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04-23-2014, 12:34 PM   #1
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Focus issues and odd auto AF / MF switching

Hi guys

I'm having a couple of issues. One relates to sharpness in all pictures. I've raised this issue with SRS where I purchased the kit from .. and the details are below for anyone that has time to read. The other is rather odd. It relates to the K3 on tripod with 60-250 and 1.4x Rear TC where the rear display kept showing the camera switching between AF.S and M without me touching anything. At the same time, you'd also see metering switching from multi-segment to something else ... I think centre weighted. It was noticeable because I was trying to take pictures of flowers with the big lens on the other side of the garden (> 5m away) and found the shutter wouldn't trigger because focus wasn't automatically being done. Has anyone else seen this ? It's only happened on the one occasion and lasted for perhaps 5 mins.

The focus / sharpness issue :


I'm having some issues with sharpness with my K3. Having shot perhaps 2000 frames, mostly playing about ... I've found that most things when cropped to 100% appear in soft focus. It's particularly clear when focusing on static things like flowers where you'd expect a lot of detail. I have run through focus test charts which show moderate front focus with the DA* 60-250 which gets worse as you get closer to the 250 end. It shows slight back focus with the Sigma 17-70 f4 'C'. I have tried AF Tuning, but it doesn't seem to make a significant improvement.

Whilst there is apparent front or back focus, the issue with sharpness is in addition to this. You'd expect if you took a close up of a flower ... even if the intended focus point was out of focus, a part of the flower would be perfectly sharp. That isn't the case. No part of the picture is very sharp. It looks like soft focus. With distant shots ... you tend to see the same ... you'd expect as you were close to infinity then most things would be in focus. That isn't the case ... everything appears to be slightly soft focused.

I've also got the HD 1.4x Rear TC. This just seems to exaggerate the issue with the 60-250 which is already worse than the 17.70.


I've done a lot of testing .. and read all the related forum threads, so I'm pretty sure I've covered everything. I'm doing single shot, spot focus with focus priority and have ensured that when hand held I have shutter greater than focal length. Where possible for testing I've made it much higher than focal length and used pictures where the target is not affected by wind. I have tried with stabilisation off and on. When on the tripod, I've made sure stabilisation is off. As I say ... the recent tests of things where I'd like a reasonable close up ... the target area is not sharp and indeed there is no sharp area in the image. I've taken so many pictures of the same subject trying to find any area that is in focus (to ensure I'm not having oddities in focus point selection) and checking to see if any part of the area surrounding the desired target is in focus ... that I know it's not an unintended focus point (which given my very amateur status would always be possible).
Seeing pictures of flowers and birds with the same camera and 60-250 show that I should be getting staggering clarity / sharpness.

This may seem a contrast to three early pictures of my children and cat which appeared to be fairly sharp ... but these weren't cropped at all, so I wasn't looking at any real detail. With these pictures, I've even filled a frame with a couple of small flowers on Macro with the 17-70 and a little cropping to zoom into the 'stems' (stamen / anther) shows real blurring and not adjacent areas in focus.

The thought of having all this expensive kit which is effectively brand new, shipped off to Pentax (I understand most repairs go to Johnsons Photopia Ltd, but SRS suggested calibration work is done in Portugal or somewhere similar) terrifies me. It's not just the inevitable introduction of shipping damage, accidental cosmetic damage or newly introduced problems ... it's also the concern that it comes back, things are the same ... and I go back and forth repeatedly never getting the fun I anticipated when buying. Has anyone who has had a similar experience had it resolved ? Are there options where I can go somewhere in the UK (eg Pentax offices in Slough) to get someone to validate face to face whether they acknowledge a fault ? It should be very easy to do.

Sorry ... trying not to panic ... but after 4 months of casual playing and being thankful I didn't have (so far) the various 'K3 troubles', I now wondering just what I should do to resolve things quickly and minimise any associated pain.

Best regards

Paul.


