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ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Zeiss scope repair (1 Viewer)

henry link

Well-known member
I just had an experience with the Zeiss repair service in the US which I think is worth passing along.

At my urging a friend recently returned his defective 85mm Diascope to Zeiss ( I’ve posted several messages about the problems with this scope seen in resolution and star testing ). Yesterday he phoned to say Zeiss had contacted him and told him they had found no problem with the scope. It was “doing what it should do “. I phoned Zeiss and left a message detailing the defects I had seen in the scope. An hour later the repair technician who works on rifle scopes returned my call. He told me Zeiss-USA have no faciilities for repairing or even evaluating the Diascopes. My friend’s scope had been given only a cursory look, no resolution chart, no reference scope available for comparison. I have better “facilities” for evaluating scopes in my backyard than what is available at Zeiss-USA, and anybody else can too.

To Zeiss credit they offered to send my friend a new replacement scope, and I beleive would have done so without my intervention, based simply on his strongly expressed dissatisfaction. I wonder, however, what would have happened if he had been willing to go along their pronouncement that the scope was fine. How many people are prepared to argue with Zeiss when they say everything is as it should be? They were out of stock, so the replacement will require a two week wait for a new shipment from Germany.

Once again I would urge birders to learn how to test and evaluate your own scope, get a resolution chart, learn how to star test. Don’t assume a high status brand name guarantees a defect free scope, and don’t expect a defective scope you return to the manufacturer to receive some sort of high tech, sophisticated optical evaluation. It may just get a quick look from somebody who knows less about it's problems than you do.
 
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Hi Henry

Good points. The Finnish Alula site made similar comments regarding the Leica Apo a while back.

Regarding the Zeiss scope, though, after a fortnight's intensive use with mine all I can say is - what a truly useful zoom it has owing to its extraordinarily wide field of view. As a birding combination the Zeiss + zoom really does take some beating.
 
elgin5050.fsnet said:
Henry,how do you test and evaluate a scope? mines is an opticron es80.

There are three recent threads that will probably tell you more than you can stand about testing: "Just Purchased NIB 85mmZeiss for $1300", "Star Testing" vs. "Business Card Testing" and "60X Resolution---What Newspaper Reading Distance".

Star testing a birding scope at 60X won't give really good information about spherical and chromatic aberrations except to show they are present, which they will be in every scope. Very high magnification of 150X-200X is needed for an accurate evaluation. The real value of star testing a birding scope is to identify the most common manufacturing defects such as astigmatism, pinched optics, and miscollimation, which should be easily visible at 60X. Even a $300 scope shouldn't have these defects in significant amounts and $1000-$2000 scopes should have none or close to it.
 
scampo said:
Hi Henry

Good points. The Finnish Alula site made similar comments regarding the Leica Apo a while back.

Regarding the Zeiss scope, though, after a fortnight's intensive use with mine all I can say is - what a truly useful zoom it has owing to its extraordinarily wide field of view. As a birding combination the Zeiss + zoom really does take some beating.

Hi Steve,

Judging from your enthusiasm for your Diascope you must have the best one they ever made. I hope my friend's replacement scope turns out to be as good!

Henry
 
Well - I look at birds rather than stars - maybe that's the reason!

((-;

More seriously, I do think the wide fov is something that few birders recognise as important. What you don't have, you don't miss, perhaps? I know that it took me a while to realise its importance to birding.

I regularly compare the Zeiss to a Nikon ED82 and a Swaro 65ED. All three scopes are top notch, but the Zeiss unquestionably allows easier spotting of birds owing to the extra view.
 
scampo said:
Well - I look at birds rather than stars - maybe that's the reason! ((-;

I have corresponded with a Zeiss product support engineer on the topic of testing and it seems that Zeiss has mixed feelings about the standard these scopes should be held to. He suggests that astronomical scopes can and should be held to higher standards of precision than terrestrial scopes since they are operated at much higher magnifications, used to observe points, and use simpler optics. Terrestrial scopes with their more complex optics, lower magnifications, and typical use where edge resolution is more critical than point resolution, are a topic of mixed opinion in the testing area.
 
I hope that Zeiss engineer didn't say edge resolution... If so, that's more than a shade ironic as their otherwise quite exceptional zoom eyepiece is rather infamous for its lack of peripheral sharpness at its lowest magnification. Not to knock it at all though - added to their equally exceptional 85T* Diascope and you have a near perfect birding scope, I reckon.

I think the points you (or the engineer...) made are very pertinent, though - spotting scopes + zoom eyepieces, in particular, do have far more glass elements in them, I should think, than an astronomical scope, and, has been said before, are corrected for quite different typical viewing distances.

(-;
 
I feel that I should point out, that shortly after buying my Zeiss scope/adaptor setup, I have cause to contact Zeiss in the UK.

It wasn't a problem with my scope however but I needed a longer screw for my adaptor. I also thought the spring action a little sloppy. Zeiss fell over themselves to help me. Actually making and sending me a screw to suit my needs. They didn't even charge me. They were quite prepared for me to send my adaptor back to have the play in the spring adjusted. However I fixed this myself.

