Mamiya 645 150mm lens with oily blades

[ian_rose]

<p>I have a 150mm lens that is showing signs of oil on the apture blades. I cleaned this lens out about 9 mounths ago rinsing the blades off with the ronsol cleaning agent (lighter fluel). I did not strip all the focusing mechinsium down.my question is is there a easy way to get most of the old lube out of focusing thread without stripping the lens down to all its component parts.<br>

1/ I was thinking of keep washing the focusing barrel until the cleaner came out clear.<br>

2/ soak the focusing barrel in ronsol for about 24 to 48 hours.<br>

3/ keep cleaning every 6-9 months until all the lube is washed out.<br>

opions as to what would work best also is there a cleaner that would work better.</p>

<p>Thanks in advance</p>

<p>Ian R</p>

[rodeo_joe1]

<p>Ian, not a good idea to remove the grease from the focusing barrel. The focusing will become sloppy and gritty and it may cause permanent damage to the alloy helicoid.</p>

<p>You need to carefully wash the oil out of the iris chamber only, which is usually a separate section of the lens. While it's a real pain to remove or dismantle an iris mechanism, it's really the best way to solve the problem in the long run without causing damage to other parts of the lens. Cleansing solvents I've found to work well are; lighter fluid, acetone-based nail varnish remover and methylated spirit. Which serves the purpose best depends on what's contaminated the iris, from light oil or dirt to ingress of grease from the helicoid.<br /> A light contamination of the iris blades can usually be cleared by applying the de-greaser on a cotton bud (Q-tip) and swabbing it off again. Flooding the whole barrel with solvent will simply wash more oil into the iris.</p>

[kevin_halcrow]

<p>I have just tried to dismantle this lens, from the rear, to the point where the iris leaves are accessible. Unlike the 80mm lens that I have had some success with, I cannot get beyond removal of the 1st mount ring of the 150mm lens. The ring below the 1st ring hangs up on something and I can't figure out what it is. Any suggestions? Are there any illustrations of the dismantling process's steps available? Kevin Halcrow</p>

[kevin_halcrow]

<p>Please ignore my previous post. It dawned on me that the 150mm lens's rear element could be removed without any disassembly if the lens is focussed at infinity, when a lens spanner will reach the lens collar. But I would still like to know how the iris mechanism <strong><em>alone</em></strong> could be treated with a degreaser! Kevin Halcrow</p>

[d.wayne_goebel]

<p>Kevin I don't know if you have seen this article: http://www.pbase.com/pganzel/mamiya_645_150mm_disassembly_and_repair<br>

I don't think the iris assembly can be cleaned separately either.<br>

Can you post pics of your dis-assembly from the rear mount?<br>

thanks</p>

[kevin_halcrow]

<p>Wayne - thanks for the link. That's a really useful set of photographs, which makes me think I should try the 150mm disassembly from the front. My cleanings of the 80 and 150 lenses have turned out to be only temporary; some oil has already reappeared on their blades.<br>

I have no photographs of my procedure with the 150. It really is as simple as I suggested. When the lens is focussed at infinity, the "notches" on the collar of the rear element are reached easily by a lens spanner. The whole element can then be screwed out, giving direct access to the iris blades. I don't have a lens spanner but made one from a vernier caliper, as described by a wonderful contributor to the Nikon Repair listserver (see http://soverf2repair.webs.com/Images/vernier.jpg). Good luck!</p>