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11-26-2022, 01:25 PM - 1 Like   #1
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I think I am giving up, and am leaving Pentax, unless there is an effective solution

I have used the Pentax system for years, and definitely Pentax is a great camera in terms of ergonomics and landscape photography. *Pentax has never been known for its autofocus capability and a number cameras had autofocus issues (K5 low light for example), and so I usually stop down a bit and was happy enough with my K5II for many years. *Last year I upgraded to the K3III, and I was really hoping that the phase detect autofocus would finally work well and would be on par with Canon or Nikon. *For many subjects the phase detect autofocus works fine, albeit all my lenses need -4 to -8 fine focus adjustment.

Now, for portrait photography with faster lenses, the phase detect autofocus is near useless, and it is mostly a miss, especially when the subject is wearing red. *I tried spot focus, continuous, large or small regions, subject detect, pretty much every focus method I can think of and am just not getting precise focusing. I want a subject who is not moving to be completely in focus. *I now have to switch to live view, focus the subject using contrast focus, turn off autofocus and live view, and take a series of photos. *This method is ridiculous, and obviously doesn't work when a subject moves around. *Next year I am invited to shoot a wedding, and I basically cannot rely on sharp images.

Lenses I use are the 70mm, 50mm and 100mm, all exhibit the same problem. I am thinking of finally switching brands and going with mirrorless, where I can rely of accurate autofocus. *Any suggestions are highly welcome. I would like to try out another K3III just to see if all cameras have the same problem. *Anyone in the Los Angeles area?

11-26-2022, 01:54 PM   #2
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I guess you take a jet plane . But seriously in your profile you just mention Sigma lenses, not any model by Pentax. Or are the 70, 50 and 100mm the Pentax lenses you use? That all your lenses need fine focus adjustment is not normal. I never had any lens I own fine adjusted, so I am wondering if the problem lies with the camera.
11-26-2022, 02:15 PM   #3
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QuoteOriginally posted by AfterPentax Mark II Quote
I guess you take a jet plane . But seriously in your profile you just mention Sigma lenses, not any model by Pentax. Or are the 70, 50 and 100mm the Pentax lenses you use? That all your lenses need fine focus adjustment is not normal. I never had any lens I own fine adjusted, so I am wondering if the problem lies with the camera.
Gosh, my profile is pretty old, and needs serious updating. All the lenses are Pentax lenses. SMC Pentax-DA 70mm F2.4 Limited, Pentax DA 50mm f1.8 lens, Pentax 100mm f/2.8 WR D FA smc Macro Lens. I also tested the configuration with my K5ii, and there were far fewer misses.
11-26-2022, 02:25 PM - 6 Likes   #4
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QuoteOriginally posted by Eric Seavey Quote
Gosh, my profile is pretty old, and needs serious updating. All the lenses are Pentax lenses. SMC Pentax-DA 70mm F2.4 Limited, Pentax DA 50mm f1.8 lens, Pentax 100mm f/2.8 WR D FA smc Macro Lens. I also tested the configuration with my K5ii, and there were far fewer misses.
As much as Pentax has historically struggled with continuous AF, AF accuracy issues isn't something it's known for. In fact, Pentax cameras had better low-light focusing capabilities than Canon and Nikon for a little while, which leads me to one of two possibilities:
  • The camera is defective, or the lenses are not calibrated perfectly. The best way to check this would be to take your lenses and test them with a lens alignment tool (e.g., as described here: Fixing Front and Back Focus - Introduction - In-Depth Articles). If you are still getting inconsistent results after applying the adjustments, or if adjustments of +/- 10 aren't enough, there is a high likelihood of a problem with the camera, which would be covered under warranty.
  • You're expecting more than the screwdrive AF system can deliver. Screwdrive lenses are tried and tested, but the camera can't control the focus as precisely as it can with a DC or SDM lens. That's why all star lenses (which are designed for demanding/professional applications) moved away from screwdrive AF many years ago. You might want to consider one of these alternatives. Chances are a lens like the D FA* 50mm F1.4 will blow you away



