Examining the Pentax 50m-135mm DA * F2.8 lens

[raist3d]

I will probably continue posting on the 50-135 thread, but decided to start a new thread on this one. So I finally got the lens and was able to play a bit more with it. Inevitably as a potential full system switcher, I have to compare from a 4/3rds perspective.

Initial thoughts: mixed bag. Some things I am like "wow, nice" and some things have left me a bit more "Hmmm. ok." But I decided I needed to play with it more because the DOF is so narrow, it's easy to mistake bad focus for bad sharpness or bad lens.

2nd thoughts after playing with it some more: better than my initial impression, part of this is getting to know how this works. I have seen the lens can be sharp enough wide open. I did see pincushion at the telephoto end.

Compared to my Olympus 50-200- is it better? I would say *probably* yes, but not much better.

Compared to the Olympus 35-100 is it very close to it? No, it isn't. It's closer to the 50-200 in that regard. But then the 35-100 costs more than twice as much (USA). It also puts some things in perspective as I will comment a bit further. That said, I would like to see some crops of the 35-100 at F2.0 because I have read in a few places it's not tack sharp at F2.0 (but that's in a way expected to some extent, just reassures me perspective wise I can't expect tack sharp on this lens either at F2.8). I saw a review in fact that described the 35-100 as rather a bit soft wide, with real life examples, but I am going to like to see more since maybe he had a bad copy or was having the back focus issue.

Focusing- focusing is not super fast (using Olympus 12-60 as a reference, for example) but I wouldn't say worse than my 50-200. Now, that's partially because of the K-5 body. Would like to see the 50-200 on an E-5.

I had to AF adjust my lens, was it was back focusing a bit out of the box. After I did that it improved quite a bit wide open. I see that AF is still tricky at full tele with moving/lower light subjects but then that's true for pretty much any system. My 620 + 50-200 can't quite handle the same level of lower light, but that's expected of an e-620.

Tonality- I see the lens has it and it's there. That certain "pop" in contrast and color.

Bokeh- circular aperture is nice. However as it goes from details to the blur, I notice some rather "not so smooth steps" in between. I find my 50-200 does better here. But I am going to continue checking a few things since I was using my Pentax without the lens hood, that may affect some things, and I regularly use my 50-200 with lens hood.

A few pictures from a place in San Francisco called Blue Bottle (I guess it's elsewhere) Coffee, which I asked if they would mind me testing the lens and they were all fine with it.

Note: there's a few shots in here that won't seem tack sharp, and that's because yes, they are not. I wasn't quite watching my shutter speed, and I forgot I needed a faster shutter speed. And these guys were all sporadically moving. You can see the shots where at ISO 800/1600 and F2.8/F4.0:

In this shot focus is on the nose:

This one was cropped a little:

I really like the tonality. And this is ISO 1600(!)

A little bluer/colder:

Very neutral face, looks like a statue to me - a bit

This guy was moving a a bit blurry. Did a sharpening with a wider radius:

The focal length of all these shots were 135 (202mm, Pentax says it's 207mm).

- Raist

 

[jonoslack]

These are lovely photos Ricardo - pretty people too.

How does it compare in size with the 50-200 (I know it so well).

 

[raist3d]

Coming from the perspective of 4/3rds here's something that is one of those things that made me think a bit. In the USA the Olympus lens, the 35-100 F2.0 SHG is about $2,500 USD. The Pentax 50-135 F2.8 is $854.xx. That's actually not even half the price but one third of the price (!). Then to my surprise the Pentax can focus closer than the 35-100 (1.4 meters vs 1.05 meters), weights less than half (!) (0.756 Kg/1.686 pounds vs 1.65Kg/3.64 pounds) and it is shorter in diameter, and much shorter (5.4'' vs 8.4'', that's 55% longer for the Olympus).

For the price of a single Olympus lens, alone, you can get a Pentax, + 50-135 + and maybe one of the pancakes on sale. For an E-5 + 35-100 combo you can get the Pentax + 16-50 DA * + 50-135 + 2-3 pancake prime lenses. It is this kind of pricing options that as a 4/3rds user made me look around. On the good side you can have the same short DOF in 4/3rds as current APS-C if you buy the SHG lenses, but you are stuck with big, very heavy equipment at a very high price. Starts looking a bit to me like the Sigma SD1, though at least the Olympus lenses deliver.

- Raist

 

[jonoslack]

Hmm yes - and it's half the size, has a quieter shutter and knock you down dynamic range.

