NikonGear'23
Reviews => Ramblings of the Fierce Bear of the North => Topic started by: Bjørn Rørslett on October 24, 2015, 11:50:12
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One by one, Nikon have added fluorite (FL) elements to the optical designs of their longer telephoto lenses. Currently we have a complete series designated 'FL' from the 400 mm f/2.8 to the 800 mm f/5.6, so most if not all needs of demanding users should now be amply covered. All of them carry the "E" designation to signal their electronic aperture mechanism: there is no stop-down lever in contrast to all AI/AIS/G lenses so far. The "E" lens is functionally the equivalent of "G" lens and thus has no aperture ring. You set the aperture through the camera's dials.
These are all fast (400 mm f/2.8, 500 & 600 mm f/4, to 800 mm f/5.6, the latter is fast for its focal length) and massively expensive lenses. You might be faced with the choice between a new, smallish car, or one of these cannons. A true photographer follows his or her heart of course and happily purchase the lens with a suitable focal length.
All lenses share a common construction principle by being made lighter from the judicious use of magnesium and carbon fibre alloys, plus the overall weight benefits from the fluorite elements which are lighter than more normal glass. The lens barrels are slimmed down quite significantly as well. The weight loss compared to older versions is appreciable. Thus, my first 600/4 (AIS, manual focus) tipped the scales at nearly 6.5 kg, whilst the new 600/4 FL is a mere 'featherweight' at 3.8 kg. Pretty amazing.
It is immediately evident when you lift any of them that they are made with press and sports photographers in mind. The cantilevered tripod feet are optimised for carrying the actual lens around, not for giving the utmost solid support on a tripod. Likely they on most occasions are put atop a monopod or similar, and the photographers is shooting the lens more or less wide open to get the shortest possible shutter speed in order to freeze the action and to maximise the isolation of the subject from its surroundings. So one naturally is inclined to ask whether these lenses can be used say for landscapes or close-ups of details as well.
The present report focuses (!) on the AFS 600 mm f/4 FL E Nikkor, kindly lent me for an extensive field review by Nikon Norway. I'm not a sports photographer so probably won't do much shooting targeted at such subjects, but might look for the occasional bird during the testing period.
Anyway, here it is in all its glory. The construction and workmanship are what we come to expect from Nikon's pro-segment lenses. Weather sealing should allow one to work even under inclement ambient conditions (if the photographer can stand it, so probably also the lens).
(https://nikongear.net/revival/proxy.php?request=http%3A%2F%2Fimaging.nikon.com%2Flineup%2Flens%2Fsinglefocal%2FTelephoto%2Faf-s_600mmf_4e_fl_ed_vr%2Fimg%2Fproduct_01_01.png&hash=2123b7395d8677ea09e6af1db2ac2f1021922b97)
The lens design is cutting edge with 16 elements in 12 groups, of which 4 are ED and 2 are fluorite.
(https://nikongear.net/revival/proxy.php?request=http%3A%2F%2Fimaging.nikon.com%2Flineup%2Flens%2Fsinglefocal%2FTelephoto%2Faf-s_600mmf_4e_fl_ed_vr%2Fimg%2Flensonstruction.png&hash=b2be8e469da6b4f7d4e300c56f7869d24a081480)
Unsurprisingly, the MTF curve is reflecting the sophisticated optics;
(https://nikongear.net/revival/proxy.php?request=http%3A%2F%2Fimaging.nikon.com%2Flineup%2Flens%2Fsinglefocal%2FTelephoto%2Faf-s_600mmf_4e_fl_ed_vr%2Fimg%2Fmtf.png&hash=2c622c3d426a1c2971940f18632669e7fd12a570)
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A couple of snapshots to learn what the lens looks like in the wild.
First, a size comparison to the new AFS 200-500/5.6 Nikkor. The difference is quite visible.
Next, the 600 mounted on a *real* tripod. In this case the Sachtler ENG 2 CF HD with Video 20 Fluid Head. I regularly use this setup as a test bench to assess tripod functionality of long lenses, as the tripod + head combination is mercilessly exposing any tendency to lens shake due to inadequate tripod support.
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Now, what can you expect from such an expensive beast? In fact, a performance commensurate with its astronomical asking price.
Nothing more and nothing less. Images are outstandingly crisp and clear, colour artefacts almost undetectable (unless you put a TC on, but even then CA issues are insignificant), scene contrast is very high, and of course it has all the pulling power of a long lens. AF apparently is very fast as well. I need more field time in order to evaluate that feature properly, however.
The scene I used for the next examples is seen below. This residential area was at a measured distance of 3.9 km from the camera position shown in the previous post. I selected this scene because it has a lot of sharp transitions from almost pure white into a darker surrounding and thus any chromatic issues would be triggered to the maximum. Besides, I like using long lenses for landscapes.
