Those of you who spend any time cruising YouTube or Reddit have probably heard of this kickstarter project called the “I’m Back” digital film cartridge – a product that mounts a digital sensor in a 35mm film camera, enabling you to use it as a digital camera. It’s an interesting idea, though priced way too high (at $900 U.S.) to be worth it for most people.
What if you could take those old lenses and mount them on a modern digital camera body?
Adapters of all kinds exist to facilitate this. In my case, I am using a Pentax M42 to Canon EF adapter – a metal ring that I purchased on Amazon for only $8.99 U.S., much more obtainable.
Screw the lens in and twist it on like any other Canon lens, and you the ultimate photography freak show – a Super Takumar 1960’s era Pentax Spotmatic kit lens (see what I did there with the title? I thought it was clever…) on a modern day Canon Rebel SL1 digital body.
But, how can this actually work? The camera interacts with the lenses in so many ways to do different settings and focus and what not – can you even meter light properly? The answer may surprise you.
There are actually two tricks – first, you must have the “depth of field preview” turned on if the lens has it. In other words, it must be set so that the aperture actually closes when you turn the ring, rather than closing up to the setting when you go to take the picture.
Second, you must use the “Aperture Priority” mode – known as the “Av” function on Canon and “A” function on Nikon.
The auto focus won’t work. There’s no way to make that work becuase there are no motors or electronics to work with here.
So on the camera your aperture reading will be 0.0. When you turn the ring on the lens, the camera will still calculate the right shutter speed and automatically pick an ISO setting.
As can be seen in these random shots, the results are not bad at all. These are unmodified shot in JPEG. I wasn’t looking for anything fancy or artistic here, so this is a rare occasion where I just didn’t bother with the RAW format. These are straight off the memory card as-is.
In short – if you have a lot of older lenses that you want to use in the digital domain, adapting is also an option.
Shoot photos, not each other!
Adventures of a Photo Nerd 
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