Reviews of optics
Published in Alula Magazine and Linnut magazine
ALULA TESTS LATEST TOP BINOCULARS (4/2000)
CANON 15x50 IS UD All Weather (4/2001)
Zeiss Victory FL a new champion? (3/2004)
Kowa TSN-883 (1/2007)
Opticron ES 80 ED (4/2007)
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Review of Optics
Zeiss Victory FL
A couple of decades ago Zeiss - together with Leica - were the top choice of discriminating birders. However, during the 1990s, the models offered by this venerable German firm fell out of favour as first Leica’s Ultra series and later Swarovski’s SLC and especially the EL series became the new favourites. Zeiss’ Design Selection binoculars were simply too big and heavy for birding, and the more recent Victory series was on the whole simply not quite good enough to convince the most demanding birders. Zeiss seems to have understood their situation, and now have mounted a counteroffensive. The team developing the new Victory FL series includes the well-known birding optics expert Stephen Ingraham, and as added bait the binoculars feature objective lenses using fluoride glass. Although Zeiss’ advertising carefully avoids using the word ”apochromatic,” it is obvious that by using an optical design similar to that in their Diascope telescopes, Zeiss has attempted to reduce chromatic aberration in these binoculars to a new level.
Chromatic aberration means that a lens system is incapable of refracting all wavelengths, that is all colours, of visible light to the same focal point. The achromatic objectives generally used in binoculars are corrected to focus red and blue to the same point, but in the yellow-green range the objective magnifies slightly less and in the violet range slightly more than this nominal magnification. This compromises image sharpness, and, especially with objects reflecting light that contains multiple wavelengths (such as white, grey or light brown), also causes purple or green fringing. Colour fringing is less pronounced in the middle of the field, but increases sharply towards the edges. The more the image provided by the objective lens is magnified, the more obvious chromatic aberration becomes, which is why telescopes are often made with lenses made of fluorite crystals or special low dispersion glass types. In recent years, image quality in binoculars has gradually evolved to a point where it is difficult to further improve sharpness, contrast and colour rendition without also reducing chromatic aberration.
How visible chromatic aberration is not only depends on the binocular but also to a large extent on the prevailing light conditions and the type of object being viewed. Some users also notice, and are bothered by, it much more readily than others. However, if we have two binoculars of otherwise equal quality, the one with less chromatic aberration will show an image that looks sharper, more real and has better contrast. Therefore, Zeiss’ courageous move is most welcome. The correction of chromatic aberration is nevertheless only one, albeit an important, aspect of a perfect image, and it is the sum of the parts that ultimately determines the quality of an instrument. Without testing and trying them out it is also impossible to say how much less - if at all - chromatic aberration the Zeiss FLs actually have, since in this respect, like as in so many others, reality refuses to fit into neat distinct categories.
In July, after much waiting, Alula received the 7x42, 8x42 and 10x42 Victory FL binoculars for testing. Our test team took the new binoculars out for a field test, and in addition I used the binoculars for a couple of weeks during my summer vacation, and so had a chance to thoroughly test their optical properties and usability.
Resolution: I measured the binoculars’ resolution mounted on a tripod both with my eyes only and with a 3x “booster.” Without the booster, I could resolve 2.8 line-pairs/mm at 10 m with the 10x, 2.5 lp/mm with 8x and 2.2 lp/mm with the 7x model. With the booster, the limit was 6.3 lp/mm with 10x, 5.6 lp/mm with 8x and 4.5 lp/mm with 7x. Compared with the reference binoculars and previous test data from other models, the resolution of the new Victory FLs is on par with the best of them. The sharpest of the three relative to its magnification was the 8x42, but the other two were also excellent. Subjective viewing impressions both with the test targets and in the field reinforced the feeling that these binoculars give a very sharp image. However, the 10x42 FL we received for testing did not always appear quite as sharp as my reference, the Nikon 10x42 SE, and also fell a fraction short with the booster and the test targets. A star test with an artificial point source revealed that the centring of both its objective lenses was a bit off, suggesting a minor quality control lapse with this particular unit. In a few other parameters discussed below, the 10x specimen also impressed us a bit less than its 7x and 8x siblings. In order to be sure that the issue is unit-specific rather than model-specific I would have needed to check out a larger number of units, but that was not possible within the available time. The 8x42 felt brilliantly sharp every time I used it, and it also appeared sharper than one test team member’s Swarovski 8.5x42 EL. For the 7x42 we did not have a corresponding reference binocular, but compared with the higher-magnification binoculars, it likewise always presented an excellent image.
