Nikon D800E manual lens focus problem - flange distance of 46.67mm

<p>As it turns out the problem - reported in an earlier thread - I am having with my manual focus lenses on the D800E appears to be that the Nikon standard flange distance is 46.67 (as against the 46.50mm you read about everywhere). Zeiss ZF lenses are apparently set to 46.50mm (which I thought was the standard) and hence this annoying problem of all my lenses focusing beyond infinity. The Nikon tolerance is +/- 0.015 apparently.<br>

I guess I just have to eat humble pie with Nikon.</p>

<p>Are you saying that the flange on the D800E is not 46.50mm anymore?</p>

<p>You or someone has their math backwards, at a flange distance of 46.67mm, a lens set for infinity at 46.50 will never reach infinity focus.</p>

 

<p>Hi Jose and Bob,<br>

Nikon just wrote to me and said that the flange distance is 46.67mm on the D800/E (and presumably everything else?) and Zeiss wrote to me a few days ago to say they make their lenses based on 46.50mm.<br>

I am merely repeating what I have been told and - on this occasion - it is not me that has this backwards. :-)</p>

<p>It is pretty normal that lenses focus beyond infinity. This is designed-in to cope with tolerances and temperature effects. If your lenses do so, don't worry. If the flange distance really were more than 46.5, the lenses wouldn't reach infinity anymore. Therefore I highly doubt that the information you got from that Nikon guy is correct.</p>

<p>Well after perusing my Nikon F service manual, it specifies measuring the film-flange distance to the outer film rails, not the inner ones. 35mm film is nominally 0.14mm thick, add that to the film-image plane distance of 46.50mm and you get 46.64mm pretty close to what Nikon told you, but that is the wrong number in this situation.<br>

The outer film rails make it much easier to measure the distance with a depth gauge micrometer and having the camera body sitting face down on a surface plate.</p>

<p> </p>

<p>Whilst I agree that many lenses (AF, ED, APO etc) are supposed to go beyond the ZFs are supposed to hit infinity exactly on the hard stop - whereas they have been going quite a way over on the D800E (probably 2-3mm of focus ring rotation).<br>

I never noticed such a problem on my D700 and D3 whereas I noticed it within a minute of using Live View for the first time on the D800E. This has precipitated these discussions with Zeiss and NPS and I don't know who to believe any more.<br>

Apparently the source of this info is one of the senior technicians in Nikon UK. The only reference to this distance I have found is this:<br>

<a href="http://www.fredmiranda.com/forum/topic/665776/0">http://www.fredmiranda.com/forum/topic/665776/0</a><br>

What, if anything, can be made of this I don't know.</p>

<p>The 46.67mm were already mentioned here: http://www.photo.net/nikon-camera-forum/00On4l and also here: http://www.astropix.com/HTML/I_ASTROP/FILM/FOCUS1.HTM</p>

<p>@James: since the lenses worked with correct hard stop on your D700(?), this appears to be a tolerance issue and could potentially be solved by shimming the mount on the D800E - maybe this is worth pursuing?</p>

<p>So, how does the Hard Stop (system) on Zeiss lenses cope with thermal expansion?</p>

<p>So -15C to +40C has<strong><em> no thermal effect</em></strong> of these lenses? Sorry, they're v.good, but I don't believe it.....!</p>

<p>.....<em>or</em> all that hokum about lenses going <em>'beyond infinity'</em> to allow for it, is just a poor excuse for very poor tolerances! </p>

<p>I don't think Zeiss use expansion-free materials.....do they??</p>

<p>With the only exception on the ED lenses, all my MF Nikkors have hard infinity stops.</p>

<p>Mike: I assume that any lens with a hard stop has to be designed such that thermal expansion is negligible. It's not unusual for lenses to have a hard stop at infinity, so this can't be new. Sure the D800 is going to be better at showing up focus errors than most, but James's lenses appear to be much farther off than I'd expect.<br />

<br />

However, it's also true - as Bob says - that the flange distance of the camera must be <i>shorter</i> than that for which the lenses is designed, not (as suggested by the reported numbers) longer - infinity is coming up with the lens racked farther than minimum distance from the sensor than it would be for infinity.<br />

<br />

Nikon seems to have some really weird QC issues with the D800, but a mount this far off seems very strange.</p>

<blockquote>

<p>@James: since the lenses worked with correct hard stop on your D700(?), this appears to be a tolerance issue and could potentially be solved by shimming the mount on the D800E - maybe this is worth pursuing?</p>

</blockquote>

<p>Hi Dieter,<br>

I have taken my D800E<em> three </em>times into Nikon UK to get this sorted but they run their tests - whatever they are - and come back to say that my camera passes them all with flying colours. This is why I have been in touch with Zeiss as well to make sure I am not missing something. This latest email from Nikon about the 46.67mm has now got me thoroughly confused though. I'll have to see what they come back with tomorrow.</p>

