[coldautumnday]

Good morning everyone.

Last week I bought a used K7 and K5 II and I've spent some time playing with them and I'm not quite sure how I feel about them yet. I come from Olympus which I used for many years.

I don't have any high end glass yet but I have a 50mm 1.8 and a 28-80. I also have the Pentax M42 adapter and I use that with my old Takumar 50mm 1.4 which is my favorite lens ever! I do really like how the Pentax bodies focus confirm on vintage manual focus glass. That feature alone makes these wonderful cameras.

Anyhow, to get the 50mm 1.8 to focus properly I had to use the focus calibration feature in the camera and move to +10 to get sharp focus on both of my camera bodies. I didn't think it would be that off...

I went down to my local camera store to try some different lenses and to chat with the resident Pentax guy who works there. He showed me how he has his Pentax K1 setup and gave me some pointers.

He had a used 16-50mm 2.8 and it's 50-135 counterpart along with a few other used lenses that I tried. Both of the lenses which are SDM focused really really really slowly on my camera. Like unacceptably slowly whereas lenses that are screw motor focused worked just fine. So, my question is, is this a lens problem? Are these used lenses damaged? Or is it my camera body causing the issue?

I also tried the Pentax guys personal 24-70 2.8 and that was a bit better. Then I tried a 60-250 lens which is a hybrid SDM/Screw driven focus system and that focused quickly and worked properly.

I'd like to hear your thoughts.

Thank you.

~Anne Marie

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Last edited by coldautumnday; 12-31-2019 at 07:02 AM.

[reh321]

Good morning everyone.

Last week I bought a used K7 and K5 II and I've spent some time playing with them and I'm not quite sure how I feel about them yet. I come from Olympus which I used for many years.

I don't have any high end glass yet but I have a 50mm 1.8 and a 28-80. I also have the Pentax M42 adapter and I use that with my old Takumar 50mm 1.4 which is my favorite lens ever! I do really like how the Pentax bodies focus confirm on vintage manual focus glass. That feature alone makes these wonderful cameras.

Anyhow, to get the 50mm 1.8 to focus properly I had to use the focus calibration feature in the camera and move to +10 to get sharp focus on both of my camera bodies. I didn't think it would be that off...

I went down to my local camera store to try some different lenses and to chat with the resident Pentax guy who works there. He showed me how he has his Pentax K1 setup and gave me some pointers.

He had a used 17-50mm 2.8 and it's 50-135 counterpart along with a few other used lenses that I tried. Both of the lenses which are SDM focused really really really slowly on my camera. Like unacceptably slowly whereas lenses that are screw motor focused worked just fine. So, my question is, is this a lens problem? Are these used lenses damaged? Or is it my camera body causing the issue?

I also tried the Pentax guys personal 24-70 2.8 and that was a bit better. Then I tried a 60-250 lens which is a hybrid SDM/Screw driven focus system and that focused quickly and worked properly.

I'd like to hear your thoughts.

Thank you.

~Anne Marie

I have found {on both my K-30 and my KP} that in-lens focus motor focuses faster than screw-drive focus motor. If the in-lens focus motor focuses too slowly, I would guess the lens is “at fault”.

[rogerstg]

Chances are that those lenses suffer from SDM problems. It's not too uncommon and a big reason those lenses are on the used market. BTW, you probably mean 16-50 since Pentax does not make a 17-50 lens. And welcome to the forums!

[coldautumnday]

Chances are that those lenses suffer from SDM problems. It's not too uncommon and a big reason those lenses are on the used market. BTW, you probably mean 16-50 since Pentax does not make a 17-50 lens. And welcome to the forums!

Oops! Yes, I just corrected that.

[pschlute]

I'd like to hear your thoughts.

The early Pentax SDm lenses (including the 60-250) are not very fast at focussing. I doubt your cameras are at fault.

Autofocus calibration is dependent on both camera and lens. On my K1 I need a +7/+10 on all my lenses for pinpoint accuracy. This tells me that the camera itself is the one that is out of perfect alignment more so than the lenses. The acceptable range is -10 to +10 so as long as +10 works for you that is acceptable. My experience is the adjustment will not change over time. Just make sure you do an accurate test (tripod/remote or 2 sec timer/ natural light) involving about 10 tests for each lens, making the camera work to focus each time. Then select the setting that gives you the majority result. PDAF will not give you 100% accuracy all the time.

The 60-250 lens will work on SDM all the time unless the lens has been modified.

The green hexagon focus confirmation relies on the same AF system for its signal.

[sergysergy]

The K-5 II is a much better camera than the K-7. You could convert the SDM lenses to screwdrive (at least the 16-50 and the 50-135) to get faster focusing.

[jatrax]

So, my question is, is this a lens problem? Are these used lenses damaged? Or is it my camera body causing the issue?

The early SDM system was not particularly fast even for its day. That said, it is also possible the lenses were starting to have motor failure. The optical quality of that series: 16-50, 50-135 and 60-250 was quite good as well as the build quality but they are not fast focusing. There is a process for converting those lenses to screwdrive which improves the speed somewhat but at the expense of the screwdrive noise.

Then I tried a 60-250 lens which is a hybrid SDM/Screw driven focus system and that focused quickly and worked properly.

I don't believe this is correct. The drive system in all three lenses is identical. The 16-50 and 50-135 can be converted to use screwdrive instead of the SDM but as far as I know the 60-250 cannot. All of these lenses include both screwdrive and the SDM motors, that was for backward compatibility on bodies that could not control the SDM motors. But as far as I know it is one system or the other, there is no such thing as "hybrid" system in the sense that both could be used at the same time.


