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)
Canon 10x42L IS WP (NEW)
Hawke 8x43 ja 10x43ED (NEW)
Leica APO-televid 82 (NEW)
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Review of Optics
CANON 15x50 IS UD All Weather
On the whole, modern binoculars and telescopes tend to be so good that when testing and comparing them one is forced to concentrate on relatively small differences in optical properties as well as on design and usability features which oftentimes boil down to personal preferences. However, these latest generation image-stabilized binoculars by Canon are a clear exception to this rule, and force testers (as well as users) not only to evaluate the binoculars themselves but also to re-evaluate their own viewing habits, preconceptions and priorities. Based on reports I had heard from abroad, it seemed that in this model Canon had managed to fix what was perhaps the worst shortcoming of the earlier IS models--their tendency to be severely miscollimated (or misaligned) when the stabilization was not activated--and I was therefore eager to test them thoroughly. In late March, the chance came to have a pair of Canon 15x50 IS binoculars on loan from the importer for about two weeks. If I were to summarize my experience in one sentence, my impression was similar to the one I remember from my youth when, for the first time, I got to use a high-quality spotting-scope. When my wife--who is not a birder but has often used different kinds of binoculars--first looked through the Canons and turned on the stabilization, she spontaneously exclaimed "Wow!"
The 15x50 IS UD is relatively large and heavy for a binocular. It can best be compared with Zeiss's, Leica's and Swarovski's 45-56 mm roof-prism binoculars or old-fashioned 7-10x50 porroprism binoculars. However, the Zeiss 15x60 porroprism, for example, is already noticeably bigger and more cumbersome to use. Having previously tried 15x binoculars only occasionally for short periods of time, I was surprised by how easy it was to view with these Canons even without the stabilization. The image naturally shakes more than with normal binoculars, but for instance when viewing birds in flight it was relatively easy to study their details. Stationary objects looked sharp and large, but the image naturally shakes restlessly. When one turns the stabilization on for the first time, it is almost impossible not to be astonished: a soft click is heard, and in about a second the image shake freezes to a stop as it were, with only a slight and peaceful residual rocking reminding one that the binocular is not supported by a three-kilo tripod but only one's own arms and hands. When viewing birds at a feeder, it was hard for me to avoid the feeling that I was viewing a high-quality nature video. I found myself studying the way a brambling used its beak and tongue as it was swallowing a seed, and examining the nuances and wear of the feathers of a bullfinch or a blue tit. When viewing a peaceful and stationary image, the human brain gets much more time to concentrate on important detail, and it is in this respect that viewing with the Canons more closely resembles the use of a telescope than a binocular. When scanning the skies, the stabilization repeatedly helped to determine whether a distant bird warranted closer scrutiny through the telescope.
However, every silver lining has its cloud, and unfortunately Canon's image stabilization technology isn't perfect either. When the stabilization is engaged, the image does not remain optimally sharp the whole time. Canon uses gyroscopic motion sensors and microprocessor-controlled vari-angle prisms to keep the optical axes of the binoculars stationary despite external movement of the binoculars. It seems that the more the prisms need to 'tilt' in order to adjust the image, the more they introduce what is called wedge distortion, meaning that they begin to asymmetrically break points of light into small spectra. How disturbing the focus wandering is seems to depend on how stationary one is able to hold the binocular, almost vanishing if you manage to hold them steady, and becoming quite pronounced if you do not. Also some who tried the binoculars did not notice it even after I told them about it, others felt that it made the binoculars very irritating and tiring to use. I was initially quite bothered by it myself, but as I gained experience in using the binoculars it became less and less of a problem. At first I always tried to actively correct the image by tweaking the focus or the eyepiece dioptre adjustment (which needs to be very precisely set for the binocular to work well), or by changing the position of the binoculars relative to my eyes. In the end, I found that I got best results by first focusing the binoculars on the target without the stabilization on, then engaging the stabilization and correcting the focus only a little and only when the image seemed to be at its best anyway. Sometimes it also helped to turn of the stabilization and then immediately back on again. Especially in normal birding use I had very little problems after adopting these methods. In resolution testing this wandering of focus had a somewhat more pronounced effect, as there the tester is all the time struggling to see detail at the threshold of his/her eyes' resolving power. Another negative aspect of the way in which the stabilization works is connected to the very fact that it tries to stop the image from moving. When scanning the scenery or following a bird in flight, the image naturally cannot and should not remain stationary. If stabilization is on at these times, it tries to lock the image in place, is then forced to let it go, stops it again etc. In Canon's earlier models, this was visible as relatively noticeable jerkiness or flutter in the image, but in this model Canon has made the steps in which the correction works substantially smaller, whereby panning now only results in very faint flutter or unsharpness in the image, settling into a steady image in about half-a-second after panning is stopped. This flutter is also more visible in the background than in the moving target being followed, and viewing flying birds with the stabilization engaged mostly succeeded very well. However, the Canon is not equally good for following fast-moving objects at close range, but here the reason is more the poor depth of field which is an inevitable by-product of high magnification and which forces the viewer to continually focus if the object is less than a hundred meters away. At normal migration or seabird watching distances there is very little need to touch the focus, and compared with more normal binoculars, the Canons provide an amazing amount of detail of far-flying birds.
