NikonGear'23
Gear Talk => Lens Talk => Topic started by: Jan Anne on July 31, 2015, 10:48:40
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DxOMark tested the Nikkor 400mm f/2.8E FL ED VR on the D810 and compared to the model it replaced and its Canon competitor:
http://www.dxomark.com/Reviews/Nikon-AF-S-Nikkor-400mm-f2.8E-FL-ED-VR-lens-review-Revised-design (http://www.dxomark.com/Reviews/Nikon-AF-S-Nikkor-400mm-f2.8E-FL-ED-VR-lens-review-Revised-design)
(http://www.dxomark.com/var/ezwebin_site/storage/images/media/images/comp117/136861-1-eng-US/comp1.jpg)
IQ wise the new FL model merely approaches the performance of the older model, it seems that the use of fluorite elements was purely chosen to save weight and not because it makes the 400 a better performing lens.
Maybe Tony can chip in, curious if he noticed any differences in IQ when using these big boys in the field.
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Whenever I've seen images from the VR 400/2.8G in large sizes (e.g. NHM WPY gallery in London) the images have had striking sharpness (not to mention the vivid colour) compared to almost any other lens in the same show. It seems with the FL version Nikon solved the primary issue with that lens (i.e. weight and its distribution) and were able to maintain excellent image quality. I think with this class of high performance lenses, the image quality isn't going to change in large humps as these lenses have a history of relatively frequent updates with the latest optics and technology. I wish Nikon put as much love into their shorter tele lenses (135mm please!).
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I notice that lenscore.org which test using a much higher resolution sensor, rate the 400/2.8E second highest of all the lenses they tested. 400/2.8G is 13th. This suggests that with the D810 the sensor resolution does not allow the new lens to show its best cards yet. Perhaps with a D7200 or a TC there is greater difference?
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As Ilkka Nissilä has stated, LenScore has the 400E as the sharpest super telephoto that they have tested and they use a 200Mp sensor so the lens score is not sensor limited. Also, LenScore tests at 5 different camera to subject distances rather than the single camera to subject distance of all other test sites (that I know of) which gives a better indication of the lens's performance in real world conditions. This seems to be borne out when using TC's as I have found that the 400 seems not to be affected by distance when using any of the TC's, it seems as sharp in the distance as it does close up, whereas just about every other Nikon telephoto that I have used seems to have a observable drop in IQ at distance. My 300 f2.8 VRII and my 500 f4 VR both drop off IQ over about 20-30mts and it is noticeable. The 200-400 has been notorious for this issue. Maybe Nikon have paid attention to these criticisms of previous telephotos and have addressed this on the new 400. It may lose a point in sharpness at standard close up tests distances (however I dispute this - I think lens variation is probably the culprit), but excels at longer distances and hence why LenScore has ended up with much higher resolution figures for the new lens.
Having used the 400E for over 5 months and over 40,000 images, I can say it is the sharpest lens I have ever used. I own the 300 f2.8 VRII and the new 400 is sharper than that lens, but on DXO Mark the 300 gets the same score for sharpness. A good indication of this is that I get quite a bit more moire/false colour with the 400, not so much with any other lens.
What I will also say is that all the extreme tele's are bloody sharp and no-one could probably tell them apart as far as sharpness goes.
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Please state what TC you're referring to ;)
I have fine IQ from the TC14E and TC20E III on 300mm AFS 2.8
Sure these long lenses are outstanding :)
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Hi Lance, your real world experience is appreciated.
The NG forum doesn't currently allow us to see info for each member. If you could share any sites where you display your work (esp. When using the teles) that would really interest me.
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Please state what TC you're referring to ;)
I have fine IQ from the TC14E and TC20E III on 300mm AFS 2.8
Sure these long lenses are outstanding :)
Hi Erik. I am referring to the 1.4x TCII and 1.4x TCIII, the 1.7x TCII and the 2x TCIII - I own all 3, sold off the 1.4x TCII when I got the 1.4x TCIII. The 1.4x TCIII is a little better at distance than the previous TCII, but the IQ still drops off a tad at distance. It has been talked about on many fora that most of the super teles seem to drop their IQ a tad over longer distances, especially the 200-400 f4. Under about 20-30mts, the 300 and 500 with TC's are excellent and sharp. In fact close in the 300 + 1.4x TCII or TCIII is almost indistinguishable from bare:
D800E + 300 f2.8 VRII + 1.4x TCII, f5.6,
(http://www.pbase.com/lance_b/image/149062706/original.jpg)
crop of above
(http://www.pbase.com/lance_b/image/149062708/original.jpg)
As you can see, there is no way you could ask for better than that!!