I know this isn't the same as having a scope tested, but I just felt I should praise Zeiss's after sales service as given to me. I am sure that had I got a problem with my scope it would be sorted just as quickly and easily.
 
galt_57 said:
I have corresponded with a Zeiss product support engineer on the topic of testing and it seems that Zeiss has mixed feelings about the standard these scopes should be held to. He suggests that astronomical scopes can and should be held to higher standards of precision than terrestrial scopes since they are operated at much higher magnifications, used to observe points, and use simpler optics. Terrestrial scopes with their more complex optics, lower magnifications, and typical use where edge resolution is more critical than point resolution, are a topic of mixed opinion in the testing area.

The Zeiss scope my friend returned was really quite poor by any standard. It was certainly a defective sample, not a design compromise. I'm confident designers of birding scopes don't incorporate astigmatism and miscollimation as part of their designs.

The great advantage of star testing, once you get the hang of it is that defects like these are easily detected and identified. Just looking through a scope may not reveal these problems because most people don't carry around a mental picture in their heads of what a good telescope image (at a particular magnification and aperture) should look like.

I think it's worth noting that the Swarovski ATS-65HD I recently tested in the same way as the Zeiss, star and resolution tested quite well and produced a much better image at 60X. Not necessarily because it is a better telescope, but because the sample I tested was not defective.
 
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scampo said:
I hope that Zeiss engineer didn't say edge resolution... If so, that's more than a shade ironic [...]

The actual quote was;

"The fact is that no terrestrial scope with a complex prism erecting system will perform up to the standard of an astronomical scope with a simple mirror or prism diagonal. Then too, astronomical scopes are optimized for point resolution. Terrestrial scopes are optimized for edge resolution, using vertical and horizontal line charts. The reason is simple. Astronomical scopes look at points. Terrestrial scopes look at broad areas where it is the edges that define detail."
 
Dave,

I was speaking rather tongue-in-cheek as the Zeiss 20-60x zoom is not exactly optimized for edge sharpness at 20x, rather for maximum field of view.

Best regards
 
galt_57 said:
The actual quote was;

"...astronomical scopes are optimized for point resolution. Terrestrial scopes are optimized for edge resolution, using vertical and horizontal line charts. The reason is simple. Astronomical scopes look at points. Terrestrial scopes look at broad areas where it is the edges that define detail."

I don't know what this is supposed to mean. I don't think there is any such thing as a scope "optimized" for point resolution vs. edge resolution. Well made telescopes will resolve both, poor telescopes can't resolve either. In any case my resolution chart uses lines, not points so it should be just right for terrestrial scopes. Perhaps, since these scopes are made for birding they should be "optimized" for "bird" resolution.
 
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"...Perhaps, since these scopes are made for birding they should be "optimized" for "bird" resolution."

Indeed, Henry. My own Zeiss Diascope most certainly is. Looking at raptors and waders over the last two weeks proved that much to me many times over.
 
scampo said:
"...Perhaps, since these scopes are made for birding they should be "optimized" for "bird" resolution."

Indeed, Henry. My own Zeiss Diascope most certainly is. Looking at raptors and waders over the last two weeks proved that much to me many times over.

Hey...No rhapsodizing allowed. This thread is for grousing and complaining only!
 
Grousing? Yes.. we saw a red grouse, too! But only needed my eyes for that - optically they would surely fail a start test, Henry, I'm sure!

(-;
 
scampo said:
Grousing? Yes.. we saw a red grouse, too! But only needed my eyes for that - optically they would surely fail a start test, Henry, I'm sure!

(-;

Left myself open for that! Fortunately our built-in low grade optics only have to deliver a very wide field 1X.
 
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henry link said:
The great advantage of star testing, once you get the hang of it is that defects like these are easily detected and identified.

Henry, I finally had a clear night last night and so I gave it another try but I just see a fuzzy ball. After reading a few pages on star testing I was wondering if the atmosphere might be contributing to the problem? I mean I'm not on some Colorado mountain top in December. I'm in muggy St. Louis in July. There is also a great amount of light pollution here. And does the temperature of the scope matter or is that just a concern for reflectors?

Thanks,

Dave
 
galt_57 said:
Henry, I finally had a clear night last night and so I gave it another try but I just see a fuzzy ball. After reading a few pages on star testing I was wondering if the atmosphere might be contributing to the problem? I mean I'm not on some Colorado mountain top in December. I'm in muggy St. Louis in July. There is also a great amount of light pollution here. And does the temperature of the scope matter or is that just a concern for reflectors?

Thanks,

Dave


Believe it or not a muggy St. Louis night in the summer will almost certainly have steadier air than a mountain top in Colorado in the winter. Use a star high in the sky. A small scope like the Zeiss should equilabrate to the ambient air temperature in no more than 15-20 minutes max.

My friend called today to say his replacemaent Zeiss scope has already come. I hope to see it in the next few days. He says it is "much better" than the one he returned.

Henry
 
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