Some K, M and A-lenses on K-1

After the M 42 Takumar era was over in 1975, Pentax renamed their lenses Pentax SMC. (Super Multi Coating.) The new mount was called K-mount and has been the Pentax mount ever since, although improved with new electronic functions. Thus we are fortunate to be able to use all earlier lenses on today's DSLRs.

The K-lenses were made from '75 till the smaller M-cameras took over in '76. These smaller cameras needed smaller lenses, and the M-lenses were introduced. There were no technical differences.

The M-system reigned till 1983, when the fully automatic A-system, with automatic A-lenses, substituted the M-line. 

We will have look at some of those lenses. As one will see, all of the tested lenses are very good! 

A scale from 1-10 is used for sharpness. 
Very soft is used when points are <6
Soft is 6-6,5
Fair is 7
Good is 7,5-8
Very good is 8,5-9
Excellent is 9,5-10.

The very best lenses are marked with a 🤪, the very good ones with a😀, and the good lenses with a 🙂

K 24/2,8:😀 Centre: Very good wide open. Excellent from 4.
             Corners: Soft wide open, fair at 4. Good at 5,6 and 8.

K 55/1,8: 😀Centre: Soft wide open. Good at 2,8. Very good to excellent from 4 to 8.
                   Corners: Soft at 1,8. Fair at 2,8. Good from 4 to 5,6. Touches very good at 8.

M 50/2: 😀 Centre: Good at 2. Tends to excellent at 2,8 and 4. Very good at 5,6 and 8.
                  Corners: Good from 2 to 4. Very good at 5,6 and 8.  

M 50/1,7:🤪 Centre: Good at 1,7. Very good from 2 and 2,8. Excellent from 4.

              Corners: Good at 1,7 and 2. Very good from 2,8 to 4. Excellent at 5,6 and 8. 

M 105/2,8: 😀 Centre: Good at 2,8. Very good at 4 and 5,6. Excellent at 8.
                      Corners: Very good wide open to 5,6. Excellent at 8.
                                  Tends to have sharper corners than the reference D FA 100/2,8!

M 200/4: 😀Centre: Good at 4, very good from 5,6, with a peak at 8. (Tested also at 11)
             Corners: Sharpness as good as in the centre!

M 75-150/4: 😀tested at 150mm:  Centre: Very good at 4. Touches excellent at 5,6 and 8.                    Very good at 11.
                 Corners: Very good from 4 to 11. A surprisingly good lens!

A 50/1,4: 😀Centre: Soft at 1,4 and 2. Good at 2,8. Excellent from 4.
             Corners: Fair at 1,4 and 2. Good at 2,8. Very good at 4. Excellent at 5,6 and 8.

A 28-80/3,5-4: