15-9-2015, last revision 1-12-2015

Test period 21-4-2015 - 1-12-2015
Serial Nr: 4304295
Origin of sample: Zeiss Germany demopool

Gone: the iconic Zeiss Z logo.

So here is Zeiss´ answer to Swarovski´s popular 42mm Swarovisions: The SF 8/10x42, "SF" standing for "Smart Focus". Curious? I sure was, and finally an early SF 8x42 sample from the Zeiss demo pool arrived here for the comparative review of five premium 8/8.5x42s. First look: Zeiss has clearly "borrowed" from the Swarovision shape but there is a third hinge (the triple bridge, hopefully not violating the Geneva Convention), and a nice modern shade of grey instead of hunter´s green. The coatings sparkle in a bright purple unlike any other binocular I know - "soon you´ll see birds like never before."

Swarovski´s Swarovisions set a new and successful standard with their unique flat field aka spectacular sharpness to the very edge of the image. And it seems that the fablulous but curved field Zeiss HT was not the right binocular to stop the Austrian supremacy in premium sport optics. The Zeiss marketing slogans introducing the SFs were aggressive, and at least the 8.5x42 Swarovision is both a revolutionary and mature design.

So how do the SFs compare to the Swarovisions? I have used the Swarovision 8.5x42 for almost a year, and its few shortcomings are a good guideline for a comparison with the Zeiss 8x42 SF (and the other 8x42 models).

This is the big question put on the wood of my garden bench... the Swarovision has one obvious advantage: Its revolutionary design has already matured for a couple of years, although Swarovski would generally not admit evolutionary changes in the optical system, probably because that would suggest they were not perfect right from the start - something customers don´t like to hear.

Zeiss SF 8x42 vs Swarovski Swarovision 8.5x42

1. My most serious quarrel with the Swarovision: the bad threedimensionality of the images, probably caused by the very flat field. Everything at close and medium distances looks unnaturally flat (which is a bit disguised by the spectacular sharpness of the Swarovision).

- Big surprise: Compared to the Swarovision, the SF 8x42 is not a real flat field design at all (although technically it does have field flattener lenses). It´s sharp only across about 75% of the field. Given that the Swarovision is basically 100% sharp across the field, and that this is the really unique property at the heart of its success, this seems strange and disappointing. To my delight though, the SF images have a notably better threedimensionality. I would like to think this was a very good and courageous decision by the Zeiss designers, but the truth may rather be this: The extreme wide field of view of the SF was the main goal in its design, and could not be implemented in a flatter field without increasing volume or rolling ball effect.

2. Colour reproduction in the Swarovision could be improved from slightly cold to a neutral look as in the Zeiss HT or Swarovski Habicht 8x30 or even to a slightly warm high contrast look, as in the SLC and Ultravid (my favourite colourwise).

- The SF has a high contrast look with a greenish colour cast. I say "look" because I assume this skewed transmission curve increases the perception of contrast, but at the expense of colour accuracy. Looking at the colour cast of the SF I´m a bit reminded of my 1961 Habicht 8x30. Especially comparing with Zeiss´ own HT this does not seem like a good idea to me at all (but it is something Zeiss could probably change quickly if enough people started to complain about it).

3. New high transmission glass for a bit more of sparkle, as I see it in the HT or the latest Ultravid.

- The SF is not a high transmission binocular, Zeiss claims 92% transmission. In fact, as with other "high contrast look" binoculars (the Nikon 8x32 SE and the Swarovski 8x42 SLC come to my mind) images to me often look a bit darker than expected.

4. Maybe flare resistance could be improved a bit in the Swarovision.

- The SF has a superb flare resistance, beating the Swarovision, and maybe even surpassing the already spectacular HT. Well done!

5. Should I wish for an even wider field of view...?

- That seems to have been one of the main design objectives of the SFs, understandably, as it should be immediately visible to anyone. Indeed the view is spectacularly wide, but this comes with many a high price: A distortion creating strong rolling ball, and compromised edge performance - in both aspects, the 8.5x42 Swarovision clearly beats the SF.

