[Santoku]

Was working out autofocus calibration on some lenses, and as part of the process I thought I would do some comparisons between the following:

Pentax-FA 50mm f/1.4
Sigma EX 50-150 f/2.8 HSM II, and
Pentax-DA* 60-250 f/4

using Pentax K-5 iis and a hotshoe mounted flash to provide more even lighting in a dimish shooting environment over time when the ambient lighting was changing.

All were shot at f/5.6, ISO 100, 1/90 shutter, and centre weighted metering on a tripod with the same relative focus point. They were processed in Lightroom from DNG with no sharpening but some slight bumps up or down in exposure to try to create a similar overall look, but didn't monkey with colour or white balance. Calibration profiles for each lens were used as per supplied in Lightroom. There is a comparison between the FA 50 and EX 50-150 @ 50mm, and of the DA* 60-250 and EX 50-150 @ 60mm.

Please forgive the boring subject matter and decor of the kitchen Inline images are what I believe are 100% crops of the focal point, and clicking the following links should take you to the full version of the photos, where you can download them in full resolution. Hardly scientific, but for fun

Pentax-FA 50mm f/1.4 @ 50mm f/5.6, 1/90, ISO 100
Sigma EX 50-150 f/2.8 HSM II @ 50mm f/5.6, 1/90, ISO 100
Sigma EX 50-150 f/2.8 HSM II @ 60mm f/5.6, 1/90, ISO 100
Pentax-DA* 60-250 f/4 @ 60mm f/5.6, 1/90, ISO 100

Attached Images

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[Scottnorwo]

No expert here , but they all look pretty good. Nothing I would complain about.

[interested_observer]

The zooms kept up with the prime rather well...

[Santoku]

The flash tended to wash out some of the normal colour and contrast, although the FA 50 still managed to retain better contrast in the green and a bit in the red. From a sharpness perspective, the zooms certainly fared well, although also 3-5 x as large and heavy as the FA

[RuiC]

We can notice subtle differences on the IQ. Other issue maybe not worth mentioning is the the Sigma exif says it is a 70-200 not a 50-150 !!
Last word is that I find Grindz costs too much!!!

[Edgar_in_Indy]

We can notice subtle differences on the IQ. Other issue maybe not worth mentioning is the the Sigma exif says it is a 70-200 not a 50-150 !!

My 50-150mm also has personal identity issues, believing it is actually a 70-200mm.

I agree that the pictures look very, very similar in terms of sharpness and overall IQ, with the prime having a tiny edge in contrast.

[crewl1]

Did your FA50 wear a hood?
If not, it might produce even better results.

[yusuf]

You might want to try and share results at f2.8 and f4 too

[Santoku]

Other issue maybe not worth mentioning is the the Sigma exif says it is a 70-200 not a 50-150 !!
Last word is that I find Grindz costs too much!!!

Yes, like Edgar mentioned, the EXIF is incorrect, and is the default choice in Lightroom for lens correction, even though I specifically corrected it for the 50-150. Would be nice to be able to easily alter that entry during PP, but it is what it is unfortunately. And yes, Grindz can cost a tad unless one hunts for a deal online. I usually just end up taking the grinder apart since I don't trust them completely anyway

Did your FA50 wear a hood?
If not, it might produce even better results.

Yes, I have a collapsible hood on the FA 50mm f/1.4. The decreased contrast overall is more a function of my ham-handed use of flash than a limitation of the lenses

You might want to try and share results at f2.8 and f4 too

Ask and ye shall receive using multi-segmented metering this time.....crops inline and full shots linked below....

Pentax-DA* 60-250 f/4 @ 60mm f/4, 1 sec, ISO 100
Pentax-FA 50mm f/1.4 @ 50mm f/4, 1 sec, ISO 100
Sigma EX 50-150 f/2.8 HSM II @ 50mm f/4, 1/1.7, ISO 100
Pentax-FA 50mm f/1.4 @ 50mm f/2.8, 1/5, ISO 100
Sigma EX 50-150 f/2.8 HSM II @ 50mm f/2.8, 1/4, ISO 100

[crewl1]

FA50 seemed back focused if it is second to last shot. Anyway thanks for doing this

[Santoku]

FA50 seemed back focused if it is second to last shot. Anyway thanks for doing this

I was using Live View for each of the shots, but can try manual focus with the FA 50 @ 2.8 and see if that improves the focus. It did seem unusually soft at that aperture.