Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
05-30-2014, 08:05 AM   #1
Forum Member




Join Date: May 2011
Location: greater Philadelphia area
Posts: 81
DA 21mm SMC vs. HD autofocus

When the DA 21mm SMC lens was introduced (7 or 8 years ago?) there were multiple complaints at PentaxForums and elsewhere about focusing issues--usually back focus, sometimes front focus, and/or variations in autofocus accuracy depending on whether autofocus was done above or below f8. One poster here at PF reported 4 copies of the SMC 21mm having the problem; a poster somewhere else reported an autofocus issue confirmed by a Pentax office in Europe. I'm debating the choice between buying a used SMC 21mm or a new HD 21mm, and wondering if this apparent autofocus issue has continued through the entire 21mm SMC and HD set of lenses, or if it somehow was resolved with the HD version (or later production SMC versions). (Or did it all turn out to be user error?) Does anyone have any experience or knowledge relevant to this question? Thanks very much.

05-30-2014, 08:15 AM   #2
Veteran Member
carrrlangas's Avatar

Join Date: Mar 2012
Location: Joensuu (Finland)
Photos: Gallery
Posts: 1,761
hmmm Ive got a used SMC DA21 not long ago and focus is spot on with K-5IIs
05-30-2014, 08:34 AM   #3
Site Supporter
Site Supporter
jatrax's Avatar

Join Date: May 2010
Location: Washington Cascades
Photos: Gallery | Albums
Posts: 12,327
Never actually heard of any problems with the DA 21mm, but 7 or 8 years ago pre-dates me. I can say mine is spot on (SMC version) and I've never had any issues. Certainly any issues that occurred back then have not carried forward because there has been no problems reported as long as I can remember. Maybe initial production runs? Maybe user error? Maybe the problem with the 4 'bad' copies was the camera not the lens? Who knows. Don't know when mine was made but I bought it used about 2 years ago.
05-30-2014, 09:22 AM   #4
Veteran Member
VisualDarkness's Avatar

Join Date: Nov 2011
Location: Uppsala, Sweden
Photos: Gallery
Posts: 4,441
Sometimes I don't get the whole deal about focusing on a few complaints about back and front focus for specific lenses. Focus calibration issues is a built in problem in the phase detection technology and as long as manufacturing tolerances are decently tight compared to the price, the result will generally be good enough.

The problem is that the tighter the tolerances get manufacturing cost rise almost exponentially so there has to be a compromise. That in combination with none matched hardware, a random camera with a random lens, creates a possibility for bad matching. In most cases it works out well or is correctable in the camera, but in some occasions both the lens and the camera end up at the same ends of the tolerances and therefore end up uncomfortable.

05-30-2014, 10:36 AM   #5
Veteran Member




Join Date: Sep 2009
Location: Southern California
Photos: Gallery | Albums
Posts: 3,229
If there were manufacturing issues at the very beginning, they appear to be resolved. Also, it seems the Vietnam factory sometimes had more QC issues with the first runs of any lens that was new to them. This wouldn't necessarily apply to the new HD lenses, however, because they're not really new designs.

So I'd say the great majority of the used lenses out there will be fine. And if not, sending the lens in for adjustment can take care of it. When I got my FA20 (used) there was just "something wrong with" the images. I couldn't even put my finger on what the problem was, but I sent it in with this vague description, and it came back performing just as I'd expected it to when I purchased it. So "bad copies" often aren't that bad at all - they just need to be sent in for simple adjustment.

Last edited by DSims; 05-30-2014 at 10:42 AM.
05-30-2014, 11:39 AM   #6
Veteran Member




Join Date: Nov 2006
Location: central Singapore
Photos: Gallery
Posts: 422
I was a DA21 early adopter. My lens did have a problem - it focused differently at at f/5.6 and onwards compared to wide open. Impossible to callibrate. Drove me nuts. Finally after many years I got the agents to send it back to Pentax and have it sorted. Now it's fine. So the problem was real and not my imagination.