6. The Swarovski Achilles heel often is the focusing wheel. It tends to be rough or uneven going.

- Zeiss advertises a "smart focus" concept without explaining what is smart about it. The length of the gearing seems to be the same as in the HT, just below two revolutions from infinity to close. My SF sample has big play in the focus wheel before it grips the gear, and a too high friction which is a bit weaker in anticlockwise direction. Both got much worse.

Body
The body feels nice and solid with perfect friction of the hinges.

Focusing
I don´t know how Zeiss technically implemented the focusing but it is definitely different from the HT. Friction is almost too tight even on a warm day, and it seems to be slighly different for clock- and anticlockwise rotation. There is a strange play in the focusing: The wheel does not immediately "grip" and focus but needs a little more rotation before it drives the focusing mechanism. This is not good at all and really needs to be improved by Zeiss.

Internal blackening and baffling
look perfect and help to achieve high contrast. Superb. Applause!

Awesome! And this is what it looks like in the Swarovision:

Hm. I would love to know why Swarovski did it this way. Probably to let you scan the image by eye movement only much easier than in any other glass...

Eyecups
have two click stops - three positions, which is definitely not enough. Am I supposed to fix the right position with some gaffer tape? The Ultravid has eight clickstops. You can unscrew the eyecups in anticlockwise direction, to be able to easily clean the oculars, as they have an unusual baffling with soft black thin rubber which prevents stray light from entering the oculars. A very clever, elegant design. The rubber baffles can be easily detached, too. I ended up making the cups a good millimeter longer by slightly unscrewing them to get my pupils in the right position.

These rubber baffles shielding the oculars from behind are brillant.

Diopter adjustment
works by pulling the ring out, adjusting and pushing it back, and adjustment was easy and reliable.

Handling
Even a bit longer than the Swarovision and the HT, the SF is a very bulky glass. Especially compared with a Nikon EDG I do wonder if this was a good move by Zeiss. The SF feels surprisingly light in the hand though. Zeiss should call that smart center of gravity (SCG). A bigger than usual part of the optical correction was assigned to the eyepieces, so objective size remains quite small for the field of view, and instead the oculars became bigger. This brings the center of gravity closer to the face of the user. The middle hinge is quite small, about 4mms wide, so that the index finger will not be forced too far away from the middle finger, especially compared to the Swarovision.

Tripod adapter
There is no dedicated tripod adapter except the old, bulky and expensive Zeiss universal adapter, but the affordable Leica Ultravid adapter will work with the SF reasonably well. Zeiss should provide a solution similar to the Swarovski SLC tripod adapter for an uncompromised tripod use and they´d easily beat the Swarovision in that respect.

Industrial design
is following the Swarovision´s shape. For my taste, the Zeiss SF looks a bit less modern, a bit more on the baroque (or gothic?) side though. The grey plastic armouring feels cheap and has ripples, this is not a texture, finish and look that reflects the price tag.

Optical quality

Contrast
Macrocontrast is excellent with outstanding flare suppression. Center sharpness is very good in handheld use, but not quite as good as the superb and cherrypicked Leica Ultravid, Swarovision and Zeiss HT samples tested, especially at close distances. If put on a tripod, those three also showed better contrast of fine details, both at textural and at resolution levels, especially in distances under 10 meters. To be fair about this: We are in very lofty heights here, but then this is where great binoculars should be. The SF does impress with sharpness as long as you do not directly compare it to the rest of the best on a tripod. This was confirmed by using a 3x12 Zeiss booster in the field when the SF below 10 meters distance together with the SLC had the softest images of the five premium binos tested. Edge performance: sharpness is good across about 75% of the field and then decreases towards the edges. Very different approach than in the Swarovision.

Resolution at open aperture and 8.54 m distance was 4.26 arcseconds, and 4.56 arcseconds at 4m distance, surpassing the DIN ISO 1433-2 norm of 5.7 arcseconds by a good margin. Resolution with objectives masked to 20mm (2.5mm exit pupil size) was 6.77 arcseconds at 8.56 meters distance and 6.44 arcseconds at 4 meters distance as with all other tested glasses.