Lots going for the K5

 

[raist3d]

These are lovely photos Ricardo - pretty people too.

How does it compare in size with the 50-200 (I know it so well).

The 50-200 is bigger and heavier. The 50-135 Pentax is in a way like an Olympus 12-60. A notch smaller in diameter than the 12-60 but about 1/3rd longer. The Pentax weights about 100 grams more. The 50-200 weights 270 grams more than the Pentax.

On the other hand, the 50-200 has much more range, so I think for what it is it's fine. It's the SHG that by forcing Olympus to make them F2.0 are crazy heavy and big. This is a review of the 35-100 and puts in perspective the issue of how 4/3rds started with size in mind and lost the advantage. This was written also when these lenses had come out and the E-3 hadn't come out yet:

http://www.e-fotografija.si/templates/?a=1071&z=93&page=3

First page: http://www.e-fotografija.si/templates/?a=1071&z=93

- Raist

 

[raist3d]

Hmm yes - and it's half the size, has a quieter shutter and knock you down dynamic range.

Lots going for the K5

I would say if you are taking shots that highlight clipping nor shadow range affects the shot, I would expect the E-5 + 35-100 F2.0 to definitively be better the Pentax. The difference may not be super immense but I would call it probably "big enough" to see an overall difference. If you are shooting for the web of some type of prints then that probably won't be noticed.

But yeah if you need the shadows or the highlights in more challenging situations then the story changes. Or of course if you need the high ISO .

Another issue with the 35-100 on that end is that if you want to shoot in daylight at F2.0 you will most likely have to buy an ND filter an attach it to it (a good one that big isn't cheap either) because you will run out of shutter speed to compensate for the exposure/brighter light.

Personally I don't see myself carrying an E-5 with the 35-100 on the basis of size/weight alone (675+785 [inlcudes hood] = 1360 grams vs 800 + 1650 = 2450 grams ). The first kit is almost half the weight(!). This all said, I want to keep this with a certain clinical objectivity and not look at it as a "my camera is better than yours." I am sure there are at least a few e-5 photographers that can work great with the 35-100 for the photography they do as the E-5 operates within the range of what they are shooting and their photography domain.

- Raist

 

[jonoslack]

Personally I don't see myself carrying an E-5 with the 35-100 on the basis of size/weight alone (675+785 [inlcudes hood] = 1360 grams vs 800 + 1650 = 2450 grams ). The first kit is almost half the weight(!). This all said, I want to keep this with a certain clinical objectivity and not look at it as a "my camera is better than yours." I am sure there are at least a few e-5 photographers that can work great with the 35-100 for the photography they do as the E-5 operates within the range of what they are shooting and their photography domain.

- Raist

Hey Ricardo - I (very sadly) gave up my Olympus gear a couple of years ago, when I realised that it really wasn't any smaller/lighter/quieter than a Sony A900 and Zeiss lenses . . . . and there is a real IQ difference.

I love the K5 for it's dynamic range, but also because the body seems to be the natural successor of the Olympus E1 - professional build quality, excellent ergonomics and a super quiet shutter (incidentally, the K5 actually smaller and Quieter than the E1) - I still have mine, sitting on a desk looking pretty. The image quality is from a different world.

I'm very well aware of how well Olympus have done with the E5, and of how great their lenses are (I still mourn my 12-60) - But I struggle to see how it bests the K5, except possibly in the pro lenses . . .

 

[raist3d]

I would say the most pleasant surprise for me perhaps of the K-5 is that I can use it as a pro style cam and as a street life cam (because it's light & small). That said, I think Pentax does have the achilles heel of its AF system. I am still not feeling all that confident when taking some shots and I am working with that.

If that feel doesn't really change, I may consider other options, since the last thing I want when shooting a wedding is to wonder if I got that shot. On the other hand I am getting more and more convinced- as my first photography teacher told me years ago- AF systems in general are prone to miss when you least want it and if you can learn to do MF that's best. So I am practicing that too.

I think this is one of the issues Pentax will probably address when the successor of the K-5 comes out. The AF is not horrible per se but the big sensor area really makes it tricky for some shots. I am getting a hunch once I intuitively understand the area it focuses on I will feel more confident about certain shots.

- Raist

 

[raist3d]

OH I forgot to mention: some of the purple fringing that occasionally bothered me with the DA70 pancake is pretty much gone with this lens. That's a pleasant surprise.

I guess the limited pancakes trade up a bit for being so small (though they can be crazy sharp).

