The 50mm f/1.4 USM and it's renown fragility

Discussion in 'Canon EOS' started by radu_vadan, May 8, 2008.

  1. There have been numerous topics around here about this Canon lens failing after
    a slight bang on the noggin. Many opinions have been posted, but the main idea
    that everyone seems to agree on is that the USM's FTM "clutch" tends to break.
    Well, mine just happened to get hit by this problem on Monday, and, since I
    don't have any warranty anymore, I decided to take a screwdriver and take it apart.

    My conclusions were mixed (i.e. I'm very disappointed by the build quality of
    the inner parts of the lens), but the main idea is that it's not the USM
    coupling that breaks. Actually, nothing really breaks, but rather, the focusing
    helicoid, which is made of really cheap plastic, bends out of shape by maybe
    half a millimeter, and blocks against the main assembly. For me it was a very
    easy 15 minute fix, and now it works perfectly. If anyone is curious I can do a
    short tutorial with pictures and all, if you want to attempt a DIY job.

  2. William Michael

    William Michael Moderator Staff Member

    Well you`ve got my initial interest:

    Do you have any idea as to why this bending happened?

    Did your lens suffer a bump or a drop?

    Do you use FTMF a lot (ie when the AF is engaged)?

  3. I'm interested in seeing what you did. After a more-than-slight whack, my 50/1.4 won't focus closer than 1.5 meters. It would be useful to see what's in there before I start tearing it apart.
  4. Hi Radu thank you this is a worthwile post if have taken a few shots please post those too.My 50 f1.4 is new and works very well but you never know.
    Cheers Manfred
  5. William, I'm pretty sure it happened because i kept it in a lens pouch together with another lens, and they hit each other face to face by accident. The other lens was a 24 f/2.8, which wasn't affected in any way. Also, the bump was definitely a minor one because I have no idea when it happened.

    I will follow up tonight with a link to the pictures and explanation.

    Mike, that's exactly how mine was behaving. I'm sure you have the same problem.
  6. Interesting thread Radu, I too would be interested in your DIY disassembly photos.
    I dropped my lens from over one meter in height onto a hard floor, and it seemed to
    have become misthreaded. Basically I was getting uneven focus as, I believe, the
    lens plane was uneven. I would not expect such a fall to go without damage, but
    insurance covered it and it was repaired to perfect working order by Canon. I imagine
    they just reassembled it properly.
  7. Many thanks for posting this, Radu. Extremely valuable and useful information. My copy is a rather bad one mechanically -- not optically -- with a somewhat loose focus switch and uneven friction as I turn the focus ring. When you were in there tinkering, did you see anything that might explain the latter? In any case, please do post some pictures of your operation. Again, thanks.
  8. Please do post a tutorial. This happened to my 50 f/1.4 a while ago. It would focus ok if it started from infinity and moved closer, but not at all the other way. I took it the Canon FSC in Irvine, CA. They fixed it for free - a "complimentary repair," not warranty. I was very glad, too, because it's about a $100 repair otherwise. Among other things - adjustments, cleaning, and such - the repair slip said they replaced the "mechanical chassis" which sounds like what you are talking about.
  9. OK, all done. Please note that the pictures were not taken during the original repair. I took it apart again to take them this afternoon. Please leave your comments and remarks.

    If you ruin your lens, I'm NOT taking the blame.
  10. The "English text in black: " thing is bogus. I wanted to write Romanian & English, but gave up on the idea, and forgot to delete this afterwards.
  11. Thanks Radu for putting your time and energy into sharing your experience with us.
  12. The images that you get back with the EF 50 f/1.4 USM are amazing.

    Radu, I couldn't agree with you more. The construction for the EF 50 f/1.4 is horrible.
    The telescoping barrel is to prone to damage, "Getting knocked out of alignment."

    CANON PLEASE - PRETTY PLEASE, redesign the EF 50 f/1.4. Please give us a
    design similar to that like the EF 85 f/1.8
  13. I already unscrewed my lens. I was hoping to send it in for repair. I guess I'll have to find a third party :(
  14. Yes, the 50 f/1.4 is overdue for a face lift - but, some extra care when carrying it should take care of that. I have had mine for years and no problems..yet :)
  15. Probably sigma 50mm f/1.4 will be another alternative for us.....?
  16. Thanks Radu, I "printed" a pdf of that page, in case the day comes.
  17. That's what I love about versus the other forums. Thanks Radu.
  18. My 50 mm EF f/1.4 recently took a short fall out of my photo backpack. Its innards just disintegrated. No scratched lenses, but the plastic mechanical pieces came apart. I've seen other lenses from Canon and Tamron go through the same or worse trauma and not be bothered. So this particular model seems to be very fragile. By the way, although optically the 50 mm EF f/1.4 is very good, I liked my the images from my FD 50 f/1.4 a lot better. The FD seemed to have less distortion and better color. That FD lens was as good or better than a Contax 50 f1.7 that I compared it to.
  19. ...there you go, modern plastic crap lenses...give me FD anyday...
  20. I think Radu's efforts deserve a permanent home (much as with Conrad Erb's fine article on repairing hotshoes) at EOSdoc:
  21. mwr


    >I liked my the images from my FD 50 f/1.4 a lot better<

    I'll bite. What's an FD 50 f/1.4?
  22. Thanks for posting the instructions for disassembly and repair. After I get some smaller screwdrivers, I'll try them out.
  23. MICK RUTHVEN: "I'll bite. What's an FD 50 f/1.4?"

    You must be too young to remember this 1973 debut of this lens.
  24. Mike, let me know how it works out. I only used one screwdriver - apparently they made all the screw heads the same size - but it never hurts to have more at hand.
  25. mwr


    >You must be too young to remember this 1973 debut of this lens.<

    Ha, I'm old enough to wish that were true. That was about the time I bought my first (and only) film SLR, an Olympus OM-1, so I didn't know much about the Canon system.

    I hope this isn't considered hijacking, but my 50mm f1.4 lens doesn't focus accurately with my XSi/450D using normal autofocus ( Two other lenses, the kit 18-55mm IS and 35mm f2, don't have that problem. I'm going to return the lens for either another one or a refund. Reading this thread makes me wonder whether this lens is worth the $. Are there better alternatives for a fast portrait-type lens?
  26. I know this is an old thread but it worked BEAUTIFULLY! Just save me $125 :) sooo happy!
  27. Thank you, Thank you, Thank you.
    I just opened my 1.4 up and bent the bit of track in to place, worked like a charm, taking sharp pictures again.
  28. Dropped my lens from about one meter, the autofocs got stuck and manual focusing was hard. Have followed the instructions, the helicoid was only slightly deformed (had to use calipers to find out, which is a good idea to do if you want to fix it the first time, not fourth like me). Additionally, the outer focusing ring was bent as well. Managed to fix both, the lens now works fine. Certainly not much to break during the disassebly, just be careful and make sure that you don't touch the inner surface of the lens.

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