Are there drawbacks to using a lens adapter?

Question

I am considering buying Super-Takumar 28mm f3.5 M42 and using an M42 to EF adapter to attach it to my Canon Rebel T3.

Are there any significant drawbacks I should take into account before doing this?

Does the adapter change the focal length of the lens? The 28mm focal length is important to me, since I am doing urban photography.

Is there any reason I would want to avoid a cheap adaptor like this?

https://www.amazon.ca/Lens-Canon-Mount-Adapter-Ring/dp/B00INWVBT6/ref=sr_1_1?ie=UTF8&qid=1487890328&sr=8-1&keywords=m42+to+ef

Answer 1

Are there any significant drawbacks I should take into account before doing this?

• You must use stop-down metering.
• You must focus using a lens ring.
• You must set aperture using a lens ring.
• You will have no EXIF information from the lens.
• The camera cannot control the aperture setting of the lens (i.e., you can only shoot in Av or M modes).
• M42 glass tends to be older than most adaptable lenses, and you must be a good judge of lens condition (e.g., operability, fungus, haze, whether it needs a CLA, etc.) or good at lens repair, or know of a reputable affordable repair service that can handle vintage lenses.
• Focus range might be compromised by the adapter.
• The default matte focus screen, and smaller/dimmer viewfinders in most crop-body dSLRs can make it difficult to judge accurate manual focus, particularly at the larger apertures (i.e., f/2 and wider). And your T3 does not allow for interchangeable focus screens. [i.e., Manual focusing might not be as easy as you hope]. You may need to use a tripod and live-view and features like focus peaking via the Magic Lantern add-on.

Does the adapter change the focal length of the lens?

No. But 28mm is not particularly wide on a an APS-C body camera, yielding a full-frame equivalency of about 44.8mm, which is very close to "normal" (i.e, neither wide or tele). Most manual glass you can adapt to a Canon dSLR was designed for full-frame and will be longer than a similar lens designed for APS-C would be. I learned that adapting a C/Y Zeiss Distagon 28mm f/2.8 to my XT. It wasn't until I got the 5DMkII that 28mm was wide angle, but then I got mirror collision issues (something the Canon crop bodies don't exhibit). I mostly use my 24-105L these days. :)

An 18-55 kit lens can go a lot wider (in fact, 18mm is full-frame 28mm equivalency), and if you can save up for the EF-S 10-18 STM, that might actually serve you better, if what you really want is a wide-angle lens. You also don't have to put up with any of the adapting drawbacks. Whatever you save in money, you pay for in inconvenience when you adapt a manual lens.

Is there any reason I would want to avoid a cheap adaptor like this?

Precision and chipping. The ability of the lens to focus near to infinity depends upon being held at the right register distance from the image plane. The ring has to make up the difference in depth between the systems. But, manufacturing is always done to tolerances. Some rings may not be as precise as others, and given that the M42 is a threaded screwmount, not a bayonet thread, there's slightly more room for error.

Also, cheaper rings tend not to come with a chip on them that can fake the lens/camera communication. While this chip will not give you autofocus or aperture control, it can communicate non-aperture EXIF communication (e.g., focal length so you can identify which lens you used), and can also give you AF confirmation with the green dot in the viewfinder.

See also: Can I use lens brand X on interchangeable lens camera brand Y?

Answer 2

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.

Answer 3

I use lens adapters all the time.

In your case, you will have the same issues I have going from other lenses to a micro 4/3 lens. The adapter, if it does not translate the electronic communications to your lens, well, you'll have to manually focus and set the lens settings as best as you can. For my experience in using adapters to EOS is if the aperture setting is done internal and electronic, your adapter just got expensive.

Let me show you what happened to me in reverse when I got adapters for all my old manual focus lenses, except for the EOS lenses. The cost for an adapter became cost prohibited (link at the end showing the difference in the adapters I have available).

I have been a freelance photographer since 1976, and before digital, I had Nikon F3, Canon AE-1, Olympus OM1, Pentax K-1000, and even a post WWII Exakta (made in the Russian side of Germany).

I kept these cameras for some reason and amassed about 100 lenses, including macros, bellows for them, etc.

Before my disability I shot with heavy Canon digital gear for the Charlotte Sun, Bradenton Herald, NY Post, Getty Images, Minneapolis-Star Tribune, and spent 8 years shooting every Tampa Bay Buccaneers Football games, and many Rays baseball games.

After 3 failed back surgeries and a future hip fusion, I bought two cameras - an Olympus PEN and the OMD-10. The lenses were the same size and just as light as my old lenses I haven't used for 40+ years.

With adapters, I know have use of all my professional Nikon, Canon, Olympus, Exacta, and Promaster lenses I used on my Pentax. There is no quality loss, in fact, I prefer, even though I need to manually focus and set either the shutter speed or the aperture, there is no camera lag in manual focus mode, so I get the photos I am accustomed to.

You do not need to get the expensive ones, each of mine cost about $15 a piece from Amazon.

HOWEVER, one caveat – if you have any EOS lenses you want to use, then you need a special adapter. For these lenses, you cannot set the aperture. So it is always set a f/2.8 or the fastest possible setting for your lens. You can set the shutter speed, but if you want to shoot at f/8 or f/11 or with your wide angle at f/32, you need to get a special adapter.

They have different kinds. The cheapest, that run about $200, have a dial that will allow your to set 5 or 6 different aperture settings and many will allow autofocus to work. Then there are those that are upwards of $500 that will translate the not only the autofocus, but set the aperture correctly.

Here is a B&H Photo Video Link of the Micro 4/3rds to EOS adapters, from the $29 to th $700+ ones.