#tech #lenses #spottingscope #zeiss #diascope #birding

Brief Review of The Zeiss DiaScope 65T* FL (Green - Straight Tube)

⏱️ Approx Reading Time: mins

Zeiss, A Brand Known For Quality Optics

Every now and again one can struggle to find the information they are looking for using the internet. It was this which inspired my well received Brief Review of The Canon EF 500mm f4.5 L USM which, after 2 years, still gets around 500 hits per month! I noticed there are a lot of these scopes for sale on eBay, so this might be useful to someone!

Naturally, I have found myself in the same position again regarding the Zeiss DiaScope 65T* FL, specifically the older Green (and silver) body versions. I was looking at buying this scope and could not find anything online about this scopes performance, apart from the odd anecdote here and there. I decided to put my trust in the Ziess name and shelled out C$1480.00 (About £800) on the straight-through version of this scope. So here I am writing about my thoughts and opinions on a piece of optical hardware I know pretty much nothing about!

Without further ado, here are my thoughts on the Zeiss DiaScope 65T* FL.

Note: I opted for the straight tube version, I won't be discussion this vs the angled version as this is down to personal preference.

An Old Scope

I don't really know exactly how old this specific scope is, and I can't really find much online about when this scope was originally produced. What I can find is a bunch of promotional material from 2014 for this scope's predecessor, a refreshed DiaScope with all black rubber armour and a single focus knob which serves as both course and fine focus. The seller told me he bought it new about 12 years ago (2013) so this lines up. I can only assume that this version I have was purchased just before the refresh.

So with all that said, I am stating this specimen I have as 12 years old, and assuming the scope was produced for several years prior to this, making is a mid-2000's scope. If you have more information on this, please do let me know so I can update this article!

Basic Specifications

I've not found much online about this specific scope, the green/silver version, but did read a post which stated that the only difference between the green and black models was the black rubber armour and the updates focus knob. I compared the specs of the refreshed version with text found in several eBay ads, all of which were identical, and basic.

All this said, here are the specs of this scope:

Unfortunately I cannot find a diagram of this scope.

Build Quality

Carl Zeiss are known for making incredibly good optics across the range of products they make. They use high quality materials to produce robust and high performing equipment. I've been lucky enough to use camera lenses produces by Zeiss in the past so I'm no stranger to the incredibly build of these products.

This spotting scope is no exception.

Positive: All magnesium build makes for a strong and light body. The metal is coated with a brushed feeling, almost sand blasted, green paint, with an etched Carl Zeiss branding. Built in plastic retractable hood helps keep rain and stray light out of the front of the scope. The hood has a what I can only assume is a sight to help point the scope. The focus knobs are ribbed rubber and offer plenty of grip, even with the slightly stiff rotation of the course knob. The all metal tripod collar and foot are well make and have a nice locking knob. The rotation is indexed every 45 degrees which is nice, but a bit useless on a straight-tube scope (aside from setting the foot at 90 degrees to use on a gimbal). A thick rubber grip is installed which protects the bottom of the scope and gives a nice grip on the scope body. Outer lens elements have the LotuTec coating to prevent dust, dirt, rain and fingerprints from sticking. Internal elements in the scope and eyepiece have the advances T* coatings which are supposed to increase light transmission considerably (I think I read by up to 80% compared to no coatings). The eyepiece has a sliding eye relief cup, which is not clicked so can be adjusted to any point. The zooming motion on the eyepiece is superb and very smooth with a perfect dampening. The eyepiece is well made too and I can see why these things carry 2/3 the price of the whole scope!

Negative: The metal body with no rubber armour can make it cold to the touch when our in cooler weather. It also has no protection from knocks and bumps so keep that in mind when using this scope. The course focus knob is stiff to turn and takes some force/effort. This could be because this specimen appears little used. Like the corse knob, the eye cup is a little difficult to pull out but not a problem. The changing exit pupil and eye relief is a bit annoying but isn't a problem.

Gallery

The body is really nice in the hand and the big rubber grip offers a good hold.

The eyepiece is super smooth to zoom and locks in with a nice click.

The eyepiece offers different zoom ranges depending on the scope it's used on.

