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next PZ lens test report: Pentax SMC DA 70mm f/2.4 Limited
#11
[quote name='joachim' timestamp='1304842363' post='8125']

Pancakes for mirror less are harder than for DSLR. On a DSLR you have between 1 and 2 cm extra distance between the mounting flange of the cam and the sensor. That helps keeping light rays less angled while the lenses are still small.

[/quote]



The Samsung NX 30mm f/2 is very decent

http://www.opticallimits.com/pentax/534-samsung30f2
#12
[quote name='Brightcolours' timestamp='1304887904' post='8139']

And... "the" pancake lenses as a result will not just fit on a camera without that mirror box. Just like with micro 4/3rds and 4/3rds lenses and Sony A-mount lenses on NEX, you need an "extension tube" adapter which makes the camera just as deep again.

BTW, the distance between flange and sensor usually is about 4cm.

[/quote]



Yes, they probably need a new range of lenses.
#13
Recently, there was a short discussion about the transferability of the tests from the K10D to the K-5 ( http://forum.photozone.de/index.php?/top...t__p__7782 ). Following the proposed (simplistic) scaling by maximal resolution leads to a good agreement for the (extreme) borders. The center, however, seems to gain a further boost.
#14
Seen from a slightly different perspective:



The DA 70 ensures the maximal possible resolution of the K-5 in the center of the image at 4 and 5.6 (about 2700 LW/PH). On the K10D, however, the maximal resolution of the sensor (ca. 2350 LW/PH, compare e.g. [email protected], [email protected]) is not fully exploited (4: "only" 2200 LW/PH).



The obvious question: Why?



Maybe the AA-Filter of the K-5 is not so bad after all <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='Wink' /> ...
#15
[quote name='froeschle' timestamp='1304941714' post='8175']

Seen from a slightly different perspective:



The DA 70 ensures the maximal possible resolution of the K-5 in the center of the image at 4 and 5.6 (about 2700 LW/PH). On the K10D, however, the maximal resolution of the sensor (ca. 2350 LW/PH, compare e.g. [email protected], [email protected]) is not fully exploited (4: "only" 2200 LW/PH).



The obvious question: Why?



Maybe the AA-Filter of the K-5 is not so bad after all <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='Wink' /> ...

[/quote]



Hi,

IMO all these comparisons are quite useless. First of all, there are measurements errors, both for lenses and cameras. There are limits of tolerance for both. In FAQ Klaus writes about 5% measure's error, so in fact we should talk about confidence intervals, but not about exact numbers. Second (assuming sample variations), usually for 95% confidence interval you need about/more 30 samples (lenses)(well that depends on dispersion, but let it be) and assuming camera's variation - 30 cameras <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' /> (lets say to evaluate sensor's decentering). This kind of testing might take a while and we can get one review in a couple of years <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' />. The numbers you see represent lens performance, but only represent. Good lens is good, mediocre is mediocre, and that's all.



A.
#16
[quote name='froeschle' timestamp='1304941714' post='8175']

Seen from a slightly different perspective:



The DA 70 ensures the maximal possible resolution of the K-5 in the center of the image at 4 and 5.6 (about 2700 LW/PH). On the K10D, however, the maximal resolution of the sensor (ca. 2350 LW/PH, compare e.g. [email protected], [email protected]) is not fully exploited (4: "only" 2200 LW/PH).



The obvious question: Why?



Maybe the AA-Filter of the K-5 is not so bad after all <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='Wink' /> ...

[/quote]





The AA Filter on the K5 is certainly weaker than on the K10D - it just has a stronger one than the D7000 etc. pp. And the AA filter has a different characteristic - the K10D has an asymmetrical AA filter whereas it's symmetrical on the K5.

We are also talking about 2 different lens samples here. In fact I was quite surprised about the similarities of the results especially because the K5 tests are more accurate due to more measuring spots.



So you are trying to spot contractions that do not exist from a real world perspective.



Klaus
#17
[quote name='arv' timestamp='1305029669' post='8201']

Hi,

IMO all these comparisons are quite useless. First of all, there are measurements errors, both for lenses and cameras. There are limits of tolerance for both. In FAQ Klaus writes about 5% measure's error, so in fact we should talk about confidence intervals, but not about exact numbers. Second (assuming sample variations), usually for 95% confidence interval you need about/more 30 samples (lenses)(well that depends on dispersion, but let it be) and assuming camera's variation - 30 cameras <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' /> (lets say to evaluate sensor's decentering). This kind of testing might take a while and we can get one review in a couple of years <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' />. The numbers you see represent lens performance, but only represent. Good lens is good, mediocre is mediocre, and that's all.



A.

[/quote]

Very helpful perspective. Thanks
#18
[quote name='IanCD' timestamp='1305064549' post='8211']

Very helpful perspective. Thanks

[/quote]



Well I am sure it is not impossible, and after few glorious decades PZ team could pretend for IgNobel for being able to respond a legendary Forums question "Which lens is the sharpest/best?" with a strong scientific background <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' /> .

A.
#19
[quote name='Klaus' timestamp='1304774384' post='8115']

Lovely lens - highly recommended:

[url="http://www.opticallimits.com/pentax/618-pentax70f24"]http://www.opticallimits.com/pentax/618-pentax70f24[/url]

[/quote]



Thank you for your testing.

Hope to see more test report about these FA - limited and other DA - Limited lenses such as 31mm,43mm,77mm;

15mm, 21mm, 35mm marco and 40mm

on the Pentax K-5
#20
[quote name='gxsyth' timestamp='1305797592' post='8602']

Thank you for your testing.

Hope to see more test report about these FA - limited and other DA - Limited lenses such as 31mm,43mm,77mm;

15mm, 21mm, 35mm marco and 40mm

on the Pentax K-5

[/quote]



No, No, No, Yes, Yes, No, Yes.
  


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