Chromatic aberration: I have usually not discussed chromatic aberration as a separate item in my tests. However, since the use of fluoride glass is perhaps the most interesting aspect of these new Zeiss binoculars, I will make an exception here. The afternoon we had scheduled for our team’s field-testing, the light conditions unfortunately happened to be such that colour fringing of high-contrast objects was barely noticeable even with ordinary high-quality binoculars, and we could not detect essential differences between them and the Zeiss FLs. In my own tests and field use, however, I determined that in the middle of the field, the Zeiss image shows hardly any colour fringes, but outside the centre area and towards the edges fringing was quite obvious, although the fringes were markedly narrower than in other top binoculars. Against a bright sky or water, birds looked very clean and distinct without any colour “spilling over.” In this regard, the Victory FLs are certainly the best binoculars I have tested far, but they are not all that much better than the second best, the Nikon SE-series porroprism binoculars. Their advantage over other top-quality roof prism binoculars is more pronounced, however, and the Victory FLs should be warmly welcomed by those sensitive to chromatic aberration.
Contrast: The 7x and 8x42 had first-class contrast. Our test team considered the Victory 8x42 to have markedly better contrast than the Swarovski EL 8.5x42. The Victory 10x42, while also excellent, had just slightly less contrast than the Nikon SE 10x42. Shaded areas surrounding an extremely brightly sunlit metal roof could be more easily and clearly viewed with the Zeiss models than with the other binoculars we had.
Brightness: The earlier Victories were already the brightness champions, and the new FLs are in the same league. In the 10x group, the Nikon SE came very close to the Victory FL. The brightness advantage of the Victory 8x42 over the Swarovski EL 8.5x42 was more pronounced.
Colour rendition: The Victory FLs are excellent in this regard as well. There is only the slightest yellow bias, so slight that it is hard to notice. Vibrancy of colours and the ability to resolve subtle hues is likewise first rate.
Flare and backlight properties: No pronounced flare was noted under any conditions. When viewing as close to the setting sun as possible, very narrow colour arches appeared in the image, but they were insufficiently prominent to disturb viewing. Detail in the shadow side of even the most brightly backlit objects was seen exceptionally well. The eyecup design of the new Victories is more conservative than in the previous models, whereby light has easier access to the eye from the sides. This did not introduce particularly prominent reflections, but with the 7x42, which has a bit more eye-relief than the other two, there was occasionally a pale halo around the image circle.
Image quality near the edge of field: It is generally easier to make higher magnification binoculars have better edge resolution, and this was also the case with the Zeisses. In our most recent test, the older 10x40 Victory had the best edge quality. The new 10x42 Victory FL is not quite as good, and fell a bit short of the Nikon SE. The sharp area in its image also does not extend as far out from the centre as in the Nikon. The 7x and 8x models are a little better than average for their magnifications. The Swarovski EL 8.5x42 has perhaps marginally better edge performance than the Zeiss 8x, although there were conflicting views about this among our team members. Pincushion distortion, which is almost always very prominent in binoculars, is exceptionally well corrected in the new FLs.
Ease of viewing: Earlier I have often found Zeiss binoculars tiring to view with, but with the Victory FL things have happily changed. Viewing is easy and relaxed, the best image is quickly found and none of us needed time to get used to the binoculars. Also when panning their image remains significantly more coherent than in previous Zeiss models. Our test team unanimously considered the FLs pleasant and easy to view with. However, the 10x42 FL (which I suspect is a slight lemon) was not as problem-free as the other two, and finding the correct diopter setting was also more difficult.
Technical properties and usability
Subjective fields of view for the new models are 60, 62 and 63° respectively, which are normal figures for wide-angle binoculars. Due to its small magnification, the real field of the 7X42 model is a whole 8.6°, or 150 m at a 1 km distance. Because of its large field and good depth of field, the Zeiss 7x42 Classic has long been popular in England and the USA, and the Victory 7x42 FL is clearly designed to inherit that position.
