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06-25-2014, 05:46 AM   #1
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2 strange AF-probs with K-500

Hi, Folks!

My K-500 (bought Dec. 2013) has 2 strange issues with the AF-System.

1/3rd of the problem is behind the cam, as usually - but I still wonder, why:
When I try to focus using the viewfinder, it seems that me and the cam have different opinions about what's the spot I'm targeting at (using AF-center-spot metering). This issue is caused by the fact that I'm wearing glasses - and it was never one with my old ist-DL2!
When I drop the glasses, things get much better - but still not perfect.
Can glasses cause some kind of parallax-error inside a pentaprism?!?! Or give me a wrong impression about what's in the center circle of the focusing screen? Some kind of off angle? As said, this was no issue with my ist-DL2!

The other 2/3rd of the problem:
For quite some time I was believing that there are back-/front-focus errors caused by the lenses (the 18-55 kit and a 18-200 Tamron).
However, trying different charts and test-setups at home showed me that everything should be fine.
Unfortunately, in the wild almost 50% of the pics I shot missed the point (while the AF HAD told me "locked on target")!
Now, I'm shooting many pics at festivals or street parades and such, and many shoots have to be done in a hurry. So I have to rely on that beep, esp. when doing a quick shot out of the crowd.

What a luck the K-500 has a shake reduction!
Really?
NO!

It's exactly the shake-reduction that caused the misfocused pics in these situations!!
I just switched it off simply to give it a last try before returning the cam to a service station - and no more unsharp pics from that on!!!

I shot around 800 pics 3 weeks ago at the Carneval of Cultures in Berlin, and almost 50% were unusable due to focus issues (SR on).
Last weekend I've been at the Christopher Street Day: 500 pics, 95% perfectly focused (SR off) - and the rare unsharp ones caused by obvious reasons, not by AF errors (fast moving target etc.).

Both shootings were made out of the crowd, so same situation for me as a photographer - many snapshots in a hurry.
A big difference was in the lighting: At the Carneval, we had blue sky and bright sunshine - at the CSD the weather was pretty bad (very cloudy and rainy). In theory, the AF should have performed much better during the Carneval. But compared to the CSD (entirely shot with SR disabled) it was a total mess!

Does anybody have an explanation for this strange behaviour??
I mean - the SR should reduce shaking of the cam, exactly in situations like these above. It should not CAUSE focus issues just because I have to do a quick shot!? Or do I miss something here??

TIA!
Belushi

06-25-2014, 06:19 AM   #2
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My K30 has missed the focus while shooting into a very strong light

https://flic.kr/p/np7375
06-25-2014, 06:40 AM   #3
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Original Poster
Hi AldaCZ,
it was bright and sunny at the Carneval, but there was no situation like in your example. Lots of contrast on the people and parade trucks, of course - but the problem also occured between more narrow standing buildings where it was shady.
06-25-2014, 07:12 AM   #4
Ole
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To your fist question about the center AF point and you disagreeing with what the camera "thinks" is in focus:

The AF points are quite large, much larger than the red squares indicate in the view finder. Add to this that the AF points may not be aligned perfectly with the position of the red squares and you don't really have any way to figure out what exactly the camera decided to focus on.

On the SR system: It could be faulty I guess, but diid you allow it to come to rest (the SR symbol must come on in the view finder) before you tripped the shutter?

06-25-2014, 08:18 AM   #5
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Hello Ole,

ok, I understand the first one. My glasses may have doubled that problem due to the bigger eye->viewfinder distance and a bad view angle.
Btw., the K-500 does not have the red indicator LEDs for the AF-Spots; only the K-50 has them. Understanding the importance of these in the meanwhile, I'm sorry not to have bought the K-50 for exactly THAT reason - not because of the weather sealing. Well, if the AF works like it did last weekend, I can live with it

Then: Well... not sure!! As explained, MANY pics have been shot in a hurry!
Imagine: There's the parade. You see something. You jump on the street, trying to find a gap in the crowd - and shoot. All that within seconds and with mostly no second chance.
It is very well possible that the SR had not come to rest in many cases. Still I think that 40-50% garbage is too much - not ALL pics have been made like that, and many of those where I had the time to carefully prepare the shot were messed up, too.
All that went away after disabling the SR!

Fortunately, there's an official Ricoh Service Center here in Berlin, so I think I will go there as soon as possible and explain the problem. Maybe they've an idea or heard of the problem before!
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