Pentax-DA 35mm F2.4 AL

General Image Quality

There are many reasons people love prime lenses. For some it's the compactness or enhanced image quality (as primes can generally be expected to be sharper than their zoom counterparts). For others it's about being left with no choice but to "zoom with your feet," ultimately forcing a more critical and deliberate photographic experience.

With that in mind and no matter which motivation fuels your pursuit, we wanted to take a look at some general image quality characteristics before diving into the in-depth analysis on the pages to follow.

35mm Focal Length

Should the DA 35mm F2.4 AL be your first prime lens or "just another" lens you're considering to add to your arsenal, we wanted to give a quick demonstration of what you can expect regarding the field of view 35mm affords you (on a Pentax APS-C DSLR). For our comparison, we used the zoom range of the Pentax DA 18-135mm WR, arguably the most popular kit lens currently available for Pentax cameras.

The below are from the same set of images (all shot on a tripod at 1/180s, F11, ISO 200, 2s Timer using the K-5 IIs). Depending on what you prefer - the one photo or the animated .gif slideshow - we decided to include both. First, here's the consolidated photo:

*That lightpole really is slightly crooked like that - not the lens's fault! Click on this image to open a higher resolution version.

For those that appreciate seeing each image individually, here is the animated .gif showing all the above seven images in sequence:

Color and Contrast

In order to properly assess how the lens renders in its natural output, let's take a look at two images shot in RAW, one wide open (F2.4) and one closed down a few stops (F8.0). All of the below images are juxtaposed between their original settings and applying "Auto Levels" in Adobe Photoshop Lightroom. No other edits were made.

The shots below incorporate an "Uncorrected" and "Corrected" version displayed in the same frame, which you can manipulate by grabbing and holding the tall green icon, sliding it across the image:

35mm at F2.4

35mm at F8.0

Again, no other edits were made - just "Auto Levels." More aggressive processing can be pursued to fit one's taste, and if these were shot in JPEG, they certainly would not have been as "lackluster." For those unaware, RAW files are always going to be less punchy than their JPEG counterparts at first because they are designed to be processed deliberately in post processing software rather than have the camera do the processing on your behalf (as is done with JPEG's).

Nonetheless, the F8.0 shot is 100% negligible in its differences, and the wide open shot seems to have been underexposed a bit after being corrected by Lightroom (not the original shot). The bottom line is that we found the 35 AL to have rich skies and color detail as well as excellent contrast. The blacks could be a bit deeper, but that is easily remedied via processing. As it stands, we have no qualms with the output of images and the richness of their color and contrast. Without getting into the technicalities of bokeh, sharpness, etc., this Plastic Fantastic certainly punches well above its weight with regard to rendering.

Metering and Exposure

We found Pentax's 35mm budget lens to consistently meter with the K-30, the K-5 IIs, and the K-3, the cameras that we tested with the lens for the purposes of this review.

As expected, the K-3 consistently exposed more accurately. We attribute that to the K-3's far more sophisticated metering system - a professional grade metering system consisting of 86,000 pixels as compared to the 77 segments of its predecessors.

There was one small nuance, though, that we came to realize only applied when shooting wide open. The lens has a tendency to slightly underexposure the image by 1/3 of a stop (1/2 maximum), but again only at F2.4. When we did a bit more research it seems we weren't the only ones to experience this. Apparently the DA 35mm F2.4 AL is based off the film era FA 35mm F2.0 AL. While never officially confirmed by Pentax, it appears to be so - they both share the same filter threading, 6 elements in 5 groups design, minimum aperture (F22), and minimum focusing distance (30cm). Assuming this to be correct, it would make sense that the DA version would underexpose a bit wide open - it is receiving and thus exposing for an amount of light equivalent to F2.0. And yet the actual aperture is F2.4, that when coupled with the slightly faster than necessary shutter speed, a slightly darker image results.

If you are a RAW shooter and do all of your processing yourself, you probably won't bat an eye at this. In fact, minor underexposure is the preference of many advanced shooters to preserve the highlights whilst taking advantage of the outstanding shadow recovery ability Pentax's recent DSLR's are capable of.

Again, it's not a deal-breaker, however we wanted to bring it to your attention so you were aware.

Lens Correction and EXIF Data

Because the 35mm AL is a Pentax DA lens, it is 100% compatible with the in-camera lens correction functions available in modern Pentax bodies, including distortion, vignetting, aberration, and diffraction correction.

Additionally, there were no issues with the image files accurately recording the EXIF data in its entirety. The same cannot be said for some third-party lenses that sometimes do not report the lens name or worse, the focal length at all. No digital Pentax lenses exhibit this problem in any form.

On-Board Flash Usage

Not exactly image quality per se, but we want to assess the ability of the lens to be used with the flash that's built on the top of your camera. You know, just in case this small caveat could make or break the usability of the lens for one of you. Because even pros sometimes use it for fill flash in a pinch.

The below image was shot at a blank wall about 2m away, and because there is no hood included with the lens, the only image we can take is sans any lens shade.

Click on the image below to open an enlargement.

As you can see, with the lens mounted on the camera, there is absolutely no vignetting caused by the lens itself, making it perfectly usable with the on-board flash should you wish to do so.