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11-26-2022, 02:41 PM   #5
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QuoteOriginally posted by Adam Quote
As much as Pentax has historically struggled with continuous AF, AF accuracy issues isn't something it's known for. In fact, Pentax cameras had better low-light focusing capabilities than Canon and Nikon for a little while, which leads me to one of two possibilities:
  • The camera is defective, or the lenses are not calibrated perfectly. The best way to check this would be to take your lenses and test them with a lens alignment tool (e.g., as described here: Fixing Front and Back Focus - Introduction - In-Depth Articles). If you are still getting inconsistent results after applying the adjustments, or if adjustments of +/- 10 aren't enough, there is a high likelihood of a problem with the camera, which would be covered under warranty.
  • You're expecting more than the screwdrive AF system can deliver. Screwdrive lenses are tried and tested, but the camera can't control the focus as precisely as it can with a DC or SDM lens. That's why all star lenses (which are designed for demanding/professional applications) moved away from screwdrive AF many years ago. You might want to consider one of these alternatives. Chances are a lens like the D FA* 50mm F1.4 will blow you away
Thanks Adam, Interestingly, the contrast AF works well. My K5II works well using Phase detect, though not perfectly but much better than the K3III. I did calibrate my lenses. The price of those lenses you suggested are a bit high..
11-26-2022, 02:48 PM   #6
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Why don't you invest in a couple of modern lenses and see if your idea changes? There is enough slack in the screw drive system to make it only semi-reliable. The 16-50 PLM, DFA * 50 and 85 are pleasures to use and are much more precise at hitting focus. If you are fixed on moving on that's one thing, but I would at least consider one of the newer lenses.
11-26-2022, 02:52 PM - 3 Likes   #7
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QuoteOriginally posted by Adam Quote
You're expecting more than the screwdrive AF system can deliver.
That's my thought as well. A couple of my screwdrive autofocus lenses (the DA 21 and the DA 12-24) I don't even bother to shoot with AF. But other than the DA 17-70, all my motor driven AF lenses have focused with a surprising degree of accuracy. For years, I shot zoo photography with the DA* 300 with older Pentax cameras like the K-5 and K-5iis and never had any issues. And the images I produced had to be have a professional level of sharpness, as the best of them were used for large posters, wall to ceiling murals in restaurant, bus adds, and electronic billboards.

11-26-2022, 03:05 PM - 4 Likes   #8
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QuoteOriginally posted by Eric Seavey Quote
Thanks Adam, Interestingly, the contrast AF works well. My K5II works well using Phase detect, though not perfectly but much better than the K3III. I did calibrate my lenses. The price of those lenses you suggested are a bit high..
Hmm, I wonder if there is some kind of malfunction with your K-3 III... it should perform better than your K-5 II.

You shouldn't need to purchase an expensive lens in order to have precise, reliable AF. My $300 Sigma 56/1.4 (on a Panasonic G9) focuses like a champ even in low light, quick and accurate.

My DA 70/2.4 Ltd and 40/2.8 Ltd were also excellent-focusing lenses on my K-70, consistently nailing focus on a cat's eye in the evening with only one lamp on.

(ISO 3200, then pushed one stop in PP)

Last edited by luftfluss; 11-27-2022 at 02:22 PM. Reason: typo
11-26-2022, 03:07 PM - 1 Like   #9
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Personally, D FA* 50mm F1.4 & older screw drive FA 77 Limited work well for me on K-1 using spot metering for portraits. I'm sure others will weigh in saying they have regular portrait successes with Pentax bodies to help you stick with the brand :-)

I'm not sure if you're trying to get that razor thin dof look, which is always likely to be hit and miss, especially if there is the slightest movement with model and/or photographer. At f5.6 in a small studio setting the focussed eye can be pin sharp while the ear is sufficiently out of focus, giving a decent 3D look, while allowing small movements. A wide aperture allow focussing in dim lighting if not actually using it to get that razor thin look. Working around f5.6 for me is a pragmatic compromise. (f8 for couples)

