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For 10x40BGA Dialyt owners only ... (1 Viewer)

Rotherbirder

Well-known member
Posted on Zeiss forum as its not really a 'for sale' notice. Rummaging around in a box the other day, I came across a pair of Aquashields that I used with my now long deceased Dialyts back in the 80s. They were marketed by Lambert's of Lancaster (a UK optics retailer) as removable, protective objective cover 'glasses' for rubber-armoured Dialyts only, hence the thread title. The photo of the accompanying leaflet describes them and their use, albeit in rather glowing terms. They do work as described and are indeed handy for sea-watching, protecting the objectrives from sand, rain and spray without compromising image quality noticeably.

They are in perfect condition and come in a nifty leather wallet. The first genuinely interested UK 10x40BGA owner who PMs me can have them free of charge.

Thanks for looking.

RB

RB P1040319.JPG P1040316.JPG P1040318.JPG
 
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Rotherbirder

Well-known member
My mistake - you are correct, 10x40 it was! Original post amended.
I found them to be a pretty unmemorable binocular, apart from the fact that the focusing failed catastrophically while birding in Nepal. I would never buy Zeiss again; YMMV, of course.

RB
 
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John A Roberts

Well-known member
Australia
A bit of history . . .
the original Dialyts were 10x40's, as were the original Victory’s. It was not until the Victory FL’s that the 10’s became 10x42’s

The Dialyt 10x40’s (along with their parent 8x30’s) were an external focus design. They focused by moving the exposed objective pair back and forth
within its housing. So the distance between the frontmost and rearmost optical elements changed during focusing

See an image from a 2015 eBay listing of an 8x30 B GA by deadbuck. The recessed position of the objective group in the rear housing is especially clear

Potentially on the Dialyts, the Aquashields would have provided more protection under all conditions from environmental contaminants entering the binocular body

However, in terms of practical advantages, see Lee's comments:
. . . my Dialyt 10x40 B and BGATs of the same era had moving objective lenses so were not really internal focusers. This never gave me problems of water or dust ingress but cleaning the objective lenses was a tricky job because the internal surface of the optical tubes always gathered a thin layer of grease where the objectives had travelled back and forth and this trapped dust and tiny fragments of vegetation.

The bellows effect of the moving objectives fed back strange changes in focus resistance when on mountain tops or in airliners.

Lee


John
 

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Mark9473

Well-known member
Belgium
I found them to be a pretty unmemorable binocular, apart from the fact that the focusing failed catastrophically while birding in Nepal. I would never buy Zeiss again; YMMV, of course.

I never had the Dialyts but a friend at university bought one, end '80s. I was green with envy ;-) Very peculiar instrument, I often think about that first viewing session with it. It had massive angular magnification distortion; I'd never seen that before.
 

Rotherbirder

Well-known member
I never had the Dialyts but a friend at university bought one, end '80s. I was green with envy ;-) Very peculiar instrument, I often think about that first viewing session with it. It had massive angular magnification distortion; I'd never seen that before.
Strange you should say that. Isn't AMD used in binocular design to counter the 'globe' (rolling ball) effect? If so, it didn't work for me as the 10x40 Dialyt sent me boz-eyed & made me feel sick when panning!

RB
 

henry link

Well-known member
AMD causes the globe effect. Pincushion distortion reduces it, or in just the right amount corrects it, or in even larger amounts causes a reversed AMD that causes objects near the field edge to radially stretch rather than compress.
 
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Rotherbirder

Well-known member
AMD causes the globe effect. Pincushion distortion reduces it, or in just the right amount corrects it, or in even larger amounts causes a reversed AMD that causes objects near the field edge to radially stretch rather than compress.
Thanks for the clarification.

RB
 

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