I would assume a recent lens would be OK.
05-30-2014, 04:55 PM   #7
Pentaxian
jddwoods's Avatar

Join Date: Nov 2012
Location: Newark, Delaware
Posts: 966
QuoteOriginally posted by Lititz Quote
When the DA 21mm SMC lens was introduced (7 or 8 years ago?) there were multiple complaints at PentaxForums and elsewhere about focusing issues--usually back focus, sometimes front focus, and/or variations in autofocus accuracy depending on whether autofocus was done above or below f8. One poster here at PF reported 4 copies of the SMC 21mm having the problem; a poster somewhere else reported an autofocus issue confirmed by a Pentax office in Europe. I'm debating the choice between buying a used SMC 21mm or a new HD 21mm, and wondering if this apparent autofocus issue has continued through the entire 21mm SMC and HD set of lenses, or if it somehow was resolved with the HD version (or later production SMC versions). (Or did it all turn out to be user error?) Does anyone have any experience or knowledge relevant to this question? Thanks very much.
I bought a used DA 21 Limited from KEH in LN- condition. I have not had any issues with autofocus. Actually this may be one of my fastest focusing lenses.
05-30-2014, 05:44 PM   #8
Veteran Member
robjmitchell's Avatar

Join Date: Oct 2007
Location: Melbourne Aus
Posts: 1,457
I was around back then. Those problems were (mostly) solved by the addition of in camera autofocus calibration (lacking on the k10). Like any lens there are still going to be the odd one that could benefit from some realignment. My HD copy is no slouch in the sharpness department from wide open for the record.

05-30-2014, 09:30 PM   #9
Veteran Member




Join Date: Nov 2006
Location: central Singapore
Photos: Gallery
Posts: 422
QuoteOriginally posted by robjmitchell Quote
I was around back then. Those problems were (mostly) solved by the addition of in camera autofocus calibration (lacking on the k10).
The problem was that adjusting AF on the camera didn't resolve the problem - if you got it right for apertures up to f/4, it would front focus at f/5.6 and beyond. God knows what caused this - all I can says is after being tweaked by Pentax, my lens no longer behaves like that. But it certainly did.
05-31-2014, 09:56 PM   #10
Veteran Member




Join Date: Sep 2009
Location: Southern California
Photos: Gallery | Albums
Posts: 3,229
QuoteOriginally posted by timo Quote
The problem was that adjusting AF on the camera didn't resolve the problem - if you got it right for apertures up to f/4, it would front focus at f/5.6 and beyond. God knows what caused this - all I can says is after being tweaked by Pentax, my lens no longer behaves like that. But it certainly did.
It sounds like this is what my FA31 may need.
06-13-2014, 05:26 AM   #11
Forum Member




Join Date: May 2011
Location: greater Philadelphia area
Posts: 81
Original Poster
Thanks for all the feedback to my original question. FYI, I purchased a used DA 21mm SMC from a reputable dealer.

It behaved exactly the same as in Timo's experience (described earlier in this thread). As received, focus was fine at higher apertures (target in the middle third of the overall in-focus area), but seriously back-focused when wide open (f3.2). But if, using a higher aperature (like f8) I pressed the shutter halfway to set focus, and then kept the focus at that point and reset the aperture to 3.2, the photo taken at 3.2 would be fine (target somewhere in the middle third of the acceptable focus area). So the better focus at higher apertures was not just something I was seeing due to the greater depth of field at those apertures.

If I calibrated focus for f3.2, then at higher apertures (over 5.6) photos were "just" useable but clearly front focused (that is, the target would be in acceptable focus, but clearly at the rear limit of the acceptable depth of field range, rather than somewhere more toward the middle third of the in-focus area).

Testing was done with tripod and focus charts, plus on isolated outdoor field objects at various longer distances.

I returned the lens. FYI, it was relatively early production (serial number was in the low 4000s) in excellent cosmetic condition. My totally uninformed guess is that the design was meant to adjust focus to compensate for something like aperture-induced focus shift, but Pentax didn't get the adjustment correct, at least on early production copies. Thus Timo's lens could be fixed/readjusted by sending it back to Pentax for repair. Again, just a guess.

