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02-12-2011, 04:52 PM   #541
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QuoteOriginally posted by Class A Quote
Regarding the distance to the target, doesn't it ultimately depend on which kind of situation (close focusing, infinity, general use) you want the best focus/compromise? I understand it is not always possible to get a setting that works best for all distances so my advice would not be to take a generic distance but think about in which situations focus would be most critical for one personally and than use a corresponding distance during adjustment. It may mean that one arrives at a setting that won't be useful/optimal for general use, though.
You are right, again

My comment is meant in a situation where distance is chosen pragmatically: close enough to obtain an uncluttered center. In many cases, that's closer than the important use case. 30x was just a hint when no other distance is obviously better.

With respect to other questions: I'll answer them when the paper goes online.

02-13-2011, 08:53 AM   #542
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OK all, just another bad news : I've just found out that under pure fluorescent lighting (fluo strips), my k5 severly back-focuses...

I had to apply a +7 AF correction to get proper focusing...
02-13-2011, 10:12 AM   #543
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QuoteOriginally posted by dlacouture Quote
OK all, just another bad news : I've just found out that under pure fluorescent lighting (fluo strips), my k5 severly back-focuses...

I had to apply a +7 AF correction to get proper focusing...
Let the hysterical piling on and 100 threads of complaints begin!
02-13-2011, 05:37 PM   #544
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OK, I have been now trying for two days to try and test this, and all I have found is that when the DOF for a particular lens is a centimeter, there is margin for error in the process.

If the AF has to focus the lens on a closer target, I tend to get back focus, if t has to focus on a target further away than it's current setting, it tends to front focus, but not all the time. If I let the camera pick the focus spot, it always front focuses, if I use the center sensor only, I get the variability in results. Sometimes it is spot on, so all I seem to be able to determine is that there is some variability in the AF system, and if we are talking about a 1cm DoF, then we are probably talking microns in terms of the change in position of the lens wrt the target.

Is it possible that this is all within the spec of the K-5 as a "Prosumer" camera (as opposed to a "Pro" camera)? Are we just asking too much?

02-13-2011, 05:57 PM - 1 Like   #545
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QuoteOriginally posted by GregK8 Quote
OK, I have been now trying for two days to try and test this, and all I have found is that when the DOF for a particular lens is a centimeter, there is margin for error in the process.

If the AF has to focus the lens on a closer target, I tend to get back focus, if t has to focus on a target further away than it's current setting, it tends to front focus, but not all the time. If I let the camera pick the focus spot, it always front focuses, if I use the center sensor only, I get the variability in results. Sometimes it is spot on, so all I seem to be able to determine is that there is some variability in the AF system, and if we are talking about a 1cm DoF, then we are probably talking microns in terms of the change in position of the lens wrt the target.

Is it possible that this is all within the spec of the K-5 as a "Prosumer" camera (as opposed to a "Pro" camera)? Are we just asking too much?
Yep, I'm asking too much for a camera to AF correctly and come without globs of glue on the sensor. But what the hell, what's $1,500 amongst Pentax and its loyal customers.
02-13-2011, 06:19 PM - 2 Likes   #546
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QuoteOriginally posted by donallison13 Quote
But what the hell, what's $1,500 amongst Pentax and its loyal customers.
As always, your contribution to technical issues is well-reasoned and brilliantly argued.
02-13-2011, 07:48 PM   #547
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QuoteOriginally posted by GregK8 Quote

Is it possible that this is all within the spec of the K-5 as a "Prosumer" camera (as opposed to a "Pro" camera)? Are we just asking too much?
What is disturbing is that you are asking these questions based upon your experience with YOUR copy of the K-5.

With respect you should think to allow for the fact that maybe the low light FF fault may not be equal or even present in every copy.

My K-5 has a low light FF problem. It's consistently reproducible. My K20D and K10D have no such problems in the same level of light
02-13-2011, 07:58 PM   #548
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QuoteOriginally posted by GregK8 Quote
Is it possible that this is all within the spec of the K-5 as a "Prosumer" camera (as opposed to a "Pro" camera)? Are we just asking too much?
I don't think it is too much to ask for that the current flagship models does not show 6cm front focus (folder image post by Blende8) in a situation that the K20D masters.

02-13-2011, 08:24 PM   #549
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QuoteOriginally posted by Class A Quote
I don't think it is too much to ask for that the current flagship models does not show 6cm front focus (folder image post by Blende8) in a situation that the K20D masters.
Well, I am going to just chalk my experience up to saying I guess my individual camera does not have this problem, and then politely excuse myself from the discussion so as not to feed the animosity.

I do believe that there are people that experience this problem, I am not trying to say it is imagination, just that I personally cannot recreate it in a repeatable and predictable way.
02-13-2011, 10:35 PM   #550
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QuoteOriginally posted by GregK8 Quote
Well, I am going to just chalk my experience up to saying I guess my individual camera does not have this problem, and then politely excuse myself from the discussion so as not to feed the animosity.
Falconeye might be interested in your measurements, just like he's interested in Christine Tham's measurements. Maybe you can help by not leaving the thread?
02-14-2011, 01:31 PM   #551
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Well, I try K-5 with my lens too. In my opinion all is OK:

DAYLIGHT:
1. K-5 FA77 daylight


2. K-5 FA43 daylight


3. K-5 DA*50-135 daylight (at 135)


4. K-5 DA*200


5. K-5 DA*16-50 daylight (at 50)


INCANDESCENT LIGHT (some photos, all OK)
1. K-5 FA77 night


2. K-5 DA50-135 night (at 135)


CANDLE LIGHT

1. K-5 FA77 Candle


2. DA*50-135 Candle (at 135)
02-14-2011, 01:44 PM   #552
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QuoteOriginally posted by MCR Quote
Well, I try K-5 with my lens too. In my opinion all is OK:
Maybe it is, maybe not. The EXIF data seems to be stripped so there's no way to tell what light level (EV) any of these were shot at.

Of course, if you're happy, that's all that really matters.
02-14-2011, 02:08 PM   #553
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QuoteOriginally posted by areidjr Quote
Well, I try K-5 with my lens too. In my opinion all is OK:
Check out my post #458 where I describe a quick test that will show you in about 5 minutes whether you have the FF issue or not.

I am interested in your results...
02-14-2011, 02:25 PM   #554
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QuoteOriginally posted by areidjr Quote
Maybe it is, maybe not. The EXIF data seems to be stripped so there's no way to tell what light level (EV) any of these were shot at.
Of course, if you're happy, that's all that really matters.
Exifs was stripped by flickr in smaller size; original size has exif : AF-k5-test - a set on Flickr
No "maybe is" - all is ok (not only in chart tests).
02-14-2011, 02:36 PM   #555
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So have Pentax silently fixed the problem in newer cameras, or is it a random thing and sometimes a good camera pops out?
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