04-23-2014, 12:47 PM   #2
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QuoteOriginally posted by pgamble Quote
I'm having some issues with sharpness with my K3. Having shot perhaps 2000 frames, mostly playing about ... I've found that most things when cropped to 100% appear in soft focus. It's particularly clear when focusing on static things like flowers where you'd expect a lot of detail. I have run through focus test charts which show moderate front focus with the DA* 60-250 which gets worse as you get closer to the 250 end. It shows slight back focus with the Sigma 17-70 f4 'C'. I have tried AF Tuning, but it doesn't seem to make a significant improvement.
Have you tried manual focus? That will remove the AF system from the equation. You might also be interested in my personal experience with the Sigma 17-70/2.8-4 (C). It is not particularly sharp when focused close (say for flowers). This is evident on the K-3 and even on my 10 Mpx K10D using a KatzEye split-image focus aide.


Steve
04-23-2014, 01:51 PM   #3
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do you perhaps have a battery grip on this setup? And is the on/off switch on the battery grip set to "on" perhaps?

M
04-23-2014, 02:24 PM   #4
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You didn't say but when on a tripod presumably you're using the 2-second timer, or remote with timer or mirror lockup. I do most of my flower shots on a tripod with 2-second timer, using live view to zoom in to 8x for manual focus. As long as the sun isn't washing out the LCD I'm able to get exceptionally sharp photos this way. If you do it this way and can't get sharp images, then something is wrong.

If you're shooting wide open, you might try stopping down to at least f/5.6 or even f/8.

04-23-2014, 02:50 PM   #5
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The AF.S flipping to M and back sounds to me that you have bad connection between the body and lens.

---------- Post added 04-23-14 at 11:52 PM ----------

When testing the focus, try to use Live View and manual focus to get the most exact focus. Then you do not have to think about the back or front focus. Just to check if the lens is sharp or not.

---------- Post added 04-23-14 at 11:55 PM ----------

One more thing when it comes to focus. You need to keep an eye on the shutter speed.
04-24-2014, 05:04 AM   #6
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Try remove any filter

I had the same issue with a da* 300. Tried live view even called pentax to see if there were any known issues. Of course none. As a last resort before sending it all in for service I removed the protective filter and voila sharp photos consistently.
04-24-2014, 05:53 AM   #7
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Focus issues

Hi everyone


thanks for the initial thoughts ...


'Have you tried manual focus? That will remove the AF system from the equation. You might also be interested in my personal experience with the Sigma 17-70/2.8-4 (C). It is not particularly sharp when focused close (say for flowers). This is evident on the K-3 and even on my 10 Mpx K10D using a KatzEye split-image focus aide.


Steve'


--> Yes .. tried manual focus on many of the same images to see if it was AF issue. Problem the same ... soft focus image even when it appears focused through the viewfinder. I'd seen good review of the Sigma including sharpness .. but I guess there are variations. If it was just that .. I'd be inclined to think the Sigma was the cause .. but given it is if anything worse with the DA*60-250 which is supposed to be the best glass available for the Pentax ... and I've seen many staggeringly sharp images on this forum with that lens on the K3 and with the 1.4x and that lens on the K3 ... it would suggest a broader issue than just the Sigma. I would be interested to see any images you have using the Sigma that show softness.


'do you perhaps have a battery grip on this setup? And is the on/off switch on the battery grip set to "on" perhaps?

M

Read more at: https://www.pentaxforums.com/forums/172-pentax-k-3/258517-focus-issues-odd-au...2zo0zclzY'


--> no battery grip. Given I get circa 300 shots (given I write RAW to one SD and JPG to the Flu-Card .. I guess it is really 600 shots) between charges with my Pentax batteries (I carry two) - I should consider a grip. Don't want to buy anything else in case it turns out it all has to go back.


'You didn't say but when on a tripod presumably you're using the 2-second timer, or remote with timer or mirror lockup. I do most of my flower shots on a tripod with 2-second timer, using live view to zoom in to 8x for manual focus. As long as the sun isn't washing out the LCD I'm able to get exceptionally sharp photos this way. If you do it this way and can't get sharp images, then something is wrong.

