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Replacing Iris Blades 400mm Telemegor Lens???

jreitsma

Member
Allowing Ads
Joined
Sep 13, 2009
Messages
29
Location
Minneapolis,
Format
Large Format
Folk;

Recently picked - up black 400mm Telemegor Lens for $10 and found that one of the IRIS blades dislodged. I managed to get the front element off thus, exposing the IRIS blades and assembly. I fumbled around a bit, found the locking ring which made the removal of the blades rather simple. Unfortunately, it appears that putting the IRIS blades back into proper working order is a bit more complex than removing them.
So, I am wondering if anyone can provide some direction on how to put these blades back in place:munch

Thanks Much;

-Joe (in Minneapolis).
 
Did you pay close attention to the blades as you took them out? If you have not taken them out carefully remove 1 blade and look at the pin ends, one end is usually different from the other, more rounded or different pin lengths.

Once the correct orientation of the blade is established pick a starting point. Insert the blades in a counterclockwise (anticlockwise) direction laying the next blade in sequence on top of the previous one. At some point the next blade in the sequence will have to slide under the first blade and continue with the next until all blades are in position. Use a pencil and run around the inside perimeter to get the blades to full open. Position the top plate onto the blades making sure each pin fits into its slot or hole and the plate is correctly aligned in the lens barrel. Secure the plate and operate the aperture. The aperture should move smoothly and its full range, if not disassemble and try again.
 


All of this. It's a slow process getting all the blades back in place one at a time and getting all the pins in the holes. Don't rush it and be very careful not to try to touch blades once you get them in place because a slight touch with your finger may/will dislodge them. The bigger the lens, the easier it is to do. Small lenses (with small blades) are pretty difficult only because of the size of them.

Be patient and you'll work your way thru it.
 
You havee to put each black on top of the previous blade at one end and under the next blade at the other end - until you form a circle. then put everything back into the aperture frame and hope it doesn't fall apart.

Figure on spending from 30 minutes to 1 1/2 hours to finish the job. You have to have a lot of patiencee and steady hands.

Be sure not to bend any of the blades.
 
What he said^
Last time I did it in a 50mm/1.8 Helios 103 (about six weeks ago) it took me exactly 1 hour 20 minutes. What I eventually did was find a cylindrical piece of scrap the right diameter, assemble the blades on the moving ring atop this cylinder, and lower the lens barrel onto the assembly. A sharp sewing needle will help you move the pins into their holes, put the point in the center of the pin and gently move it under the hole. If I had started out this way I could likely have saved an hour.
 
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