Here are the new modular Swarovski scopes (1 Viewer)

[Surveyor]

But it is very possible that his chart is more demanding and/or he has a more strict standard for "resolved" than you or I do. I have one small photo chart that Jan has graciously given me many years back. It is not identical, but is similar, to the ones you see in his photos. I have found that although it looks good through a loupe and although it has four line orientations rather than two, and despite having a finer gradation between elements than the USAF, it does not seem to give as smooth a progression in my use as the USAF does. Myself, I have deliberately chosen a rather lenient standard for "resolved" in my testing, simply because it is the only way I can somewhat reliably tell apart "resolved" from "not resolved". For me, trying to determine where ridiculously small lines are just beginning to blend is almost impossible, whereas determining whether or not I can make out the orientation of a line pattern is relatively easy. Hence I use the latter criterion, which will give very good results but ones which I feel are much more consistent and repeatable between my various testing sessions.


Kimmo

Kimmo, Henry, Steve and all;

I have attached the description for a resolved element from ISO 14490-7, along with their recommended target group.

A group/element is resolved as long as you discern the direction of all parts of the element without refocusing in the center field.

Further down in the standards they do make allowance for other bar type targets.

 

[kabsetz]

Ron,

Thanks for the ISO description. That is fortunately at least very close to what I have been doing. The only difference is that I don't emphasize the "easy" part of the detection. If I can consistently detect all directions, that is enough for me even if it is not actually easy. This is especially so in unboosted measurements, where the eye-optics combination is what is being tested.

Kimmo

 

[henry link]

Thanks for that information, Ron.

I wonder if Jan isn't applying a standard close to the clean separation (26% contrast) required to meet the Rayleigh Limit for double stars. The point where I've been considering line pairs resolved is likely closer to the 3% contrast of the Dawes Limit for double stars and is probably similar to Kimmo's standard.

Looking at Ron's ISO instructions makes me wonder about establishing the "best" focus with astigmatic optics. Do you go to the sagittal or tangential focus to achieve best resolution for one group of lines even though that means worse resolution for the group with lines rotated 90º or do you try to find the mid point between the sagittal and tangential foci so that no line orientation is really sharp, but all groups are equal?

Resolution measurements are useful, but they can only tell us so much. I wish Jan also performed star-tests so we would have a better idea about why the resolution of a particular scope measures as it does.

Henry

 

[Surveyor]

Another spec. that I failed to mention is that a minimum exit pupil size of the booster be 0.8 mm. I know I fairly routinely violate that one.

Henry, I take it to mean that that you set best focus for the group of four directions in the center field.

 

[kabsetz]

Henry, Ron,

If there is astigmatism, I look for the best compromise between sagittal and tangential foci. But, to be honest, if there is astigmatism to the extent that this becomes necessary, I cease to be interested in that particular scope specimen. I can tolerate astigmatism only when it is weak enough that I don't really see it in resolution charts at the maximum unboosted magnification of the eyepieces available for the scope. If there is any more, my eyes will tire more quickly and viewing with the scope is unpleasant.

So, to explain more clearly, weak enough astigmatism for me is when I can detect slight ellipticity in out-of-focus star patterns that changes orientation between inside and outside focus, but cannot yet with my visus detect a clear difference in best focus line groups in different orientations.

Kimmo

 

[Surveyor]

Kimmo;

I actually find astigmatism troublesome before I can see it in star tests.

I am not familiar with scopes, only visiting here because nothing new in the bino forum and the topics are a lot more interesting.

I have attached an example of what I find from a test of the ZR bino from several years ago. I find that at about 1/2 diopter I start to see very minor defocus at 2.5° from center (my limit for the sweet spot) and the defocus gets more obvious the farther from center. As you can see, this small amount barely shows in the star test, which looked a lot better to the eye than they photographed.

My accommodation is two to three diopters, so you can see that, if not for astigmatism, these would most of the time be sharp to the edge for me.

I will have to get my ATS80HD Swaro out and try things out.

I think Henry does S-T curves for scopes, or at least eyepieces, but I have never paid attention to them or seen what he considers objectionable in his case.

 

[kabsetz]

Ron,

I was talking about on-axis resolution and on-axis astigmatism, not off-axis astigmatism. The latter I tend to consider in context of edge performance or sweet spot size, separate from centerfield resolving power. With scopes, because their max magnifications are at a level where the scope, not my eyesight acuity, is the limiting factor, I tend to pay most attention to image quality in the field center. But, between scopes or binoculars with similar edge performance, my preference is for those with the least amount of off-axis astigmatism and more field curvature or SA rather than more astigmatism and less field curvature or SA.

Kimmo

 

[Surveyor]

Thanks Kimmo, it has been so long since I have seen measurable on axis astigmatism that it did not even come to mind until you mentioned “on axis” then I immediately knew what you meant.

 

[kabsetz]

Came to mind that perhaps another clarification should be made. The star-test, or point source diffraction pattern, specifically reveals on-axis astigmatism and does not tell about off-axis astigmatism since the point of light being examined is typically centered on the optical axis. Thus, the aberrations that show on the out-of-focus diffraction patterns or best-focus star image pertain to the axial performance of the optics. Of course, it is possible to place the point source off-axis, and thus examine the performance of the optics for that point in the view field, as Henry does when he uses point sources to examine vignetting. However, in the vast majority of cases, the point source is placed as close to the optical axis as possible.

Kimmo

 

[Neil]

I'm still having fun with the STX 95 but I haven't done any comparative testing yet.
On Tuesday I tested a DSLR on the TLS APO Adapter - the Nikon D7000. This kingfisher video was shot at 30x,55x and 70x. https://vimeo.com/55432553
I still haven't settled on a tripod/head combo for the 95 mm but I'm taking it down to Sydney on Saturday for two weeks where I have my heavy duty kit. The light should be better too.
The first 3 photos are with the V1 and the last 2 with the D7000. Distances were 25 - 45 meters. The cormorants were at 70x.
Neil
Hong Kong,
China.
Dec 2012

 

[Sleeper]

Thanks for the input Neil

May I ask how you feel about the 30x starter mag? Do you feel that the bird can be over full in the frame at all. I fancy the 95 but I remember having a 30x ww on a zeiss scope and I found I was walking backwards to get thr bird in the frame....

 

[Neil]

Here are some digiscoped photos from my last day out on the mudflats for the year on Thursday (I'm off to Sydney today for the holidays ).
This video of the roosting Dunlin is my first for this species because they don't roost with the other birds at the high tide but go off on their own, and nobody knows where. Here they are heading off https://vimeo.com/55597233
The Grey Plover grabbed this worm so quickly I would have missed it taking stills.
https://vimeo.com/55641997
Neil
Nikon V1 plus TLS APO adapter ( photo 1)
Sony RX 10 and Swarovski STX 95 mm Scope and DCB 11 adapter

Mai Po Nature Reserve,
Hong Kong,China
Dec 2012

 

[Neil]

I'm having fun with the STX 95 in Sydney, shooting with the NEX 7 and the V1, both with and without lenses. I haven't got out as much as I would like but at the local waterhole I had some luck.
I had to shoot at 30x and use the V1 with the 11-27.5 mm lens to keep the birds in the frame. With doves and bigger I couldn't do it at 6 - 9 meters.
First 3 with V1 and 4/5 with Nex 7.
Neil
Nex 7 plus TLS APO adapter
V1 with 11-27.5 mm lens
and STX 95 and Kowa Balance Bar

Sydney,
Australia
(somewhere on the Northern Beaches
December 2012

 

[Neil]

Thanks for the input Neil

May I ask how you feel about the 30x starter mag? Do you feel that the bird can be over full in the frame at all. I fancy the 95 but I remember having a 30x ww on a zeiss scope and I found I was walking backwards to get thr bird in the frame....

I'm still getting to grips with the specs of the new kit. The TLS APO has a built-in 30 mm lens. You can actually take photos with it on the camera , although focusing is a tad difficult. I presume this means that the magnification is reduced by 30/50 ( 50 mm being 1 optical or near enough ).
I'm waiting on confirmation on this though from those more knowledgable.
Neil

 

[RJM]

I'm still getting to grips with the specs of the new kit. The TLS APO has a built-in 30 mm lens. You can actually take photos with it on the camera , although focusing is a tad difficult. I presume this means that the magnification is reduced by 30/50 ( 50 mm being 1 optical or near enough ).
I'm waiting on confirmation on this though from those more knowledgable.
Neil

Neil, the crop sensor turns that 30mm lens in the adapter a ~45mm equivalent, i.e. basically a "normal" lens, so little if any reduction of the scope magnification.

 

[Neil]

Neil, the crop sensor turns that 30mm lens in the adapter a ~45mm equivalent, i.e. basically a "normal" lens, so little if any reduction of the scope magnification.[/QUOTE

Thanks Rick. Swarovski confirmed that they choose 30 mm to match better with Micro Four Thirds cameras as close to 1x optical at 60 mm ( 2x Crop ).
The V1 at 2.7x gives some serious magnification.
Neil.

 

[Pasquier]

Neil
What adapter are you using with the V1 - the DCBII or the ATX?
Impressive photos!
Thanks, P

 

[Neil]

Neil
What adapter are you using with the V1 - the DCBII or the ATX?
Impressive photos!
Thanks, P

I use both. With the TLS APO adapter a T thread adapter for your brand of camera it's not necessary to use a camera lens . With the DCB 11 I use the 11 - 27.5 mm zoom ( new ).
I'm liking the TLS APO adapter approach as I'm getting used to Manual Focusing.
Neil.

 

[Sc0tty]

I use both. With the TLS APO adapter a T thread adapter for your brand of camera it's not necessary to use a camera lens . With the DCB 11 I use the 11 - 27.5 mm zoom ( new ).
I'm liking the TLS APO adapter approach as I'm getting used to Manual Focusing.
Neil.

Neil
Is there any difference in picture quality between the two approachs?
Thanks.

 

[Neil]

Neil
Is there any difference in picture quality between the two approachs?
Thanks.

Rich,
I haven't done any comparison testing yet but my feeling is that the going straight to the sensor from the scope eyepiece is better than putting a zoom lens in the way. It's not a significant difference at short distances ( up to 30 meters ) but becomes more noticeable at longer distances ( 100 - 300 meters).
If I need AF then I go with the lens solution but for slow moving or stationary subjects I prefer MF with the TLS APO.
Neil.