Pentax-FA 50mm 1.4 vs Pentax-M 50mm 1.7 Image Quality

Kentax · 12-20-2007, 12:44 AM

Did a side by side comparison of the FA 1.4 and M 1.7 today and noticed the images from the 1.4 were softer then the 1.7. Is it possible I received a defective lens? Or does the 1.7 produce sharper images?

Edit: Had time on my hands today so i did a comparison of the 50mm Pentax-FA 1.4, Pentax-M 1.7, Pentax-A 2.0, and a cheap e-bay Cosinon-S 50mm 2.0 lens

Lenses taken at 2.8

FA1.4 @ 2.8

M1.7 @ 2.8

A2.0 @ 2.8

C2.0 @ 2.8

Lenses taken at 4.0

FA1.4 @ 4.0

M1.7 @ 4.0

A2.0 @ 4.0

C2.0 @ 4.0

Lenses taken at 5.6

FA1.4 @ 5.6

M1.7 @ 5.6

A2.0 @ 5.6

C2.0 @ 5.6

Lenses taken at 8.0

FA1.4 @ 8.0

M1.7 @ 8.0

A2.0 @ 8.0

**Ole** · 12-20-2007, 01:25 AM

Here is a related discussion on your topic which might be of help:

Thoughts on FA 50mm 1.7

creampuff · 12-20-2007, 04:39 AM

Too close to call. But more interestingly the M lens definitely renders a cooler tone.

truonganh · 12-20-2007, 10:17 AM

Originally Posted by Kentax

Did a side by side comparison of the FA 1.4 and M 1.7 today and noticed the images from the 1.4 were softer then the 1.7. Is it possible I received a defective lens? Or does the 1.7 produce sharper images?

I have an FA 50 and a M 50 version. I do find the f1.4 softer wide open than the f1.7 wide open, they look the same as f2.8 and up (razor sharp) Generally it's true for most lens that they aren't at their best wide open.

Also, my FA-50 front-focus ever so slightly. I don't think it's really the camera since my Sigma17-70 has razor sharp pinpoint focus, that makes a big diff when shots are taken wide open.

Did you take the test shot wide open or with same aperture?

Kentax · 12-20-2007, 03:08 PM

i shot them wide open. thanks for the replies, i will do another comparison with the lenses at the same aperture soon.

Edit: continue from original post

C2.0 @ 8.0

Lenses wide open

FA1.4 @ 1.4

M1.7 @ 1.7

A2.0 @ 2.0

C2.0 @ 2.0

*ytterbium* · 05-09-2009, 05:06 AM

Is it just me, or you've written that "...images from the 1.4 were softer then the 1.7."
But in your first post i see FA1.4 tack sharp at 2.8 in first image, with very soft M1.7@2.8 in the following (second) image.

ILoveVerdi · 05-09-2009, 05:19 AM

Originally Posted by ytterbium

Is it just me, or you've written that "...images from the 1.4 were softer then the 1.7."
But in your first post i see FA1.4 tack sharp at 2.8 in first image, with very soft M1.7@2.8 in the following (second) image.

Yes, I see the same. The FA looks the sharpest in all the tests.

*8540tomg* · 05-09-2009, 05:42 AM

FA is the winner hands down in every image. The M to my eye looks a bit out of focus.

Tom G

*ytterbium* · 05-09-2009, 05:50 AM

Unless there is some mismatch between pictures, labels and description.
Odd that the previous posters dosnt seem to notice it. Second post with wide open images looks more like description (FA and M is at least equal sharpness).

asdf · 05-09-2009, 06:39 AM

Originally Posted by ytterbium

Unless there is some mismatch between pictures, labels and description.
Odd that the previous posters dosnt seem to notice it. Second post with wide open images looks more like description (FA and M is at least equal sharpness).

Yeah, the labels make no sense.

Here's M f/1.7 supposedly at "f/1.7":

And here it's at "f/8":

bdery · 05-09-2009, 06:42 AM

I'd say that impresses me is that the Sosinon performs pretty darn well!

The M underperforms, compared to what I have read elsewhere. Maybe your MF was not on par?

asdf · 05-09-2009, 06:47 AM

Originally Posted by bdery

I'd say that impresses me is that the Sosinon performs pretty darn well!

The M underperforms, compared to what I have read elsewhere. Maybe your MF was not on par?

It's (EDIT: also) likely that the images are all mixed up. M is defying the laws of physics by being supposedly sharper at f/1.7 and softer at f/8.

AndrewShirley · 05-09-2009, 07:14 AM

There is definately something wrong with the "M" shots. They're not anywhere near as sharp as I would expect. It should be on-par with the FA50.

- Andrew

*alexeyga* · 05-09-2009, 10:54 AM

Originally Posted by AndrewShirley

There is definately something wrong with the "M" shots. They're not anywhere near as sharp as I would expect. It should be on-par with the FA50.

- Andrew

I'd have to agree... FA50/1.4 was a disappointment for me in terms of sharpness in comparison to my old A50/1.7... Wide open it is... And I was dumb enough to sell the A... That gave me a good reason to unload the FA50 and get the K50/1.2 instead....

AndrewShirley · 05-09-2009, 12:19 PM

Ah yes, the legendary and elusive 1.2. I would love to see shots with it.

- Andrew