What I am noticing is that the 400 doesn't suffer image degredation over distance when compared to the 300 and 500.
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Hi Lance, your real world experience is appreciated.
The NG forum doesn't currently allow us to see info for each member. If you could share any sites where you display your work (esp. When using the teles) that would really interest me.
No problem. My PBase site is:
http://www.pbase.com/lance_b (http://www.pbase.com/lance_b)
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OK.
What my non scientific testing has led me to 'think' is that the build length of the TC is critical, that is; If it's not the correct physical length but longer or shorter, there will be issues with IQ...
Brian Caldwell should be able to contribute with further on this, and maybe Bjørn? ;)
It is a serious issue with the SpeedBooster design I remember
Yes I have seen the issues of 200-400mm AFS at distance, very obvious on the NG safari in 2009 I remember! I think we had at least 4 of those with us...
The other long telelenses with performance issues... ? must be due to air disturbance or lack of proper support / shutter speed or VR IMHO
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OK.
What my non scientific testing has led me to 'think' is that the build length of the TC is critical, that is; If it's not the correct physical length but longer or shorter, there will be issues with IQ...
Brian Caldwell should be able to contribute with further on this, and maybe Bjørn? ;)
It is a serious issue with the SpeedBooster design I remember
Yes I have seen the issues of 200-400mm AFS at distance, very obvious on the NG safari in 2009 I remember! I think we had at least 4 of those with us...
The other long telelenses with performance issues... ? must be due to air disturbance or lack of proper support / shutter speed or VR IMHO
No, I am sure it's nothing to do with air disturbance or lack of proper support/shutter speed or VR issues. I know how to use and test long lenses and from extensive use with the 1.4x TCII and compared to the new 1.4x TCIII, I can assure you it is better therefore ruling out any of the issues you refer to, ie it would manifest itself on the new TC as much as the previous TC if that were the case. I have also AF fine tuned the lenses and done critical testing to get the best from them with and without the TC's. I also know that the new 400 does not suffer from distance related IQ drop off when using any of the TC's, whereas the 300 does and the 500 did. It's not huge, but it is observable.
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If your lens and camera body is calibrated by Nikon Service there should be no need to use any manual AF fine tuning. IMHO
Their lab equipment by far exceeds what is possible for DIY.
But then comes the TC... I don't know how much info is stored regarding AF calibration values in the TC and relayed onto the camera body.
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I think autofocus accuracy may well contribute to some loss of sharpness at long distances. I adjust all my TC+lens+body combinations that have fast or moderately fast apertures before I use them. Another matter is simply the lens MTF. A higher MTF lens may tolerate a bit more atmospheric degradation before the image quality imperfections become visible in the image. Also a higher MTF lens may work better with a TC again leading to satisfactory image quality even in the presence of some degradation due to distance and atmosphere.
As for Nikon service calibrating the AF, it may be a good plan a) if you only have a few items to calibrate, or b) in some extreme cases where the camera or lens is way off typical, and c) if you have a service facility nearby. However I cannot give away all my camera bodies and TCs to service every time I add one lens to the kit (so that the bodies could be adjusted by Nikon to focus with the lens properly), or give all my lenses to be tested when a new camera is added and adjusted (not to mention if they adjust the lens, all the cameras will have to be adjusted as well, and may lead to problems when selling the lens for use with another camera). The equipment is purchased for my use, not for sitting at service. I prefer to adjust the combinations that I have myself with testing in my applications. it usually leads to satisfactory results or at least better than out of the box. I realize that service facilities have more adjustments that can be done than the user (and perhaps better techniques for measurement) but there is a trust issue with that approach. If they explain what they are doing, why they are doing it, and how they are doing it and I can monitor the work as it is being carried out and give my input to the process then ok, but I'm afraid this is more access than they care to give me.
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If your lens and camera body is calibrated by Nikon Service there should be no need to use any manual AF fine tuning. IMHO
Their lab equipment by far exceeds what is possible for DIY.
But then comes the TC... I don't know how much info is stored regarding AF calibration values in the TC and relayed onto the camera body.
OK. Having had lenses "calibrated" by Nikon service, no, they don't have sophisticated test equipment to test for focus accuracy at distance. They showed me their test shots and they were of a building across the street! At close focus, yes they use test charts to accomplish this, but then so do I and I also use other real world objects as well. What they do is, they test at close distance on the test chart and then they check that AF Fine tune at distance by focusing on a building across the street. In the end, they weren't any better than I was at getting accurate AF Fine tune.
