I've recently bought a Pentax K-50 and I'm looking to move beyond the 18-55mm kit lens. I'm a beginner hobbyist and my main aim is to take beautiful photos of Tokyo, where I live. So mostly street scenes and landscapes, and a lot of night photography, sometimes in the rain. From some reading around the subject, it seems like what I need for these things is a fast "standard" prime lens.

I understand "standard" to mean around 30mm on an APS-C like the K-50. The problem is that there doesn't seem to be an affordable prime in this range, with the exception of the Pentax DA 35mm F2.4 AL. This lens is very cheap, but as a beginner I don't know whether this is because it has significant limitations. Once I buy a lens for this purpose I'm unlikely to ever buy another one, so I want make sure this will be the right purchase in the long term.

My specific questions:

  • At f/2.4, the maximum aperture is not as wide as many other prime lenses provide, and I'm wondering if that will limit me when it comes to night photography. I am a beginner and have no experience to judge this; I've only used the kit lens, whose maximum aperture of f/5.6 does make it hard to get the shots I'd like.

  • Initially, before I fully understood how focal length relates to field of view I had my eye on the Pentax DA* 55mm F1.4, which is just about within my budget and is weather sealed. Is there a similarly-priced lens that I've missed that has the advantages of this lens (very fast, well-regarded optics and preferably also weather sealed) but with a wider field of view?

  • Alternatively, is the DA* 55mm F1.4 itself a reasonable choice for what I want to do? Its field of view is similar to my kit lens when fully zoomed in, and it feels to me like that's too narrow, but maybe once I'm more practiced at composition that will be less of a problem, I really don't know.

In short, I'd like to know whether the DA 35mm F2.4 AL is suitable for my purposes as I've described them, and if not, what the alternatives might be.


4 Answers 4


I used the 40mm f/2.8 as my main lens on Pentax cameras for many years, and have experience with a lot of the others. I did a general overview of the Pentax APS-C prime lineup at Which prime lens for Pentax APS-C? — it isn't updated for the refresh of the DA Limited lenses from SMC to HD, but things haven't really changed much.

Let me first address your concerns in order:

  1. Is f/2.4 sufficiently fast? This is 1½ stops slower than f/1.4, so it's definitely a meaningful tradeoff in absolutes. But, f/1.4 can lead to really shallow depth of field, so in many cases you want to be at f/2.8 or f/4 even in low-light anyway. The tradeoff is that this lens has relatively high optical quality while still staying cheap, small, and light — none of which should be sneezed at. And, since Pentax offers in-body image stabilization, if you're not trying to freeze subject movement, you can generally get that 1½ in shutter speed back — or more. So, in summary: I think it's fine.

  2. Is there a wider-angle equivalent to the DA★ 55mm F1.4 SDM? Short answer: no. For many years, Pentax teased us with a DA★ 35mm F1.4 on the roadmap, but it never appeared — it seems they went the budget 35mm f/2.4 route instead.

  3. Is the DA★ 55mm a reasonable choice, particularly given the focal length? Well, it's a little odd, but you could certainly make it work. Your results would tend to be a little closer with less context, and that's not necessarily a bad thing. They'd be different from the typical 35mm-e or 50mm-e street photography, and different from most people's phone-camera shots (which tend to be around 35mm-e). That's not necessarily a bad thing either. But, the DA★ 55mm is kind of an odd duck. Its rendering is very optimized for portraits, with a lot more center sharpness than in the corners and edges. That doesn't sound like it necessarily matches what you want. Plus, it's really, really slow to autofocus — one of Pentax's worst.

So, I really won't recommend that DA 55★ for you; I think the DA 35mm f/2.4 would be a generally better choice. Unfortunately, there's nothing in the "normal prime" range with weather sealing — if that's the most important consideration, I'd suggest looking at the DA★ 16-50mm DFA 24-70mm WR f/2.8 zooms. Or, if you want step up a bit from the DA 35mm f/2.4, look at the very well-regarded DA 35mm f/2.8 Macro Limited — or even the FA 31mm f/1.8. (See my comments on these in the other question.)

