[jatrax]

Personally I don't buy cameras or lenses through Amazon. I feel there is too much risk of gray market items, seconds, or rejects. No proof, just Amazon has some known problems plus the suspiciously low prices. Not worth the hassle to me.

Not trying to defend Amazon, but I think you are confused. Amazon pricing is exactly the same as B&H or Adorama and they are a licensed dealer for Ricoh. Keep in mind that Amazon is not just 'Amazon' the seller, it is a marketplace that allows most anyone to sell there. I do in fact. Here is my shop: Zigzag Mountain Art | Amazon Handmade Independent sellers on Amazon may be shady or sell gray market items, but Amazon does not. Just make sure the seller is "Amazon".

Be careful with tightened quick release screws in the tripod thread, they messed up my results. With and without screw fixed the results varied by 8 steps or so.

Now that is an interesting thought. I just recently had trouble with my Arca-Swiss plate getting loose and really torqued it down so it would not happen again. I think I need to take that plate off and retest the lens. The lenses I already re-tested were close to the old settings, but some were off a bit. And the DFA 28-105 was actually off a lot which I assumed was an outlier.

I re-calibrated the AF through debug mode using PK tether,

Can you explain how to do that or give me a link perhaps?

I strongly believe that the vast majority of lenses are fine, you don't see people posting new threads titles "I got a lens requiring no adjustment".

I agree, there have been really few posts about issues with this lens which is why I finally made up my mind. And so far what I've seen when adjusted has made me happy.

I want a light and fast focussing zoom and was keen on getting this. The fast AF and close up capabilities sound awesome. But now I'm having second thoughts.

I'm not sure one less than stellar experience should outweigh 100's or more good experiences.

I'm going to take off the camera plate and retest and see if that makes any difference. I would hate to be giving an otherwise great lens a bad mark if the problem is the camera, not the lens.

[3by2]

Can you explain how to do that or give me a link perhaps?

This is the link for a K5 explanation. Each camera employs a different method for getting into debug mode and the debug menu will be different. I imagine the principle is the same though. The K5 doesn't make any note of what changes you make to the AF base adjustment so I'd advise you to keep a note of what you do as you're effectively setting a new base zero for the AF. I found a 100um is equivalent to plus or minus 10 on the AF scale depending on which way you go.

K5 Back Focus issue solved: Pentax SLR Talk Forum: Digital Photography Review

[Kevin B123]

Originally posted by zapp*
Be careful with tightened quick release screws in the tripod thread, they messed up my results. With and without screw fixed the results varied by 8 steps or so.
Now that is an interesting thought. I just recently had trouble with my Arca-Swiss plate getting loose and really torqued it down so it would not happen again. I think I need to take that plate off and retest the lens. The lenses I already re-tested were close to the old settings, but some were off a bit. And the DFA 28-105 was actually off a lot which I assumed was an outlier.

I took this to mean the tripod collar around the lens, tightening the screw too much introduced some form of distortion on the lens diameter that caused the issue but I may be wrong.

[jatrax]

I took this to mean the tripod collar around the lens, tightening the screw too much introduced some form of distortion on the lens diameter that caused the issue but I may be wrong.

I think he means the tripod thread on the bottom of the camera that holds the quick release plate. There is no tripod collar on the 70-210. If the plate is not 100% flat or has an anti-twist tab logically I can see where torquing it down a lot could cause a deflection in the camera body.

This is the link for a K5 explanation.

Thank you! Filed for future reference.

[Kevin B123]

I think he means the tripod thread on the bottom of the camera that holds the quick release plate.

In that case I don't understand the mechanism that would cause this. I thought the body is too robust and the internals too remote for the tripod plate to have any effect, at least I don't think I've seen such a thing in my body, but I habitually use an L bracket and perhaps that helps some.

[RICHARD L.]

Personally I would never part with my DFA* 70-200 mm f/2.8. Perfect from the start and magnificent rendering. You can't do much better than this (K3, f/6.3, handheld).

[jatrax]

I thought the body is too robust and the internals too remote for the tripod plate to have any effect,

I've no idea if the plate is the issue for sure but not all plates are the same. The one I have been using has two small anti-twist tabs on it that bear on the camera body rather than the camera bottom plate.

---------- Post added 04-07-21 at 05:10 PM ----------

So I removed my old arca-swiss plate and put on one that doesn't bear on the camera body. I had already ordered it last week because the plate I was using was twisting. I had really tightened it down to stop that but I was still uncomfortable with it. Fortunately the new one arrived today so I was able to put it on and retest the lens calibration.

