepiece. Plenty of them go significantly above 70 deg these days.

 

[wllmspd]

You’d need to check if people have tried them, ie will they come to focus with the ATS and what the eye relief is
Televue ethos 100degree, naglers 82degree
Explore scientific dot 82/100degree
Baader Morpheus are nice eye relief 76degree
Pentax xw 85degrees
Vixen ssw 83degrees
Apm 82degrees
Plenty of options for focal length/magnification, though the costs could mount up if you wanted a handful.

Peter

 

[Phil Bishop]

Naglers vary a lot with eye relief, though not sure which ones are still available. Could not cope with the original 13mm and 9(?)mm but I have and enjoy the later 12mm design, and used it occasionally when i had the older grey Swarovski. A bit old hat now I guess but I also used a couple of Radians as well for digiscoping back in the day.

 

[wllmspd]

I used a pair of 13mm type6 naglers in the binoculars, but they’ve got some pretty severe distortion and the eye relief isn’t so good, replaced them with some Baader Morpheus, which are very nice.

Peter