Home > Consumer Reviews > Pentax DA 40mm f/2.8 Ultra Compact Lens for Pentax and Samsung Digital SLR Cameras

After using the old Pentax-M 40mm pancake for a while, I decided to get this DA Limited version. 40mm on a Pentax dSLR is a great focal length for portraits and for regular walk-around use. The 1.5x multiplier of Pentax dSLRs makes the focal length work out to the equivalent of 60mm on a 35mm film camera.

The f/2.8 aperture is nice and fast, especially if you're coming from the kit lenses. It's fast enough to take pictures indoors (shake reduction doesn't hurt either) and creates a pretty narrow depth of field for portraits.

The super compact size makes my K100D feel very light and easy to carry around. It's perfect for outings where you'll end up taking pictures of people and close objects.

The autofocusing is super fast and I haven't seen it hunt around like my DA 18-55mm and 50-200mm lenses.

Pros:
- Very fast autofocus. Doesn't seem to hunt around like the kit lenses.
- f/2.8 makes it pretty fast and very usable, especially with shake reduction. The sharpness is decent at f/2.8.
- Super compact and light. It makes my K100D a lot easier to carry around all day.
- Great focal length for portraits.
- "Limited" means that it's all metal in construction, which definitely helps this diminutive lens feel nice and solid.
- Works great on some film bodies! See below.

Cons:
- The lens is so small that there's nothing to hold on to. I often find myself gripping the focus ring while the lens is trying to autofocus.
- I've seen a good amount of purple fringing with this lens wide open. Stopping down a bit quickly clears it up though.

Overall, this is a great lens for traveling. The cons that I listed can easily be fixed with some practice and good technique.

Edit 11/27/07: One interesting thing to note is that this lens works on film bodies without vignetting. However, keep in mind that this is a DA lens so there is no aperture ring! Cameras like the ZX/MZ-5n, ZX-10, etc. don't have a dial to control the aperture so this lens is really only useful in full auto or Tv modes. This lens works perfectly on the *ist film, ZX-L/MZ-6, MZ/ZX-7, PZ-1(P) or any other Pentax film body that has a dial for aperture control.

I just purchased this lens this week, so this is something of a preliminary review...

My initial impression of this lens is very positive. It focuses faster than any other Pentax lens I've tried, including the DA* zooms with the hyper-sonic moter. The lens doesn't turn very far at all in either direction - this, along with the small-and-light construction, means that even when hunting the lens can travel all the way to infinity and back very rapidly.

It performs fairly well in low-light, thanks also to the low aperture. The build quality is excellent, as the construction is all-metal, and it comes with a unique hood and cap. The construction conveys quality and confidence when shooting, and I've actually had no problems manipulating the small focus ring.

The pictures I've gotten so far have met my expectations. The 60mm equivalent makes for a versatile lens, but you might have to shoot a little bit tighter than you're used to (a good thing IMO). I also own the 50mm 1.4 and the 10mm wider makes a lot of shots possible that aren't feasible there. In addition, it focuses much more quickly, allowing you to catch the shots that don't stick around and wait - a super-wide aperture doesn't count for much if your autofocus is hunting the whole time.

My only complaint about this lens is the focus distance - I often wish it could go a hair closer. Of course, the excellent 35mm Macro fills this niche, but I would've put up with a little bit more size for close range improvements. Also, in very high-contrast situations keep an eye out for purple fringing.

Overall, this lens is a great deal. The build quality is awesome, it is very versatile and convenient, and the price, like most Pentax lenses, is super low for what you get. I'm anticipating this lens will be my most used, even more so than my 18-250. You won't be disappointed.

More sample images and updates to follow...

The Pentax DA 40mm f/2.8 Ultra Compact Lens for Pentax *ist Digital SLR Cameras is a great prime lens. Gave me nice clean, clear photos with excellent detail and color reproduction. Comes with a lens pouch and a lens cap that also doubles as a lens hood.

I bought this after getting the Pentax FA 50mm f/1.4. The Pentax FA was slow on autofocus, but the DA's (this lens and the kit lens) are much faster. It's a little bit wider but not by much. Most things you photograph are not 1.4 so 2.8 is still really good. The lens is rather flat with a small lens cap, which I'll probably lose at some point.

Pros: small, lightweight, fast autofocus, wide aperture, strong build


Cons: none found yet.

I have had it for more than a month, bought right before the price surge (lucky me). No doubt this is a great lens - sharp, high-grade build quality, extremely compact. I think the sharpness, color and CA control out-perform my SMCTak 55/1.8 and 50/1.4. Most appealing to me is the combination of size and quality - I mount it on my istDL, making an almost-pocketable, high-quality shooting device.

That said, I would like to share some thoughts on what could make it even better. They are precautions for those interested, but not to be taken as drawbacks (the price is gentle anyway).

Focal length: with 60mm equiv on 35mm, it is a little too long for wide-angle shots. This limits its versatility. For a walk-around lens, I think 30 or 35mm on APS-C would cover the wide end better.

Macro: if it has some macro ability, I would be much happier. There are times when I walked around in parks with it dangling from my wrist and saw a beautiful flower or leaf, but couldn't get close enough to capture its detail.

Speed: f2.8 is not fast enough for shooting in door. You need ISO 800 to get enough shutter speed, but with downgraded IQ.

Portrait: in my opinion, it doesn't replace your 50/1.4 in DoF, Bokeh and creamy feeling. 50/1.4 is reportedly less sharp wide open. but isn't it what we need for human portait shooting?