The eyepiece is marked with zoom markers for both the 65 and 85 mm scopes

The eye cup slides up about 12 mm, though I don't tend to use it.

LotuTec coatings keep the outer elements clean.

The tripod collar is super robust, rotates smoothly, and has a nice lock mechanism.

The tripod foot is not arca-swiss but does provide all common thread sizes.

Overall the scope has a very nice design, feels great, and performs well.

Manual Focus

Positive: The two knob system is actually nice and mirrors the setup of many microscopes I've used. The coarse knob take about 5 turns to get from one end to the other (from each stop). The fine focus is easy to rotate and gives lots of precision. I had no issues focusing the scope on birds close and far.

Negative: The coarse knob is not super easy to turn. I don't know if it's overly dampened, or if it's just not been used much so hasn't loosened. Moving from far to near focus can take about 5-10 seconds as you have to rack through quite a few turns. But on the whole this isn't an issue in the field.

The left most knob is the fine focus and the left most the coarse knob.

Image Quality

Image quality is the most important thing really. As expected, Zeiss has produced a stellar piece of equipment here. I'm coming from Vortex Diamondback 12x50 bins and a range of Canon gear, including the legendary EF 300 f2.8 and EF 500 f4, so have a good idea of what is good and bad.

15x Zoom

At 15x, the image is super bright and clear. There is a slight yellow tinge to the image which I read is to do with the older generation of the external coatings. It doesn't make a difference in the real world as lighting changes and our eyes adapt. The centre of the image is tack sharp and this goes out to about the 75% of the circle. The last 25% is slightly softer. The view is distortion free (note the train car lines). There are no visible chromatic aberrations even when pointing at a dark mountain side with overcast skies behind. The field of view is large and the eye relief (exit pupil is large).

15x cropped to square. Note the slight corner softness and the yellow tinge

25x Zoom

By 25x zoom, the softness is mostly gone and the colour has improved a bit. The image is super clear with good contrast. Some distortion is present, bowing the train car slightly. The eye relief shortens a tad making it slightly less easy to get right, but on the whole still very good.

25x cropped to square. Note the improved colour and edge sharpness.

35x Zoom

At 35x we see the same as 25x in terms of quality improvements with more contrast and much better colour. There is some more bowing in the train car due to distortion, bit nothing major. The eye relief shrinks a tiny bit more. This has been reported by many and is an effect of the optics in the eyepiece. That said, everything here is pretty good. I did notice a slight dimming of the view at this point, but nothing to worry about. After all this is a 65 mm optic so wont be as bright as the larger versions.

35x cropped to square. Note a small amount of distortion but great colour and contrast.

45x Zoom

Zooming all the way in sees the eye relief increase back to normal, and gives a great view. The sharpness is incredible though there is some distortion. The view does dim a tiny bit more, maybe by 35% compared to 15x, but it's really not an issue most of the time. If you want to view in darker conditions, you will already by considering the 85 mm version I'm sure. I do not see any chromatic aberration at this zoom level, even against dark trees and overcast sky.

45x cropped to square. The colour and contrast look great and sharpness is spot on.

On the whole, it's difficult so say much more than 'this is a really great optic at all zoom levels'. I have used the Vortex Viper, and while this is a fantastic optic, the Zeiss holds out much better when zooming. I have had comments from Viper users who are impressed by the view at 45x compared to 60x on the Viper.

The image below is another poor attempt at digiscoping, but it really does show the quality of this optic. It was taken at 45x zoom by holding my iPhone up to the eyepiece.

Northern flicker taken at 45x with the DiaScope 65T FL

Summary

In summary, I would say that this is an excellent spotting scope for most people. Optically, it out performs some of the modern scopes in its second-hand price range, and still provides most of the features you would want from a scope. I opted for the straight-tube version as I will use it on the go and from a car, and wanted it to fit in my bag easily alongside my 500 prime, but the angled version will be as good I'm sure. I appreciate I might have been lucky and got a good copy, so do test before you buy. But in terms of capability, this is a very capable scope.

I'll update this post as I get more use out of it and see if anything changes, but for now here is a my take.

If you have any questions or want to chat about this optic, get in touch, I'm active on emails.

Created by Niall Bell (niall@niallbell.com)