[Paul the Sunman]

It fits in my jeans pocket! Partly for this reason, it gets far more use from me than the 35 Art (by a factor of 3), even on FF. Especially when travelling internationally, there is never any reason to leave it home. Being relatively fast, it supplements my DFA 28-105 for low-light work. Besides, I really like its rendering, especially for street photography, where it has the bonus of being inconspicuous.

The OP says he cares more about optical quality than portability, but the 40 is definitely vastly superior optically than a 35 Art you don't have with you.

[luftfluss]

All fair responses. I was speaking clearly from an optical standpoint, but the easy portability of the 40 is understandably appealing. Personally, I don't mind walking around with something as big as the Art. I care about optical quality over ease of use so I don't mind lugging around a bigger lens, but I admit I'm probably out of the norm when it comes to that.

You should be looking at the DFA 50/1.4.

But many folks want more than one focal length when they go out shooting. Instead of a high-end prime like the DFA 50/1.4, you can tote the similarly-sized DFA 24-70/2.8... or all of the Limited primes.

[7.62lew]

I had the 40mm hd limited and sold it (regret) to get the 35mm ltd (don't regret, should have kept both ). I now have a 40mm xs to compliment the 35 limited. Optical quality is just once aspect of why I choose a lens. If I were to choose a lens strictly based optical quality, I could just buy the best lens optically I could find( and get rid of the rest)...one lens solution. For me that is not reality.

The 35 limited is fantastic optically, but trying to capture a 2 year old running around is difficult with the 35 due to the long focus throw. The reason the 40mm works for me is: great optically, super fast focus and it is small and light. With the 40mm on my camera with a wrist strap, it is very easy to work with and quick. If i need faster aperture or small apeture, a 50mm 1.7.

Each person has to decide what is most important in a lens and try to find that perfect lens...which is why many of us have LBA. I would like to try every k mount lens made at least once...how many would that be?

[Aaron28]

is there ever a reason why you'd need a 40?

L B A

besides the XS is a great lens! you should try it....you'll be glad you have it or regret giving it up

[clickclick]

What format are you shooting it on? I have the Sigma 35 Art, 40XS, and 43 Ltd, . I am more likely to use the Sigma on crop than on full frame. I go back and forth between the formats more with the 43. I think this ties into 35 on crop is closer to a "normal" field of view, but a little wide in comparison on full frame. The Sigma is really a different animal from the other lenses. If you're after sharpness as your definition of optical quality, it's the answer. I think the 43 gets the character award, and that's perhaps the problem with the 40's - they're kinda plain Jane. Good performers, but nothing to blow your socks off. The 43 is center sharp wide open and stops down nicely, but it's strength is in it's character. And I know you didn't include the 43 in your question, but I can't leave it out of the discussion. It's closer in speed to the Sigma and too close to the 40 in focal length to ignore. The final test is I wouldn't miss my 40 XS, but I will not give up my 43.

[Kozlok]

The DA40 is a great lens. One of the best. It's also one of the few lenses I've ever sold. When I got the 43, I didn't see any reason to keep the 40. The 43 is NOT edge sharp wide open, and I don't care. Not even a little. I'd get rid of both the 35 and the 50 and go with just the 43 to replace them both. I know that's what I'd do because I've done it. The Sigma 35 is super sharp, and the photos have a lot of character, but it's a boat anchor for me. If not too heavy for you, then great, keep the 35.

[UncleVanya]

I really like the images I get from my da 40. The lens just makes great photos with ease. I use it on a k3.

The 35 you use isn't in my arsenal. I had the DA 35 plastic fantastic but never quite fell for that lens. I like my FA 35 but an accident crippled it (acts like an M lens now). My FA 31 is quite nice but different. As someone else said the 40 also makes a good street lens, it puts people at ease.