TC's are all saved separately to the lens bare, ie, if you are have a 300 f2.8, then you have a calibration for the bare lens, but then you also have a separate calibrations for each TC attached, with a 1.4x TC attached and another for the 1.7C TC and another for the 2x TC.
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I think autofocus accuracy may well contribute to some loss of sharpness at long distances. I adjust all my TC+lens+body combinations that have fast or moderately fast apertures before I use them. Another matter is simply the lens MTF. A higher MTF lens may tolerate a bit more atmospheric degradation before the image quality imperfections become visible in the image. Also a higher MTF lens may work better with a TC again leading to satisfactory image quality even in the presence of some degradation due to distance and atmosphere.
As for Nikon service calibrating the AF, it may be a good plan a) if you only have a few items to calibrate, or b) in some extreme cases where the camera or lens is way off typical, and c) if you have a service facility nearby. However I cannot give away all my camera bodies and TCs to service every time I add one lens to the kit (so that the bodies could be adjusted by Nikon to focus with the lens properly), or give all my lenses to be tested when a new camera is added and adjusted (not to mention if they adjust the lens, all the cameras will have to be adjusted as well, and may lead to problems when selling the lens for use with another camera). The equipment is purchased for my use, not for sitting at service. I prefer to adjust the combinations that I have myself with testing in my applications. it usually leads to satisfactory results or at least better than out of the box. I realize that service facilities have more adjustments that can be done than the user (and perhaps better techniques for measurement) but there is a trust issue with that approach. If they explain what they are doing, why they are doing it, and how they are doing it and I can monitor the work as it is being carried out and give my input to the process then ok, but I'm afraid this is more access than they care to give me.
OK. Having had lenses and camera calibrated by Nikon service, they filled me in on how they do it. If your lens is out of calibration, they can actually reset it in lens and there will be no need to have a calibration amount in your camera's AF Fine tune settings. So, if your lens needs +5 they can reset the lens to suit a +5 setting but actually show zero in the camera's AF Fine tune settings. In other words, there is a re-calibration that can be done in the lens. However, Nikon would rather you send your camera in as well for calibration as they will adjust your camera body with a reference lens so as to have a starting point and get your camera correctly set. If they do not get the camera set correctly, then they will forever be chasing their tail trying to get lenses set correctly for any other body that you may subsequently bring in for calibration. By this, I mean there is no point resetting your lens in the lens's memory to suit a particular camera as the next camera may require the lens to be something different. It is therefore best to get the camera set to a known reference point, using a reference lens that they use to achieve this. After they calibrate your camera to that starting point they will then effect calibration to your lenses.
Now as for the belief that TC's work better with fast lenses, I fully agree. However, my 300 f2.8 VRII is a fast lens and yes it does work better with TC's with less IQ drop, but it still suffers from distance related IQ drop as did my 500 f4 VR. Having talked to other users of Nikon super tele lenses and using TC's, they also notice a drop off in IQ at distance. No, it is not an AF Fine tune issue as we have all AF fine tuned our lenses.
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... (and perhaps better techniques for measurement) ...
It's a computer running a long series of tests directly on the lens while it's is actually focusing and hitting an/or missing target, storing the information in the lens CPU! There is no Perhaps in that sentence.
Nikon calibrate the body completely independent from the lens and vice versa. No need to had over all of your gear...
As Lance states :)
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Thanks for elaborating on this Lance, it's more clear now!
Then the old rule of thumb still stands, a lens without TC is preferred - For distant shots - we then add ;)
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It's a computer running a long series of tests directly on the lens while it's is actually focusing and hitting an/or missing target, storing the information in the lens CPU! There is no Perhaps in that sentence.
I haven't seen all the service centres and what equipment they use, hence "perhaps." I also haven't seen all their worldwide service people at work to see what their personal standards and work ethics are. There is no way I could know without going there and seeing (and even if I had done that my observations would be suspect to human observation error).
Nikon calibrate the body completely independent from the lens and vice versa.
Such a procedure would not account for body+lens cross effects, which are the main reason focus fine tuning is needed (as far as I'm concerned). If Nikon calibrates bodies and lenses independently at factory (which they should, of course) then there would be no benefit from repeating that kind of calibration afterwards, unless the equipment is damaged. However, calibrating body and lens independently is not sufficient for accurate focusing (of wide aperture lenses in particular) and calibrating the particular body and the particular lens together is needed. With the D800, I had standard deviation of 9 points on the focus fine tuning scale from lens to lens (after AF calibration of the body at JAS tekniikka). They told me to come back with the lenses if there are still problems, but as I said my lenses are in use. With the D3X the std was only 5 points. This illustrates that lens to lens variations in optimal fine tune depend on the particular body and are not something that can be dealt with independent calibration of bodies and lenses. The D810 however is closer to the D3X in variation from lens to lens requirement for fine tuning (interestingly, it shows less color temperture dependent focus shift but more zoom focal length dependent focus error).
