[Egg Salad]

Round 1.

Contestants:


.....SMC Pentax 50mm F1.4..............Pentax-F 50mm F1.7........................Sigma 50mm F1.4................+ Pentax DA* 16-50 (just for fun)


First conclusion that I can draw: this will be the first and last time I did a comparison like this. I don't know how many hours I wasted on making the crops, renaming each of them, putting them in seperate folders, then uploading them and reformatting again...
But now I have the lay-out together so maybe I will present the other rounds here as well.

Reminder: this is round 1 - and I have shot 8...

Another thing I have to mention:
even though I focused every lens manually using live view and 4x magnification, the Pentax-F 50mm F1.7 seems to be front focues in this whole series.
So it may not be that representative for this lens' performance.
My 16-50 seems to be decentered...badly. The upper right corners generally look much better but are still poor.

Target as you can see was a plain newspaper taped to my TV (walls aren't nearly as flat). Shots were of course taken with a tripod and mirror lock-up.
But since there is no tethering tool for my camera I had to touch it for every consecutive aperture setting. I tried not to move it but my tripod is highly overstrained holding this quite heavy set-up in place. With the 16-50 it even tilts forwards...

I'm too annoyed to write down my other findings right now, so built up your own opinions.

Done in Lightroom 2.2

Resolution test settings (round 1-7):
White balance reference: Pentax-F 50mm F1.7
White balance set for this lens then applied to the others. Differences you see are really the lenses' coatings!

exposure: +1EV (Exposure setting were the same for each lens. Differences in brightness are the lens' fault!)
black: +5
clarity: +30
contrast: +20
standard sharpness settings

Subject distance ~1.75m
The whole page


All pictures except the first one are just the thumbnail views!
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/1.4
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

f/1.4 upper left corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4



f/1.4 lower right corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4



f/1.4 center
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4

SMC Pentax 50mm F1.4


--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/1.7
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

f/1.7 upper left corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



f/1.7 lower right corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



f/1.7 center
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/2
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

f/2 upper left corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



f/2 lower right corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



f/2 center
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/2.8
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

f/2.8 upper left corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm




f/2.8 lower right corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm



f/2.8 center
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm



--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/4
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

f/4 upper left corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm



f/4 lower right corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm



f/4 center
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm



--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/5.6
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

f/5.6 upper left corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm



f/5.6 lower right corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm



f/5.6 center
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm


If you're not satisfied with my choice of crops then just do the comparison yourself!
Here are the images of round 1 in full size for DOWNLOAD.


Round 2

Subject distance 0.66m

Everything else just like before.

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/1.4
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

f/1.4 upper left corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4



f/1.4 lower right corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4



f/1.4 center
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4



--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/1.7
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

f/1.7 upper left corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



f/1.7 lower right corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



f/1.7 center
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/2
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

f/2 upper left corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



f/2 lower right corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



f/2 center
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/2.8
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

f/2.8 upper left corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm




f/2.8 lower right corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm



f/2.8 center
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm



--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/4
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

f/4 upper left corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm



f/4 lower right corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm



f/4 center
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm



--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/5.6
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

f/5.6 upper left corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm



f/5.6 lower right corner
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm



f/5.6 center
........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm


Here is round 2 for download in full size.
I really encourage you to download them and make your own conclusions.


Round 7 (3 to 6 were resolution tests with my other lenses)


Distance ~0.7m

Settings:
-0.2EV
recovery: 5
black: 5
brightness: +50
contrast: +25
clarity: +20

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/1.4
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4



--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/1.7
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/2
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/2.8
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm



--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/4
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm


--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/5.6
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7..........................................Pentax DA* 16-50mm


Again, full size pictures of round 7 and 8 packed for DOWNLOAD.


Round 8


Distance 0.8m(?)

Settings:

-0.9EV
fill lights: 5
black: 6
brightness: +101
contrast: +37

clarity: +20
livelyness: +20

high tones: -24
middle tones: +2
low tones: -17

standard sharpness setting

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/1.4 and f/1.7 for the Pentax-F
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
f/2
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

........................Sigma 50mm F1.4...............................................SMC Pentax 50mm F1.4.........................................Pentax-F 50mm F1.7



Estimated focal lengths based on my tests:

Pentax DA* 16-50...............45mm
Sigma 50mm F1.4...............47mm
SMC Pentax 50mm F1.4........49mm
Pentax-F 50mm F1.7............51mm

---

Last edited by Egg Salad; 03-15-2011 at 09:10 AM.

[dasuhu]

I'm a little surprised it takes until f/4 till the Pentax prime lenses appear satisfactorily (to me) sharp in the center, unless it's an issue of focusing. Sigma appears 1 stop sharper compared to the Pentax primes (zoom not in the running at all)

Or maybe I'm telling myself this, since I don't want to buy more lenses.

[enoeske]

I gotta disagree with the results as well...I have the smc 50mm f/1.4 and its razor sharp at f/2 and up. At f/1.4 is a little soft but not unusable. Looks like focusing error or something to me.

I don't have my gear with me at work here, and I haven't shot newspaper like your tests, but here's 2 real world shot at f/2



This lens out resolves the sensor on my k20d. So sharp even at f/2

[Halchemy]

Thanks for the hard work. I think you have confirmed what many of us think, though we have not done the tests in a scientific manner.

