Canon 50mm 1.2 disappointment

[bmauter]

Hi everyone, I recently bought a used 50mm 1.2 lens from a local guy on Craigslist. I'm trying to figure out what's going on. I don't know if it's just me, it's my camera or it's the lens, but I'm getting really cruddy shots.

Focusing. With AutoFocus, if I tell the lens to focus on a spot, it's never in focus when viewed at 100%. I've heard that backfocusing is a very common problem with these lenses. So I tried to find out how much so I could compensate. It's as if the picture is never in focus, or if it is, it's certainly not anywhere close to my subject. Closer shots are worse than farther shots. The shutter speed is definitely more than 1/50.

I have always had problems with auto-focus, but I've always blamed myself. Some lenses manage to take terrific shots eventually though. My 70-200 f/2.8 IS L usually nails it. There again, I have to be quite far back from my subject, so maybe there's something in common to that and the 50. I've never been really happy with my 50mm 1.8 either. That's partly why I upgraded to the 1.2.

Chromatic Aberration. Anytime there's a large contrast, I get a pink and blue glow along the border. At first I thought I was overexposing, but I'm not sure of that. I've never seen it with the 50mm 1.8, 70-200, 28-135, 17-40 or the kit lens.

Here's an example. I focused on her right eye but it's not in focus. Her left eye has the pink and blue aberration. The EXIF data says it's at f/1.2 for 1/50s. I apologize for the slow website. It's hosted over my DSL modem.

What do you all think? Did I get a lemon? Is this something that can be fixed?

Thanks,
-Brian

[inkista]

Umm.... have you ever shot with an f/1.2 lens before? Because there is a learning curve involved in nailing focus with an f/1.2 wide open (especially with autofocus). Add in the 50L's focus shift issue and it's probably one of the hardest of Canon's lenses to master. I doubt you got a lemon--it's just a really hard lens to use, and the AF performance is more problematic than with the other L primes.

Give yourself a break and shoot with it stopped down for just a few frames to check your autofocus when the DoF isn't razor-thin, (just to save your sanity). Also check and see if some other part of the frame is in focus.

[bmauter]

I've shot with the 50mm 1.8 for 2.5 years. The 1.2 is thin, but surely it's not THAT much thinner than the 1.8. I need to set it up on a tripod with a ruler on a 45º angle and trip the shutter with a remote. If I focus on a certain spot and it didn't nail it, I now have what's needed to compensate I guess.

What do you think of the pink and blue fringe?

[RustySterling]

Originally Posted by inkista

Umm.... have you ever shot with an f/1.2 lens before? Because there is a learning curve involved in nailing focus with an f/1.2 wide open (especially with autofocus). Add in the 50L's focus shift issue and it's probably one of the hardest of Canon's lenses to master. I doubt you got a lemon--it's just a really hard lens to use, and the AF performance is more problematic than with the other L primes.

Give yourself a break and shoot with it stopped down for just a few frames to check your autofocus when the DoF isn't razor-thin, (just to save your sanity).

Inkista is correct. That lens is a monster to handle. the other that is just as difficult is the 85mm f/1.2L -- and for the same reasons. The depth of field is razor thin. It takes lots of practice. I had the 85 for while and just couldn't master it. So I changed to an 85mm f/1.8, which works much better for me.

Good luck and keep playing with it.

[Digidave]

Very few lenses work well wide open(f/1.2). If you were about 3 ft. away from your subject, your Depth-of-Field would be about 0.05 ft.. I don't know what the works out to in inches but it's really small! Try taking a shot stopped down to at least f/4 & see what you get. In order to do a complete test & rule out all external influences, you need to do it on a tripod without flash.

[LoveDSLR]

Originally Posted by bmauter

I need to set it up on a tripod with a ruler on a 45º angle and trip the shutter with a remote. If I focus on a certain spot and it didn't nail it, I now have what's needed to compensate I guess.

Good idea! Does your Canon DSLR allows fine tuning?

Some people have focus shift problems with this lens although I have no problem with my 85 f/1.2 L II. No wonder it only has a rating of 8.4/10 at fredmiranda while 50 f/1.4 has 9/10 and 85 f/1.2 L II has 9.7/10.

[RustySterling]

Opps, wrong thread.

[inkista]

Originally Posted by LoveDSLR

Some people have focus shift problems with this lens although I have no problem with my 85 f/1.2 L II. No wonder it only has a rating of 8.4/10 at fredmiranda while 50 f/1.4 has 9/10 and 85 f/1.2 L II has 9.7/10.

Actually, a lot of folks have focus shift issues. I don't recall all the details, but I think that if you have the lens stopped down a little at certain distances, it will exhibit focus shift far more than most folks think an L lens ought to. I know the dpreview guys had found a workaround, but all I remember is that it seemed like waiting for a 50 f/1.2L II was a good idea. And it explained why the "Holy Trinity" of L primes is always given as the 35L, the 85L, and the 135L, skipping over the 50L.

OTOH, from what I read, it also sounded like the 50 f/1.2L was a big improvement in sharpness wide open over the 50 f/1.0L.

This is when a rangefinder makes sense. Focusing a Noctilux has gotta be simpler.

[LoveDSLR]

Originally Posted by inkista

I know the dpreview guys had found a workaround, but all I remember is that it seemed like waiting for a 50 f/1.2L II was a good idea. And it explained why the "Holy Trinity" of L primes is always given as the 35L, the 85L, and the 135L, skipping over the 50L.

Someone at fredmiranda uses the outer focusing points instead of the center AF to avoid this problem.

[bmauter]

I have a Digital Rebel Xti (400d) body. Unfortunately this means I don't have the ability to adjust the camera to compensate for the back focusing. I think the Live View mode of the 40d or 50d would be helpful if I clicked over to manual focus. I could then zoom in on the preview window and really nail focus that way.

Also, because I have the Xti, the only 'precise' AF point is the center. I've tried the other 8 AF points, but I'm not having much luck there either. I used to be a fan of focus and recompose. Now I compose, choose my AF point, focus and then capture.

These two features are partly why I mentioned that it may be the camera (as opposed to me or the lens). I'm just more inclined to believe it's me making mistakes.

0.05 feet is a tad smaller than 5/8 of an inch. I agree that's thin, but it still seems doable. If I tell the camera AF to focus on an eye, then it should be able to nail it (and eyelashes) and even remain in focus if I cause a small amount of movement when I squeeze the shutter.

I always considered the trifecta of primes to be the 35, 50 and 85. The 135 being considered in that group is new to me, especially with an APS-C body. With the 50, it's like I'm shooting an 85.