Lance B Offline Upload & Sell: On
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hiepphotog wrote:
I think some members here took the criticisms toward this lens as personal attacks. Is there any Nikon lens designers here? If not, we are all pretty clueless about what is really going on behind the scene regarding the why, the how, etc. So you're just as much an armchair critic as I am. And I would not take any statement too seriously along the line of "never" and "will not" as if that is so certain. These things happen if Nikon thinks there is enough market for it.
That is why I said: "Until we know the full facts behind all the decision making exercises or are a lens designer, then you are not really in a position to make judgement".
hiepphotog wrote:
No one in their sane mind would say this lens is not amazing in term of optical prowess. But Nikon's decision on choosing MF-only for this lens is something up to debate. I have not seen any concrete evidence on the extent of IQ compromises when you are forced to go the AF route, though it's often cited. Regarding the smaller glass element for AF, I have seen it mentioned by lens designers several times. However, Canon did not really let it get in their way with the RF 50/1.2 and 85/1.2. Their USM motors can handle larger elements just fine (though not really silent). I have seen a lot of event togs switching to Canon RF system just for the 28-70/2 (the most expensive, heaviest, biggest normal zoom!?)
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You say that "smaller glass elements are used in AF and mentioned by lens designers" which should be a hint that MF does not require this constraint and thus give the lens designer more freedom to possibly save weight, cost and lowr aberrations due to not needing to use certain glass to correct for this etc. The fact that Nikon *did* make this a MF lens seems to show that AF was not a priority and that there must have been some design constraints that pushed them to MF. There is no reason to go MF if AF was on the table to get the IQ results that Nikon wanted. So, there must have been a reason for MF over AF. So far, the only reasons I can see are the design constraints of the elements needed to be used for movig the AF section of the lens and/or the price/weight/size that would have resulted whilst keeping the IQ results as they had decided on.
As for Canon making their 50 f1.2 and 85 f1.2 AF and moving supposedly large elements is irrelevant to what design parameters Nikon was after and one being low focus breathing which they have stated is a parameter they have decided to adopt on a number of lenses. But it may not actually be the size of the AF elements that are the issue but *what* elements need to be moved in AF to get the result that Nikon wanted. In other words, it may have compromised the bokeh, and or wide open sharpness and or CA or a number of parameters in an already large lens. Yes, they may have been able to fix this with extra elements but it may have been an even larger, heavier and more costly lens than it is already. At the end of the day, I am sure they could design an optically perfect lens, but it would be huge, weighty and very costly. Again, that is what I am trying to convey and as I stated above, "Until we know the full facts behind all the decision making exercises or are a lens designer, then you are not really in a position to make judgement". See video link below.
hiepphotog wrote:
Now the video-centric (minimal focus breathing) emphasis is also puzzling to me, but that is for another time.
It shouldn't be puzzling. Nikon has realised that video is going to be a large part of their future and they are making some of their lenses that are low focus breathing. Whether Canon or Sony care about that aspect is irrelevant.
All this came about because someone stated that Nikon should have made the 58 f0.95 an AF lens. I'm sorry, but I'm sure you'll find it isn't that easy just to make that decision in this type of lens given it's already large size, weight and cost and the IQ that they were after.
This video goes on to show what the design constraints are for lenses. It is for ARRI lenses for cinematography, but the basics are the same. At the end of the day, these lenses are incredibly expensive, large and heavy compared to their 35mm counterparts that we use:
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