If you're shooting wide open, you might try stopping down to at least f/5.6 or even f/8.'


--> I am using 2-second timer. Didn't want to introduce any shake from me. I do frame with LV and then shoot with viewfinder. Not tried zooming to 8x and then manually focusing .. sounds like a good idea. I'm not getting good sharp images though .. in any example with manual or AF ... so I'm guessing it is something else. I will try that process though. Many thanks.


I'm shooting as close to wide open as possible - 2.8 with the Sigma, 4 with the DA* and 5.6 with the DA* and 1.4TC. My hope was that the wider open the crisper shorter DoF for the better overall image. I don't think it is DoF related as I get soft focus with more distant images at infinity as well as softness at mid distance with the telephoto (perhaps 5m) where a 100% would mainly be filled by the head of a single flower. In each case, nothing slightly closer or further away is sharp ... which indicates it's not me getting the focus point wrong or a DoF issue.


'The AF.S flipping to M and back sounds to me that you have bad connection between the body and lens.



--> Yes ... I assumed this ... but it was engaged and there is no way to make it firmer or otherwise.

---------- Post added 04-23-14 at 11:52 PM ----------

When testing the focus, try to use Live View and manual focus to get the most exact focus. Then you do not have to think about the back or front focus. Just to check if the lens is sharp or not.


--> Second suggestion to do this .... so definitely will try. For shooting static objects ... even if I get things resolved, this seems like sensible good practice, particularly with the zooming in LV. Given nothing in the image around the focus point is any closer to being sharp and DoF is small ... it would suggest it is not just AF as such .. but rather the ability for my K3 with the two lens (and TC) to achieve sharp focus at all.


---------- Post added 04-23-14 at 11:55 PM ----------

One more thing when it comes to focus. You need to keep an eye on the shutter speed.'


--> Yes Shutter always > focal length. This last week .. it was sunny and on the tripod with ISO <= 800 I was able to keep faster that 1/400 in all shots. Also made sure any sign of wind had stopped before firing. Certainly shouldn't have been enough at those shutter speeds to consistently result in soft focus.


'I had the same issue with a da* 300. Tried live view even called pentax to see if there were any known issues. Of course none. As a last resort before sending it all in for service I removed the protective filter and voila sharp photos consistently.'


--> I'm going to sound like a complete tit here (and not like the lovelies flying around the garden all week) .. what protective filter ? I do have Kenko UV filters that were supplied by SRS. I'd hope they were the good SMC ones. SRS seem like a great bunch to me. I can try and shoot without it you think it makes sense - certainly to rule them out. I'd be terrified to leave a filter off such an expensive lens for any long period.


I know there are some more hard core pro and semi pro people on the forum that understandably treat the cameras as the tool they are really supposed to be .. and therefore things like the odd bit of cosmetic damage or sending off to foreign lands for calibrating / fixing doesn't seem like something to worry about ... but I also detect a number like me who are just enthusiastic amateurs who see their camera kit as a staggeringly expense toy to be cherished ... and don't want anyone taking it apart, especially in it's first year of newness. I'd say both are completely understandable attitudes .. for me ... I just feel if I buy new .. and something is clearly faulty from new ... It should be replaced with new - not 'repaired',


Again ... many thanks for all your thoughts. I eagerly await others ... and will hopefully get to chat to SRS and Ricoh about it soon.


Paul.
04-24-2014, 08:37 AM   #8
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QuoteOriginally posted by pgamble Quote
I would be interested to see any images you have using the Sigma that show softness.
The lens is new to me and I have not fully characterized the close-focus behavior. I noticed the softness when working with THIS image and other similar shots. That one and one other were the only two closeups of the morning* that were adequately sharp to share, and then only after applying USM in PP. I will have to confirm, but it is my impression that a crop from further back would have provided a sharper final image.


Steve

* ...all taken on tripod with 2s delay and manual focus using a KatzEye screen...no wind...


