06-10-2011, 06:01 PM
[quote name='Brightcolours' timestamp='1307689957' post='9115']
You can't all too accurately compare the numbers, especially when the lens tests have been done a long time apart.. Different RAW converters and other factors change the outcome a bit. The numbers, they represent what is possible with the sensor the lens is tested with... the maximum possible with a sensor is the maximum figure on the vertical bar. So, yes, the numbers will be lower for a K10D.
You can however globally compare the bar heights from review to review. When comparing, don't do it too precise, different RAW converter generations, lens sample variations and other factors influence the exact outcome a bit. Look at for instance the 70mm f2.4 on both bodies:
K10D:
![[Image: mtf.gif]](http://www.opticallimits.com/images/8Reviews/lenses/pentax_70_24/mtf.gif)
K5:
![[Image: mtf.png]](http://www.opticallimits.com/images/8Reviews/lenses/pentax_70_24n/mtf.png)
You can see that as a trend, both outcomes are pretty close. But the K5 test shows a bit higher center resolution. Why that is, I can't tell you. Sample variation, newer RAW conversion, progress in measurement system...
Bottom line, it is not super important to compare down to the last millimeter. Look at the general trend, and you do get a good idea how lenses compare. And yes, sharpness wise the 300mm f4 and 300mm f4.5 are very similar.
[/quote]
Thanks very much for your pompt and detailed reply. I really appreciate both the time and effort you have put into replying, and your willingness to share your understanding. I suspected that the numbers couldn't be easily compared accurately because of the different sensors. My K5 records much more very fine detail in macro shots than do my K10D and K20D.
I did try to compare the test results you've shown here, as well as those of the DA40. I couldn't find any easy correlation between the sets of numeric results for either. I noticed the lenses were supplied for testing by different people and thought it probable that sample variation might be involved. But I had totally failed to consider the difference in raw converters, or advances in the software used in testing.
I had suspected that the graphs would give me the best idea of how the lenses compare. It is good to have that suspicion confirmed, and also to know that the sharpness of the lenses are very similar. Because of some truly exceptional shots with the DA I've seen on the Web I had wondered if I might benefit from replacing the F with the DA. Sharpness and background blur quality were the only aspects of lens quality that I thought might be better with the DA, since I've never noticed a CA or vignetting problem with the F lens and autofocus has always been spot on (even with the K10D). Because of the excellent autofocus I don't need the DA lens' quick adjust focus. And Klaus has shown the DA has the same problem with bokeh that I sometimes see in shots from the F. The DA is heavier than the F, and the only remaining point I can think of where the DA is better than the F is it focuses a bit closer. I don't need the DA for this since I have I never shoot closeups with the F. Because of all of this I won't be replacing the F with the DA. You and Klaus have saved me at least $1500. Maybe now I can afford to get the 60-250 as my zoo lens instead of the 55-300.
Again, my sincere thanks to you (and Klaus).
You can't all too accurately compare the numbers, especially when the lens tests have been done a long time apart.. Different RAW converters and other factors change the outcome a bit. The numbers, they represent what is possible with the sensor the lens is tested with... the maximum possible with a sensor is the maximum figure on the vertical bar. So, yes, the numbers will be lower for a K10D.
You can however globally compare the bar heights from review to review. When comparing, don't do it too precise, different RAW converter generations, lens sample variations and other factors influence the exact outcome a bit. Look at for instance the 70mm f2.4 on both bodies:
K10D:
K5:
You can see that as a trend, both outcomes are pretty close. But the K5 test shows a bit higher center resolution. Why that is, I can't tell you. Sample variation, newer RAW conversion, progress in measurement system...
Bottom line, it is not super important to compare down to the last millimeter. Look at the general trend, and you do get a good idea how lenses compare. And yes, sharpness wise the 300mm f4 and 300mm f4.5 are very similar.
[/quote]
Thanks very much for your pompt and detailed reply. I really appreciate both the time and effort you have put into replying, and your willingness to share your understanding. I suspected that the numbers couldn't be easily compared accurately because of the different sensors. My K5 records much more very fine detail in macro shots than do my K10D and K20D.
I did try to compare the test results you've shown here, as well as those of the DA40. I couldn't find any easy correlation between the sets of numeric results for either. I noticed the lenses were supplied for testing by different people and thought it probable that sample variation might be involved. But I had totally failed to consider the difference in raw converters, or advances in the software used in testing.
I had suspected that the graphs would give me the best idea of how the lenses compare. It is good to have that suspicion confirmed, and also to know that the sharpness of the lenses are very similar. Because of some truly exceptional shots with the DA I've seen on the Web I had wondered if I might benefit from replacing the F with the DA. Sharpness and background blur quality were the only aspects of lens quality that I thought might be better with the DA, since I've never noticed a CA or vignetting problem with the F lens and autofocus has always been spot on (even with the K10D). Because of the excellent autofocus I don't need the DA lens' quick adjust focus. And Klaus has shown the DA has the same problem with bokeh that I sometimes see in shots from the F. The DA is heavier than the F, and the only remaining point I can think of where the DA is better than the F is it focuses a bit closer. I don't need the DA for this since I have I never shoot closeups with the F. Because of all of this I won't be replacing the F with the DA. You and Klaus have saved me at least $1500. Maybe now I can afford to get the 60-250 as my zoo lens instead of the 55-300.
Again, my sincere thanks to you (and Klaus).