The new DFA 24-70 should be as fast as most screwdrive lens. But I wonder if your body needs a firmware update to be able to best control that much newer lens.

If I were looking for a new lens for a K-7 or K-5 series camera I would try either the 16-85 or the 18-135. Both are faster than any of the SDM lenses and designed for the APS-C format of those bodies.

[Mikesul]

If you read through the forum you will discover that most of us feel that the early SDM motors were very slow and unreliable. For whatever reason Pentax still calls its new focus motors SDM but they are in a completely different league. The FF 150-450 and 70-200 2.8 for example and the APS-C 55-300 PLM are fast focusing lens. Lenses released in the last few years all seem to be much faster and more decisive than the early motor driven lenses. Conversion to screw drive seems to be the only solution if you want fast focus on those early DA* lenses.

[aslyfox]

this article might be of interest:

The 5 Lens Autofocus Drive Types Explained
Pentax AF technologoy overview and comparison
By beholder3 in Articles and Tips on Aug 19, 2018

Camera lenses today use many different technologies to facilitate autofocus. Under the hood, there needs to be some way for the camera to move elements inside the lens, which in turn changes what's in focus. In this article, we'll be taking a look at the different types of focusing implementations currently in use by Pentax. In addition, you'll learn more about some of the terminology used by Pentax and other manufacturers.

Pentax users currently have access to both manual focus lenses and lenses with one of 5 different autofocus drive technologies.

These have evolved over many years, and as almost everything in life, each comes with its pros and cons. For example, fast focusing in single autofocus mode (AF.S) is not the same as fast continuous autofocus (AF.C). In-lens motors can fail. Gears in drive mechanisms can shatter. Powerful motors take up space. Modern, larger drives allow more torque. The list goes on!

It is important to stress from the very beginning that many of the designations given to the drive types (e.g. SDM or DC) are generalizations. Different lens models can have different autofocus implementations even if they go by the same name. Ultimately, this can mean that a drive type that is commonly known to be fast may actually appear slow in a certain lens and much quicker in another. . . .

Read more at: The 5 Lens Autofocus Drive Types Explained - Articles and Tips | PentaxForums.com

[DWS1]

Welcome to the Pentax community and best wishes in your search for all that amazing Pentax glass. The amazing thing about your post is that you have a local camera shop and it has a Pentax guy. Nowadays that combination is almost extinct.

[ramseybuckeye]

Those older SDM lenses are definitely slow. But you also have to realize that those cameras are not the latest in autofocus technology. Pentax at that time was known for rather slow autofocus. The newer camera models have vastly improved autofocus, as do the newer lenses.

[coldautumnday]

I don't believe this is correct. The drive system in all three lenses is identical. The 16-50 and 50-135 can be converted to use screwdrive instead of the SDM but as far as I know the 60-250 cannot. All of these lenses include both screwdrive and the SDM motors, that was for backward compatibility on bodies that could not control the SDM motors. But as far as I know it is one system or the other, there is no such thing as "hybrid" system in the sense that both could be used at the same time.

Hello there. I'm basing my information on this from the Pentax/Ricoh website.


Sorry, if my terminology is off. I'm only a week into the world of pentax. I see what you guys are saying though. If a body has SDM it will use it and if it's an old body it will use the screw drive motor.

[jatrax]

I see what you guys are saying though. If a body has SDM it will use it and if it's an old body it will use the screw drive motor.

Yep, that's it exactly. My point was only that all three lenses have the same system. SDM if the body supports it, screwdrive if not. The 60-250 is not any different than the other two so why they would call one a 'hybrid' and not the others is puzzling.


I used the 16-50 and 60-250 for about 5 years. The 16-50 was my work horse on a good number of different bodies from k-x through K-3II. It was converted to screwdrive when the SDM failed and performed (IMHO) slightly faster as screwdrive. The 60-250 was perhaps my favorite lens on APS-C and after modification was also used on the K-1. If I were setting up an APS-C kit at this point I would buy the DA 16-85 and the DA*60-250. I do not think the 16-50 is worth the extra money unless you need an f/2.8 lens.

[coldautumnday]

Welcome to the Pentax community and best wishes in your search for all that amazing Pentax glass. The amazing thing about your post is that you have a local camera shop and it has a Pentax guy. Nowadays that combination is almost extinct.

Yes, we have a shop called Dodd Camera in Cleveland and they don't have as much Pentax stuff as they used to but a guy named Eric works there who is a Pentax user.

[pentasonic49]

I have one of the first 16-50 lenses which is on its original SDM motor, it has been taken apart a couple of times to get it going in the past. It always works now and I tried a couple of empirical focussing speed tests with it. Facing a plain wall to make sure it could not lock on a focussing point, I ran the lens on my K5 and my K3ii.
Starting at infinity, the lens will run to closest focus and back to infinity, then stop. Using the AF button on both cameras, I cycled ten times. The k5 took 20 seconds and the K3ii, 18 seconds.
When I first had the 16-50, it was used on my K100D which only has screw drive, and also on my K10D, which also used screw drive until I updated the firmware. Of course, not long after the firmware update, the SDM went on the blink until the lens was dismantled to free up the motor. Optically, the lens is sharp right into the corners, but does suffer from chromatic abberations.