Think this one John, 24mm - 50mm - 100mm.
I certainly love the 100mm range.
Then something in the 24mm and around 50mm should be nice, I'm not to exact about these numbers though 1 or 2 mm smaller or bigger isn't that bad.

With current DA lenses my choice would be.
DFA 100mm
DA* 55mm
DA 21mm ltd

That's quite strange since your numbers are of course without the crop factor for the field of view, so I at least am liking longer lenses then what is or was normal.

I can agree partially on that Martin, the term "distinctive background areas" is too undefined

Lets keep it simple and keep it with OOF highlights only.


From left to right - bad - bad - average - good bokeh.

You can not make it simpler as that, it's you that makes it far more complicated and putting far more meaning in the word then it really is

The only thing we have to fear is fear itself.

Don't know how the contacts really work but maybe some are multiple purpose???

The power required for the SDM goes over the PZ contacts as you can see in the first image "power-zoom power contacts"

I think the SDM and the Power-zoom motor are DC motors so the current decides what direction they turn, makes sense right?

Just to make all contacts complete.
We have r3, m2, *, m1, r2, r1 and a seventh contact.


More info about that contact here link

So what are needed for SDM???
PZ contacts - delivers power
digital information contact - At the time the KAF mount was introduced only F-lenses and newer have that contact so I assume that the camera will use the Screw-drive to focus the lens when the camera gets digital information and with the SDM I assume that is in the digital information so when the camera reads it's a SDM lens it will use SDM instead of the screw-drive. Does that make sense:
.... hmmm.... anymore contacts you think that are needed?
Focusing sensing is done inside the camera by the AF system so it simple moves the lens in focus or till it hit the focus limit and then reverse the direction. When it hits the limit you clearly hear it hit the limit and then it almost seems like it is thinking and then reverses.
This makes position demand unneeded, it simply moves between the full focus range and if it doesn't lock on it's out of the focus range.

Really read this Understanding Boke by Harold M. Merklinger
It's an article on luminous landscape by Harold M. Merklinger 1996, he has writing a lot of books about focusing so I believe he knows what he is writing about.
If you want to read one of his books link

So read the article Understanding Boke and then we will talk further

Yes the camera has it but the lens doesn't so what kind of information would the TC need to carry if the the lens doesn't have the contact?

Nope



I believe the extra contact is the m2 (FCM contact) on a K-A mount



From bdimitrov.de link
Aparently r1 r2 r3 encode the aperture range in half stops, m1 m2 encode the minimum aperture.

Sorry I thought the right one was from a SDM lens, it looks like the collar of the DA*300mm you see in the background so I drew conclusions

But as you can see the SDM lenses doesn't even have the extra contact the SHQ TC has so that isn't the problem since the MC seems to have alll the contacts that are needed.
So somthing else is going on.

It can be that the AF is not calibrated correctly.
With the K10D there is a special Debug mode but you can only adjust the whole focus systen for all lenses while with the K20D you can do it for 20 seperate lenses. So find out if it's just one or that all the lenses are out of focus.

IF it's just one you need to send it to Pentax with the lens and they will calibrate it for you. If it's all the lenses you can do it yourself.

Martin, who said that a poor bokeh is bad for a photo???
Sometimes a poor bokeh is fitted for certain photos and sometimes not, that's subjective. If the bokeh is fitted for the photo or not but not the quality of the bokeh.

And that's the comment in fig.3. It's commonly accepted that the older lens designs with lot's of blades
are capable of producing the smoothest bokeh.
No it doesn't say that, what has number of blade to do with distribution of the light???
Certainly wide open all apertures are round regardless the number of blades
(from below Luminous landscape: Whether a lens exhibits the 'bright ring' or 'bright core' circle of confusion depends upon the details of how the spherical aberration is corrected.)

Wikipedia link
Bokeh characteristics may be quantified by examining the image's circle of confusion. In out-of-focus areas, each point of light becomes an image of the aperture, generally a more or less round disc. Depending how a lens is corrected for spherical aberration, the disc may be uniformly illuminated, brighter near the edge, or brighter near the center. Lenses that are poorly corrected for spherical aberration will show one kind of disc for out-of-focus points in front of the plane of focus, and a different kind for points behind. This may actually be desirable, as blur circles that are dimmer near the edges produce less-defined shapes which blend smoothly with the surrounding image.

luminous-landscape link
The 'bright ring' effect is what I suggest leads to 'bad boke' and especially 'ni-sen'. The 'bright ring' type circle of confusion allows some aspects of detail in the original scene to show up in out of focus areas and even to be replicated. An extreme example of the 'bright ring' circle of confusion is that produced by a typical mirror lens. Figure 10, by Kevin Hawk, shows a background out-of-focus spire as a very distinct double image.

The 'bright core' type circle of confusion is observed with the 35/2 Summicron on both sides of the point of focus. I suggest the bright core circle of confusion leads to pleasant out-of-focus images, provided the core is not too strongly concentrated. If the central bright core is too small, again some fine detail is painted into out-of-focus areas — although at least it is not replicated.

It would be an over simplification to say that normal spherical aberration (as for the Imagon) leads to 'good boke' while over-corrected spherical aberration leads to 'bad boke', but it is probably true that out-of-focus backgrounds are more likely to be encountered and are potentially more disturbing than out-of-focus foregrounds.

Whether a lens exhibits the 'bright ring' or 'bright core' circle of confusion depends upon the details of how the spherical aberration is corrected.

No problem Pauly, thought that you said you liked the full frame as well (more) so hence the question.

I like that one Bob, better then the first ones you posted to be honest.