  • \$\begingroup\$ I have no idea why Pentax doesn't offer a WR normal/wide prime lens. That seems like it'd be a killer feature with their WR bodies and in-camera IS. But... apparently their market people don't see it, and they're probably in a better place to make the call than I am. Instead, they seem to offer a dichotomy: you can get WR zooms, or the jewel-like Limited primes, but not both together. \$\endgroup\$
    – mattdm
    Commented Oct 8, 2016 at 14:51
  • \$\begingroup\$ In the end I went for a second hand DA 35mm f/2.8 Macro Limited. (I got the SMC version in mint condition for a good price.) So far I love it, and I wouldn't have considered it at all before your post because of its relatively narrow maximum aperture. But that hasn't been a problem so far. I get a surprising amount of use out of the macro feature too. \$\endgroup\$
    – N. Virgo
    Commented Oct 21, 2016 at 6:43
  • \$\begingroup\$ @Nathaniel Awesome — glad I could help, and glad you are enjoying the lens. \$\endgroup\$
    – mattdm
    Commented Oct 21, 2016 at 13:33

To get maximum aperture at a wider angle, I suggest looking for used lenses, too.

For instance, the FA 35mm f/2.0. It may be hard to find, though. I own(ed) both this FA and the DA 35 f/2.4, and found that they both are somewhat lacking in image quality at full open aperture, e.g. they both have rather strong so-called purple fringing at high-contrast motives, especially towards the corners. And that's what makes the DA a fairly cheap lens, IMO: The use of cheaper materials (e.g. plastics vs. glass) for the individual lenses causes more visual artifacts. And then there are newer materials that are even better but more expensive. So, if you get a "fast" standard lens, I'd prefer the old FA 35mm over the DA 35mm for the extra half apterture step. However, the anti-glare coating may be better on the newer lens, which may be important to nighttime pictures with lots of spot lights. But the good thing is that the FA 35mm does not lose value - if you get it used, and you don't like it, you may be able to sell it easily again without loss.

I also have the DA* 55mm, and find it not so great, either. Weather sealing is nice, but it has quite strong chromatic aberrations (at widest aperture). I prefer the much cheaper DA 50mm f/1.8 as it's much lighter to carry as a second lens around and good enough for my casual picture taking.

Also, consider a better zoom lens, such as a f/2.8 in the 18-50 range. I own both the DA* 16-50mm and the Tamron 17-50mm. I like the Tamron much better, and it's much more affordable, only lacking the weather sealing. The Tamron is usually my default lens, and then I may carry a super wide angle one (back then, there was only the Sigma 8-16mmm, but now there are more choices from Sigma, though they're rather expensive).

See the 30mm f/1.4 and the 18-35mm f/1.8 by Sigma.

I can also recommend the Tamron 90mm f/2.8. That's not only a fairly "fast" telephoto lens (e.g. for portraits) but also a macro lens. Opens a whole new set of opportunities.


The first step when selecting the right prime for me was to take my kit zoom lens (it's the same one you have), set it at a fixed focal length, go out to the park and take pictures without zooming. Next I repeated those steps at different focal lengths until I had a feel for the differences.

Regarding the DA 35mm F2.4 AL, there's probably not much else available new or used at that focal length, with a better aperture at a comparable price. At 50mm there are a lot of used manual focus lenses that fit the K-mount with wider apertures.

Practically speaking, an f2.4 lens means giving up two thirds to one and one third stops depending on budget. Realistically, it's one stop or less. And that may not matter much when it is going from ISO 100 to ISO 200 or from 1/125 second to 1/60 second...or 10 seconds to 20 seconds. '

'Walking around' with the zoom set at a fixed focal length will probably provide a good feel for how much a faster aperture matters. It won't provide a good field for how much harder it will be to shoot with a shallower depth of field.

Finally, the cost of the DA 35mm F2.4 AL is not so great that buying it is a huge commitment. And it is a useful focal length for a set of primes.


One more point of view.

I see you focus on a 35mm lens and its okay but why 35mm? I will suggest you some other lenses that can also bring you good results.

Have you heard about the 28mm lenses? An example of that could be the SMC Pentax F 28mm f2.8 that in a crop body like the K-50 would be around 40mm in a FF body.

You can also try to get a SMC Pentax 24mm f2.8 lens if you wanna play with manual focus lenses.

Maybe a good idea to get you understand what do you like could be grab a 50mm lens manual focusing, and see if that suits you well. There is lots of 50mm lenses on the K-Mount and many are cheap. The best of that is that there is no 50mm bad every 50mm lens is good.

You can also choose the F version of it, the DA or any other older version and would help you understand if you need longer or shorter focals for the kind of images you'd like to get.

If you consider getting a longer lens, I do suggest you the Pentax M 135mm f3.5 lens that is inexpensive, very small for being a 135mm and produces wonderful images even tho is not the fastest lens ever. I have one and I just love mine. And i did a bit of street photography with it and its a great performer. For example, it helps you get that person having a coffe in the terrace of a cool bar issolated without need to approach super close to the subject and loose that momentum the subject is having. You can find them very cheap, around 40$ usually. Oh! And it has a built in lens hood !


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