[Conqueror]

The FA 35mm f2 is my most used lens for a variety of reasons.

I seriously contemplating selling it to upgrade to the FA 31... is this madness?

I will be losing size but gaining some IQ... will I be gaining enough IQ in your opinion?

Body is K-5iis, so not holding me back

[i83N]

think about SMC Pentax-DA 35mm F2.8 Limited Macro or HD version

[robjmitchell]

The only way to know is to look at lots of images from both and see if A/you can see a difference and B/prefer the 31ltd. From memory the 35 is a pretty sharp but in comparison to the 31 a clinical lens. The biggest difference in rendering will be wide open. There is also the mater of whether there are any other lenses on your wish list. Will this be your first taste of fa ltds?

[Conqueror]

I've never owned any of the famous three 31/43/77.

This is my current line-up (below). The 55mm DA* being the most recent acquisition. I have been surprised by its quality. The 35mm remains my go-to focal length though.

15mm DA < ~10% usage
35mm FA < ~80% usage
55mm DA* < ~10% usage
100mm WR < almost no usage atm
55-300mm DA < very rarely using... useful somewhere with mountains abroad!

The other lenses I'm interested in is one of the Samyang 10/14/16mm manuals but that is for night/astro usage only. I need to use the 15mm in that situation more to see first.

[nicoprod]

If the extra $ for the 31 is more valuable the extra IQ, don't buy.

[Driline]

The FA 35mm f2 is my most used lens for a variety of reasons.

I seriously contemplating selling it to upgrade to the FA 31... is this madness?

I will be losing size but gaining some IQ... will I be gaining enough IQ in your opinion?

Body is K-5iis, so not holding me back

I never had the FA 35, but I did own the DA 35 2.4. Although sharp, the DA 35 2.4 offers a more flat boring picture. I never fell in love with it so I gave it away to my brother. The FA 31 looks more 2D ish and the rendering is just awesome. You pay for that look however But I did buy my FA 31 used for $750, so there are deals out there. Mine is the Made in Japan version as well.

[kiwi_jono]

I must admit, as a FA35 f2 owner, I wonder about getting a FA31 too.
I love my FA35 and use it a lot at f2 where I find the rendering pretty good actually (stopping down the bokeh does degrade IMO).

There are some nice looking FA31 photos around which attest to it containing pixie dust.

I wonder if the FA31 pixie dust more than makes up for the extra size + cost? For me probably not at the moment. If I had spare money kicking around then maybe I would grab it.

[pinholecam]

I have both.

The FA31ltd is about 0.5stops brighter in T-stop and its clearly better for the smooth bokeh (in most situations)
It is also wider (obviously) This can affect the working distance you have got accustomed to with 35mm.
They are comparable in sharpness.

I have gotten shots I liked from both so its a wash when it comes to that.

[akanarya]

35/2 is the lens that I use most like you and want to sell lastly.
Surely there are some advantages of 31mm.
if you have budget, buy 31mm, keep and use them both and decide.

[LeRolls]

All I can say is that I love my FA31 to death. I've taken some of my favorite photos with that wonderful piece of glass.

https://www.flickr.com/photos/chris_rankin/sets/72157645951005042/

[dms]

"FA 35mm f2 is my most used lens for a variety of reasons" and you are thinking of what???

[Paul the Sunman]

I recently bought the Sigma 35mm f1.4 Art. It is much cheaper than the FA 31mm, and super-sharp across the frame (it's FF). It is HEAVY though, and mine often overexposes on my K3, which none of my Pentax lenses do. Still deciding whether I like it.

[Digitalis]

I recently bought the Sigma 35mm f1.4 Art. It is much cheaper than the FA 31mm, and super-sharp across the frame (it's FF).

The FA31 is an unusual lens design, compared to most 35mm lenses it produces results that are distinctly different. the Biggest differences that can be see between the FA31 and the sigma 35mm f/1.4(and the 18-35mm f/1.8 ART) is the Bokeh. The OOF transitions on the FA31 are smoother than both lenses at mid focal lengths. Sharpness is nice but it doesn't make every image ART.


Pentax K5IIs - Pentax FA31mm f/1.8 @ f/1.8


Pentax K5IIs - Pentax SMCP-FA31mm f/1.8 Limited @ f/1.8

[Paul the Sunman]

The FA31 is an unusual lens design, compared to most 35mm lenses it produces results that are distinctly different. the Biggest differences that can be see between the FA31 and the sigma 35mm f/1.4(and the 18-35mm f/1.8 ART) is the Bokeh. The OOF transitions on the FA31 are smoother than both lenses at mid focal lengths. Sharpness is nice but it doesn't make every image ART.

Adam keeps telling us that the bokeh of the Sigma 35mm is better than that of the FA 31mm. I am not convinced, but it certainly is smooth.

[Digitalis]

Adam keeps telling us that the bokeh of the Sigma 35mm is better than that of the FA 31mm.

I have had several 35mm f/1.4 lenses that I used on my D800E - I had a copy of the Sigma 35mm f/1.4 for a while but later on I changed over to the Carl zeiss 35mm f/1.4, the Zeiss had better color rendering than the sigma. The Zeiss also had higher overall resolution and no focus shift.