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02-01-2011, 10:07 AM   #1
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K-5 and Manual Focus

Hi,

I apologize for yet another front focus thread, but I have a question regarding manual focusing.

I recently bought a K-5 and overall think it is way amazing. No regrets and it will be my camera for the next three years!

I like to use old lenses and manual focus a lot, so I bought a Katzeye screen (for the K5) as I had good success with one on my K20D. However, even with the Katzeye I notice a bit of front-focusing at large apertures. For example, with a Pentax-M 50mm 1.4 and shooting at 1.4, correct focus is attained when the screen is ever-so-slightly split in favor of more distance. Although I didn't use a focus chart or anything extremely scientific, I did use a tripod and am pretty sure of the results.

Question 1: From reading some older discussions it is my understanding that focusing screen shims will not help with front focusing. Is this true?

Question 2: If even manual focus is front focusing then is it possible that this could be fixed via firmware? I would think it would have to be a hardware issue and I would have to send it in.

Question 3: Is there a certain manufacturing tolerance that is deemed acceptable? In other words, is it just my tough luck if I want to focus at such wide apertures? I can get used to it and always try to account for it, but would rather not if Pentax can fix it.

Question 4: Out of curiosity I've tried the autofocus micro-adjust global setting at -10. It seems to have zero effect on manual lenses. I realize that it is for "autofocus" lenses, but I thought that by making such an adjustment it would at least alter the AF confirmation that I so often rely on when using older manual lenses.

Thanks in advance for any insight anyone can provide.

Dan

02-01-2011, 02:12 PM - 1 Like   #2
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I would say that this shim definitely helps you.
I just installed thiner shim (washer) in my K5 which solved front focus at manual focusing with the Katzeye split screen (I use KatzEye Plus Split Prism w/Microprism Collar). Now I have compliance between AF and manual focus.

My K5 was delivered (and my previous K7 as well) with 0.40mm washer. I ordered 5 washers between 0.15-0.35 and after some testing I installed 0.25mm one, which gave almost perfect result.

Split focusing screen has nothing to do with the micro AF adjustment.

K5 and K7 have identical part numbers of these washers :

77240.M02200A - 0.10mm
77240.M02200B - 0.15mm
77240.M02200C - 0.20mm
77240.M02200D - 0.25mm
77240.M02200E - 0.30mm
77240.M02200F - 0.35mm
77240.M02200G - 0.40mm
77240.M02200H - 0.45mm
77240.M02200I - 0.50mm

The price is $0.72 each.

You can order them at:
Pentax Division
National Parts Administrator
3500 N. Windsor Dr. Suite-400
Aurora, CO 80011
Ph. (720)988-2653
Fax (303)799-9213
E-Mail: lynn.badillo@wildernestlogistics.com
02-01-2011, 03:59 PM   #3
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Price in France is 4€ each... You think twice before ordering 5 shims!
02-01-2011, 06:48 PM   #4
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QuoteOriginally posted by dlacouture Quote
Price in France is 4 each... You think twice before ordering 5 shims!
What a rip off!!!

02-01-2011, 07:23 PM   #5
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Thanks Jan67. I will order some of these washers tomorrow and give it a try.
02-02-2011, 12:42 AM   #6
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QuoteOriginally posted by babajoof Quote
Question 1: From reading some older discussions it is my understanding that focusing screen shims will not help with front focusing. Is this true?
This is true.
The matte side of the screen is pressed against the prism.
AFAIK, you cannot move the screen closer to the prism.
I don't understand how shims can help here.
02-02-2011, 01:21 AM   #7
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QuoteOriginally posted by blende8 Quote
QuoteOriginally posted by babajoof Quote
Question 1: From reading some older discussions it is my understanding that focusing screen shims will not help with front focusing. Is this true?
This is true.
The matte side of the screen is pressed against the prism.
AFAIK, you cannot move the screen closer to the prism.
I don't understand how shims can help here.
Nope, the shims goes between the prism and screen. And with the K-5 has most probably come out of the factory with a 0.4mm shim, so you will be able to adjust focus in either direction by increasing or decreasing the thickness of the shim used. I had a severe front focus error before changing to a 0.2mm shim and now it is almost perfect (the 50/1.2 seems to requires more accuracy than the 0.05mm intervals, but for other lenses it is fine).
02-02-2011, 02:15 AM   #8
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QuoteOriginally posted by Smeggypants Quote
What a rip off!!!
And I'm not even talking about shipping charges... Which were about 5...

