MOD - Click-stop aperture – 7Artisans 35mm F1.2 lens

7Artisans 35mm F1.2 lens has click-less smooth rotating aperture ring by design. Its texture is very different from focus ring so it’s easy to identify by just touching rings while keep looking into viewfinder. However when you want to check the aperture value during shooting you have to look at the top of the lens to read it, and make sure desired value is set. Alternatively I’m simply rotating aperture ring to the very end to set F1.2.

Today I’ve finally modified this lens to the aperture click-stop version.

Initially my point was to avoid any direct lens modifications like drilling or cutting. I’ve tried few different designs for click-stop mechanics, but all of them failed in a short time, or didn’t provide enough feedback. Then I decided to implement one of most simple and reliable solution: spring loaded ball.

This design is used by many lens brands, including Fujinon XF model line. I like the idea of having noticeable loud clicks on aperture stops. The aperture ring also securely holds the position once metal ball is catching the slot.

So the first step is to find good place for about 3-3.5mm deep hole under the aperture ring. I’ve drilled it very carefully to not drill it through, and used 2.4mm drill in super slow mode.

Secondly I’ve marked hole positioning aperture ring for different values using pencil, and later hand drilled single tiny spot marked for F1.2 setting. On the picture below you can see all slots, but I’d recommend to start with one first to make sure the ball location perfectly fits the stop position.

I’ve found small 1.9mm metal ball, and also cut 3.5 turns of metal spring from regular lighter (used to push the flint up). I’ve gently curved the spring ends to make them more flat.

Then I’ve put the spring to the lens hole, and gently located the ball on top, so only half of the ball is visible. I’ve applied aperture ring and rotated it few dozen times to make a line on the inner side of the aperture ring.

Later I’ve used the line formed by the ball to perfectly center the aperture stop slots and make them wider up to 1.6-1.8mm. I’ve intentionally made F5.6 and F8 slots smaller, so stop-clicks are less intensive there.

As a result I have audible clicks wile rotating the aperture ring. It feels like the Voigtlander aperture, with only difference that I didn’t add half-stop points. Also aperture value remains the same until I decide to change it, no more accidental rotation of aperture ring.

Later Ive decided to add visible red dot on the silver mount ring of 7artisans 35mm F1.2. It’s much more visible now which F value is set.