- Raist

 

[jonoslack]

I think this is one of the issues Pentax will probably address when the successor of the K-5 comes out. The AF is not horrible per se but the big sensor area really makes it tricky for some shots. I am getting a hunch once I intuitively understand the area it focuses on I will feel more confident about certain shots.

- Raist

Well, my percentage of OOF shots has really dropped - changing systems always takes a little time to accommodate to. I haven't shot a wedding with the K5, but I do have a concert to do next week, and it's not worrying me.

 

[raist3d]

Well I think I found the one thing that was bugging me about this lens. I am eating now but I am going to post some shots and a comparison with 4/3rds to show what I mean. Basically the bokeh often has this aspect where the blur seems to happen in "one direction" and looks a bit cheap. Reminds me of my Sigma DP2- the lens can be sharp but often has this aspect too.

GRrrrrrr……

- Raist

 

[raist3d]

So here's what I mean.

Firs the Pentax shot:

And now a 100% pixel peeperTM crop - notice the black arrows. This shows just one are of many of how the blur and stretching of the object's definition goes, in that direction, but the opposite direction is not blurring in that direction as much creating the impression there's smear in one direction.

Now let's take a look at an E-620 Olympus shot - using Panny leica 25mm at F1.4 (the 50-200 behaves similar, I tried it too):

Whole shot:

Pixel PeeperTM 100% crop:

The crop and focus i not the same on the pictures but it really doesn't matter. I tried a few other objects and saw the same effect. You can also pick some other letters closer to the point of focus to be more similar in comparison to the Pentax shot. I marked with arrows the point- that the "blur" grows "outwards" in all directions. This looks very pleasing to me and imho, how it should be.

Something was bothering me about this lens and this seems to be it. If you have a distant background I find this a no issue, but the problem is that areas of say, an object/person/animal/subject you are focusing on that may not be quite in focus, are going to exhibit this phenomena - unless of course you make sure your whole subject is in focus and the background still far enough to do a lot of out of focus (one stop easier to do on APS-C).

I don't know if this means my 50-135 is "decentered" or what not, but i have to admit I am a bit disappointed by this. In many images this doesn't matter but in some others I think it does.. I will do more experimentation but I find this a bummer.


- Raist

 

[raist3d]

Update: if you were reading this just now and are puzzled by the pictures, clear your browser cache and reload the page. I mixed the links when I first posted.

- Raist

 

[jonoslack]

HI Ricardo
no matter how many time I flush my cash I'm still a bit confused - I understand what your getting at, but isn't it simply a case of slight front focus?

(perhaps I'm being a dumb-***)

 

[raist3d]

No, it's not a front focus issue. I am examining what happens when things go "into the bokeh blur"- out of focus. That's why I am highlighting crops with out of focus areas. It's the nature of how they go out of focus what I am talking about.

So basically for the pentax- the letters in this case "grow in blur in mostly one direction" as if there was a light with the opposite shadow relationship. On the 4/3rd lenses, the letters grow in blur "outwards" from where they are in all directions creating what is to me a very nice bokeh.

The first type of "grow" looks a bit cheap. Like more of what a P&S lens would do. The later looks more like what a Leica lens would do.

Makes sense now?

- Ricardo

 

[raist3d]

Also I am exploring when does this happen more than not. When looking at the coffee people shots, the background which is a bit farther away from then, this doesn't seem to be as noticeable or happening. But when having something going out of focus close to the point of focus/focal plane of focus it seems where it happens the most.

- Raist

 

[Knorp]

Ricardo/Raist,

I'm no expert nor do I know what I'm talking about (well most of the time), but to me it looks like more as 'bleeding' of the white area.
Look at the darker 'shadow' beneath, that still has very well defined edges, no sign of blur.
I can't explain it, just my observation.
Could be the lens or very well the sensor, what do you think ?

Kind regards.

 

[raist3d]

Ricardo/Raist,

I'm no expert nor do I know what I'm talking about (well most of the time), but to me it looks like more as 'bleeding' of the white area.
Look at the darker 'shadow' beneath, that still has very well defined edges, no sign of blur.
I can't explain it, just my observation.
Could be the lens or very well the sensor, what do you think ?

Kind regards.

You are describing the effect per se quite accurately, but it's not bleeding. If the sensor bleed this way it would be horrible! That's too much I noticed this out of my Sigma DP2 with the lens too. My primes are not doing this, I chalk it up to the lens.

- Raist