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04-29-2008, 05:12 AM   #1
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How does back focus work?

I noticed this past weekend that, while shooting some close ups, I get a pretty pronounced back focus. With the 17-70, I was pretty much on top of the flower, and it was focused about 1-2mm behind where I was trying to focus. I'll try to post a sample after I reshoot, as in my frustration, I think I deleted all the samples. Is this a normal amount? I was thinking about it and it seems that the back focus would get worse as the distance gets longer, however the in focus range would get larger too. Is that others findings?

I am think of sending this in to Pentax to get repaired, as the bottom plate is cracked as well. Any idea of what this may run when out of warranty?

Thanks,
Scott

04-29-2008, 05:34 AM   #2
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Hi Scott

My Ford Focus driving friend says this thing really is all a load of old auto 'hocus-pocus'......sorry about that, but the opportunity was simply too good too miss.......lol !
You can always revert back to v 1.1 of the K10D's operating firmware, which has an option to adjust both front or back focus anomalies. Failing this remedy, why not invest in a decent split-circle microprism screen from a supplier such as Katzeye and use manual focussing instead ? I know it sounds like a royal PITA, but where critical focussing of close-up subject matter is concerned, there really is nothing better. Hope this helps a little.....

Best regards
Richard

Last edited by Confused; 04-29-2008 at 05:39 AM.
04-29-2008, 06:27 AM   #3
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Call me a pickie but of I spend $$ on a K10D, like I have, I want it to focus sharp and clean without having to go into a manual mode. Is that too much to ask for?
04-29-2008, 06:35 AM   #4
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Here is a sample (please ignore the wb issues - it was COLD this morning!). I actually focused on the out of focus blob in the center.

Next I will try the charts and see if I can quantify this (and verify my suspicions on distance/amount/length).

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04-29-2008, 08:03 AM   #5
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QuoteOriginally posted by sabarrett Quote
I noticed this past weekend that, while shooting some close ups, I get a pretty pronounced back focus. With the 17-70, I was pretty much on top of the flower, and it was focused about 1-2mm behind where I was trying to focus. I'll try to post a sample after I reshoot, as in my frustration, I think I deleted all the samples. Is this a normal amount? I was thinking about it and it seems that the back focus would get worse as the distance gets longer, however the in focus range would get larger too. Is that others findings?

I am think of sending this in to Pentax to get repaired, as the bottom plate is cracked as well. Any idea of what this may run when out of warranty?

Thanks,
Scott
Pentax fixed the back focus problem with one of my K10D bodies and my 21mm DA lens and they replaced the baseplate which had developed a chip. But both lens and body were still under warranty. Still, I personally feel they should at least replace your baseplate at no charge.

As for your closeup shot, I think manual focus is usually better for subjects like that. Even at its best, autofocus is less than perfect.

Richard
04-29-2008, 09:21 AM   #6
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Does not work in my case, MF that is.

The photo is focused in the finder, they way i want it, but not in the actual picture. Mine are like the sample, important bit OOF, and the bit behind in.

As i say, the bit i want, looks focused, but its not, in AF or MF.

When my K10D gets back tonight from a loan out, it and the new DAF 50 are going back, for round three.

If its is not solved by this return, i'll start buying more Nikons.

Dave
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