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06-04-2012, 12:18 AM   #1
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Back Focusing... :(

Hi all.

Looking for some advice please.

I received my new K-5 on Saturday and noticed that every shot I took was OOF with the only lens i have a 1.9/43 Ltd.

The concept and process of Micro-adjustment is not alien to me (I used to have a Canon 7D!!!), and turns out that I need greater than +10 to achieve focus. That's too much so needs a check and calibration from Pentax.

Being in the UK, can anyone let me know if I can take it down to any camera shop as a "go-between" or do I have to send it direct to Newcastle-Inder-Lyme? I got it from a German internet trader, so can't really take it back to them to coordinate!

Thanks in advance


06-04-2012, 01:54 AM   #2
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I would first of all speak with the guys you purchased it from. If that fails try through a local dealer.
In the worst case you can access the debug menu and make adjustments beyond the +/- 10.

Edit: Reason I would try the guys you bought it from first is that they might cover shipping etc.
06-04-2012, 05:54 AM   #3
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Hmmm...since you just got it, why don't you just return it for another copy? Isn't that possible with that dealer (and if not why not?)?

FWIW, my K5 and 43ltd are stellar, so if there is an issue, it isn't typical.

Make sure the AF is locking onto what you expect it to when checking for FF/BF.
06-04-2012, 01:25 PM   #4
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I'm quite certain that it's BF. Here's a shot with no MA:

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06-05-2012, 08:02 AM   #5
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Wow - that is really off! Which AF point/area(s) were you using? I take it this a crop?

Last edited by jmg257; 06-05-2012 at 09:28 AM.
06-05-2012, 09:38 AM   #6
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@jmg257: you're really right! It is a long way off with no MA. It's almost in the next galaxy! The shot is a crop, yes, and the focal point is the centre box of the 3x3 with AF-S and single shot, centre point focus (I've used this Lens Align for a while with my old Canon 7D kit and MF lenses, so I know how to use it). At MA +10 the 8 is almost in focus, so it needs to go back to the shop .

Other than this I'm really liking the K-5. But coming from a 7D (which has the worlds most complex and fast focusing system) is a bit of a back-step reality check but great to have the options I only need and not the ones that cover all possible eventualities and make the camera the size of a small African country! Just got to get this AF issue sorted with a calibration at Pentax then that'll be fine.

Oh, I'm also at F/W 1.13.
06-05-2012, 09:53 AM   #7
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QuoteOriginally posted by jmg257 Quote
Make sure the AF is locking onto what you expect it to when checking for FF/BF.

There has recently been a long and lengthy thread about the size of the AF sensors in Pentax cameras. One user hypothesized that many of the purported front/back focusing issues may be related to Pentax users not knowing/understanding the size of the AF sensors which are quite large. The link below might be useful reading.

Last edited by CMS Houston; 06-05-2012 at 09:54 AM. Reason: Question answered by OP in previous post.
06-05-2012, 10:13 AM   #8
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@CMSHouston: Thanks for the note. I've seen that before and understand what's going on. But when I use Lens Align at a focus distance of 1.125m at f/1.9 on a 43mm Ltd it's quite plain to see that it's really back focusing and not me focusing on the trees in the background.

06-05-2012, 01:04 PM   #9

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I may as well raise my old bugbear: are you using any filters on your lens? If yes, ditch the filter. If no, carry on

Also the Pentax procedure for AF testing involves a FA50 1.4 shot wide open, using Av mode, centre-spot AF, with the target illuminated to EV12, target distance to about 1m (depending on lens of course), and two shots apiece after manually turning the distance ring to infinity, shooting, and then doing same from minimum focus distance.

Except for the EV12, your test seem pretty close to what's kosher, I guess.
06-06-2012, 12:29 AM   #10

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I had similar problems with my K5. You can send it for adjustment to Pentax or use non-Pentax software to reset the rough position of the focus fine adjustment. Afterwards the lens should focus in the +/-10 range. Make sure that your other lenses still fall in the same bracket. It is the camera and not the lens causing the trouble!!! Return the camera to Pentax under warranty and add the 43 for adjustment. Make sure that they also adjust the placement of the focusing screen. Changing the AF to sensor adjustment also changes (requires adjustment) of the focusing screen to sensor distance.
With lens align make sure that your focus spot is really on the front plate - 1 out of 3 shots is completely off with my K5 and most lenses - bad focus - and I know how big my foucs spots are.

In conclusion: Pentax AF system and quality control are crap on my K5 and probably on your K5 as well. Check out all the AF threads here to realize that Pentax cameras are below average regarding quality control and AF system. I had a nice conversation with the people from Katzeye. They are not just selling focusing screens, but know how many people need to shim the screen in their cameras (not only Pentax) as well, ... I decided not to dump my K5, but to keep and adjust all parts - took me several hours spread over several weeks. Now live view focus and manual focus are in agreement. AF still sucks in little light (not low light, not darkness) situations and the size of the focus spot issues are also a bummer.
06-06-2012, 12:45 AM   #11
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@zapp: Thanks for the note.

It seems that no matter which brand or type of DSLR in the "enthusiast" range I go for, I end up concluding the same: Their QC and AF systems stink! I'm hopeful that I'm just unlucky.

I'll send it back to Pentax under warrantee of full AF calibration and focus screen adjustment (thanks for the pointer - I had a KatzEye on my 7D; might get one again if I go MF). And I'll also send the 1.9/43 with it for a service & calibration and also calibration with the body.

It's a shame that I feel a whole load of disappointment: but will get there in the end; the other options are just as bad as each other. That's cost cutting and globalisation for you - I wouldn't mind paying a bit more for decent QC!

06-08-2012, 10:00 AM   #12
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had the same problem with my 3 lenses 18-55WR, 50-200WR and 40XS...all needs to adjust +10 on the AF adjustment....i used pk_tether to enter debug mode...adjust af to +100microns...turn off debug mode...return AF adjustment to 0 (zero)...and...done!...bye bye BF!

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