[causey]

What SMC Pentax 50mm are we talking about? The K or the M version? In my experience, the K is satisfyingly sharp wide open--in any case, nothing like what your test seems to indicate...

[Egg Salad]

As I said there is something weird going on with the Pentax-F.
It's sharpest at the upper part, slighty left to the center (not included in crops).
I blame the tripod: it has a quick relase plate that has some play. So whenever I touch the camera it can rotate slightly. With these shallow DOFs it can make a difference.
Additonally if the lens isn't completely level you get areas in front and behind of focus. And I think that's what happened here.

I'm not really sure if my tests are that representative - I mean if you could and should judge the old SMC Pentax' performance on them but the 2nd round (same target but at 0.66m) indicates the same result.
Center sharpness is ok wide open but not great and everything more off center is rather poor.

But my other series prove this as well: the Sigma literally destroys the other 2 (16-50 is in it's own sad league).
Getting closer the edges are poorer on the Sigma but otherwise it rules them.

What I think is the reason is its rather old design and strong field curvature to go with it.
So it's not that soft but the focal plane just doesn't fit a flat target.

The Sigma however with its huge elments seems to have a far flatter focal plane.
Other pictures indicate that as well - in the very center I couldn't tell the Sigma and the SMC apart in terms of sharpness - even focus fringing is very similar.
But everywhere off-center the newer Sigma wipes the floor with it.
Yes, about 1 stop sharper. Sharpest ares of Sigma and SMC match up at f/2 for the Sigma and f/2.8 for the SMC.

Causey: it's the SMC Pentax - K series.

The Pentax-F pretty much dissappointed in the resolution tests.
It is said to be sharper (up to f/2.8) than the faster f/1.4 counterparts. Couldn't prove this. If anything its edges are better because of less field curvature.

Link to round 2 at the bottom of round 2...

[Pentaxor]

thanks for the tests. I kinda agree that there is something wrong with the F. it sucked at wide open which is weird and center resolution isn't really the best. maybe some misalignment issue or needs a bit of lens correction compensation adjustment might help.

[Egg Salad]

Misalignment...possible but unlikely.
And this is no AF issue - I focuses them manually wide open in live view. Kinda hard to tell but I decided by the artifacts on the screen when the sharpest point is reached.

[causey]

Causey: it's the SMC Pentax - K series.

Well, the K 50mm 1.4 I sold a week ago was definitely much sharper than your copy... Also, a Super Tak 50mm 1.4 I had was definitely sharper than your K 50mm 1.4...

[Egg Salad]

Glad to read it's supposed to be better.
Still strange. Sample varition wasn't normal back then and my copy is in great condition.
Luckily I don't have to care since I will sell mine soon, too. Except it stays as a macro lens. We'll see.

[Egg Salad]

Moved round 2 to the first post for better view.

[NeverSatisfied]

thanks for the tests. I kinda agree that there is something wrong with the F. it sucked at wide open which is weird and center resolution isn't really the best. maybe some misalignment issue or needs a bit of lens correction compensation adjustment might help.

"Misalignment...possible but unlikely.
And this is no AF issue - I focuses them manually wide open in live view. Kinda hard to tell but I decided by the artifacts on the screen when the sharpest point is reached."

I had the F50/1.7 and must agree, my copy was sharper as well. One thing I did notice in a comparison I did against the M50/1.7, was that the focus ring on the F is really pretty poor. Manual focus with that one was rather imprecise and results were actually better using AF; sharpness for the F50 in AF, vs MF with the M lens, both wide open, was a tie.

[bdery]

The f1,7 is surprinsingly close to the Sigma, I find. It's visible that the Sigma has an edge wide open, but less than I would have expected.

[Egg Salad]

NeverSatisfied (great name),
that was also and still is my impression - this lens is so plasticky and poorly built that even MF sucks - although it still has more focus throw than the Sigma (Pentax: 160°, Sigma: 90°).
I didn't want to rely on the AF since I wasn't sure if it would really nail it.
Did a focus accuracy test recently and now I'm sure it does.

I guess I should redo the comparison between these 3 (16-50 is so out of competition) but only up to f/2.8 this time.

Frankly, I was also surprised not to say shocked by the results. I didn't expect them to perform that poorly.
Still: download the whole bunch and compared the sharpest parts yourself.
Off-center i found the Pentax-F's images to look way better than in the very center.

Probably due to a flawed test methology. Tripos just oh so slightly tilted = foocal plane shifted.

bdery,
if you are referring to the 2nd round than I agree.
At very close focus the Sigma loses lots of resolution in the edges - center sharpness isn't that much affected.
The Pentax-F holds up way better.
SMC Pentax matches the Sigma's performace in the center but can't keep up in terms of edge sharpness. By f/2 it's one stop behind the Sigma.

[Pentaxor]

much better 2nd test, although there might be some marginal focusing error possibility, but the test results are pretty much consistent to what is already known. I would guess that the first test shots are pretty tough to do even when focusing LV considering that those were taken a bit farther away. considering the short focus throw of the 50/1.7 would make a big difference even with a slight adjustment. in other words, focusing with the 50/1.7 isn't as forgiving as other lenses with a longer focus throw. but anyway, the 50/1.7 is really impressive among the 4 lenses if I were to say it.