Last edited by stevebrot; 04-24-2014 at 08:42 AM.
04-24-2014, 08:56 AM   #9
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Steve ... that is beautiful


And ... I have to say ... a lot sharper than I'm getting. You have pretty good edge definition. It appears focus is on the front surface and left edge of right petal with a very short DoF resulting in drop off in sharpness by the middle of the flower. The water drops on the front petal surface look good to me ... the top ... a little fuzzy. I'd be really happy with this.


Paul.
04-24-2014, 09:16 AM   #10
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I would highly recommend removing the 'Kenko UV filters' I have not used a so called filter since film days.
Always use the lens hood, protects the lens front and reduces flare........
nothing to loose, you may see a big difference.
see my images with the the SMC PENTAX-DA*300 F/4, no filter.

https://www.flickr.com/photos/paulrookes/

+1 for SRS too
04-24-2014, 03:54 PM   #11
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QuoteOriginally posted by pgamble Quote

'The AF.S flipping to M and back sounds to me that you have bad connection between the body and lens.



--> Yes ... I assumed this ... but it was engaged and there is no way to make it firmer or otherwise.
It doesn't necessarily have to be a physically loose contact; it could simply be a dirty contact, perhaps due to some lubricating oil being present, fairly normal for a new piece of kit straight out of the box. As suggested. the behaviour sounds exactly like what happens when the camera doesn't recognise the lens (the camera reverts to manual focus and center-weighted metering when it "thinks" there's a non-A-type lens attached... does the little LCD on top of the camera show a blinking "F--" when it happens as well?), and the fact that it's intermittant only supports that idea.Just give the contacts a good dry wipe and see what happens.
04-24-2014, 05:11 PM   #12
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Hey Paul I had an Hoya Protective MC (not cheap) filter on my lens and removing it made a world of difference.
Night and day.
I have read some posts elsewhere with regards to have a UV or protector on the lens or not and I am now of the belief that you pay a lot of money for a lens only to throw a even say 100 dollar filter on the front of it.
IF you like I can upload some pictures with and without the filter on the lens.


Kwong
04-24-2014, 05:21 PM   #13
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QuoteOriginally posted by Kwong Quote
Hey Paul I had an Hoya Protective MC (not cheap) filter on my lens and removing it made a world of difference.
Night and day.
I have read some posts elsewhere with regards to have a UV or protector on the lens or not and I am now of the belief that you pay a lot of money for a lens only to throw a even say 100 dollar filter on the front of it.
IF you like I can upload some pictures with and without the filter on the lens.


Kwong
I have come to the same conclusion so I never put a filter on any lens unless it has a purpose like a polariser, ND or IR. These also degrades IQ but then it is a choise.
04-25-2014, 12:18 AM   #14
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QuoteOriginally posted by Tjompen1968 Quote
I have come to the same conclusion so I never put a filter on any lens unless it has a purpose like a polariser, ND or IR. These also degrades IQ but then it is a choise.
Whilst I understand the mentality and agree to a degree on the IQ argument there is also times where a filter protects.

Motor sport is a clear example if your getting pebble dashed on a corner.

or in my case where the camera gets exposed to corosive chlorine I'd rather etched £50 filters than coating stripped £1000 lens
04-25-2014, 02:49 AM   #15
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QuoteOriginally posted by awaldram Quote
Whilst I understand the mentality and agree to a degree on the IQ argument there is also times where a filter protects.

Motor sport is a clear example if your getting pebble dashed on a corner.

or in my case where the camera gets exposed to corosive chlorine I'd rather etched £50 filters than coating stripped £1000 lens
Maybe I wasn't clear, Like others have said, this was an issue regarding image sharpness.

I use B+W filters when needed, 10 stop, Polarizer........., I'm in a desert now and have a filter on for protection....(Polarizer), if i feel it is safe to do so, no wind, moist air......it will be removed for the best image quality which includes sharpness.

Again as highlighted by others, my choice, I know it will affect the image quality but as you say sometime it is required.
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