Above I have attempted to describe both the positive and, in as much detail as I can, also the negative aspects of the way in which the stabilization works, as for most of us this is a new and unfamiliar technology. However, I also tested the "normal" optical performance of these binoculars in the traditional way, whereby it became evident that Canon has succeeded in producing an excellent binocular and not only an interesting technological gadget. The image is bright, open and easy to view. In normal use, image sharpness seems excellent. Contrast is very good, although not quite as steep as with the best of the 8-10x binoculars. Colour rendition is otherwise very good with vibrant colours, but there is a yellowish bias which is more pronounced than is customary in the best binoculars today. Exit pupil diameter is only 3.3 millimeters, whereby colour definition in very low light is compromised. On the other hand, large magnification helps to bring out detail better in low as well as bright light, and in near-darkness the Canon outperformed all the best 8-10x binoculars I compared it with. Image quality near the edge of the field is exceptional: there is no detectable curvature of field, whereby the same focus position provides an image which is sharp both at the centre and the edge, and resolution at the edge drops only by about half compared with the centre field. There is some pincushion distortion, but very little of the curving of the image plane while panning which often plagues binoculars with otherwise good edge performance. Due to the binoculars' high magnification, the depth of field is poor: focused to infinity, the image was sharp down to about a hundred meters. The use of UD-glass would lead one to expect exceptionally good correction of the secondary spectrum, but in this respect the Canon surprisingly exhibits only average performance. A yellowish-green or purple fringe is easily visible around high-contrast objects such as birds flying against the sky. However, with high-magnification binoculars this is more the rule than the exception, and is all too common even in normal-sized binoculars. When viewing against the sun on snow-covered March days there were no problems with stray reflections or loss of contrast, and even in viewing right next to the sun at sunset there was only moderate flare to bee seen, although the Canons were not quite on the level of the best binoculars tested in ALULA 4/2000. Viewing stars at night, reflections also remained minimal, but wedge distortion resulted in comatic (shuttlecock-shaped) star images unless the binocular was held very steady or the stabilization was switched off. Collimation, or the alignment of the optical axes, was also quite good both with and without the stabilization engaged: only very slight vertical misalignment was noticed, and even that could apparently be adjusted away under warranty, and a second unit I tried later had essentially perfect collimation. My general impression is thus that when viewed purely as a binocular, without consideration of the merits of the stabilization technology, the optical quality of the Canon is very high indeed and they can be highly recommended on the admittedly limited markets of 15x binoculars.
Image sharpness was tested with the bank note test explained in ALULA 4/2000, but this time it was conducted indoors in order to more easily control light levels and to avoid atmospheric disturbances. Leica 8x32, Nikon SE 10x42 and Zeiss 15x60 served as reference binoculars, and at the first stage all binoculars were tripod-mounted with the Canon's stabilization turned off. The following resolution distances were obtained as an average for two testers: Leica 4.56, Nikon 5.72 and Canon and Zeiss both 8.47 meters. Within likely margins of error, these results correspond to the ratios of magnifications for these binoculars. In other words, with the Canons as well as with the other binoculars, we can speculate that the limiting factor was the visual acuity of the testers (both of whom have well above average vision), as of course should be the case with top-quality optics. With the Canons hand held with stabilization engaged, the result was 8.22 meters, or 97% of the tripod mounted result. Hand held results of the Zeiss and Canon (now without stabilization engaged) averaged 7.5 meters, Nikon's about 4.6 and Leica's about 3.5 meters. What is surprising about these hand-held results is that when the ratio of magnifications is taken into account, the results were better for the larger magnifications, not worse as conventional wisdom would suggest. However, even very brief glimpses of the barring in the test target were counted as a resolved target, and it is possible that the larger mass of the bigger binoculars gave them an advantage here. Whatever the case, subjective factors are more pronounced in hand-held testing. To further test the performance of the stabilizer, an experiment was conducted outdoors (Helsinki, March 27, 7.45-8.00 p.m., sun had just set, clear skies) where the Canon was compared with the Leica 8x32 in reading a leg band of a Herring Gull (white C, #C5S26). We measured the distance at which we could with certainty read the number 5 and the letter S, which were easily confused. With the Leica, the average of the distances obtained by two testers was 20.5 meters and with the Canon 44.9 meters. To summarize, the above results indicate that with the stabilized Canon one can resolve detail at 1.8-2.3 times farther than with hand held conventional 8-10x binoculars. In addition, the stable image gives the viewer more time to analyze what is seen, meaning that in real-life bird identification situations the advantage might be even greater. The differences in question are thus by no means small and insignificant. Someone might say that we should have tested the ordinary binoculars with finnsticks rather than just hand held. This might well be, but in my experience - reinforced by experimentation - I have noted that the use of a finnstick does not markedly improve the viewer's ability to resolve detail, but rather improves viewing comfort and prevents premature fatigue. Besides, anyone is welcome to test the influence of a finnstick on their own binocular and use the correction factor they might come up with to adjust the results presented here.