Here are the results:
_____________Old plate ____New plate

DFA 70-210 ____+10_________ +2
DFA 28-105 ____+10_________ +5
DFA 24-70 _____+2 __________-2
DFA 100mm ____+8 _________+3

I used the same setup to test, same chart, same lighting, same distance, multiple repetitions. The only difference is the quick release plate. I have to conclude that the combination of my somewhat odd ball plate and me torquing it down excessively caused enough flex to put the camera calibration off a bit.
I am not sure that this is something that is of general concern, my plate was not a standard configuration, though it has worked fine on the K-1 for a number of years. My getting excessive with the wrench to tighten it is almost certainly the issue.

I want to thank everyone who made suggestions and comments. Especially @Zapp for his comment about the camera plate that got me thinking.

The new plate is the custom one for the K-1 by RRS. Expensive and I resisted it for years but it fits perfectly and I feel silly for not just getting it years ago.

I will be keeping the DFA 70-210, my second copy. I do think that the first copy I had could not have been brought into calibration since my estimate was +15 was needed. Of course there is no way to tell about that now.

---

Last edited by jatrax; 04-07-2021 at 05:15 PM.

[ncallender]

jatrax - what's your impression of the AF speed and precision now that you fixed the base plate? Specifically when it comes to action/sports - any observations so far?

[gatorguy]

My copy has been fine straight out of the box. I am very happy with it, to the point where I am considering the wisdom of keeping my DFA*70-200.

Some sample photos HERE if you're interested.

TBH, I can see a difference in the images you captured from both, but it may only be due to you perceiving the 70-200 as a "premium professional" lens and choosing the subject and image accordingly. I think sometimes we try to do our finest work with what we believe to be our finest lenses.

With that covered, I would not mind at all if I were to learn the 70-210 is essentially indistinguishable from 70-200 renders at the same apertures. The latter is a heavy beast, most massive lens I own, and I would not mind trading it if the 70-210 is really no different. The plus is it's a KAF4 while the 70-200 is KAF3. From what I'm understanding that may make a difference on the K3 III focus.

[jatrax]

what's your impression of the AF speed and precision now that you fixed the base plate?

The lens focuses quickly and surely with no hunting or back tracking. Just whirrr - lock. Speed is good, though probably not as fast as PLM lenses. It seems quite good at going from very close to very far away and back. There does not seem to be any difference in lock on time between near - near or near - far. I am quite happy with it so far, with very limited use.


I would say it is noticeably faster than the DA*60-250 I bought it to replace. I do not shoot action / sports of any kind, though I did take a picture of a walking cow once . So I am not going to be a good source for that type of evaluation. I would assume it would be quite good at tracking AF, but unfortunately I would not even know how to turn that on in my camera.

[pukipuki]

Whoa, nice thread. I'm selling my Tamron 70-200 with a plan to buy 70-210 afterwards. After reading this I would rather buy 70-210 right away and check if it works for me. Tam 70-200 was one of my favorites for years - would be sad to pay more than twice and get disappointed

[mtngal]

Interesting thread, indeed. I never thought about a tripod plate on a camera affecting focus adjustment like that. Since I hate plates that rotate, I have a RRS L-bracket for the K1 and a 3-legged thing generic L-bracket for the KP, sure wish I had a custom L-bracket for the KP but the 3-Legged Thing one works reasonably well.

I bought one of these lenses when it came out and mine needed focus adjustment with both the KP and the K1. I think it ended up being a +7 for both cameras, perhaps slightly different on one of them, and it’s one of the few lenses I have that have needed adjustment. Once I got it set up, I found myself using it a lot, though the ergonomics are awkward and it took some getting used to. But once I got used to it, I found myself forgetting about its quirks and enjoying just using it.

Not sure everyone would find it as quirky as I do, or have any issue with it’s weight and size. It’s a lot smaller lighter than the 70-200 f2.8, but it’s not a small Limited lens by any means.

[jatrax]

I found myself using it a lot, though the ergonomics are awkward

So far I am liking the lens. The only issue I'm having is that the focus ring is right where I naturally put my left hand for support. Which in a few cases has caused me to move the focus manually after it was set with the AF.

[mtngal]

So far I am liking the lens. The only issue I'm having is that the focus ring is right where I naturally put my left hand for support. Which in a few cases has caused me to move the focus manually after it was set with the AF.

I did the same thing, had to work at keeping my left hand strictly on the camera. The focus ring is fairly big and I had trouble reaching past it to the zoom ring. I couldn’t operate it with the fingers of my left hand, if the left hand was only on the camera (my fingers are short) and supporting the camera. I started using my right hand to operate the zoom rather than hold the camera and lens completely with the grip and move my left hand off the camera to operate the zoom. It just seemed more comfortable for me for some reason. And I’m less likely to get a “death grip” on the camera which usually introduces extra camera shake.

Others probably won’t find it as awkward as I do, and that’s why I call it quirky rather than lousy.

[jerryleejr]

I have the original 70–210 which has stayed on my film bodies, now I’m curious how it would work on my K1MKii….

JJ