Contrast check at 3x boosted magnification at about 4-6m distance in the field, and 8.56 and 4m distance from the USAF1951 chart indoors: Images looked somewhat soft at open aperture. This was together with the SLC the weakest contrast performance of the 5 bins tested. I interpret this as residual aberrations, especially spherical aberration, and a lower than usual MTF performance at higher spatial frequencies. All this is not really relevant for handheld use, and performance towards infinity is better.

Flare suppression top notch, bettering the HT in many cases, but the Nikon EDG outperforms both in this respect. Images are very "quiet" as a result even when a lot of panning under difficult light conditions is done, this is a big advantage of both Zeiss 8x42s. A bright street lantern in the frame did not induce much flare. Against a low sun, the SF suffers badly from flare though, just as all other tested 8x42s. Here there is much to improve still for all models and makers and again, with the Nikon EDG being the most advanced design.

Distortion and rolling ball
This looks like a "wavy" distortion across most of the field (some say "inverse mustache"), so lines first bend pincushion like towards the edges but then change direction and bend the other way when reaching the outer part of the field. The very edge of the field looks pretty rectilinear to me, so lines become straight. The Swarovski 8.5x42 SV is real pincushion over most of the field and then changing to rectilinear. This sounds academic, but makes a big difference in rolling ball effect. With the Zeiss SF I suffer from the strongest rolling ball effect ever (I cannot compare directly with the 8x32 Swarovision though). For me, this is definitely inacceptable and the main fault in the design of this binocular. Zeiss should really try again and be more conservative and careful. The distortion is introducing a lot of extra movement by warping the image structures when they move towards the edges of the field, and together with the extremely wide field this engages my peripheral vision too much, and distracts me from concentration on the image center. After all, we have evolved to detect movement in the whole field of view using our peripheral vision so we can quickly react to that predator approaching in the shelter of some bushes. This would also explain why rolling ball generally is so unpleasant, making a relaxed viewing difficult when panning the binocular.

Field of view
is a class leading 148 meters at 1000 meters distance and very immersive, as long as you don´t suffer from rolling ball.

Threedimensionality
of images is astonishingly good. Center-to-center distance is 4mm wider than inthe oculars, less than in the Zeiss HT (6mm) but more than in most other competitors, so the stereo base is wide for roof. Moreover, the not strongly flattened field and the wide field of view probably help perceived 3D.

Close focus
is extreme with 1.5 meters minimum distance. I found the Nikon EDG to be easier on the eyes at close distances. Sharpness suffers a bit in close focus, nothing dramatic in handheld use though.

Coatings
are very high intensity purple/red on both the objectives and the oculars.

Above is the Swarovski Habicht 8x30 from 1961. Its images look very contrasty, but also darker and yellow-greener than the competitors from the same era. And here is the Zeiss SF:

Compare with the fabulous HT: Coatings look very similar to the SF from this perspective, but...

... a closer look shows that there is also a good deal of green reflections, something the SF is totally lacking.

Colour reproduction
to my eyes is problematic with a green cast. This is the second serious fault in the SF´s design. To me images often look a bit sick and muddy because of it. White objects, especially if in bright sun, will look white, as our brain will correct a lot of colour casts and bright highlights seem more robust with regards to colour casts. Midtones are stronger affected, as in grey birds. Accordingly, greens sparkle very saturated, but purples and skin tones are a bit subdued. Red autumn foliage will look browner and more desaturated compared with other glasses. Zeiss is really pushing it hard here and I resent this approach from the bottom of my heart. Zeiss, please change it.

For more on colour and brightness comparisons, please read here.

Brightness
is as in other modern non high transmission glasses, around 92% transmission is claimed by Zeiss. Compared to the HT the SF looks visibly darker. The Swarovision to me seems a bit brighter, too, because it has slightly cold colours that do not create that high contrast look which tends to make the images look darker. The studio test for colours and brightness yielded excellent results for the SF.

