DIY: Turn any Manual Pentax Lens into a Cine Lens

Declicking Pentax Lenses: New Hot Video, Old Trusty Lens

By Mister Guy in Columns on May 28, 2016

Many articles on Pentax Forums try to give you opportunities to click your way to a bargain.  This is about how and why you might go the other way.  The beautiful quality and feel of legacy Pentax glass might give you a good enough reason to consider popping to a used lens store and declicking your way to a deal!

In essence, by declicking a lens, you can make the aperture ring turn as smoothly as the focusing ring.  This can have many benefits, especially if you're into shooting video.  Read on to learn all about it.

It was originally my intention to simply use this article as an excuse to breathe some new life into my first and favorite lens, my SMC Pentax-M 50 F1.7.   It may not have the latest coatings or fancy tricks like autofocus, or the full ability to meter properly on DSLRs, but it's a great little lens that is built solidly and has served me well.  The problem I quickly discovered is I wasn't actually willing to do the declicking on my lens, but that was a problem I was easily able to solve with a quick trip to the used lens department!  Soon enough I found these little guys languishing in the case:

Super-Takumar 105mm and SMC Pentax-M 50mm F1.7

I quickly found a replacement volunteer M 50mm F1.7 and a Super-Takumar 105mm F2.8.  As time goes on, people prefer new technology, and some really beautiful lenses with amazing features have been released.  However, it's going to be a long time before you can get those lenses at under a hundred bucks, for both!  (This lens rescue message brought to you by your local chapter of Lens Buyers Anonymous; Rescue a lens today!)

Before we go digging into our lenses, let me get to the why of it.  Why bother with a poor man's version of a cine lens?  This is the point I'd planned on saying, "Because it's free!" That point got a little shot when I talked myself into two new lenses.  Instead, I'm going with something very similar, "Because they are an a excellent value!"  Plus, virtually no cine lenses currently exist from third-parties that otherwise support the K-mount.

Video is something your Pentax equipment is becoming able to do better and better, but at this point, it's likely that if you had serious professional DSLR video needs, you've probably invested in a different brand.  For those of us who want to be able to produce quality results without switching product lines, the vast pool of legacy glass is too rich to ignore.  One little ball stands between us and smoothly transitioning apertures during video.

The culprit: remove this and your aperture ring turns smoothly

Declicking your lens gives you two abilities at the cost of being able to quickly change the aperture precisely without looking.  The first is the ability to fine tune your aperture, in general.  If you have ever found yourself in a shooting situation in which you wished you had just a hair more control over the exposure or the depth of field, this may something for you to play with.  

The second has to do with video.  Cine lenses allow videographers to adjust the aperture smoothly and silently, as easily as you'd follow focus.  You can fine tune depth of field and exposure manually and cleanly, and change your settings while recording to get it exactly right.  Many models of DSLR camera now allow aperture adjustments during video recording, but even so, there are times riding the aperture manually feels like the way to go.

After Disassembly - Click to Enlarge

M 50mm F1.7 Mount

There are many good tutorials and articles on how to disassemble vintage Pentax lenses. I won't go into an excessive amount of detail, but for the SMC line you carefully remove the mount, wiggle the aperture ring a bit, and then put the mount back on.  Nice and easy. The metal ball that normally causes the aperture ring to click will come flying out.  The Takumar takes a little more confidence, but isn't as tricky as it feels like it's going to be.  It just takes nimble hands, an extremely small JIS screwdriver, and care.  You carefully twist off the front bezel with a makeshift tool, most likely, and then remove the lens assembly in order to remove the focus ring so that you can remove the aperture ring.  All to remove that tiny, tiny little ball.

A small disclaimer: while the declicking is fully reversible, it may prove to be a challenging task if you're inexperienced with Pentax lens disassembly.  Be sure to save the metal ball if you'd like to be able to put the click back in.

Super-Takumar 105mm F2.8

After Disassembly - Click to Enlarge

As you will soon see in our in-depth review, it turns out that the Pentax K-1 has slightly better video capabilities than the K-3 line.  Whether or not that's sufficient for your needs, it's still a feature you may want access to if you intend to upgrade.  Pentax's dedication to the K-mount has allowed us to keep beautifully-made older equipment functional and useful for a while to come.  Check out your local camera shop and see what kind of a deal you can declick for savings.