Fisheye Surgery

I picked up Asahi Pentax SMC 17mm Fisheye (introduced 1975) before I left for my tour of the world. This lens is great for traveling because its extremely compact and built like a tank. It’s optics are superior and it captures a 180º impression of the world on a full sensor DSLR or 35mm film camera—not to mention that analog lenses just look and feel rad. I scored the lens on eBay for $200. 

 The Asahi Pentax SMC 17mm Fisheye lens mounted on my DSLR

The Asahi Pentax SMC 17mm Fisheye lens mounted on my DSLR


While the lens is analog (i.e. requiring manual focus on a DSLR), I purchased up a cool Fotodiox lens mount adapter that lets it interface with the electronics of my Canon body. With this particular adapter, I can confirm focus with my camera’s autofocus points and also dial the aperture while taking the photo for inclusion in the metadata — so provided I posses the spirited initiative to dial in the digital aperture reading (corresponding to the aperture set manually in the lens), I could go back and learn from my settings while reviewing my images in Lightroom.

Sounds great, right! Alas, things weren’t quite so simple out of the box. This is a K-mount lens and as such had an aperture lever and protective edge (see image below) that had to be removed so that they would not break the camera’s mirror. (Note that this is only an issue for full-frame DSLRs as smaller mirrors of APS-C (“crop”) sensor cameras do not interfere with the aperture mechanism, I’ve been told.)

 The offending lever and protective edge 

The offending lever and protective edge 

My initial plan was to open up the lens and see if I could peacefully extricate the the aperture lever. But after struggling with getting the mount screws to loosen and contemplating that I merely had to reduce the height the offending aperture structures so they would not damage the mirror, I determined that opening the lens was not worth the risk or the hassle. Moreover, since any post-surgical scars would be hidden inside my camera body, aesthetics were of little concern.  So like a Civl War era surgeon, I proceeded with the bluntest of tools: a hacksaw and an assortment of wire-cutters and pliers. My aim was to amputate the brass aperture lever and plastic protective edge as close as possible to the base of the lens mount so that there would be no components peaking over the horizon of the Fotodiox adapter. 

 Deciding on which tools to use. 

Deciding on which tools to use. 

Although the operation did not require a good aesthetic outcome, I still had concerns as to the safety of the lens. I had to be carefulnot to damage the aperture blades while attempting to cut the aperture lever and also avoid letting plastic filings enter the lens elements as I sawed off the plastic aperture lever guard. I had read that the aperture lever could be twisted off without causing unintended damage. However, the plastic guard was, well, guarding the lever, so I had to deal with removing the first. Ergo, I used a pliers to bend the aperture lever in half so that it would be out of the way while I sawed off the guard. To protect the internal elements, I wrapped Glad Press n’ Seal around the backside of the lens — cutting a small hole through for the guard to poke through. This Saran Wrap-like product that has a light sticky side — perfect for sealing the protective plastic snugly against the guard and making sure that there would be no slippage while sawing it away. Before putting over the lens, I was sure to make sure that the rear element was all the way inside the lens so that there would be no sticky residue on the glass.

 The lens with plastic covering

The lens with plastic covering

The guard was easy to cut through with hacksaw. It only took a few seconds and I got a pretty clean cut without much debris. Before taking off the Press n’ Seal, I used a brush to remove any lingering plastic filings. (Contrary to the picture, I actually held the lens upside down I brushed away the filings so that any loose plastic would fall away from the lens.) 

 Smoothing the plastic with a brush

Smoothing the plastic with a brush

The final stage was to twist off the aperture lever. I don’t have any pictures because it required two hands, but it was also fairly easy — although perhaps I erred in having folded the aperture lever (in order to get it out of the way of sawing off the plastic guard) as it was difficult to bend back into an upright position without pulling up and damaging the aperture blades. When I finally managed to do so, I used a pliers to rotate the lever back and forth until the metal weakened enough for me to clip through it with wire cutters. 

 Post-op

Post-op

The result was not all that pretty but it worked. The lens was not damaged in the process and no components peaked over the adapter. I finished with the feeling that I had earned at least one gratuitous fisheye photo!

 My late grandfather's grand piano

My late grandfather's grand piano