The autumn air was crisp and clear and ambient temperature nice around +7 to 8 deg.C. Add sunshine and what more can one ask for?
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I captured the above scene with two different camera, Nikon D3S and D800.
Is there a major difference between the two when used together with the new 600? Basic instinct would say *yes* as we have 12 vs 36 MPix. Compare yourself from this A:B 100% crop below.
There are detectable differences, no doubt. However, would one expect a more massive difference? In no way have I tried to make the 12 MPix output "better" as one normally would if the aim is making a huge print from the file.
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I guess the long distance atmospheric effects reduce the advantage of a high pixel count camera in this type of application. There is some improvement in the definition some of the vegetation, and the wavy lines in the building due to atmosphere are more sharply defined (whether they add to the image quality is debatable ;-))
How do you find the tripod mount, do you have to avoid certain shutter speeds with the 600mm? Thanks.
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To remove any lingering doubts or duplicities, the left image is D3S, the right-hand side is D800.
Do keep in mind the D800 only offers about 70% better resolution than the D3S and its ilk. Easy to notice with a test target in a lab, not entirely equally dramatic in the field.
I consider long-range shots actually being excellent test subjects for lens contrast. Only lenses with inherent high contrast will be able to overcome the attenuation and decline of subject contrast that atmospheric haze introduces. The visibility of turbulence depends also on shutter speed.
I guess with less exotic tripods than the heavy-duty Sachtler and its Fluid Head you will encounter signs of lens vibration from 1/100 sec and longer. Some of these can be combated by VR some not.
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The shadows are much cleaner with the D800 and the atmospheric disturbance is well resolved.
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I never said there wouldn't be differences. Obviously, there are. Upsampling from 12 MPix will not give you equally clean 36 MPix as the native sensor. But seen in the light of what the photos eventually are used for, perhaps the megapixel frenzy isn't as important as many tend to think.
Another way of "getting more" is to add a TC. The 600/4 FL apparently copes well with TCs and the TC 14E Mk.3 is an easy approach to extract more details from the scenery.
Same camera stand point as the photos posted already. 100% crops to show the naked lens (left) and with the TC 14E.3 (right). Pixel peepers and other nit pickers might find a tiny increase in CA, all other sensible people just note the better resolution of minute detail due to the increase in magnification. AF still functioned without a hiccup with the TC attached.
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Going now from the remote subjects to the near range of the 600 FL: Here I'm capturing a late-flowering Oxeye Daisy (Leucanthemum vulgare). The lens was used hand held and VR engaged in Normal Mode. Camera was my Nikon D800. I operated the lens around its near limit at 4.5 m.
Shots around 1/100 sec in general lacked the last degree of sharpness to make me consider them passable. However, in a pinch most could be used after being downsized and judiciously sharpened, so they weren't complete write-offs.
After seeing the results, I increased ISO to get 1/400 sec shutter speed, and results now were much improved in their rendition of critical detail. Still not the equivalent of what a tripod-mounted lens would deliver, but getting there despite vestiges of double contours around the bright white rays of the flower head. One easily observes the very shallow zone of acceptable sharpness at this close range.
First, the overall scene captured to show everything in the background is completely thrown out of focus (the alder stems in the background were located about 4 m further away). Then, a 100% crop to show the attainable detail. Do note the slight tendency for blue fringing, and occasional double contours.
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I did some side by side comparisons between the "old" and the new 600 mm in october and it seemed to me that the new FL-version didnt have as narrow FOV as the old version. Do you have any comment regarding this apparent discrepancy? Looking at pictures side by side on the computer gave me that impression straight out of camera and also when I toggeled between the two pictures on the lcd-screen on the camera.
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The IF design incorporates a focal length shortening trick. So, unless you focus at infinity, there is no guarranty that the focal lengths of two different models are the same. The designated focal length on the catalog only applies to the lens focused at infinity.
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Thanks for your reply! That might explain the discrepancy I observed at close range. Maybe the closer, near focus limit on the 600 FL, might compensate? I had the feeling I was shooting with a shorter focal length at the time I did the comparison.
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The industry tolerance on a property like nominal focal length is 5%. Thus, even at infinity there might be 10% difference between two lenses of the same specification. Do note the tolerance is to the design property, so a lens might range from 570 to 630 mm and still be designated 600 mm. However, individual samples of a given lens should be very similar in actual focal length when focused to the same distance.
For the near range, the detail magnification (in the focus plane) must be identical in order to compare angular view. Having the same distance to the subject is not sufficient on its own.
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Thanks for your reply! That might explain the discrepancy I observed at close range. Maybe the closer, near focus limit on the 600 FL, might compensate? I had the feeling I was shooting with a shorter focal length at the time I did the comparison.