Close focus and focus wheel action: All three models focus down to about 2 m. Focusing is quick: focusing from 10 m to infinity takes an 80° turn of the large, fully rubberised and nicely ribbed wheel. Our team considered the focus action to be quite successful. Despite its speed, it is precise enough for easy fine-focus. There is no play in the movement, but smoothness could still be improved somewhat. On the other hand, the action is stiff enough to prevent the focus from changing inadvertently. The depth of field was considered to be normal for the magnifications in question. Usually, fast focus makes the depth of field appear shallow, but with the new Zeisses we did not need to fiddle with the focus any more than usual.
Use with glasses and diopter adjustment: Measured eye-reliefs were 16mm for the 7x, 15mm for the 8x and 14mm for the 10x models. For those wearing glasses these are good figures and markedly better than what I measured for the 10x roof prism binoculars in our previous test. In all three models the eyecups twist out 12mm. The eyecups have a straight edge and are covered by relatively hard rubber. At least when new, they feel very solid and have no play. In addition to fully extended and fully retracted positions, they also have notched intermediate positions at 4 and 8 mm extensions. The fully extended position suited me best, but another member of our team was grateful for the 8 mm position. My benchmark glasses-wearer in turn preferred the 4 mm setting, so this simple improvement clearly meets a real need! There is also a pretty ample margin past infinity for those who are heavily very near-sighted. As in the previous models (and Swarovski among others), the diopter is adjusted by pulling out and then twisting the focus wheel. There is a notch for the zero setting, but I was glad to notice that otherwise the adjustment is continuous. The notch unfortunately makes fine adjustment just around the zero setting impossible, so it could also be omitted, especially since the adjustment scale is clearly marked. With this mechanism it is impossible to simultaneously focus the left eyepiece and adjust the diopter setting.
Other observations: Victory FLs are waterproof and nitrogen purged. Their body is fully rubberised with a ribbing reminiscent of Zeiss’ old classic models. Our test team was not particularly enamoured with the aesthetics of the Victories. Some considered them cheap looking, and the most favourable comment was “practical design.” One team member also disliked the tactile feel of the rubber armouring. Zeiss specifies the weights as 740-765g. With the strap, eyepiece rainguard and objective lens caps I measured the weights as 830-845g. In field use the weight seemed just right and balance in the hands was very good. Zeiss has also managed to get rid of the plasticky aura of the previous Victories, and these new models have a solid feel. The centre hinge is also stiff enough to stay as you set it. On the negative side, the FLs, like so many premium binoculars, do not have a threaded hole for a simple tripod mount. Instead, the Zeiss brochure shows yet another large, heavy, complicated (and probably expensive) “universal tripod fixture.” Finnish Victory FL buyers will thus have to practice their whittling skills while crafting custom Finnsticks for their new glasses. The guarantee is 10 years, which is the longest possible period according to the current EU rules concerning binoculars. The price includes an eyepiece rainguard (again, an annoyingly tight fit), nicely padded carrying strap, Swarovski-style good tethered lens covers and, at least in Finland, a proper padded cordura case with its own strap and belt attachments. List prices in Finland for the 7x, 8x and 10x models are 1,540, 1,590 and 1,640 euros, making them a little more pricey than the Leica Ultravid and Swarovski EL.
Victory 7, 8 and 10x42 T* FL binoculars are Zeiss’ victorious return as a top contender among premium binoculars. All of our test team members considered them excellent with no essential weaknesses in image quality or usability emerging during our trials. Image sharpness, brightness, contrast, colour rendition, backlight properties and correction of chromatic aberration were all as good as is presently available in any model from any make. Usage is also easy and natural. There is still room for improvement in image quality towards the edges of the field, the focus action could be smoother, and the styling classier. Our favourite among the models was the Victory 8x42 FL, which our test team considered to be narrowly but unequivocally better than the number one of recent years, the Swarovski 8.5x42 EL. To put matters in perspective, however, the old Leica 8x32 Ultra we had alongside the newer contenders also offered a very satisfying view. We thus conclude that the Zeiss Victory FL is currently the best birding binocular on the market and definitely should be on the short list of those planning to buy a new pair of binoculars. However, in our opinion, the difference is not great enough to warrant an upgrading frenzy among serious birders.