What are the drawbacks of using an M42 lens on a Canon Rebel T3 with an EF adapter?

Asked 2/23/2017

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I’m considering using a Super-Takumar 28mm f/3.5 M42 lens on a Canon Rebel T3 with an M42-to-EF adapter. What practical drawbacks should I expect? In particular: does the adapter change the focal length, are there limitations with focusing or exposure, and is there any reason to avoid a very cheap adapter?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

9y ago

2 Answers

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There no significant disadvantage (but see the link in the comment above).

However when you say 28mm is an important focal length for you, I'm not sure if you are aware that on a an EOS T3 you have a crop frame sensor. The effect of this is that focal lengths quoted on lenses should be multiplied by about 1.6x to work out the equivalent focal length on a full frame body (like an old 35mm film body).

The 18-55 kit lens which you may have therefore covers the equivalent of about 28-80 on full frame.

By using the 28mm M42 lens you are interested in, you will actually be getting a field of view equivalent to about 45mm on full frame (which is not a wide angle).

It's hard to know if you want a wide angle (in which case that 28mm lens will be pointless for you) or if you understand the crop sensor issue already and know what to expect.

But also note that your kit lens already covers 28mm and it's doubtful you'll get much benefit from using the older lens instead of the kit lens. I'd really give this some consideration.

Originally by user46861. Source · Licensed CC BY-SA 4.0

user46861

9y ago

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AI Answer

Generated from our catalog & community — verify before relying on it.

An M42-to-EF adapter is usually just a mechanical spacer, so it does not change the lens’s focal length. A 28mm lens remains 28mm. However, on your Rebel T3’s APS-C sensor, its field of view is similar to about 45mm on full frame, so it will not look wide-angle.

Main drawbacks:

  • Manual focus only
  • Manual aperture control on the lens
  • Stop-down metering
  • No lens EXIF data
  • Camera cannot control the aperture, so you’ll generally use Av or M mode

Other concerns with vintage M42 lenses:

  • Lens condition matters a lot (fungus, haze, stiffness, need for service)
  • Accurate manual focus can be harder on crop DSLR viewfinders
  • Some adapters may affect focus range if not made to the correct thickness

A cheap adapter can be fine if it is correctly machined, but poor-quality adapters can cause fit or focusing issues. The bigger practical issue here may be field of view: on the T3, 28mm behaves more like a normal lens than a wide one.

UniqueBot

AI

9y ago

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