[tlwyse]

Just recieved my new Pentax K-5 IIs (upgrading from K20D) last week and just got the new Sigma 35mm f/1.4 "Art" series lens a couple of days ago. Since I was borrowing a friend's Pentax FA 31mm f/1.8, I thought I'd do an informal test between these two lenses and throw in my Tamron 17-50mm f/2.8 just for grins.

Since the Sigma 35mm was new to me, as is the K-5 IIs....and I've got a shoot planned for Monday....I decided to run through my standard gauntlet of focusing calibration tests using my LensAlign tool. I typically photograph the LensAlign at 25x, 50x and 100x the lens focal length to find the AF adjustment. I was HOPING that the new K-5 IIs would need minimal adjustment compared to my K20D which needs a pretty healthy +8 with all my lenses. Turns out, the K-5 IIs needs about +6 with the couple of lenses I've tested thus far.

What I found in my little lens comparison will probably sound like heresy to the Pentax faithful. As you know, the FA 31mm enjoys some sort of legendary/mystical status and I believed this enough to consider purchasing this lens instead of this new Sigma....but since the Sigma was getting such rave reviews on sites like DxOMark.com and others, I thought I'd check this lens out and compare it to teh FA 31mm before committing.

What I found was that this new Sigma "blew away" the FA 31mm...yes, it's true. What was perhaps even more surprising was my lowly Tamron 17-50 did very well and even bettered the FA 31mm at least in terms of sharpness (bokeh, maybe not so much). The one thing I've seen in a few of the Pentax lenses (I've got a DA* 50-135 and a DA Limited 70mm) I own is really bad CA/chromatic aberration. Before I got the Tamron, I thought this was normal....but the Tamron has virtually no perceptible CA which seems pretty amazing to me for a mid-level quality zoom.

Anyway, without further ado, I offer you some 100% and 200% magnified screen shots taken from Photoshop. In all my focusing tests, I ran through a full series from +/-10 in even-numbered increments. From this, I chose the best one visually in Photoshop and also looked at the file size in bytes.......a little trick when doing focusing test series like this is to shoot high-quality JPEGs and then look at the exact file size of all the images.....without fail, the file with the largest file size/least compression is also the one with the best visual focus. On a Mac, you select the file and choose "Get Info" and look at the file size in bytes. On Windoze, you'll right-click and select "Properties" and look at the size in bytes.

In the screen shots, the new Sigma 35mm f/1.4 is on top, the FA 31mm in the middle and the Tamron 17-50mm zoom (set at 35mm) is on the bottom, I didn't move the camera position (tripod) and all were shot with the 2" self-timer to avoid vibration. I also included a 50% zoom showing the LensAlign along with some background.....not the end-all/be-all of bokeh tests but it does reveal some bokeh characteristics.

Terry

Attached Images

       

[tlwyse]

Corrections/Additions....

The highly magnified screen shots were a 200% zoom in Photoshop, the bokeh screen was @ 50%.

I shot both the Sigma 35mm and FA 31mm @ f/2.0 and the Tamron 17-50mm @ f/2.8. I virtually never shoot wide open but for this test I decided to "push" the lenses a bit. Obviously, this choice of shooting aperture left the Sigma at a slight advantage since that's a full stop down from it's maximum aperture, leaving the FA 31mm only 1/3 stop down and the Tamron at wide open.

And, by the way, I don't consider this to be a conclusive test.....maybe I have a particularly good copy of the Sigma 35mm and Tamron 17-50mm and my friend has a particularly bad copy of the FA 31mm. He loves this lens so I assume it's performance is typical.

Terry

[JimmyDranox]

Very good test. And surprising results. Good for my 18-50 Tamron.

[Nick Siebers]

The Sigma 35 1.4 looks pretty darn good. The FA 31 looks worse than I would expect, but I haven't shot this type of scene with mine. Certainly my Tamron is rarely better than my FA 31.

[snake]

I am looking at the Sigma 35 to replace my FA35 (on the Euro market, I can nearly double what I paid for it and put that towards the Sigma). The FA31 is ok, but horrifically overpriced, not sharp enough when I tried it at wide open (where most of my shooting with it would be). Is has a slightly different character, but side by side, one would be hard pressed to know the difference. The Sigma 35, on the other hand, is a world apart. Already several of my friends are using it under pro-shooting conditions. Simply amazing, thus far and a huge step forward.

The Tamron 17-50 is also my go-to zoom. It has produced very sharp shots, which were deemed "sellable", so I'm plugging away with it. It does have PF, but I can easily control it. It's not as bad as some FA lenses, by far. I never did a side by side with the FA31 and Tamron at the same aperture. However, the Tamron fits very nicely within my FA35 and F50 1.7's color, contrast, and sharpness profile that one can't tell what I shot with unless the EXIF data is pulled. Even prior to processing, they don't look terribly different.

[yusuf]

Results look different from another comparison

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/226388-quick-b...1-limited.html

[snake]

Results look different from another comparison

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/226388-quick-b...1-limited.html

How so? I hope this isn't like the FA31 vs FA35 comparison on this forum that are referenced on the web from time to time with laughter. You know, the one that was never done blind, that had barely any difference between both lenses, yet the people here all picked the FA31 citing "massive" differences that weren't there. It was supposed to be followed up with a blind test and never was, which speaks volumes.

I'm looking at the pics and the Sigma is "all that" and more.

