Today I'm taking apart the Pergear 12mm F2. This guide may be useful if you decide to change the lubricant or repair the focus mechanics. If you just need to calibrate the focus accuracy to infinity, it can be done without disassembly by following the guide by focus calibration.

Disassembly steps

I'll start disassembly from the back. First, unscrew the three silver bolts on the fastening ring.

I remove the ring. It's nice to see a brass gauge plate underneath, looks like Pergear engineers use them to fine-tune the mount thickness for different camera systems.

The next step is to unscrew the three black bolts sitting deep in the sockets. Unfortunately, it's not that easy - this example of a Pergear 12mm F2 lens has pretty strong adhesive around the bolts. I use a drop of acetone on each bolt and wait a few minutes for the adhesive to loosen a bit. After that, I carefully unscrew them.

After removing the black ring, I remove the outer aperture ring.

Now it's time to use a wide flathead screwdriver to unscrew the long brass diaphragm actuator bolt.

Then I remove the inner aperture ring.

Now I check that the focus ring is at infinity, and then I mark the position of the “red diamond” with a pencil. This is important for the correct assembly of the helicoid. Make sure that after this the focus ring does not rotate and remains at the infinity mark.

The next step is to carefully unscrew the four silver bolts and pull out the brass rails. ATTENTION : do not unscrew the two bolts marked with red arrows, most likely they hold the iris module inside the lens body, if unscrewed, it may move, and a complete disassembly will be required to eliminate this.

Be aware of the location of the screw guides and bolts, it is important to install them exactly in the same place during assembly.

Then I hold the front lens and rotate the top lens frame counterclockwise. After two full turns it will look like the picture below. Don't forget to set the focus ring's infinity mark directly to the "red diamond".

Doing more one a full turn, and then very slowly continue the rotation and every few degrees I try to lift the ring. This example of a Pergear 12mm F2 lens has a detach point at about 0,35m of the distance indicator. It is important to attach it back and engage the threads in exactly the same position when assembling.

The helicoid has multiple passes (about 10), so if you mistakenly hook one adjacent turn during assembly, the lens will be under/overfocused and reassembly will be required. Here you have convenient access to the lens block, and, if necessary, to the diaphragm.

I half unscrew the three small bolts on the focus ring and remove it. The middle ring of the lens block can be unscrewed, but this time I do not. If you need to do this to change the grease, make sure you first mark the position of the rings with an indelible marker.

The focus ring has a focus rotation restriction zone.

Assembly stages

Now I'm putting everything back together. However, there are a few important steps that are required. With the focus ring attached to the frame at the infinity mark, I tighten the three bolts in turn until the focus ring moves to the desired position.

Then I connect the focus ring in the same place where it was pulled out and do three full turns clockwise until the "red diamond" lines up with the pencil line. Then I check if the guide slots are correctly positioned and insert them there.

Then I fix the guides with four bolts and check the smoothness of focusing. The next step is to insert the diaphragm inner ring and align the bolt threads with the actuator.

I slowly screw in the long brass bolt and center the diaphragm drive. NOTE: This bolt must go through and engage the notch on the helicoid ring and must not be fully tightened.

After installing the aperture ring, it should rotate smoothly.

Finally, attach the rear ring, brass spacer and bayonet.

Brief conclusions

The mechanics of the Pergear 12mm F2 lens are very well designed. All components are precision machined, and all internal surfaces are anodized - even the helicoid threads, which is very nice to see - prolong the life of the focusing mechanics. The Pergear engineers use a lot of lubrication at the friction points and I love the brass guides. Overall, disassembling this lens is relatively easy.

The only disappointment is the use of glue on the second set of bolts in the mounting area - they can be difficult to unscrew for maintenance. Without the use of an adhesive solvent (such as acetone), the bolt heads can be stripped, requiring a complex process of removing and replacing them.

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