<blockquote>

<p>So, how does the Hard Stop (system) on Zeiss lenses cope with thermal expansion?</p>

</blockquote>

<p>The same way that it does/did on all my Bronica ETR & SQ , Zeiss Hasselblad V, Zeiss Contax, Leica R, Leica M, Mamiya 645, Pentax 67 & some 645 etc lenses that I have had over the last 15 years that all had infinity hard stops. What they do to combat it I have no idea but I have never had this problem before - presumably use material that expands only negligibly as Andrew suggests.<br>

The same ZFs that give me grief on my D800E worked fine on my D700 which alas I sold as part of this upgrade. I can easily accept that the D800E is going to be much more demanding to focus relative to anything else I have had before but the extent of this issue seems to indicate there is something out on the camera. </p>

 

<p>I never bought the "explanation" that AF lenses don't have "hard infinity stops" because of thermal expansion - manual focus lenses didn't seem to have the problem. I am not saying - since different materials are involved - this isn't a valid explanation. But my guess was always that AF lenses focus "beyond" infinity to allow the AF system to go past the "sharpest" focus from either direction to determine the correct focus - even when the subject is at infinity<br>

@James: I am just guessing but since tolerances are involved (and "unfortunately" third party lenses) it seems possible that though the camera is "within specs" the lens/camera combo is not. Suppose the camera is at one end of the tolerance range and the lens at the opposite - either is fine, but together, they are out. Did you send your lenses with the D800E to Nikon when they did the three attempts to fix the problem?</p>

<p>The 46.67mm have me baffled as well - but it seems from the few references linked to in this thread, that it isn't the flange-to-sensor/film distance but the one to the outer guide rails in a film camera (and whatever that distance is in a digital camera (back of sensor?)). In a film camera, that would equate to the maximum distance the focused image would ever have to be at - and likely the outer rails were chosen because the distance can easily be measured. No idea what the equivalent reference point in a digital SLR is - but it seems possible that the same reference distance was used as before. In any case, I don't think that Nikon made such a significant change - this has got to be an issue of the lens/camera combo being out of their combined tolerance range.<br>

.</p>

<p>Hi Dieter,<br />Yes they have had my 50mm f1.4 ZF and 25mm f2 ZF2 - but I get this same issue on the 35mm f1.4 and 100mm f2 as well to the same degree. To have one or two lenses out a bit I can believe but to have all four out sounds like there is something up with the camera particularly as I have used the 50mm and 100mm for years on the D700 without noticing this whereas I spotted a problem immediately on the D800E.<br />Also when I used my AF Nikkor 50mm f1.4 G it achieved infinity focus just shy of the infinity mark too. But Nikon maintain that the camera passes all their tests.<br />I would be very curious to hear from other ZF users if they are having this same problem with the D800E. If it is a problem with the way ZF lenses are made then I would imagine I would not be the lone voice on this forum raising this problem. I can only conclude that my camera sits precariously at the edge of (or beyond) its allowable tolerance and hence the "it passes all its tests" spiel I get from Nikon.<br />As for the 46.67mm business heaven knows where that comes from. If it is rubbish then unfortunately it is Nikon UK's senior technical guy who is coming out with it - which may explain lack of progress in getting this fixed.</p>

<p>I have just tested two of my MF Nikons, and the flange up to the pressure plate is definitely longer than 46.50mm... 46.67mm makes more sense.<br /> But this plate lean on that outer guide rails, leaving a channel for the film to pass; there are another couple of rails, where the film emulsion is in contact. This rails are in another different (shorter) level. So I still think that the real flange (mount to emulsion film side) is "still" 46.50mm (at least on film cameras).</p>

<p>BTW, a 50mm lens @ f2.8 reach infinity at an hyperfocal of 30meters (for a "standard" CoC of 0.03mm). My D700 confirm focus at such distance, and the infinity mark fall in the "middle dot/line" in the barrel. <br /> If you set the CoC on 0.015mm (for e.g., a 16x20" print), the hyperfocal is at almost 60meters... so I think it`s better not to have a hard stop to reach that point (and to have LiveView or a better system to focus at exactly that distance). The AF system doesn`t distinguish between 30 and 60 meters (at least on my D700 with the 50/1.4AFS), the infinity mark stays in the middle. If the camera can take a pic with such accuracy level, is another topic.<br /> I know this is not an issue with James, because "his infinity" doesn`t even reach the infinity mark on the lens.<br /> --</p>

