What MTF in K10D does exactly?

[ioannis papadogiannis]

One question and one coment.

1)In the menu at custom setting there is the choise of program line and there

is the MTF priority program.Does anyone knows

what it does because the manual does not say much.

 

2)Before three days i bought the DA 16-45 f/4 extremelly good lense much more

better than the DA 18-55.

 

Thank you in advance.

[andrewg_ny]

I don't think we know <I>exactly</I> what the MTF does, other than that each FA, FA-J, D-FA, and DA lens is encoded with the aperture at which the lens will be sharpest and the AE logic will do what it can to "prefer" shooting at that aperture. I don't know whether there is a single number for this, or if it might vary based on zoom focal length. The actual program line would depend on which lens is fitted. The program AE logic has many factors (focal length, manual/auto ISO selection, exposure compensation, manually/auto shutter speed) that it would also consider. Presumeably if you were to shoot in light that isn't too dark or too bright for the configured ISO, it would shoot at its sharpest aperture.

[johnmarsden]

MTF stands for something like 'Modular Transfer Function' a lens description parameter (no doubt someone will tell us what it really stands for) - but in essence it is the aperture that Pentax have decided their lenses work best at realistically reproducing an image. This then defines a program line of speed and aperture. For me its a no brainer - just select this as your preferred option for progam mode and forget about what MTF actually stands for (which you can see is what I have done).

 

If you have problems sleeping here is a link

 

http://www.photodo.com/topic_108.html

 

Agree the 16-45 is a lovely lens. The 18-55 sits on my spare body just because you have to keep it somewhere.

[mountainvisions]

pentax tested the lenses for optimum performance as various focal lengths and apertures.

 

the MTF picks the highest resolution aperture for any given lens based on focus distance and focal length.

 

it essentially avoids the lenses weak spots giving you optimal results from any given SMC lens with electronic coupling.

 

i'd think this is better for the lower end lenses and for zooms. primes are typically always good from 2.8-16 so it's not all that hard to pick a good aperture based on the DOF needed. But zooms can be trickier and I think the MTF is useful while using zooms.

 

BTW, this isn't new. Pentax has had it since at least the mid 1990's.

[johnmarsden]

Your right Justin, the mtf option was (is?) available on the Pentax Z1p. Do you know if they had it before this? I go mine in 1995 or 6.

[mountainvisions]

John,

 

The PZ-1P was my first AF camera so I don't know about prior to this. It was a program line CF with the Z-1. I got mine in 1998.

 

I believe any camera with Program line CF after this should have had it. I know the MZ-S and the ist 35mm have it.

[tom_fox1]

<p>It was on the Z-1 (PZ-1) in 1991. I think it was introduced on this camera.</p>