45mm 2.8 dissassembly

[b_m5]

<p>I have a 45mm 2.8 with sticky aperture. The rear element is very easy to remove, however, I cannot see how to remove the front one.<br>

In addition, the focussing does not go past ~0.9m (stays below) and is a bit stiff. Where should I start with this issue?</p>

[ondebanks]

<p>I opened up one of these several years ago. IIRC, it was like any other M645 lens, in that the front group is also easy to remove with a lens spanner, once you first screw off the flat ring with the lens name and serial number. A rubber ring of the right diameter grips this ring for easy removal - e.g. an o-ring. I sometimes use a shallow rubber cup (designed for going under the legs of furniture) as a handy tool for this purpose.</p>

[b_m5]

<p>Thanks for a swift reply. I have removed the flat ring. However, hooks for lens spanner are nowhere to be seen on the front element. </p>

[ian_rose]

<p>I have just finished one of these lenes ounce you have the frount ring off you then remove the houseing the ring screws into. see image 1<br>

you can then grip the houseing of the front element and unscrew it. I used a pair of rubber gloves</p><div></div>

[rodeo_joe1]

<p>Which model of 45mm lens is it? The early version has a 77mm front thread and a flat "cover" over the actual lens retaining ring, IIRC. To remove the dished cover you need to use a friction spanner; this is just a rubber ring that fits inside the lens filter thread and contacts the cover. A correct sized rubber "O" ring will usually do the job.</p>

<p>In any case the trouble will most likely be with the stop-down mechanism rather than the iris itself, and this can all be reached from the back of the lens. Check the levers and springs for stiction with oil or grease between them and their mounting plate. It only takes a little bit of oil stickiness to upset the balance of tension between the opening and closing springs.</p>

<p>Sorry, just read that much the same was posted previously. Apologies for the duplicated info.</p>

[b_m5]

<p>Thanks for the replies. <br>

I am able to remove the front ring with the lens name on it, also the hood-like thingy goes of after unscrewing several bolts. However, I cannot see how to remove the glass itself.... <br>

(I can remove the very front element by unscrewing a retaining ring. However, I cannot see any sort of retaining ring or stopper for the element behind it)</p>

[b_m5]

<p><img src="http://img89.imageshack.us/img89/4967/imag0084t.jpg" alt="" /></p>

<p>I think a picture might be handy.<br /> So, I removed the metal assembly (lens name ring + hood-like barrel + 3 screws) (1 in the picture),<br />then unscrewed the retaining ring (2),<br />and removed the very front element (3),<br />but still cannot see how to remove the remainder of the assembly (4) to access the aperture blades. (I have removed 3 screws that seem to link the focusing helicoid (?) with the assembly)<br /> Rodeo, thanks for a good advice. In my case, I had a look at the mechanism, but it seem OK. Also, I can see quite some oil on the blades, and moving them without the rear element makes sound. I guess, rinsing the blades would still be helpful anyway.</p>

<p>Edit: attachment</p>