I disagree with Nikon's policy regarding some aspects. For example they don't calibrate f/1.4 lenses wide open, whereas I would only want the wide open image to be considered for calibration. Now, it is well known that focus calibration wide open is problematic and introduces a host of issues but since I would use the lens wide open 95% of the time this is what I require.
Anyway, no amount of calibration will completely get rid of focusing errors, as there is quite a bit of shot to shot random variation in DSLR autofocus. This is easy to demonstrate with a tripod and stationary subject; not all shots will be focused alike even with an easy target. These random errors tend to be more significant at long distances (Nikon even notes in the manual if I recall correctly that autofocus may be inaccurate at long distances, which is an understatement) - I suppose it is a question of speed vs. precision tradeoff - to be able to rack the lens quickly from infinity to nearest distance, the focusing cannot be infinitely precise at all distance ranges and with increasing pixel densities there is more pressure to gear lenses to allow more precise focusing with some cost in speed (as is inevitable). Which is one of the reasons I am not so hot on high pixel density cameras since the AF hasn't kept up with the development of sensors and so there is a lot of waste. But since Nikon only makes their best camera (for my requirements) with a high density sensor I don't have much choice.
Getting back to the long lenses, the random variations in focus especially in low light tend to increase as the aperture is closed from f/4 to f/5.6 and using a TC magnifies the image and any focus error that might exist. So for use with e.g. 2X TC, the lens's focusing system would need to be redesigned to allow finer adjustment to get optimal results. This is very obvious with the 200/2 specifically at long distances and 2X (even though the lens is f/4 with the TC) - there is not sufficient precision to get consistent results with that TC in the long distances (50m+). Perhaps it would be nice if Nikon would make it possible for the lens motor to run at half speed (or quarter speed) when used with a TC to account for the shallower depth of field and consequent requirements.
I would not be surprised if the FL series (and other new lenses introduced in the 36MP+ era) have been designed to autofocus more precisely to account for the increasing demands by people who inspect the image at the pixel level instead of just making practical sized prints (I think we all do some pixel level evaluation to determine which shot has best focus).
Anyway, so long distance performance can depend on:
1 lens MTF itself (and lens+TC combined MTF) - due to atmospheric effects the image quality can fall perceptably but it's better to start with a sharp lens allowing the user to slightly shift the point where the combined lens MTF + atmospheric degradation become perceptible in the final image
2 precision of the AF (i.e. how fine adjustments to focus can the camera control on a particular lens in the long distance range; a TC degrades the precision because of light loss as well as by decreasing DOF)
3 AF calibration of body and lens (i.e. how much systematic bias there is in focus i.e. back or front focus)
4 light level (contributing to 2 precision of the AF in particular)
and probably some other factors that I'm not just thinking of now.
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There is no human factor or error involved in the service procedure identical to the factory calibration. Done when they open the lens up mount on off or similar...
You hook the lens up to a sensor and a computer does the rest. Fool proof.
Sorry, you use too many words for me to respond to each part now.
I belive you worry too much about what might be an issue.
Eddit to add, the system and procedure is in their repari manuals.
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Here is a link to a similar repair manual, details about calibrating the lens starts page L-45
http://allphotolenses.com/public/files/pdfs/72bacb0b30e2ffd0c0fdbed1ba93ee57.pdf
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I fail to see what new information a lens calibration system (used independently of the camera which the user is to use it with) could obtain of the lens that was not available at the factory. So there should be no change in the lens' behavior if it was properly manufactured and calibrated in the first place. If Nikon later changes the process of lens calibration, they should send notice to registered users so that they can have the lens adjusted by the improved calibration process. This is what car manufacturers typically do, for example.
The more important and serious effects that we see as users are calibration errors that are not due to the lens or the camera but the combination of the two. It is easy to demonstrate that the optimal AF fine tune is not a sum of body adjustment and lens adjustment plus TC adjustment (you can certainly adjust it with such an approximation but it will not yield a completely satisfactory result) but there are cross terms as well.
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I wish Nikon were more transparent with regards to service procedures and actually work with the customer to find a solution with which the customer is happy.
