I upgraded from K200D to K5 a month back. So far I have 4 lenses –Pentax 18-250mm, Pentax DA 35mm f2.4, Pentax A 50mm f1.7 and the Sigma 50-150mm f2.8 acquired 2 weeks back. I would like to point out that I am not a fan of either using flash or LV until and unless it is a ‘Do or die’ situation.
I am having a ‘not so good time’ trying to get the autofocus on the K5 to work accurately. I am not sure if it is a something wrong which I am doing (which is easily fixed), is this a problem with the K5, a problem with one or more lenses, or I am simply trying to push the tools to their limit which is causing this. The K200 was unable to autofocus in most of these cases so I am happy but because most of the times the focus is off, it is not of much help. So far most of my testing has been indoors in well-lit tungsten lighted hotel room but I have had the privilege to take the camera out on two weekends, once with the 18-250mm and 35 mm and the other time with the Sigma and the 35mm.
I was facing some initial challenges with the autofocus but once I upgraded the firmware to 1.14 it seemed to fix the AF to a large extent, or maybe it is just my perception.
The Pentax 18-250mm seems to be working fine in most cases and the focus seems to be spot on, maybe I feel so because of the large F number. This has been my workhorse lens for most of the 5 years I have used it with the K200 and my favorite walkabout lens.
I have not yet tested the A 50mm f1.7 as it is a manual lens so keeping it out of the equation as of now.
The other two lenses are the ones which I seem to have issues with
First - The 35mm f2.4 (when shooting wide open)
I mostly shoot it wide open, I know it is a bit soft at that setting but with the K200 I needed the additional light. With the K200 I did notice at times that the subject would be front focusing if not lit properly, eg. the subject has the sky in the background, etc but having the flash on, took care of that. Also, if the distance from the subject was large, then again it would be out of focus by a large magnitude. But in most cases (approx. 90%) it stood ground. With the K5, it is a similar experience but maybe much lesser accurate focus shots. Did not have LV with K200 so cannot comment but with the K5 using the LV, the focus is spot on.
Now for the Sigma (when shooting wide open most times which started all of this)
Before the K5 firmware upgrade, the focus was all over the place. Post the firmware upgrade, I was able to focus it consistently by dialing in -10 on the AV Micro Adjust. It was still not a 100% there but almost. Following the advice of some ‘Gurus’ on the forum consistent with elsewhere on the net, I sent my K5 and the Sigma lens to Sigma for recalibration. Got it back last evening and still had to dial in -10 to get it nearly there. Still not there 100%. Not a major change from before. The focus via LV is perfect and spot on (when it works).
https://picasaweb.google.com/104645425869793713046/ScrapbookPhotos#5857227846587287570 - using view finder
https://picasaweb.google.com/104645425869793713046/ScrapbookPhotos#5857227846891060738 - using LV
So not sure if it is a lens issue or a K5 issue.
Major observations
• Overhead lighting seems to force the AF to front focus considerably. So far have tested it only with tungsten lighting both at home and at a concert.
https://picasaweb.google.com/104645425869793713046/ScrapbookPhotos#5857226934049031426 https://picasaweb.google.com/104645425869793713046/ScrapbookPhotos#5857226971362355378
• When shooting up close, the focus is acceptable (not 100% accurate though) but as the distance from the subject increases, it gets worse.
• I noticed yesterday that when shooting a subject lit by tungsten at 150 mm the focus was fine but the same subject when shot at 50mm was front focusing substantially
• Bright light sources seem to throw the focus off. Also, shooting a glass covered subject, eg.a clock there was a significant back focus.
https://picasaweb.google.com/104645425869793713046/ScrapbookPhotos#5857226930593967346
• Backit subjects cause front focusing substantially.
https://picasaweb.google.com/104645425869793713046/ScrapbookPhotos#5857226930387686098
I am not sure if the size of the AF points is a problem but I am aware of that and can work around it. Or if the lack of 2.8 AF sensors in the K5 are causing this which has been rectified in the K5II. Or if low light is a problem but the 18-250 works fine in the same light so a faster lens should work better.
I desperately need help. This is driving me nuts. I am wondering if I made the mistake of buying into the K5 (rather than the K5II (additional 40%) or jumping the gun to Canon 7D (additional 50-60%)).
I can post sample pictures for whichever point you need data on.
Last edited by skamalpreet; 03-19-2013 at 06:26 PM.