[nicoprod]

Hello

I used to own a F50 1.7, then I bought a FA version just because it looks cleaner on my K-x/K-5. I've been really satisfied with these two very good lenses. However I'm considering getting a DA55 1.4. I like the idea of the extra length associated with the wider aperture. I'm thinking it might help me create a smoother bokeh for portrait...

I would like to know more about the IQ from this lens as I already understand the WR, Quick shift and SDM features. Sharpness is key for me, I want very sharp results to start with.

1. Is the DA55 very sharp and "contrasty" at f/2 or wider?
2. Is the DA55 bokeh better than the FA50? (The FA creates good bokeh but not as good as the FAs limited, is the DA55 bokeh as smooth as or close to the FAs limited)

Should I upgrade based on IQ only?

Here's an example of what I like to do with my FA50.

Thank you!

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[6BQ5]

That picture is very, very nice! I'd say that if the DA 55 gives your kid an even cuter expression then upgrade. Otherwise, I think you're just fine with that FA 50mm!

[Aristophanes]

That picture is very, very nice! I'd say that if the DA 55 gives your kid an even cuter expression then upgrade. Otherwise, I think you're just fine with that FA 50mm!

I concur. If you're capable of getting that with the FA 50, no need to upgrade unless you put the kid in the rain

[adpo]

To answer your questions, yes and yes. I've found it to be sharper, has more contrast, handles PF better and has smoother bokeh. However, the extent at which it performs better is very marginal and you're probably better off spending that money elsewhere. My broke-college-kid logic says that the diminishing returns you get for essentially spending 2-3 times the money for the DA* isn't really worth it, especially since the baseline performance coming out of my FA50 is so solid. If you have to have "the best", then go for it. Otherwise, just save your money.

[Rondec]

I don't know that you would see a lot of difference. The DA *55 does give a little smoother out of focus areas (more circular highlights). It is reasonably sharp at f1.4 and really sharp at f2.

(this is one at f2.2)

[grahame]

FA50/1.7 is a great lens, and you made great shot!

DA55 is better than FA50 at wide aperture, say from wide open to 2.2-2.8. After that, FA catches up in the center resolution but still lagging behind in the corners.
Yes, DA is more contrasty, again at wide aperture; stop down, FA is also very contrasty. There might be color difference, but both are very contrasty.
Bokeh... both are not the best. DA tends to have harsh edges, and FA is a little busy also.

One thing to keep in mind: DA focuses quite slow. you kid will be more active before long, and you might have trouble in catching moment like you showed us with DA.
IMHO, DA's strength is the edge/corner sharpness at wide aperture. But corners are not important for portrait.

I would suggest keep your FA.

[6BQ5]

Could at least some of the differences between the DA and FA lenses be reduced with good post processing? You mention color, contrast, and what I would call definition or "pop" as being some of the biggest differences.

[grahame]

I like my DA55, and sold my FA50/1.7 after that. But if I had a chance to do the test before buying the DA, I will probably stay with the FA and use the extra $400 for something else.
I actually regretted and bought an FA 50 back recently, for its quicker AF.

ON the other hand, DA's resolution at F1.4 is amazing. I owned FA50/1.4 before, at 1.4, DA is much much much better.

[JinDesu]

I find the DA*55 to be sharp enough at F1.4, and very sharp by F1.8.

Full size images are linked below each image (both shot at F1.4):

https://farm3.staticflickr.com/2830/11829559855_fcbd219a87_o.jpg (look at the eye)


https://farm8.staticflickr.com/7385/11429762316_4a7bddaed0_o.jpg (the center resolution is very good, but I was also surprised at how good the corner resolution is)

Comparo to my Sigma 50 F1.4, which some have considered to be the sharpest AF 50mm for Pentax.
https://www.flickr.com/photos/jindesu/11830257953/

More comparo pics are on my Flickr stream. I think I have a weaker copy of the Sigma and a stronger copy of the DA*.

[nicoprod]

Thank you everyone.

Comparo to my Sigma 50 F1.4, which some have considered to be the sharpest AF 50mm for Pentax. https://www.flickr.com/photos/jindesu/11830257953/

This Sigma definitely not as sharp.

(this is one at f2.2)

Great picture Rondec