j4nu
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 Re: Sony 85mm f/1.4 GM II Announced—Pre-Orders Now Open! | |
Steve Spencer wrote:
j4nu wrote:
Steve Spencer wrote:
j4nu wrote:
Steve Spencer wrote:
j4nu wrote:
Steve Spencer wrote:
j4nu wrote:
Steve Spencer wrote:
j4nu wrote:
Tony Ross wrote:
The 50mm f/1.2 GM has two pairs of focus motors - two bigger ones on one focus group, two smaller ones on another focus group.
The 135 GM also have two pairs of focus motors.
The 85mm GM II has one pair of focus motors, reportedly bigger than usual to speed the AF in this lens.
Just received my GM II. Taking it out to shoot tomorrow.
Comparing the GM and GM II, the new lens is narrower near the mount. I recall that a few people complained about clearance between the original GM and the grip on Sony cameras, so the new will make a few people happier.
Wait, so it's not 4x AF motors?
It is only 2 XD motors. I thought I saw reports of 4 motors, but this is directly from the Sony site:
"2 XD (extreme dynamic) linear motors and high-speed control give the FE 85mm F1.4 GM II AF speed that is up to 3x faster than previous model. Moving subject tracking is improved by as much as 7x, allowing reliable capture even when using extremely narrow depth of field at F1.4. The 120 fps capability of the α9 III with its global shutter is fully supported."
Here is the link to page for the lens at Sony:
https://electronics.sony.com/imaging/lenses/all-e-mount/p/sel85f14gm2?srsltid=AfmBOoptmKSC3ThSg6D86LG2loG4tqzAYowL1IjCCF91dVzpAGBbasIn
Thanks, so it might be the same case as with 50/1.4GM where the tracking is not as great as one would expect...
I am not sure the numbers of XD motors is going to be a great predictor of how well the AF works. The size of the motors and the size of the focussing group(s) they are moving is going to matter at least as much as the number of motors. For the record of the second generation GM lenses here is the number of motors each has:
35 f/1.4 GM - 2
50 f/1.4 GM - 2
50 f/1.2 GM - 4
85 f/1.4 GM - 2
135 f/1.8 GM - 4
All else being equal more motors is probably a good thing and especially so if it means more focussing groups and keeping those focussing groups smaller, but all else is not necessarily equal. In my view we will have to wait until we see lots of real world performance to see how the AF actually performs and in my view that is how it always is with AF.
Sure, let's wait and see.
Maybe 85GM II will be the 2-motors exception...
I don't think there is any sort of exception as it is a basic matters of physics. The speed of the AF will be a function of the power of motors (summed across 2 or 4) by the weight of the elements that are being moved. The problem is we don't know either the power of the motors or weight of the elements being moved so we have to wait to see how it works in practice. By the way, the 35 f/1.4, IMO, has excellent and fast AF with no problems keeping up with even demanding AF needs, so I don't think all 2 motor lenses will be deficient, and even the tests reported recently with the 50 f/1.4 GM although not optimal showed pretty decent AF in a very demanding situation. I think it is one of the consistent features of this new generation of GM lenses with XD motors that they all have excellent AF capabilities.
Exception to the list you provided, where it's easy to pick the best focusing / tracking lenses and their common element  ...
And with such a small number of lenses (we are talking 5 here) it is also easy to think that one common element is affecting performance when it is really is a different characteristic altogether that is affecting performance  . Like in this case it might be cumulative power of motors and not the number of motors that is affecting performance and make a wrong inference. Five of anything just isn't enough to make a sound inference about whether the presence or absence of any feature is related to performance. It is super easy to see false associations with such a small number of instances (i.e., lenses in this example). Basic statistics tells you that with only 5 examples any association you see would occur simply by chance fairly often. That is why we need tests for AF and not merely look for associations that may or may not be real.
Yes, but these are not random 5 lenses, but as you said it yourself, 5 GM 2nd gen. lenses (which means they share some common tech, design capabilities, etc.) .
Anyways, no matter how we look at it, if 85/1.4GM II proves to be the fastest focusing lens of them all, it will still be a 2-motors outlier ...
I think my point is with 5 instances you can't have an outlier and yes these aren't 5 random lenses, but that does not change the fact that you should not draw any inferences about the relation of the presence or absence of any characteristic with any sort of performance from just 5 instances. That is simple basic statistics.
That's the thing, it's not "simple basic statistics" because these are not independent cases, but related lenses. 5 lens release of a new (2nd) gen, which span from 04.2019 to 09.2024, is a lot.
You can throw in 70-200GM II as well.
Anyways, the trend now is visible and it is that 4-motor lenses are better/faster at AF than their same-gen 2-motor counterparts.
Can 85/1.4GM II change that? Sure, but it will be an outlier .
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