[spystyle]

Hey I just discovered MTF program mode on my (new to me) K20.

It's really exciting to me that all my (compatible) lenses will be at their best aperture

What a smart feature I'm stoked to go on a photo walk tomorrow.

At the moment my (seemingly) compatible lenses are :

1. Pentax DAL AL 18-55mm 3.5~5.6

2. Sigma DL 100-300mm f/4.5~6.7

3. Pentax F 35-80mm f/4~5.6

4. Pentax FA 28-80mm f/3.5~4.7 (power zoom)*

5. Pentax F 80-200mm f/4.7~5.6

I'm curious if other camera makers have a similar mode, I wonder if Pentax Pioneered this mode. It's confidence inspiring LOL

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For those who don't have MTF mode, I'll tell you the apertures my K20 chose :

1. Pentax DAL AL 18-55mm 3.5~5.6
18mm ~ 30mm = f/5.0
32mm ~ 37mm = f/5.6
40mm ~ 55mm = f/7.1

2. Sigma DL 100-300mm f/4.5~6.7
100mm = f/6.3
108mm ~ 170mm = f/7.1
180mm ~ 220mm = f/8.0
230mm ~ 260mm = f/9.0
280mm ~ 300mm = f/10

3. Pentax F 35-80mm f/4~5.6
35mm ~ 40mm = f/5.6
48mm = f/6.3
50mm ~ 60mm = f/7.1
68mm ~ 80mm = f/8.0

4. Pentax FA 28-80mm f/3.5~4.7 (power zoom)
28mm ~ 31mm = f/5.0
32mm ~ 42mm = f/5.6
43mm ~ 55mm = f/6.3
58mm ~ 80mm = f/7.1

5. Pentax F 80-200mm f/4.7~5.6
80mm = 7.1
88mm = 6.3
93mm ~ 143mm = 7.1
153mm ~ 200mm = 8.0

Of course you could probably make a list like this by looking at MTF charts, but I don't know how to read them LOL

Cheers,
Craig

*Incidentally, power zoom feature works on the K20

[carrrlangas]

Only FA and DA lenses work with the MTF program line. The lenses have relevant information recorded on their chips. I don´t know how the body does it with the sigma or F series and older lenses

[Adam]

AFAIK yes, only Pentax FA/DA/DFA/DA L lenses support MTF mode. All others will just follow the "normal" program line.

[spystyle]

AFAIK yes, only Pentax FA/DA/DFA/DA L lenses support MTF mode. All others will just follow the "normal" program line.

I'll test that now ...

Nope, normal program and MTF program are not the same on the non FA DA lenses I tested.

1. Pentax F 35-80mm
35mm normal = f/5.6
35mm MTF = f/5.6
80mm normal = f/5.6
80mm MTF = f/8

Pentax f 80-200mm f/4.7~5.6
80mm normal f/4.5
80mm MTF = f/7.1
200mm normal = f/5.6
200mm MTF = f/8

Sigma DL 100-300mm f/4.5~6.7
100mm normal = f/4.5
100mm MTF = f/6.3
300mm normal = f/6.7
300mm MTF = f/10

So, the K20d is choosing different apertures for normal program mode and MTF on these unsupported lenses.

[carrrlangas]

Notice that the MTF program line is stopping down the lens 1 or 1 and 1/3 stops consistently (why do you use your camera in 1/3 EV stops? I find 1/2 is far more practical)
If someone had the F and FA version of the same lens we could see the difference. Though small, I guess it would be there.

I just tried the MTF program line on the DA16-50 and it says f/4 for all the range

[spystyle]

I guess we could compare my results with the MTF charts (?)

[carrrlangas]

I guess we could compare my results with the MTF charts (?)

Sure! dou you have the MTF charts for your lens?

Believe it or not, the chips on F lenses do not support the MTF program line. Tha camera, based on focal length might and maximum f-stop (provided by the F lens), must be making an aproximation.

[spystyle]

Hey I learned how to read MTF charts

Czech out this quick video explanation (if you don't know how) :

You Tube

You Tube

Sure! do you have the MTF charts for your lens?

Believe it or not, the chips on F lenses do not support the MTF program line. The camera, based on focal length might and maximum f-stop (provided by the F lens), must be making an approximation.

I don't have any MTF charts, but I'll see if I can find some.