The exterior design and usability features of the Canon are relatively successful. The eyecups are an exception, however. They are of the old-fashioned rubber fold-down type, and their diameter both in the extended and pushed-down positions is a whopping 47 millimeters. As a result, those of us with anything but the smallest of noses have difficulty fitting the binocular to our eyes. An additional annoyance is that pushed-down eyecups have a tendency to pop up again on their own initiative. The binocular has (barely) enough eye-relief for viewing with glasses, and here the size of the eyepieces is no longer a problem either. The binocular has internal focus, is rubber-covered, and Canon talks about water resistant all-weather usability. In our March weather with its sub-freezing temperatures everything, including the stabilizer, worked as intended. Canon specifies an operating temperature range of -10 - +45° degrees centigrade. Focus action was smooth and very precise as the focus wheel has a slow gear ratio (ca. 430° from the closest focus of 5.5 meters to infinity). However, the focus wheel is positioned too close to the eyes. Thus it is out of fingers' reach when holding the binocular at the point of optimum balance and comfort. This is annoying as the binocular is heavier and needs to be focused much more than normal binoculars. By contrast, the stabilization on/off button is very well placed under the right hand index or middle finger. Continuous pressing keeps the stabilization on until the pressure is released, and a brief push turns the stabilizer on until the button is either pushed again or an automatic shut-off feature turns it off after 5 minutes. A small green led next to the button indicates that the stabilization is on, but it's position is such that you cannot see it when the binocular is hanging on your chest. Underside in the middle of the binocular there is a flat area which incorporates a 1/4 inch mounting thread (finally in the place where it should be - no brackets or adapters required!) and the battery compartment lid. Like in many cameras, the lid opens and closes by turning a slot with a coin: not very convenient after hours of birding in the freezing cold. Batteries also need to be changed quite often. Actual power drain depends on use and ambient temperature, but Canon specifies that a pair of AA alkalines give 2.5 hours of constant stabilization use at 25C°. For a day of active birding, you therefore need to start with a fresh set of batteries and take a spare set along. Fortunately for the active birder, though, the binocular works very well on a pair of 1600mAh NiMH recharcheables, with one fully loaded pair easily providing a long birding day's use. As an accessory, Canon also supplies an external battery pack which houses four D-size batteries and provides 14 times the operating time of the standard AA-batteries. The battery pack with batteries weighs 790 grams, and connects to the binoculars' battery compartment via a coiled cord. Supplied accessories include a semi-soft, well-designed case and a rather modest strap. However, it is unforgivable that Canon does not provide an eyepiece rainguard even as an option, as it is one of the most essential accessories for any binocular, and as the Canon eyepieces are so large that as far as I know, only Fujinon's marine binocular rainguard is large enough to fit over them. A binocular this heavy would also need a wider, softer strap to be comfortable. In these two respects, Canon has simply cut costs in the wrong place.
It is difficult to summarize a review of a binocular like this. On one hand, it lets you resolve detail and identify objects at roughly twice the distance possible with conventional binoculars. On the other hand, the narrower field and increased need to focus while viewing brought by the 15x magnification, the larger size and heavier weight, and the shortcomings of the stabilization technology discussed above make using the Canon less easy and natural than we are used to. In a way, both its performance and its ease of use place it somewhere between normal binoculars and telescopes. However, in speed and ease of use it is quite close to other binoculars, and in performance not very far behind a telescope at 20x magnification. Two weeks of field testing did not suffice to show the extent to which the Canon would, for me, replace my normal binoculars. However, I did not come across a single instance where I regretted that I was carrying the Canon and not my conventional 10x binocular. At sea, the advantages offered by stabilization technology are very significant, and it should also be considered by those whose birding is such that taking a scope along is either impossible or who often encounter situations too fast for setting the scope up. Based on my test results and field use, I unhesitatingly recommend closer acquaintance with the Canon 15x50 IS UD. However, being such an unusual and exceptional product, it is important to try it out personally in order to determine if it is what you want.