pentax k-x and metering with manbual focus lenses

[jacobmiles]

<p>Hi. I'm very interested in the Pentax K-x, and I'd like to use my 50mm lens from my K1000. Does anyone know if it will meter with manual focus lenses? I know that cameras like the Nikon D300 let you dial in the focal length and its metering modes will still work. Is the same true of this one?</p>

<p>Thanks for any help.</p>

<p>- Jake</p>

[stemked]

<p>Jake.<br>

I don't have the K-X but from what I have read it is not a 'crippled K' mount. Therefore it will meter fine on manual. Now if your 50mm has an A setting you will be able to use a bunch more features (exposed flash settings, aperature priority, etc.).<br>

With my K10D the only time you 'dial in focal length' is if you want to use the image stabolization feature of the camera. I assume the K-X works similar but others are better to address that question.</p>

[orly_andico]

<p>Doug,<br>

You mean it has the aperture coupling cam? and therefore it has a better mount than the K10D / K20D?</p>

<p>That I'd like to see.. on second thought I better visit the local camera store and check for myself.</p>

[andrewg_ny]

<p>The 50mm lens from your K1000 will work, but how conveniently so depends on which 50mm lens you have. If it is a Pentax-A 50, with the 'A' position on the aperture ring, you use that 'A' position all the time and you get full compatibility with all shooting modes.</p>

<p>If it is an older Pentax-M or SMC Pentax that didn't have the 'A' on the aperture ring, you're restricted to shooting in Av wide open only, or in Manual shooting mode with stop-down metering. Basically in 'M' mode, you'll press a button and the lens will stop down and automatically set the shutter speed to match the aperture you select on the lens aperture ring. Also, in this mode you're restricted to center-weighted or spot metering, and the built-in flash will only fire at full power.</p>

<p>In either case you can enter the focal length for purposes of tuning the shake-reduction for your lens but this doesn't affect exposure/metering.</p>

[tomadakis]

<p>It will meter. Plus more functionality depending on which model it is.</p>

[shaloot]

<p>@Orlando - you can go into an <em>actual</em> store and pick up a <em>Pentax</em> camera in your hands?! wow! Where do you live?! :-P</p>

[Tony Evans]

<p>Doug/Andrew,<br>

I'm wondering like Orlando. Are you saying Stopped Down metering works with manual lenses on the k-x? They cetainly don't on the K20D.</p>

[orly_andico]

<p>Somanna, Singapore. Yes there are actual stores with actual Pentax gear. :-)</p>

<p>Although some items are extremely rare, I've been looking for a 50-135/2.8 for many months now. Back in the Philippines (where I am from) they do have the 50-135 in some stores. Didn't buy one the last time I was there..</p>

[andrewg_ny]

<p>Tony, in what sense do they not work on a K20D? On every Pentax digital body I know of (I own *ist DS2, K10D, K20D) you can stop down the lens with a button while in manual mode, usually a green button, or AE-L if the model doesn't have one. The shutter speed is automatically set. Alternatively, you can stop down the lens by holding DoF preview lever and the meter is 'live' while stopping down; in this case the shutter speed is not automatically set but you can change it with the e-dial as you wish. With a non-K-mount lens like M42, you would stop the lens down manually with the lens' auto/man switch + aperture ring.</p>

[Tony Evans]

<p>Andrew,<br>

They do not work in the sense that the exposure chosen is seldom correct, unless the aperture ring is set wide open. I will shortly open a new thread to illustrate this.</p>

[orly_andico]

<p>Tony,<br>

Actually the exposure is seldom correct wide-open. It needs about +2 stops correction. The exposure is generally correct around f/5.6 or so.</p>

<p>This is a well-known failing of the green button. There was some talk that the K-m would fix this, but I have no idea if true.</p>

[alex_kinnan]

<p>I had not heard about any such metering issues with the K20d. Is this common? I get pretty good results using the AE-L button on my *ist DL for metering with manual lenses. Should I expect less decent results if I finally switch to a K10d or K20d?</p>

[orly_andico]

<p>I'm using a K20D and before that, a K10D. The metering issue is trivial to demonstrate. It's there.</p>

<p>So basically all that you get in terms of "backward compatibility" is that the Pentax body can stop down the lens! that's pretty much it. The metering is inaccurate but consistent, hence you can apply a correcting factor, you just have to think a bit.</p>

<p>Ironically, with the very same Jupiter-9 M42 lens, a Canon EOS1000D fared better in Av mode than my K20D. Hmmm.</p>

<p>And yes I have heard that the istDS and friends meter better with these old lenses, than the K10/K20. I did swap the focusing screen in both my K10 and K20 but it didn't improve things. Others have reported differently.</p>