[zburatoru]

Well, I didn't spend much time with this lens but I hope that with the coming of spring to get better feeling about this lens. For the moment I'm not amazed: My copy looks quite bad at the body( it doesn't look expensive so that's a plus &#128512 but the glass is clean; it needed +2 focus adjustment but still not very sharp at wide aperture... Where it really shines it's at f2.8 and above: crazy sharp, contrasty and colorful! Maybe I'm not comfortable with this focal even if I've had Sigma 30mm first variant and the last one... But didn't like the rendering so I've bought the queen! So, I'm sharing my thoughts and some samples! Any thoughts are welcome! Thank you!

[BigMackCam]

Honestly, I can't see anything wrong with those results. They look great to me

Your findings confirm what various reviews and tests have suggested - i.e. that it seems most capable from f/2.8 and narrower, with peak performance between f/4 and f/5.6.

Honestly, I wouldn't have the highest of expectations for any lens - least of all a film era model (even if it's a premium one) - when shot wide open...

[normhead]

The difference between the 31 and the SIgma's based on test shots posted on the forum was slightly better out of focus rendering at the same stop. Honestly, for the images you posted, you would have been better off with the DA*55 1.4. I've always considered the 31 to be the ultimate FF landscape lens, and with it's superior size and weight characteristics for slightly better performance fo that use it's a no brainer. But that won't mean it's the best choice for every use. You have to use these lenses to their strengths. If you want lenses that do everything all through itheir range you will be looking at DFA* 50 1.4 type lenses. The 31 has great bokeh wide open and solid edge to edge stopped down. That is actually a really useful set of compromises, if you use it to it's strength, almost like a "2 for the price of one" lens. If you're looking for edge to edge sharpness wide open or smooth bokeh stopped down, you might have the wrong lens.

[biz-engineer]

In all of those shots, DoF is too narrow for the image to render enough of the subject in focus.
- First image: the lens is sharp half way between the eyes and ears of the cat, DoF razor thin, and if the eyes were focused on, AF is back focus.
- Second image: the focus plane is located between the flowers, that's why nothing appear to be tack sharp.
- Third image: again back focus in the middle of subject in a shadow area, the front of subject isn't fully sharp.
- Fourth: again back focus, focus plane is behind the eyes of the person.

For AF calibration I don't rely on a calibration scale due to depth of defocus not being balanced between front and back prevent precise adjustment of AF (although a number of people use a depth chart, I don't find it the best way to calibrate). Instead, I put a newspaper on the wall, camera on tripod perpendicular to the newspaper, pre-focus at infinity. Then I take one shot of the newspaper with each setting of AF fine adjust from -10 to +10 (-10, -8, -6, -4, -2, -, +2,+4,+6,+8+10), for each shot I prefocus the lens at infinity then let the camera AF and take the shot. I then review each shot with 100% magnification and rank them from most sharp to the least sharp, the setting used to the most sharp shot gives me the best AF adjust setting.

[sungibr]

I think the cat and the BW portrait turn out really good. But I share some of your concerns.

Mine copy was great, but over time it developed some wobling in focus ring, that sometimes, in portrait orientation, affects focus precision and everything shot at f1,8 will be soft. Specially after I droped it on the floor one day. The lens survived, but I have some issues sometimes.

That beig said, I recomend you don't give up the FA 31mm so fast. Even considering the fact it is a 1990's era design, the lens really performs amazingly well for today's standards.
My opinion is, optically the lens is as best as a lens can get, but need a much more precise af system to perform better with those high resolution cameras we have today, as I fell that much of the oof focus is because screwdrive can't match the precision it needs to deliver crispy sharpness in a body like K1, or so.

But if after all, you really don't like it, I believe you won't have much problem in get rid of it.

[normhead]

Specially after I droped it on the floor one day.

Sending it for a cleaning and having them look at the seals will probably fix that for you. I've twice had to replace the seals on my DA*60-250 after a drop. It comes back nice and tight.

[zburatoru]

I think the cat and the BW portrait turn out really good. But I share some of your concerns.

Mine copy was great, but over time it developed some wobling in focus ring, that sometimes, in portrait orientation, affects focus precision and everything shot at f1,8 will be soft. Specially after I droped it on the floor one day. The lens survived, but I have some issues sometimes.

