D850 and D5 AF System -

BamBamBambrick

This thread was open briefly but the "she's a troll' crowd got it closed over at DPR. Hopefully this forum has a little more curiosity about the issue.
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Nikon states that the D850 would have the same AF system as the D5.

Jim Kasson, has recently quantitatively determined, on top of practically every other person that has shot both cameras, that the D850 DOES NOT Auto Focus as well as the D5.

http://blog.kasson.com/d850/d5-af-s-accuracy-with-58-1-4e/#comment-230902

Nikon states that the D850 would have the same AF system as the D5. (see current website)


1. Nikon did not implement the D5 AF system in the D850.

2. They did, but they are sandbagging the AF in the D850.

3. They did, but the D850 needs an upgrade that implements refined predictive algorithms unique to the D850.

4. They did, but the internals of the D850 aren't up to the task.

5. All of the above and other.

PB_PM

This topic already has a thread, just so you know.
https://forum.nikonrumors.com/discussion/5350/d850-af-not-as-good-as-d5-as-advertised

BamBamBambrick

There is now objective data and not just subjective speculation.

BVS

As another person commented on one of the test blogs:

"D5 and D850 don't share the same prism, mirrors, shutters... There's a bunch of things that an af system is dependent on. Having the same sensor array and af engine doesn't imply equal performance. You wouldn't think an MB s500 and an e500 have the same performance just because they share the same motor?"

spraynpray

Good point BVS.

WestEndFoto

BVS made his point well.

Even if there are some differences, and I am sure there are, this is a non-issue. The D850, with the right lens (another very important variable) has the best auto- focus money can buy, with the likely exception of the D5.

And if minor differences here are an issue to a user, then the user’s own auto-focus is malfunctioning.

Topaazy

hey guys.
Have a little question here:
D5 and D850 don’t share the same prism, mirrors, shutters… There’s a bunch of things that an af system is dependent on. Having the same sensor array and af engine doesn’t imply equal performance. You wouldn’t think an MB s500 and an e500 have the same performance just because they share the same motor?
Info by Bitcohen

WestEndFoto

Topaazy said:

hey guys.
Have a little question here:
D5 and D850 don’t share the same prism, mirrors, shutters… There’s a bunch of things that an af system is dependent on. Having the same sensor array and af engine doesn’t imply equal performance. You wouldn’t think an MB s500 and an e500 have the same performance just because they share the same motor?
Info by Bitcohen

Certainly.

SDunn

I had always thought, perhaps wrongly, that this was a mirror black out issue. The D5 is going to get to "see" more of the scene at the focus module as there is less mirror blackout in a given period of time.

I would like to see these tests redone with the MB-D18 and the EN-EL18 to see if the 30% less mirror blackout makes a difference.

Presumably the gigantic prism in the D850 should be beneficial. Mirror is a mirror unless there is some crazy semi-seethrough thing like Sony did.

If we take Nikon at face value and assume the module is the same. If we assume that the prisms are at least equal and the mirrors reflecting into the prisms are still mirrors. Then further extrapolate it wasn't worth them making a secondary "dumbed down" software for the same focus module (ok its Nikon so...) then the big difference between them is the mirror speed.

Overall I fell in love with my D4 from the first shutter fall to current day. I didn't buy a D800, it never clicked for me. I did buy a D810 but I found it to be VERY challenging. I have only had my D850 for a few clicks now, but it seems to be much more of a D4 than the D8XX ever was before. Its megapixels punish bad form, but I find it less punishing than the D810 was, which leads me to believe the focus module is "keeping up" (compensating for my mistakes) much better than the D810 ever did.