# Just Got My New 50L



## photophreek (Jan 31, 2012)

I've had this lens just a few days and I'm noticing that it back-focuses just a bit (-3). The 50L I rented two weeks ago was tack-sharp at all apertures and pushed me to pull the trigger on the 50L that I've been looking at for awhile. 

My question is should I send it back to B&H or bring it to Canon Canada for callibration(I'm 45 mins away from Canon). I live in Ontario Canada and UPS back to B&H would cost me about $30 and I can't be certain if the replacement will back/front focus.

A little background....I'm shooting with a 7d. Probably the most frustrating lens/camera combination ever. I plan on adding either the 1D X or the 5D III and keeping the 7D. None of my other lenses have ever needed MFA.

Any advice, tips or tricks regarding the 50L would be greatly appreciated. I already have the 85 1.2L II so I'm pretty familiar with the paper thin DOF of these fast primes and a good amount of my test shots were done with a tripod and shutter release and SS >1/125.


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## Mt Spokane Photography (Jan 31, 2012)

I'd use ma and not worry about -3. The next body you get will have a different MA, as long as they are close, its OK.

Also, the MA will vary by distance to subject, so even if its perfectly adjusted by Canon on their reference 7D, it will be different if the distance changes significantly.


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## photophreek (Jan 31, 2012)

From all that I've read about the 50L, MA is necessary and -3 is pretty standard. Even my 24-70L, right out of the box, was bang on sharp. I guess I've been spoiled with all my other lenses.


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## Mt Spokane Photography (Jan 31, 2012)

photophreek said:


> From all that I've read about the 50L, MA is necessary and -3 is pretty standard. Even my 24-70L, right out of the box, was bang on sharp. I guess I've been spoiled with all my other lenses.



I thought my lenses were all close or right on until I bought FoCal MA software, and compared it to my lens align results. I don't know if they have a trial period, there were some beta versions available. The software will take images from a ma of -20 to +20, and retake images that are obviously not tight. You will get a bell curve (Pro Version) like my photo below where the highest point represents the best MA. It can be a broad curve, so with some lenses, -10 to -5 does not have much variation, as in the image below

Ive found it to be more accurate than my eye. You can also see the peak of the bell curve move at different distances to the target.


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## scottkinfw (Jan 31, 2012)

I agree with Mt. Spokane.
If you want to send the lens to the factory, be sure to bring camera so they can calibrate the lens specifically to your equipment.

sek




Mt Spokane Photography said:


> photophreek said:
> 
> 
> > From all that I've read about the 50L, MA is necessary and -3 is pretty standard. Even my 24-70L, right out of the box, was bang on sharp. I guess I've been spoiled with all my other lenses.
> ...


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## tron (Feb 2, 2012)

hello,

some thoughts:

1. Even if you send the camera too for better adjustment there is probability that it will need MA with a future camera.
Is it possible to test your lens with another camera that has MA capabilities?
Even that wouldn't be conclusive but you can get an idea...

2. Is -3 consistent with the distance ? (This has already been mentioned above) 

I guess you can decide what to do depending on the answer to the above questions.


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## ss396 (Feb 3, 2012)

The 7D allows to to adjust by lens for such things... No need to send it anywhere.....


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