Last edited by BarryE; 11-26-2022 at 03:19 PM.
11-26-2022, 03:08 PM   #10
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When I use my K-1 II with my Pentax 70-200 and my K-3 II with my Pentax 16-85 the autofocus is excellent. If a user is dealing with masses of one color and there is not contrast in the subject it may be more difficult to focus on than a subject with a moderate amount of contrast, but I find that the majority of shooting does not present that as a significant difficulty. Also, a setting for a fair amount of depth should be included if the user is looking for enough detail. Of course we have different equipment, but this is my experience.

Last edited by C_Jones; 11-26-2022 at 03:14 PM.
11-26-2022, 03:11 PM   #11
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One thing I'll call out also, when comparing the K-3 family to the K-5, is that the former has a faster/more powerful screwdrive motor. This speeds up focusing and makes continuous AF less sluggish, but I've always had a sense that this could negatively impact accuracy.

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11-26-2022, 03:18 PM - 1 Like   #12
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QuoteOriginally posted by Eric Seavey Quote
Gosh, my profile is pretty old, and needs serious updating. All the lenses are Pentax lenses. SMC Pentax-DA 70mm F2.4 Limited, Pentax DA 50mm f1.8 lens, Pentax 100mm f/2.8 WR D FA smc Macro Lens. I also tested the configuration with my K5ii, and there were far fewer misses.
MMMMM, I hardly have any problems with screwdrive (experienced it from the first SFX), but must admit that SDM and DC lenses are quicker focusing. I never had any problem with the focus speed of Pentax, but what I got back was accuracy. I have tried Panasonic S5 and Nikon Z5 and I honestly can not say that they are faster than my Pentax bodies with focusing. Perhaps the AF sensor in the camera is causing the problems, because you state that contrast AF works well. If I were you I would consider returning the K-3 and get another copy or have it repaired.
11-26-2022, 03:21 PM - 2 Likes   #13
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QuoteOriginally posted by Rondec Quote
Why don't you invest in a couple of modern lenses and see if your idea changes?
Yes - try a rental before you buy? Gives you a chance to check out the lenses for not too many $$$
11-26-2022, 03:24 PM   #14
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I got a puppy a couple of months ago, and set up the camera to do all the autofocus thinking - no zones or selecting or anything. Nearly all my dog shots are with the DA 18-135, and I've never did any fine focus adjustment on any lens. The only thing I do is make sure the group of AF points are actually on the subject. For me, this totally works. The puppy isn't exactly still, and he's 14 lbs so the target is smaller than a person.

This is the not very helpful kind of reply, but I post it to suggest that the camera should be working better than it is. If it didn't work this well for me, I would just have switched back to manual focus or selecting just the center point, like my older cameras.
11-26-2022, 03:39 PM - 4 Likes   #15
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QuoteOriginally posted by Eric Seavey Quote
*Pentax has never been known for its autofocus capability and a number cameras had autofocus issues
That has been sorted with the introduction of the KP; the K1 II; and the K3 III

QuoteOriginally posted by Eric Seavey Quote
*For many subjects the phase detect autofocus works fine, albeit all my lenses need -4 to -8 fine focus adjustment
That is what the AF/FA is there for. Canon and Nikon and others have the same menu adjustments.

QuoteOriginally posted by Eric Seavey Quote
Now, for portrait photography with faster lenses, the phase detect autofocus is near useless, and it is mostly a miss
I do a lot of portrait photography and for me it is rarely a miss.

Can you post links to a number of photos where you have an issue focussing. It may help to sort out your problem.

But the AF/FA menu when used correctly (per lens ...APPLY ONE) is extremely effective. Can you detail how exactly you are setting the AF/FA per lens, you may be making an error in the procedure.
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