Not to mention, bringing the Sigma to 1.8 to compete a bit with the FA31, the sharpness I've seen in every test is ASTOUNDING. And it's like 600 EUROS cheaper and getting cheaper by the day. Size, sure, but I'll deal.

Stuff like this from the other thread shows how much reaching there is:

Sigma seems a little too saturated, but lightroom could easily fixed the issue. Where is my wr primes pentax?

First time I've read that as a problem, not to mention, something easily fixed with tone curves in-cam or in ANY PP program.

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Last edited by snake; 07-28-2013 at 08:29 AM.

[tlwyse]

Results look different from another comparison

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/226388-quick-b...1-limited.html

Interesting about the bokeh as it relates to high contrast lines...I'll have to look for that.

One thing I failed to mention is about the Sigma HSM focusing.....ABSOLUTELY silent.....the FA 31mm screw-drive focus sounds archaic in comparison.
More importantly, I can grab the focus ring (nice and wide) of the Sigma and tweak the focus at any time. With the FA 31mm, the focus is "locked up" so you either need to move your focus point or switch off the AF to tweak the focus....PITA in my opinion.

I'm sure there'll be guys here attempting to protect the reputation of the FA 31mm (wouldn't want the resale value to drop!) but for my money, and my albeit limited test, I'm convinced that the Sigma 35mm is more than slightly superior to the FA 31mm....and just maybe the K-5 IIs helps to reveal/widen the gap between these two lenses.

Anywho, got more lens focusing tests to run today....next up will be my broken (SDM) DA* 50-135mm, the Tamron 17-50mm and the DA 12-24mm. I'm shooting tomorrow's nude in an abandoned school so I'm sure I'll get lots of use out of the 12-24mm....better make sure it's dialed in to the new body.

Exciting stuff for me after having been saddled with the K20D for 4-5 years...difference is like night/day on many levels (there goes the resale value of my K20D!).

Terry

[tlwyse]

How so? I hope this isn't like the FA31 vs FA35 comparison on this forum that are referenced on the web from time to time with laughter. You know, the one that was never done blind, that had barely any difference between both lenses, yet the people here all picked the FA31 citing "massive" differences that weren't there. It was supposed to be followed up with a blind test and never was, which speaks volumes.

You know, when folks start talking about the "color rendering" of one lens vs. another or it's "3D" quality, I just kind of chuckle.....and, of course, this is all "easily" revealed in a downsampled-to-72ppi image of the original viewed in a non-color-managed browser on an un-calibrated/profiled display! (sorry, I do color management for a living so I find critical color evaluation of a browser image laughable...unless someone's done their homework).

With the kind of control you get in LR/PS, you can pretty much make any image look like any other from a color rendering standpoint.....what you CAN'T easily fix are things like sharpness, CA and other lens defects. I'll take the lens that has the superior technical characteristics and worry less about what "artistic" merits, perceived or real, that a lens may have.

Terry

[yusuf]

No I am not trying to protect, I myself is a big fan of Sigma 30mm (and previously FA35), but I have seen better from FA 31. I don't have Sigma 35mm to compare, but I FA31 is certainly sharper than 17-50mm at 31mm.

[oxidized]

I think that they are both amazing lenses. I am not gonna get into a pixie dust discussion. All else equal, the Sigma takes the prize (btw I have a 31 ltd) but I think at the end of the day neither lens is going to prevent you (or limit your ability) from getting the perfect shot. I think that both of these lenses have a potential way above what most people who use them can actually harness. And this kind of testing is very useful for people deciding which one to get. If I had to buy one right now id probably get the Sigma, however nothing from what I saw above is making want to sell my 31 ltd and get a Sigma instead.

Its sort of like, yes you can buy a brand new mustang with more horsepower and better fuel efficiency, however the retro one wouldnt be so bad either. For probably 99% of the purposes you use them for you will not see a difference. Maybe if you are using it to race, the new one would be better. Pardon my reference if I am wrong. Im terrible with cars and I really dont like Mustangs. Just trying to make a point

[stevebrot]

but I have seen better from FA 31.

I have to agree. I suspect there is something wrong with your friend's FA 31. Your shots are not congruent with other posted examples for that lens and are more in line of what I generally get with the DA 18-55/3.5-5.6 kit lens.


Steve

[stevebrot]

Pardon my reference if I am wrong. Im terrible with cars...

I learned to drive in a '66 Mustang and I can assure you that the modern product is a much different and, in most ways, a much better experience.


Steve

[oxidized]

I learned to drive in a '66 Mustang and I can assure you that the modern product is a much different and, in most ways, a much better experience.

Okay. Maybe not that vintage. How about 2000 mustang? My point was that for someone like myself who would be driving it at 70 mph at the most (99% of the time) --- Analogous to the average 31 ltd usage -- it wouldnt make much a difference

[stevebrot]

With the kind of control you get in LR/PS, you can pretty much make any image look like any other from a color rendering standpoint.....what you CAN'T easily fix are things like sharpness, CA and other lens defects. I'll take the lens that has the superior technical characteristics and worry less about what "artistic" merits, perceived or real, that a lens may have.

Terry,
You may be a color consultant, but I know from experience with multiple lenses (I have dozens), that there are distinct limits to what can be done with color manipulation in PP. Perhaps you could do a better job, but I would have a difficult time making a photo taken with my FA 77/1.8 have equivalent color rendering as my Jupiter-9. The FA 77 (pixie dust and all) has a fairly generic color rendering while the J-9 is, well, "unique". Quite simply, you can only enhance or remove what is there and nuance is often a matter of what is there in small quantities.


Steve