Chromatic aberrations
Two lenses of fluoride containing glass are used in the design, explaining why chromatic aberrations are state-of-the-art low in the center, maybe even a tad better than in the Swarovision, increasing a bit towards the edges (magenta-cyan or red-green fringing). At the very edge of the field though strong blue fringing occurs and the colour cast turns from warm yellowgreen to icy blue. This was easy to see when panning across shrubs with white flowers as they change their colour when reaching the edge of the field. I sometimes also noticed that when tilting the binos upwards, quite a wide ringshaped area in the periphery would look a bit brighter and colder then the center.

Residual aberrations
I can´t comment on coma, astigmatism and spherical aberration as this is beyond my competence and I only had a brief look at the night sky.

Eye relief
is about 17 mm as stated by Zeiss.

Ease of view
is very good, although for my eyes the Swarovision remains the class leader in this respect as it is the only glass that allows to easily scan the image by eye movement only.

Conclusion

The Zeiss SF 8x42 seems to be optimized for:

1. a class leading wide field of view

2. improved ergonomy

3. a high perceived contrast in handheld use

Pros:

1. Widest field of view in its class - in direct comparison, most other glasses will only provide a tunnel view.

2. Ergonomy: the centre of gravity is closer to the eyes due to big oculars, the glass feels extremely light in the hands. This is the most revolutionary feature in the SF.

3. Excellent flare suppression, similar to the HT, a really big advantage of the Zeiss 8x42 designs, only bettered by Nikon EDG.

4. Very good macrocontrast with "high contrast look" in handheld, daylight use.

5. Ease of view is improved from the HT, the SF is more tolerant with regards to exit pupil position.

6. Elegant and effective baffling of oculars with soft rubber.

Cons:

1. Especially on the tripod I found this SF sample to underperform a bit in sharpness and in microcontrast at textural and resolution level comparing it to the competition and Zeiss´ own HT. This should not be generalized though.

2. The focusing wheel has play and too much friction. This might not be the case in newer, less used samples, but it is at least a potential general problem.

What I dare to generalize for the SF:

3. I found the rolling ball effect of the SF annoying.  Zeiss needs to address this to make the use of the SF more comfortable for a wider group of users.

4. The colour cast of the SF is too green. Zeiss in my opinion really needs to change this.

5. Texture and finish of the grey plastic armouring lack the finesse of a premium product.

Opinion

The Swarovision still has a lot to offer:

1. A real flat field with a100% sharp image field might be preferable to a wider field of view with an only 75% sharp field.

2. An easy to scan by eyemovement only field of view. This is unique.

3. Neutral colours instead of high contrast look with yellow-green tinge.

4. Much less rolling ball.

But the SF will give you:

1. The widest field of view.

2. Great ergonomics.

3. Awesome flare suppression.

4. Much better threedimensionality.

At the moment I would still prefer the Swarovision, but the Zeiss SF might become the better binocular once the main issues are solved.

During long days in the field, small becomes very beautiful, and while I will acknowledge that the Ultravid has flaws, the case is different with the Nikon EDG. Here we have an almost faultless, very easy to use flat field design with awesome image quality and perfect mechanics. To me, the EDG makes the SF look rather oversized and complicated. While the Nikon feels like designed from the scratch, straight to the point, the SF tries to improve on the already bulky Swarovision, a path which understandably leads to more bulk. Has Zeiss really found the right way to deliver a pair of binoculars that will prove irresistable to birders?

Afterthoughts - 2-11-2015

Some users have complained to me about the greenish-warm colour cast of the SF, especially when observing grey birds. Most don´t seem to care about it, some even love this look.

The focusing problems are a real issue, some noted it when trying out new samples, some had to send back their samples for repair when the problem developped. I assume Zeiss will solve this problem.

As expected, street prices have now come to the level of the Swarovision, early adopters really paid a very high price. Now it is Swarovski´s turn again to be leader in highest pricing.

What others say

Lee Thickett published a short, telling interview with Gerold Dobler on birdforum, highlighting the design decisions.