Thanks again for the feedback.
06-13-2014, 06:07 AM   #12
Pentaxian
bdery's Avatar

Join Date: Mar 2008
Location: Quebec city, Canada
Photos: Gallery
Posts: 7,484
QuoteOriginally posted by Lititz Quote
there were multiple complaints at PentaxForums and elsewhere about focusing issues--usually back focus, sometimes front focus, and/or variations in autofocus accuracy depending on whether autofocus was done above or below f8
Never heard that it was more prone to problems. Maybe users were more vocal.

In any case, I tested my own copy (SMC) and the new HD side by side (sample size : one of each) and they performed identically. With eyes closed, it would be impossible to tell them apart.

QuoteOriginally posted by Lititz Quote
One poster here at PF reported 4 copies of the SMC 21mm having the problem
That particular case sound smuch more like a camera problem.
01-29-2015, 06:19 PM   #13
New Member




Join Date: Jan 2010
Posts: 13
我手里有HD和SMC版本的饼干镜头,目前在K3上SMC的都有不同程度的跑焦(focus issue)包括DA21和DA70,HD版本的镜头每一个对焦都很准DA15、DA40、DA35Macro,最近很纠结不知道是不是要把手里的镜头全部换成HD版本的。

另外DA21的跑焦我感觉是这个镜头和宾得的对焦系统配合有问题,因为在LV模式下对焦是准确的,这只镜头以前在1600W像素以下的机身上看不出跑焦,在K3上跑焦严重让人抓狂
01-30-2015, 04:09 AM   #14
Pentaxian
kh1234567890's Avatar

Join Date: Sep 2010
Location: Manchester, UK
Photos: Gallery
Posts: 2,600
QuoteOriginally posted by freefire Quote
我手里有HD和SMC版本的饼干镜头,目前在K3上SMC的都有不同程度的跑焦(focus issue)包括DA21和DA70,HD版本的镜头每一个对焦都很准DA15、DA40、DA35Macro,最近很纠结不知道是不是要把手里的镜头全部换成HD版本的。

另外DA21的跑焦我感觉是这个镜头和宾得的对焦系统配合有问题,因为在LV模式下对焦是准确的,这只镜头以前在1600W像素以下的机身上看不出跑焦,在K3上跑焦严重让人抓狂
I love Google Translate

'My hands have HD versions of biscuits and SMC lens, the SMC is currently K3 have different degrees of out of focus (focus issue) , including DA21 and DA70, HD versions of each one focusing lens very accurate DA15, DA40, DA35Macro, has been a very tangled do not know all put into the hands of the lens HD version .

Another focus DA21 run I feel this lens and Pentax AF system with a problem , because in LV mode Focus is accurate , this lens before speaking at 1600W pixels below the fuselage could not run focus in on K3 serious people crazy out of focus'
01-30-2015, 04:36 AM   #15
Site Supporter
Site Supporter




Join Date: Feb 2011
Location: Syracuse, NY
Posts: 651
I currently have the HD version, but previously had the SMC version, and haven't noticed any issues with either.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
21, 21mm, autofocus, da, da 21mm smc, focus, hd, issue, k-mount, pentax lens, poster, slr lens, smc
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
SMC 15mm vs 21mm Ltd adell Pentax SLR Lens Discussion 20 02-05-2014 10:31 AM
DA HD vs SMC built quality scorpioh Pentax SLR Lens Discussion 16 01-17-2014 08:26 PM
HD vs SMC Limiteds: Comparative Review Posted Adam Pentax SLR Lens Discussion 18 12-07-2013 06:18 AM
HD DA vs SMC DA beachgardener Pentax SLR Lens Discussion 9 10-18-2013 11:00 AM
DA21 - Crude SMC vs. HD comparison JPT Pentax SLR Lens Discussion 17 10-09-2013 08:33 AM



All times are GMT -7. The time now is 03:15 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top