By luck, my K5 does not need shims and is spot on, whereas my K7 would have done with a smaller one, maybe a 0.25 (but I sold it for the K5 )...

02-02-2011, 03:58 AM   #9
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QuoteOriginally posted by Jimfear Quote
Nope, the shims goes between the prism and screen. And with the K-5 has most probably come out of the factory with a 0.4mm shim,
I didn't know this.
Where is this shim?
When I open the screen holder, there is nothing.
Any images of this?
02-02-2011, 05:54 AM   #10
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You can see a little metal frame going around the pentaprism, locked into place by a small lever (just like the focus screen was) located slightly on the side of the main lever.
Quite hard to see, and harder to handle!
02-28-2011, 10:30 PM   #11
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QuoteOriginally posted by Jan67 Quote
My K5 was delivered (and my previous K7 as well) with 0.40mm washer.
How can you tell what size came with the camera? is it stamped on the part?
03-01-2011, 06:40 AM   #12
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QuoteOriginally posted by GregK8 Quote
How can you tell what size came with the camera? is it stamped on the part?
Measured it with Micrometer.
04-28-2011, 02:06 PM   #13
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QuoteOriginally posted by Jan67 Quote
I would say that this shim definitely helps you.
I just installed thiner shim (washer) in my K5 which solved front focus at manual focusing with the Katzeye split screen (I use KatzEye Plus Split Prism w/Microprism Collar). Now I have compliance between AF and manual focus.

My K5 was delivered (and my previous K7 as well) with 0.40mm washer. I ordered 5 washers between 0.15-0.35 and after some testing I installed 0.25mm one, which gave almost perfect result.

Split focusing screen has nothing to do with the micro AF adjustment.

K5 and K7 have identical part numbers of these washers :

77240.M02200A - 0.10mm
77240.M02200B - 0.15mm
77240.M02200C - 0.20mm
77240.M02200D - 0.25mm
77240.M02200E - 0.30mm
77240.M02200F - 0.35mm
77240.M02200G - 0.40mm
77240.M02200H - 0.45mm
77240.M02200I - 0.50mm

The price is $0.72 each.

You can order them at:
Pentax Division
National Parts Administrator
3500 N. Windsor Dr. Suite-400
Aurora, CO 80011
Ph. (720)988-2653
Fax (303)799-9213
E-Mail: lynn.badillo@wildernestlogistics.com
Very cool, I wonder if they have replacement LCD screens:

https://www.pentaxforums.com/forums/pentax-dslr-discussion/140200-lcd-screen-...ment-part.html
07-05-2011, 06:37 AM   #14
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QuoteOriginally posted by dlacouture Quote
And I'm not even talking about shipping charges... Which were about 5€...

By luck, my K5 does not need shims and is spot on, whereas my K7 would have done with a smaller one, maybe a 0.25 (but I sold it for the K5 )...
"By luck" actually refers to the manufacturing tolerances of Pentax - 0.25 mm is an awful lot in the camera business. Since all parts involved come from Pentax, they should adjust for the user. OK, shipping a camera back and forth is more expensive. I have a Leaf camera back that is off 0.3 mm which is horrible without shimms infront of the camera back. Well, Pentax offers shims to solve the problem.

Did any of you try a lens align focus control tool to figure out how much shimming is needed for a certain offset.

And a hint. Image sharpness on the focusing screen is an inverted focusing problem. Use a lens with short focal length and large aperture to optimize results. A long focal length lens has a thin extent of sharpness in object space, but a fairly long extending barral distance to move from close up to infinity. A short focal length lens travels only by a very short distance from close up to infinity, small shim distances have much greater effect here.

Last edited by zapp; 07-05-2011 at 06:58 AM.
07-17-2011, 11:10 PM   #15
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User Installing Focus Screen Shims (Washers)

How are shim-washers changed?

Is there any tutorial on how to do this, preferably with photos and/or video?

Is this a Pentax recommended user procedure?

Does the K-5 have more than one available focus screen, and is it user-changeable per Pentax?

Does changing a focus screen or shim-washers void the Pentax warantee?
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