We have tested the new Zeiss Victory DiaScope 85 T* FL with the 20-75x zoom eyepiece. Its 20-75x eyepiece makes it the highest-magnification top birding scope on the market.
The big question in our minds was how well the new Zeiss DiaScope would perform at 75-power magnification. Would it be able to maintain as much sharpness 75x as at 60x?
Yes, it does.
A telescope's magnifying ability is limited by the size and quality of its objective lens. That front lens creates an image that the eyepiece magnifies and presents to the eye. Increasing the power of the eyepiece will let you see more detail only if that detail exists in the image created by the objective lens.
With inexpensive scopes, as you zoom the eyepiece towards 60x, at some point, the image stops showing more detail and just starts to get fuzzy.
We tested the new Zeiss scope using the same optical resolution chart and under the same conditions as we tested the high-end scopes in our November, 2009, High-end Scopes Review.
We were amazed at how clear and sharp the image stayed even at 75x. We saw significantly finer detail with the Zeiss at 75x than with any of the other high-end scopes at their highest magnification of 60x. Putting a doubler behind the eyepiece confirmed that even at 75 power there was resolution to spare.
In our above-mentioned review, we assigned the highest resolution score, of 5, to the Kowa TSN-883 Prominar 88mm scope, which had the best resolving power at maximum magnification. If we had to use the same scale to rate the Zeiss 85mm DiaScope with its 20-75x zoom, we would have to give it a 6!
Field of view
The field of view at 1000 yards of the Zeiss 20-75x zoom eyepiece is 120 feet at 20x and 48 feet at 75x. Compare to the Kowa TSN-883 Prominar, which provides 115 feet field of view at 20x. Of course, we'd like to compare the field of view at 75 power, but we don't have any other 75-power scope to compare it to.
The new DiaScope is fully rubber armored in a nice matte black covering. It's hand friendly, it's non-reflective, and it makes for quiet operation.
Dual speed focus
Zeiss has cleverly re-designed the focus mechanism so that one knob handles both slow, precision focus and fast, gross focus. This Zeiss innovation is completely intuitive to use.
The first 270 degrees of rotation either way is precise and slow. After that, the knob shifts gears and starts moving the focus five times as fast.
When you stop turning the knob, it automatically goes back to the precision mode.
Very nice. No longer will you fumble finding the right knob. There's one less thing to think about when you are excitedly trying to get on a bird. It's like upgrading from a stick-shift to an automatic transmission.
Weight and size
The new 85mm scope with the 20-75x zoom eyepiece weighs 72.4 oz. The new body is the same weight as the old Diascope body, but the 20-75x eyepiece weighs about 7 oz. more than the old 20-60x eyepiece.
Surface LotuTec lens coatings
Zeiss LotuTec coating sheds water, dirt, grease, and grime. The lens can be easily wiped clean without smearing.
-- Copyright 2010-2012 Michael and Diane Porter
What Zeiss says about their FL Optics Concept
The FL Concept
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