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12-23-2009, 08:31 PM   #1
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Why only center point focusing for manual lenses?

I just got a nice macro lens that has got silky smooth manual focus (Lester Dine 1:1 macro). However, K-x (and I suppose all Pentax DSLRs) only allow center focus point for it. Is there a technical reason why is this the case? Would be wonderful if we can use other focus points for manual lenses.

Thanks.

12-24-2009, 10:36 AM   #2
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I had the same problem with my K10D, but my K7 allows selection of focus point for manual focus confirmation. This is one of the improvements I really appreciate. I am surprised this has not received more attention.
12-24-2009, 12:11 PM   #3
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QuoteOriginally posted by LightBug Quote
I just got a nice macro lens that has got silky smooth manual focus (Lester Dine 1:1 macro). However, K-x (and I suppose all Pentax DSLRs) only allow center focus point for it. Is there a technical reason why is this the case? Would be wonderful if we can use other focus points for manual lenses.

Thanks.
No expert here, but I would say that the other focus points are more for the AF feature.

Focus, recompose, snap!
12-24-2009, 12:42 PM   #4
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I dunno. I just use the focusing screen and trust my eyes when I have a manual focus lens on the camera.
I'd prefer that the dancing lights would just go away when there is a manual focus lens mounted.

12-24-2009, 01:23 PM   #5
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Hi Lightbug,

My perspective is that there really is no technical reason, but you're really not losing any functionality from the manual focus film days where the only focusing aids were split screens or microprisms, which were at the center of the focusing screen.

When I consider the revenues sacrificed over the years by the continued backwards compatibility of the K-mount, I do not begrudge Pentax for leaving out more advanced features for manual focus lenses -- at least we can still use them with the close to the full functionality that they originally had with the bodies that they were designed for. Owners of other makes cannot nearly claim the same.

Even if their motive was blatantly to attempt to drive users to buy new AF lenses, I'll still give them kudos for not changing the essentials of the mount (and allowing users the option to use some fine MF glass, even if the company would not profit from the sales) as all of the other mfgs did with the advent of AF, leaving previous users with bags full of high quality, expensive, and essentially useless or only very basically functional glass.

. . . just my 2 worth. . .
12-24-2009, 01:46 PM   #6
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I don't think its an issue of Pentax trying to force users to buy new AF glass but the fact that the target group the camera is marketed for is very unlikely to use manual lenses at all. A very large number of people who buy "entry level" DSLR's leave them in full auto all the time.
12-24-2009, 02:04 PM   #7
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QuoteOriginally posted by tkelly Quote
I had the same problem with my K10D, but my K7 allows selection of focus point for manual focus confirmation. This is one of the improvements I really appreciate. I am surprised this has not received more attention.
Wow, that's great... don't know if it is an AF feature - if you can select focus point on MF lens - that is better than focus and recompose (prone to error and changing perspective).

Thanks, I am waiting for my K-7....
12-25-2009, 10:06 AM   #8
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I have the K20D - and I use one of those magnifying eyepieces that work very well, but tend to blur as you get further from the center. So, it really is unfortunate that the center focus confirmation is your only confirmation on manual focus lenses. Not only does focus change when you shift perspective (especially in close focusing and macro modes), but some lenses have significant focus field curvature.

Kudos to Pentax for upgrading the functionality of the older lenses by making the modification in the K-7. Of course, all the K-X users can say that the functionality seems pretty much the same either way (as the body has only center focus confirmation), but that is a not-so-proud "accomplishment" for Pentax. Smart marketing, though, as you will see many a K-X user upgrade triggered by this omission alone.

12-25-2009, 02:02 PM   #9
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Well, just tried with my K7 and a takumar 35mm/2, and focus point is set to center only!

Guess this works with A-lenses only...
12-25-2009, 04:03 PM   #10
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QuoteOriginally posted by dlacouture Quote
Well, just tried with my K7 and a takumar 35mm/2, and focus point is set to center only!

Guess this works with A-lenses only...
I don't get selectable focus points on my K-7 wit my A*200/2.8, so maybe it's only with some lenses.

Scott
12-25-2009, 05:29 PM   #11
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You mean my K100D can use multiple focus points?

Seriously, I switched to spot focus when I discovered I could not focus on a bird in a tree. The camera tried to grab a foreground or background branch. I have never enabled multi-point focus since. But, other people use that feature so I'm glad they have the option.
12-26-2009, 04:23 AM   #12
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QuoteOriginally posted by ScooterMaxi Jim Quote
So, it really is unfortunate that the center focus confirmation is your only confirmation on manual focus lenses. Not only does focus change when you shift perspective (especially in close focusing and macro modes), but some lenses have significant focus field curvature.
Exactly, I noticed this limitation when I tried to use a third-party manual focus only macro lens. I hope selectable focus points for manual lenses become available for K-x via firmware upgrade.
12-26-2009, 08:31 AM   #13
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I have firmware 1.01 on my K-7. Saw no reason to upgrade any further yet. I've just ran across all the menus and never could I find an option that would allow me to turn on focus confirmation for manual focus lenses off-the center. If there is such an option, I'd be glad to be pointed at it.
12-26-2009, 05:32 PM   #14
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Why would you ever want to change the focusing point?


The "manual" way to change your focus point is to point the lens directly at what you want focused, and then re-compose the picture and shoot. All those focus points are for is the autofocus system. If your trying to get the focus capture thing to go off, then use the manual way and when it beeps don't touch the focus ring anymore.

Simple
12-26-2009, 06:51 PM   #15
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QuoteOriginally posted by Raptorman Quote
Why would you ever want to change the focusing point?


The "manual" way to change your focus point is to point the lens directly at what you want focused, and then re-compose the picture and shoot. All those focus points are for is the autofocus system. If your trying to get the focus capture thing to go off, then use the manual way and when it beeps don't touch the focus ring anymore.

Simple
Sometimes focus-recompose will cause subject to not be in focus, especially in close distancing focusing such as macro shots. Hence it's convenient to have selectable focus points even for manual focusing.

Here's some background on why sometimes focus-recompose will cause focus error:

Why Focus-Recompose Sucks

BTW, I don't agree with the title of above link, I use focus-recompose a lot myself, but I would prefer to use selectable focus points whenever it may give me better result than focus-recompose.
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