<blockquote>

<p><strong>I would be very curious to hear from other ZF users if they are having this same problem with the D800E.</strong></p>

</blockquote>

<p>I`m now curious, too. Also waiting to hear from other users.</p>

<p>Expansion co-efficient of Duralumin is 0.00225%/degree K. So a two inch long lens will expand by just over 1 micron per degree C. I don't think that's a very big deal, and certainly not enough to account for a noticeable shift in the end stop. Plus that expansion would be spread from back of lens to front and would alter the separation of the glass elements as well as just extending the lens. It's possible the element shift would partly counteract the physical expansion?</p>

<p>I don't suppose James fancies ramming the end of a depth gauge against the sensor face to test the actual lens-flange to sensor distance once and for all? But then there's the IR and AA filters in front of the sensor to take into account as well.</p>

<p>BTW, my own experience with Nikon UK is that they'll say anyththing to avoid addressing a real problem. Standard procedure appears to be:<br>

1) Blame the customer or throw some doubt on the fact that it's anything to do with their camera/lens.<br>

2) Keep the equipment for "testing" or "awaiting parts from Japan" for such a long time that the customer is just glad to have their gear back again.</p>

<p>P.S. James, UK consumer law states that for the first 3 months after purchase it's up to the <strong>seller</strong> to prove to the buyer that the goods are fit for purpose. Your contract is also with the retailer and NOT with Nikon UK. Therefore it's up to the vendor to <strong>prove</strong> to your mutual satisfaction that the camera performs as it should. Since no proof appears to have been forthcoming, the vendor is in default. If you let this ride for more than 3 months, then the burden of proof of being unfit for purpose shifts to the purchaser (you!). DO NOT, let those shifty sods at Nikon UK keep your camera until the 3 months is up. Get your local trading standards officer involved if necessary.</p>

<p>Rodeo Joe - thanks for the tip. I have kept Wex Photographic in the loop from the start so will be onto them unless Nikon suddenly have a change of heart. I am off on a month long trip to Hawaii at the end of next week and need to get this sorted quickly now. As I spend an awfully large amount of money with them I'm pretty sure they will be obliging.<br>

More exciting updates on this story tomorrow I suspect. Along with the arrival of a Sony RX100 which I hope will be problem free...</p>

<p>I just tested three of my Zeiss ZF lenses; 21/2.8, 35/2.0 and 100/2.0 on D800E and all focused on their hard stop infinity. The focus point was set on a horizon (high rise buildings and trees) at least 2-4 km away. Tests were done through OVF (difficult to notice any small focus changes when reaching or 1mm near the hard stop mark at that distance) and using LV + maximum magnification and 10x magnifying glass. <br /> I also used two Leitax-ed Leica Summicron-R lenses; 35 and 50mm. Both reached infinity at their hard stop infinity marks as well.</p>

<p>Wow - thank you very much Jack.<br>

Were they shot wide open?<br>

I am going to give Nikon UK a great big b@ll@cking today I feel...<br>

James</p>

 

<p>James, I shot at f/8.<br>

Do you experience focussing beyond infinity issue using both Live View and OVF? Just a thought, but there may be a chance that mirror alignment in your camera may be off a bit. When I received my D800E I noticed a slight front focussing with most of my lenses (focussing through OVF didn’t match magnified focussing via LV) A simple adjustment of mirror angle corrected this issue allowing accurate focusing via OVF using MF lenses.</p>

<p>I`m now at work, where I can measure with way more accuracy the flange on my F3.</p>

<p>Mount to "pressure plate" distance: 46.67mm ("outer rails", if you like).<br /> Mount to inner rails distance: 46.50mm, (the inner rails are the rails where the film stands, on the emulsion side).</p>

<p>As far as I know, "flange focal lenght" means <em>lens mount to film distance</em> (or sensor equivalent).<br /> If they use the same name for whatever other parameter, it`s beyond me.</p>

<p>OK Nikon came back and corrected their statement of yesterday - it is 46.50mm:</p>

<p >"Hi James,</p>

<p > </p>

<p >You are correct in that the distance from the lens mount to the focal plane is 46.5mm however our technicians need to ensure the rear of the sensor is actually 46.67mm. Sorry for the misleading information. We can confirm however that the depth on your camera is 100% accurate."</p>

<p >Still doesn't explain why my lenses all remain so far out.</p>

<p>Hi Jack,<br>

Thank you again for looking at this. There was a mirror alignment issue as well but they sorted it.<br>

Could you possibly have another go when you have a minute and just test where infinity falls when you shoot wide open as depth of field at f8 will mask problems to a certain extent? If you get sharp focus at the infinity stop then I still have a problem in spite of their assurances that my camera is bang on.<br>

Many thanks,<br>

James</p>