[yozza]

I am on the lookout for a second portrait lens for a k1 with my focus on full body fashion shots. I have just got the 77mm though it also leaves me stepping back quite a bit to get what i am after. I know there several 50mm lenses (1.4,1.7 etc) as well as the 55mm, and have had some great advice on here.

Which 50mm lens would give me the sharpest picture and best resolution for full frame, or is the 55 going to be better?

Thanks

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Last edited by MarkJerling; 10-29-2016 at 03:21 AM.

[pathdoc]

The 55, being a DA* lens, ought to be better. That being said, there are questions of both sharpness and rendering when it comes to portrait photography, and the sharpest lens wall-to-wall is not necessarily the best portrait glass. For wall to wall sharpness, the D-FA 50/2.8 Macro seems to have an outstanding reputation and is designed for full frame. The FA50/1.4 is the only other fast fifty still in current production, if new-in-box and factory warranty matter, but can be soft wide open. A fast normal is supposedly in the pipeline, but I'm guessing you can't wait that long.

[Saltwater Images]

Why wouldn't you consider the FA 43 Limited? It's the natural compliment to your FA 77 Limited - all things being equal the image quality and colour rendering should be consistent across focal lengths. here's a DPReview on the 43:
[Review] SMC Pentax-FA 43mm F1.9 Limited: Pentax SLR Talk Forum: Digital Photography Review

[pathdoc]

Isn't the FA43 beset by problems of unpredictability? I notice that some swear by it, others at it, and still others variably both at one time or another, depending on what is photographed. It seems to be a very controversial lens.

That didn't stop me from thinking about it once, and I may yet get it in time as a replacement/trade-in for both my DA40 Limited and my SMC-M 40. It isn't that much bigger, and it does work on all K-mount platforms.

[Na Horuk]

Which 50mm lens would give me the sharpest picture and best resolution for full frame, or is the 55 going to be better?

DFA 50mm f2.8 macro, probably. Macro lenses tend to be the sharpest, most highly corrected optics. But now you will learn that resolution is not everything, that aperture, bokeh, rendering style, and even price all play a role in the lens buying decision.
But if you want pure sharpness, then the DFA 50mm is probably your best bet.
That said, for me, the Pentax M 50mm f1.7 is sharp enough. Very few 50mm primes are lacking in sharpness, especially once you stop them down a little.

[pathdoc]

But now you will learn that resolution is not everything, that aperture, bokeh, rendering style, and even price all play a role in the lens buying decision.

That was my thought initially but OP's focus is full-body fashion shots, which makes me think this is more like product photography than portraiture and sharpness across the frame is more important than character in that situation.

[UncleVanya]

A DA 50 f1.8, an F 50 f1.7 or FA 50 f1.7 would be an inexpensive way to see if the focal length works for you. The DA* 55 has high recommendations from some who own the K-1, but I'd try the focal length before committing to it. The DA 40 and FA 43 limited lenses are another option as someone else mentioned. The DA is an f2.8 lens which may not give you as much background separation as you want, but you will be closer to your subjects which could bring back some separation if the setting is right.

[blan01]

The DA*55 is very nice on full frame, I really like the color produced from this lens; sharpness is equal to DFA 50 marco at f2.8!!
If you like a little bit wider, then the legendary FA43 is the one to go, the rendering of this lens is just special.
If you want something cheaper, I highly recommend FA 50 1.7.

[aurele]

Having owned the Fa50 and owning the DA*55, let me tell you that the DA* is really in another league from the FA.

It's sharper, bokeh is smoother, the transition from in focus to out of focus is nicer (IMHO).
There is also less aberration.
Color are better "as is" when shooting. Closer to reality, but also more flatering with skin tones.

To make things very clear : f1,4 to f2 is very good, and thus absolutely usable.
On the FA, from 1,4 to 2, i would never use it, quality wasn't up to m'y standards (i print quite often 30x45 prints).

The DA* is more expensive, but to me, it's 500€ well spent so far. Far better than the 250 of the FA.

[Fenwoodian]

Both the DA 55 and the D-FA 50/2.8 Macro are incredibly sharp. Maybe the DA 55 has a tiny TINY bit better colors.

The DA 55 has horrible purple fringing on high contrast areas. While the D-FA 50/2.8 Macro does not.

[yozza]

Having owned the Fa50 and owning the DA*55, let me tell you that the DA* is really in another league from the FA.

It's sharper, bokeh is smoother, the transition from in focus to out of focus is nicer (IMHO).
There is also less aberration.
Color are better "as is" when shooting. Closer to reality, but also more flatering with skin tones.

To make things very clear : f1,4 to f2 is very good, and thus absolutely usable.
On the FA, from 1,4 to 2, i would never use it, quality wasn't up to m'y standards (i print quite often 30x45 prints).

The DA* is more expensive, but to me, it's 500€ well spent so far. Far better than the 250 of the FA.

That's very helpful Thankyou Aurele

---------- Post added 10-29-16 at 10:30 AM ----------

Both the DA 55 and the D-FA 50/2.8 Macro are incredibly sharp. Maybe the DA 55 has a tiny TINY bit better colors.

The DA 55 has horrible purple fringing on high contrast areas. While the D-FA 50/2.8 Macro does not.

Thanks Fernwoodian I'll need to check that out, Thankyou

---------- Post added 10-29-16 at 10:46 AM ----------

From reviews it seems that the 55mm has af problems. Does anyone here find that, whether it be on a k1 or other, and is this more so for sports/wildlife versus portraits or for all?

[Gray]

Here you go

Pentax DA55 and FA50 - a comparison

[aurele]

Here you go

Pentax DA55 and FA50 - a comparison

In your test, the DA* is clearly not well calibrated regarding the AF. I don't have such huge purple fringing with my lens. There is some if you shoot wide open a black object on a white background, of course, but not as much as in the "test" (which is a tad loosy IMHO).

The DA has a focus field less curved than the FA. That's partly why it have a better resolution across the frame.
The DA has is still some focus shift (the focus move slightly if you stop down).

The bokeh is not the same as the FA : the less curvated zone of focus is probably responsible. Higlight bokeh is a tad different too.
Optical formula is different, so maybe something in it too.

The FA show some sort of haze wide open, which the DA show too wide open, but far less pronounced. Contrast increase faster with the DA than the FA.

About AF : the SDM can sometime be a bit hesitant. But it never have been an issue so far. It's more body related to me. Since i've the K5ii, AF is really more decisive than the K-x was.

[Gray]

In your test

Not my test. It is their's: Digitale Fotografie an der AG Digitale Medien, Universität Bremen

[leekil]

The DA has is still some focus shift (the focus move slightly if you stop down).

How does that happen?