[zapp]

All fair responses. I was speaking clearly from an optical standpoint, but the easy portability of the 40 is understandably appealing. Personally, I don't mind walking around with something as big as the Art. I care about optical quality over ease of use so I don't mind lugging around a bigger lens, but I admit I'm probably out of the norm when it comes to that.

We all had this phase, thinking that bigger is better and weight does not matter. Sooner or later you will see the advantage of a small lens. A big lens is not only heavy, but it draws attention to it. DA40 and other DA ltds are nice for street photography, very unobtrusive.
I tried two Art35, and honestly DA40 performed better. AF did not work well with Sigma. Pentax makes lenses in the 40 range with larger aperture, not the most recent designs, but quite unique.
If you are after Sigma Art f/1.4 lenses, Pentax may not be the best option.

[aaronjamesgray]

I need to learn more about lens design. How can something like the FA 50 1.4 be so small but a 35 1.4 or an 85 1.4 be so big in comparison to the 40 and 50?

[TwoUptons]

I need to learn more about lens design. How can something like the FA 50 1.4 be so small but a 35 1.4 or an 85 1.4 be so big in comparison to the 40 and 50?

You need to have a look at the DFA 50mm f1.4...

It’s huge in comparison to the older ones, with a lot more glass...

Whether it’s worth it is a completely different question...

-Eric

[pres589]

How can the FA 50 1.4 be so small and something like an Art 85 1.4 be so huge? The design of the FA 50 1.4 is pretty simple and has been honed over many decades. It also survived through a period where compactness was a real selling point. Further, the FA 50 1.4 isn't near the optical performer that an Art 85 is; the 50 isn't bad but it's not *that* sharp wide open in the center and worse at the edges. The FA series is also the last series of lenses Pentax made before the digital era where star charts and brick walls became so much fun to argue about on the internet.

You could also compare the FA 50 1.4 to Pentax's DA*55 1.4 which is larger, heavier, and more complex. It also performs better.

[aaronjamesgray]

Right, I understand that much. I'm just curious from a component standpoint why the 1.4 is so much smaller on a 50 than it is on a 35. Like how the construction dictates the size. More groups? More elements? I know it's not just about the aperture. Lens composition is something I've been wanting to study, guess now is a good time to start.

[clickclick]

I need to learn more about lens design. How can something like the FA 50 1.4 be so small but a 35 1.4 or an 85 1.4 be so big in comparison to the 40 and 50?

I think it's all about what is optically necessary when going for maximum sharpness and correction. The smaller lenses do not compare for across the frame sharpness wide open nor control of things like chromatic aberrations, flare, etc. As you go to make all of those things "perfect", you end up with larger elements and typically more too.

[pschlute]

I'm just curious from a component standpoint why the 1.4 is so much smaller on a 50 than it is on a 35

I think that is an over-simplification.

The Sigma 35mm 1.4 ART lens weighs 665 g and has 13 elements in 11 groups. The Pentax DFA 50mm 1.4 weighs 910g and has 15 elements in 9 groups.

Then there is the FA 50mm 1.4 which weighs just 220 g and has 7 elements in 6 groups.

I know nothing about lens construction, but the more elements the heavier/larger the lens will be.

[Cambo]

I hear a lot of people talk about the 40, either in XS or non-XS form. it gets good reviews, seems clean and shoots well. Not bad for an f/2.8.

But, if you already have a 35 f/1.4 (the Sigma art in my case) and a 50 f/1.4 (the FA in my case), is there ever a reason why you'd need a 40? A slower lens at that. Why would the 40 also not be released with a faster aperture? It's in the same length range. Shouldn't be that hard to produce.

Just idle curiosity on my part.

incredible rendering, contrast, colours, etc. And, of course, teeny...




Handheld, in a dark nightclub, ISO 3200, 1/40th, F3.5, Pentax K3ii.

Studio shot:



Just do it, and sell your Stigma...you could buy another Limited!

Screw them if they won't support Pentax!


Cheers,
Cameron