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06-14-2009, 11:17 AM   #1
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K20D and non-A lenses.

Hello everybody, I'm new here. Just bought a K20D with de 18-55 II kit lens. The combo price was very good, but the lens isn't all that impressive (although it's perfectly usable).
I was hoping I could use some old fixed lenses on it, and knew there were limitations. I've read several posts about the subject, and there's a lot of information, but I'm not sure if I'm getting it right.
For what I've read, the A lenses work without the obvious limitation of no AF, that seems quite straightforward.
And now, for the rest of the manual lenses, let's see if I got it right: the camera would provide stopped down metering when in M mode by pressing the green button, and it should work BUT there's a glitch with stopped down metering using the standard K20D focusing screen which makes exposure erratic. So, if I buy a non A lens, the green button method is the theoretical way to go, but in practice I should expect exposure errors?
(I was almost running to get a 135/2.5 I saw cheap, but now I'm not so sure about it).
Is this right or are there any corrections?
Thanks in advance for any info!!!

06-14-2009, 11:44 AM   #2
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There is a lengthy article at the top of the Beginner's forum. Have a careful look at that and most of your questions should be answered. Second note, the exposure errors are well known with the K10 and K20. I solved my problems by substituting the LL-60 focusing screen for about $55. Many others did so, and it took them quite a while to converty me, by the way.
06-14-2009, 01:52 PM   #3
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Agree with Albert.
Green button metering should be better with the LL-60 screen, but not far off if you don't have one.
Give it a try under different lighting conditions and see how it performs...
06-15-2009, 11:54 AM   #4
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Thanks very much for the feedback, I guessed this topic would be treated somewhere, but I was looking only in the DSLR section. Well, I guess I'll have to try them and learn.

06-15-2009, 01:31 PM   #5
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max

the 135 F2.5 is a great lens.

As to the metering, i sugfgest you check the following post to explain what to expect, and how to test your lens when you get it.

ifg you know what to expect K lenses are easy to use, and just check the histogram when shooting to validate your selection

https://www.pentaxforums.com/forums/241716-post69.html
06-15-2009, 03:09 PM   #6
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Excelent Lowell, that's very detailed information!! Should I assume then that using the original focusing screen of the K20D (in your example it's a K10, any differnce?) I could get a correct exposure with any lens doing a green button measurement with the lens set at f/3.5 and then extrapolate?
By the way, i do own some Canon fd gear, and I have a 135/2.5 lens, that's part of the temptation of the Pentax version. These were so beautiful, and I'm sure they can produce incredible results (the canon was great). and the focusing and the view was a pleasure too.
You can tell the kit lens is a little hard to swallow when you are used to the other stuff.
06-15-2009, 04:09 PM   #7
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Max

I have actually plotted all my lenses so I know how they behave.

I use a block wall in sunlight,. and run through every exposure click, using green button to meter.

to answer your other questions,

yes if you meter at F3.5-F4 it should be good and then set your stops / exposure from that.

from what I understand the K20D uses the same screen exactly as K10D, and several others have confirmed similar findings.

the new K7 has some form of -60 screen and there are tests shiwing similar performance to my *istD.

Metering was a big reason I didn't go for a K20, other than I usually try to wait 3 years between them, and more than one body. there were 6 cameras released between the *istD and K10D, but only the K200 (downgraded K10D) between the K10D and K20. Now with the K-M (K200) and K7 there is enough progress to consider a new body and although more expensive, I an considering heavily the K7
06-16-2009, 08:58 AM   #8
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Max, I mostly agree with the other posters. I own the Pentax K 135 F2.5 and I too, find it to be a great lens. I have also found that it meters slightly better on my K20D than it did on the K10D. Don't know why. I've just changed to a Katz-eye focus screen and have yet to test the 135mm on that. I will post here when I have.

NaCl(am hoping that the K-7 clears up this annoying problem)H2O

06-20-2009, 11:39 AM   #9
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I just got a 135/2.5 lens, finally. Most of what was said here is pretty accurate. I'd say mine gets a good green button reading at 4 or 5.6, tending to overexpose 1 stop above f/8 and underexpose 1 at 2.5/3.5. With that in mind, it's quite easy to manage.
The lens is great. Very sharp. It can feed the K20D sensor and may be a little beyond, from some very sharp shots I got in the first try. But it's already a very demanding game, even with stabilization on, it gives you more than you can handle, literally, most of the time.
And the gradation and colors are beautiful. The newer lenses have better coatings, for sure, but most of the time images are a little "hard" (color and contrast are a bit too strong) for my taste. This one I really like. Well, just a first impression.
Thanks again, very much, for all the useful info!
06-22-2009, 11:01 PM   #10
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QuoteOriginally posted by max889 Quote
I just got a 135/2.5 lens, finally. Most of what was said here is pretty accurate. I'd say mine gets a good green button reading at 4 or 5.6, tending to overexpose 1 stop above f/8 and underexpose 1 at 2.5/3.5. With that in mind, it's quite easy to manage.!
I'd say that the above is about what I find with my K 135/2.5 on my K20D (with a Katz-Eye screen).
06-23-2009, 12:44 AM   #11
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Regarding the k20, metering suffers from the same focus screen, and so is also greatly improved by the LL60...
Only thing that was improved IMO is the matrix metering behavior, as it is much more constant across wide lighting situations, whereas the k10 was easily fooled by contrasty scenes.
06-24-2009, 06:53 AM   #12
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One note about metering with the green button : it's really, really easy to have the camera evaluate metering, take a test shot, and work from there. If your scene does not change for a while, you have to set your exposure once, and you're good to go.

I learned to trust the green button a bit, my eyes much more, and to adjust ISO and shutter speed as needed. I once went to a football game, adjusted the exposure once with the green button, and tweaked the settings as time passed during the whole afternoon without touching the green button again.
06-24-2009, 09:19 AM   #13
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I'm well aware of the fact that this method is not everybody's cup of tea, but I, shooting exclusively with a variety of M43 screwmount & manual K-M0unt Pentax lenses, avoid the mismatched metering problems by using hand held meters.
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