I have, on occasion, brought both body and lens to Nikon service Switzerland for calibration. This involves a 4 h return trip for me or shipping by mail, so not something I can do "over lunch". You tell them your problems and then it takes one or two weeks after which you might get the gear back with a small note "everything within spec", meaning the problem was not acknowledged nor solved. If you ask for further information you are told to send the gear in once again. There is a complete lack of interactivity to this whole process which is quite unnerving. When I bring a car or bicycle for repair I can chat with the mechanic directly which saves a lot of time for both. I wish the same were possible with cameras.
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There is no difference between the factory and the service center... never said otherwise. Out of the box it should work...
So it's down to wear/use/damage...
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I fail to see what new information a lens calibration system (used independently of the camera which the user is to use it with) could obtain of the lens that was not available at the factory. So there should be no change in the lens' behavior if it was properly manufactured and calibrated in the first place. If Nikon later changes the process of lens calibration, they should send notice to registered users so that they can have the lens adjusted by the improved calibration process. This is what car manufacturers typically do, for example.
The more important and serious effects that we see as users are calibration errors that are not due to the lens or the camera but the combination of the two. It is easy to demonstrate that the optimal AF fine tune is not a sum of body adjustment and lens adjustment plus TC adjustment (you can certainly adjust it with such an approximation but it will not yield a completely satisfactory result) but there are cross terms as well.
Lenses and cameras from the factory have a tolerance. If the tolerance of the camera and lens combo are both additive or both subtractive, then you will end up with an AF Fine tune error either back or front focus. This is a fact and the very reason why AF Fine tune is offered in all higher end DSLR's these days because of tolerances when manufactured. Having spoken to the Nikon service manager at Nikon, this is a fact. The fact that lenses have a tolerance doesn't mean that it won't focus correctly on the camera and thus may look fine to the owner of that lens and camera combo. I mean, why else would they provide AF Fine tune unless one or both components may be out of adjustment? If everything was spot on from factory, there would be no need for AF Fine tune.
As I stated in my posts and having spoken to the Nikon service manager, Nikon first get the camera AF calibrated to known reference lens so that the camera can be considered correct so that when they adjust a lens to suit that lens will more than likely suit a future camera that lens is attached to, unless that future camera is out of adjustment. They then adjust the lens's focus so that it is correct, but this adjustment is done in lens, not on the cameras AF Fine tune, therefore, when you get the camera and lens back it, the AF Fine tune will read zero but will now focus correctly.
Having had my lenses and camera calibrated by Nikon, the system works perfectly.
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This is the same experience I have Lance.
The situation with camera in one direction and the lens in another, to sum up the fault is very unlikely, although it of cause in theory can happen...
AF fine tune is a nice feature if you borrow a faulty lens that is off to get a job done for instance, but basically it should not be used IMHO your findings may wary! ;)
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Having played with many, many Nikon lenses and more importantly, many, many long Nikon lenses, not only my own but those of friends as well, I have a lot of experience on how AF Fine tune works with these lenses. Not only that, I have also discussed it with the Nikon service techs extensively. Friends and I all talk and discuss these long lenses and how they work both bare and with TC's. Not only that, but it has been a topic of conversation on other forums as well so, I can assure you that I and others agree that the previous Nikon long super tele lenses can have a bit of a slight IQ drop off at distance. It is not huge, but it is a slight drop off and can be noticable. It has nothing to do with incorrect AF Fine tuning as we can all see where the perfect focus is when testing these lenses, no matter what the distance is. It has nothing to do with atmospheric conditions either because that would also affect my new 400 f2.8E when using TC's as well, but it doesn't. It also has nothing to do with how we support these lenses as it would also affect the 400 + TC's, but it doesn't. A case in point. If I use my 500 f4 VR + 1.4x TCII @ 700mm or my 300 f2.8 VRII + 2x TCIII @ 600mm and compare it against the new 400 f2.8E FL + 2x TCIII @ 800mm, I can assure you that the 400 looks basically just as good close in as it does at distance. The same cannot be said for the 300 and 500 with the afore mentioned TC's attached. What I will say is that the new 1.4x TCIII is better than the old 1.4x TCII on the 500 f4 VR at distance, partly confirming my thinking that Nikon is addressing this slight issue.
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Thanks for sharing your findings! Both Ilkka, Lace et al I really appriciate you input!
I'm definetly not a 'distance shooter' I prefer to 'Get closer' ;)
Bjørn has loads of experience with long glass but I know he rarely shoot with TC's