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My 50 1.8 STM back-focuses a little when focused through OVF.

I visited Canon Service in Bangalore today.

The technician there outright told me that there is no adjustment possible for 50mm 1.8 stm lens.

I am in a bit of disbelief. Is it true that there is no AF adjustment possible for this lens? Did anyone here got this particular lens AF adjusted?

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  • \$\begingroup\$ What camera are you using? Does your camera body support AFMA? If not, you can try using Live View. \$\endgroup\$
    – xiota
    Aug 16, 2019 at 8:13
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    \$\begingroup\$ Suppose someone told you it is possible. Where would you have it adjusted, if not a Canon service center? \$\endgroup\$
    – xiota
    Aug 16, 2019 at 8:14
  • \$\begingroup\$ AFAIK older 50mm1.8 could be adjusted.I was surprised to now that this one couldn't be. I don't have AFMA body. Given that I live in a country with pathetic after-sales service of almost everything, I wouldn't be surprised if tech lied to me. \$\endgroup\$
    – GPS
    Aug 16, 2019 at 9:25
  • \$\begingroup\$ Since the focus sensing is done in the body, wouldn’t the camera body need the adjustment, not the lens? \$\endgroup\$
    – Eric S
    Aug 16, 2019 at 13:45
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    \$\begingroup\$ @EricShain It could be either. PDAF is not completely "closed loop". The camera tells the lens to move a certain amount. The lens moves. The camera then uses position sensors in the lens to check if the lens moved the instructed amount. The PDAF sensor is usually not used to measure focus optically again because many times the mirror is already moving up by the time the lens moves and the position is checked using position sensors. \$\endgroup\$
    – Michael C
    Aug 17, 2019 at 18:09

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Searching Canon India's website for a lens repair facility, there does not seem to be an actual Canon Service Center anywhere in the state of Karnataka. All of the locations listed for various cities in Karnataka state are Collection Points that appear to be third parties affiliated with Canon in some way (such as a dealer for Canon copier products). These businesses probably don't repair any Canon lenses, but forward them to an actual Canon Service Center.

If you look at the listings for Delhi, for example, you see there is a Master Service Center listed. I would contact whichever such Master Service Center is nearest your location (I'm not familiar with the geography of India - there are also Master Service Centers in Cochin and Andheri) and inquire from them if the EF 50mm f/1.8 STM can be adjusted the way you need. There are also a few Authorized Service Centers and Authorized Service Franchises located throughout India. If one of those is much closer to you than a Master Service Center, you might try contacting them.

If it turns out the lens is not adjustable, then you might consider having your camera checked to see if the PDAF sensor array is properly adjusted to be the same optical distance from the lens as your camera's imaging sensor is.

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  • \$\begingroup\$ There is one Canon Master service center in Bangalore. \$\endgroup\$
    – GPS
    Aug 16, 2019 at 14:54
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    \$\begingroup\$ @GPS It's not listed at Canon India's website in the "lens" category, only under the DLSR category. They may send lenses out to another facility and only work on camera bodies there? \$\endgroup\$
    – Michael C
    Aug 17, 2019 at 18:03

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