Using the flat scalpel edge angled down and flat against the blade, smooth the edge of the blade, trying not to apply to much force which will curl the blade up. It will take several scores to cut the blade, start gently and increase the pressure with each score until the free (exposed) part of the blade comes away by itself. Now with a scalpel cut round the coin making sure to keep the blade against the coins edge. Do not cover too much of the blade or you will weaken it too much. I've used a five pence piece (approximately 18mm diameter) clamped onto the blade, equidistant from each end and covering approximately 2.5mm of the blade width at the middle. Gently wipe any oil from the blades with a soft absorbant cloth. Tip the blades out onto a suitable surface, you may have to use a small screwdriver blade to gently push the anchor pins through from the other side. Now you can see the aperture blades, note the orientation of the blades (another photo here would be advisable). Note the position of the screw-hole in the plastic aperture ring through the cutout in the side of the aperture assembly.Ĭarefully release the spring-clip and remove it from inside the aperture assembly.Ĭarefully lift out the plastic aperture ring. Now you can unscrew the aperture assembly from the front optics. Unscrew the aperture ring (normal thread), holding the preset ring.Ĭlean off the grease from the threads and locate the grub-screw which holds the aperture assembly in place, unscrew this grub-screw (be careful it's very small and easy to break). Then carefully remove the aperture actuating screw (this is screwed into a plastic ring so be gentle). Now remove the aperture ring limiting screw with a flat screwdriver. Now take note of the amount of thread protruding from beneath the aperture ring (where the screwdriver tip is pointing), you'll need to get this right when re-assembling the lens (taking a photo of this part will be useful). Unscrew the rear lens assembly and put it to one side (being careful not to scratch the glass elements). Hold the lens by the base and unscrew the optical assembly using the preset aperture rings (if it's never been taken apart it might need a sharp turn to start it, it's a normal thread - anti-clockwise to release) If you don't feel comfortable taking on this task you may find one of these lenses (and maybe some other interesting lenses) for sale on my ebay account here:įirst off we need to release the focusing mechanism from the optical assembly. I will not be held in any way responsible if you screw up your lens, you have been warned. There may be other lenses where this is possible but I haven't found any yet. I would not advise starting with your best Helios (if you have more than 1), if your 1 and only helios 44-2 is in great condition then you might want to buy another one for your first attempt.īy the way, this will only work with the Helios 44-2 which has 8 blades anchored at each end. That being said, these are not expensive lenses so a replacement will not break the bank. It is very tricky and there is a high probability that most people who are not used to taking fiddly things apart and altering them will screw-up their lens. This procedure is not a complex idea, it's simple, But it requires a high level of technical skill. This is not a cardboard cutout in front of the lens but an alteration to the aperture blades.īelow is the whole process with lots of pictures. Ok, so I've been modifying the ubiquitous Helios 44-2 to give it an aperture that produces square bokeh. If you would like to support the forum directly, you may also make a donation here. Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase.
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