Yes, I suppose so. The shortened focal length was much discussed also when 70-200/2.8 VRII was released.
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The industry tolerance on a property like nominal focal length is 5%. Thus, even at infinity there might be 10% difference between two lenses of the same specification. Do note the tolerance is to the design property, so a lens might range from 570 to 630 mm and still be designated 600 mm. However, individual samples of a given lens should be very similar in actual focal length when focused to the same distance.
For the near range, the detail magnification (in the focus plane) must be identical in order to compare angular view. Having the same distance to the subject is not sufficient on its own.
Thanks for the clarification!
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Thanks for your reply! That might explain the discrepancy I observed at close range. Maybe the closer, near focus limit on the 600 FL, might compensate? I had the feeling I was shooting with a shorter focal length at the time I did the comparison.
The shorter focal length is a result of close focusing. The basic lens equation is 1/f = 1/u + 1/v, where f is focal length, u is distance to the object and v is distance to the image plane. When u is very large - "infinity", as one might say with only slight exaggeration - 1/u is so small it can be ignored, and 1/f = 1/v. But if u is relatively small, 1/u is larger, so either v has to get bigger to match, or 1/f must get bigger and f must get smaller. V gets bigger if the lens gets longer, and once upon a time lens did indeed get longer when they focused closer. Now we have internal focusing, so the lens does not get longer when it focuses closer, so focal length predictably gets shorter at close focus, and the closer the closest focus the shorter the focal length.
In a complex lens it is not quite that simple, because physical lens lengthening is not the only way 1/v can change, but the principle is the same.
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Actually it is much more complex because the Thin Lens Equation assumes internodal distance = 0, which almost always is not the case for a real lens. A zoom lens or a design with CRC moves the nodal planes around a lot thus making the internodal distance a fourth variable. Even further complicated because one really needs to measure the conjugate distances (u,v) from the nodal planes (pupils).
In practice, one keeps sanity and frustration in check by setting up any comparison to make detail magnification in the focused plane identical. For shorter focal lengths there is no real alternative although many testers apparently is unaware of such basic facts.
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It`s complicated, but since the nodal point seem to move because of close range corrections, that might explain the discrepancy. The near focus limit, the physical construction and measurements of the lens also play a role. Maybe I shouldn't bother my head with such complicated stuff ::)
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Agreed. One uses lenses for photography not equations.
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Even though the thin lens equation is messed up by the modern optical design tricks, the effectve focal length can be calculated simply based on the focusing distance and the magnification factor of the image projected on the image plane, I guess?
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Even though the thin lens equation is messed up by the modern optical design tricks, the effective focal length can be calculated simply based on the focusing distance and the magnification factor of the image projected on the image plane, I guess?
The thin lens equation applies to complex lenses exactly the same as to simple lenses, in that for any complex lens there is an equivalent single thin lens. In a complex lens the lens equation is harder to use because you do not know where the nodal planes from which U and V are measured are located. A telephoto lens, like the 600mm, is a lens whose focal length is greater than its physical length in that the rear nodal point is in front of the lens. The ordinary Nikon 70-300 extends its physical length by (roughly) 50mm in zooming from "70mm" to "300mm", so it is movement of the rear nodal point away from the lens that accounts for the extra (roughly) 180mm. It is not that zooming causes the nodal point to move: zooming is the movement of the nodal point.
As far as measuring the focal length by measuring magnification and focus distance, yes you can, but the problem is accuracy. If you use an optical bench, an accuracy of 1% - 6mm in the case of the "600mm" - would be a good result. If you don't use an optical bench the results will be very approximate.
From a photographic point of view, the important point is that a lens' focal length getting shorter as it focuses closer is not a design fault, it is a fundamental property of a lens. There are ways you can mitigate that effect - lengthening the lens, eg - but they have drawbacks.
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Let us return to the topic at hand, please.
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Any comments on the new beast's performance and general feel compared to your first 600/4 (AIS, manual focus)? Having seen an ad for an ai-s 600/4 tripped this question, although I am confronted with the lack of support gear for such a tool (street photography, maybe? ). thanks and a happy 2017!
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The earlier versions were even heaver (> 6 kg) and it would be dangerous to your health to consider using such a lens without adequate support.
Even though the new lens is considerably "lighter", it still is 4 kg of high magnification optics. Thus it requires some kind of support than is better and tires less than hand-holding it.
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And for those of us not blessed with two tripods to enhance stabilisation , but rash enough to use long, but old fashioned optics hand held with in-body stabiization cameras when the light is strong, we would then need to adjust the stabilization settings knowing the actual focal lenght.
Luckily, i do not own such exotics.
p.