That beig said, I recomend you don't give up the FA 31mm so fast. Even considering the fact it is a 1990's era design, the lens really performs amazingly well for today's standards.
My opinion is, optically the lens is as best as a lens can get, but need a much more precise af system to perform better with those high resolution cameras we have today, as I fell that much of the oof focus is because screwdrive can't match the precision it needs to deliver crispy sharpness in a body like K1, or so.

But if after all, you really don't like it, I believe you won't have much problem in get rid of it.

Thank you all for your thoughts! First of all I have the 55mm sdm and surely the queen it's got better bokeh especially wide open, one of the smoothest I have ever seen!
I'm sure that my calibration it's the best at +2 because I've got the best sharpness at this setting...
My lens wobbles too, just 1mm or so in the front of the lens...
I like this lens but it's not love for the moment... I'm not planning to get rid of it just to shoot the hell out of it!

[sungibr]

Sending it for a cleaning and having them look at the seals will probably fix that for you. I've twice had to replace the seals on my DA*60-250 after a drop. It comes back nice and tight.

The FA31mm has no sealing
But it was serviced.

The wobling is caused by the rollers of the helicoidal on the focus group beig worn out. The technician I send it said he can't find a replacement. I live in Brazil and servicing pentax lens here is close to impossible, so I got it back with the best he could do to adjust it.
The lens is fine, but sometimes things that are focused in the right/up side of the finder will be soft if I shot wide open, in portrait orientation. In lanscape, everything are fine.

[pete-tarmigan]

Well, I didn't spend much time with this lens but I hope that with the coming of spring to get better feeling about this lens. For the moment I'm not amazed: My copy looks quite bad at the body( it doesn't look expensive so that's a plus &#128512 but the glass is clean; it needed +2 focus adjustment but still not very sharp at wide aperture... Where it really shines it's at f2.8 and above: crazy sharp, contrasty and colorful! Maybe I'm not comfortable with this focal even if I've had Sigma 30mm first variant and the last one... But didn't like the rendering so I've bought the queen! So, I'm sharing my thoughts and some samples! Any thoughts are welcome! Thank you!

Apparently, the designer of the Limited lenses intended to design lenses with unconventional rendering. This was partly because one of the goals was to design compact, large maximum aperture lenses. Another goal was to make the lenses render images that appear somewhat three-dimensional. See the article at the following link for a detailed discussion.

Lessons from a Legendary Lens Designer | Photographic Ideals, Basic Principles | The Northcoast Photographer

[zburatoru]

Apparently, the designer of the Limited lenses intended to design lenses with unconventional rendering. This was partly because one of the goals was to design compact, large maximum aperture lenses. Another goal was to make the lenses render images that appear somewhat three-dimensional. See the article at the following link for a detailed discussion.

Lessons from a Legendary Lens Designer | Photographic Ideals, Basic Principles | The Northcoast Photographer

Some legendary separation between focus and out of focus, f2.8, I believe and some pop not quite 3d at 5.6...

[kernos]

One thing to remember about the FA31 was that the designer wanted to bring it in at f2.4 but was overruled. I don't think this lens performs best wide open but is really nice slightly stopped down to a lot stopped down. But any lens is a matter of taste.
FA31, K5iis, f2.5 natural light

[zburatoru]

One thing to remember about the FA31 was that the designer wanted to bring it in at f2.4 but was overruled. I don't think this lens performs best wide open but is really nice slightly stopped down to a lot stopped down. But any lens is a matter of taste.
FA31, K5iis, f2.5 natural light

Really nice result!

[UncleVanya]

One thing to remember about the FA31 was that the designer wanted to bring it in at f2.4 but was overruled.

I had never heard that, very interesting.

[HYS]

I had never heard that, very interesting.

The three FA Limited 43, 77 and 31, was originally developed by Jun Hirakawa. However, Jun prefered smaller lenses that should look more elegant. He originally designed a FA31/2.4, based on the optical formula of the old K30/2.8. However, the decision maker at Pentax/AOC didn't like that for some reasons but wanted to have a faster lens. Soon later, Jun was replaced by another two AOC optical designers to take up the project, namely, Mr. Ito, Takayuki (伊藤 孝之) and Mr. Murata, Masayuki (村田 將之). And they finally made the FA31/1.8 Limited lens

[normhead]

Some legendary separation between focus and out of focus, f2.8, I believe and some pop not quite 3d at 5.6...

And really smooth out of focus areas, very nice examples. It's actually the smooth out of focus areas other lens manufacturers have never been able to match.