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Super Contributor
Posts: 211
Registered: ‎01-27-2018

Best way to test used lens is working

Hi All,

 

I have decided to go for the Canon 500mm F4 IS Mark I used.

 

Cosmetically, the lens seems to be in pretty good condition minus the scratch marks on the body. Apart from that, no other blemishes that I am aware of it. That said, it is a used lens, what would be the best way to test to make sure the lens is functioning as intended?

 

My plan was to take my camera along, take a few test shots. Test the autofocus, test the manual focus. Test the varios F stops. Test how well it handle light and not so bright. Not sure how I would go about testing the IS feature. And lastly, should i take my laptop to check the photos are actually sharp?

 

What else?

Thank You!

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Respected Contributor
Posts: 1,029
Registered: ‎01-25-2018

Re: Best way to test used lens is working

Your plan sounds good, I would add to that to check that the focus ring/mechanism turns smoothly.

 

Look closely through the lens from both ends with both ends open to check for any mold growing on the glass.

 

Shake it gently, there shouldn't be rattling noises.  The white primes will stand a lot more than a gentle shake but if anything is going on that will reveal it and you don't want the shop owner to have a heart attack.

 

Check the focus stop buttons to make sure they work (and focus preset if the 500 is so equipped, it probably is because that is found on most of the long primes).  Check the focus limiter settings and make sure that it focuses properly close and far.

 

IS is fairly obvious in operation.  I don't know which version of IS this lens has but try the lens handheld with IS on at 1/250 and 1/125 and you should be able to get sharp photos with reasonable care while holding it.  Try repeating this with IS off and you should see a noticeable difference.  You will hear IS working, it makes different sounds with different models and I have never used an EF 500 so someone else may be able to describe the normal IS noise from it.  You can also see IS working as you try to hold the lens steady on a subject or follow a subject.

 

I would take your laptop if you want to be sure it is sharp before you buy but make sure that you calibrate the lens to your camera or your results will just be misleading.  The method I use for micro focus cal is a little different than what Canon suggests in order to make it faster.  Set up a target, something in the grass that the camera can focus on works well but if the parking lot is heavily textured you could use it however there needs to be enough detail in the parking lot (which is why grass is better) to indicate clearly what is in and out of focus.  Set the target up at a reasonable working distance for the lens and use a fast shutter speed with the lens wide open.  Camera should be set to a single focus point on the target in single shot with servo focus off.

 

Throw the lens out of focus between each shot and takes 3 shots each with micro AF offset of 0, +3, +5, +8, -3, -5, and -8.  The offset data is in the EXIF so you can see that when you use DPP so there will be no question where the offset is for a given shot.  AFter you take all of these shots, run the files through DPP and carefully check if the best focus is on, in front of, or behind the target.  My great whites and 1DX series bodies have mostly been dead on and all were withing 3 points of offset even with extenders but your results may vary.  Probably one of the initial chosen offsets was correct but if not this first run will give you enough data to choose the exact point of offset.   I have never had a Canon lens require more than 6 points of offset and unless other lenses require a lot of offset on your body I would be leery of one that requires a tremendous correction.  Once you have the AF dialed in, then make the rest of your test shots.  It takes me under 10 minutes to calibrate a lens to a body using this method of making multiple shots with different offsets in a single run.

 

Rodger

EOS 1DX M3, 1DX M2, 1DX, 5DS R, 1D M2, EOS 650 (film), many lenses, XF400 video
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Esteemed Contributor
Posts: 2,148
Registered: ‎11-19-2017

Re: Best way to test used lens is working

Greetings,

I looked at the 3-4 other threads you started, all pretty much pertaining to the purchased of this lens.  I thought others advised against the purchase.  I can't tell because you've started so many threads?

 

A Tamron 150~600 or even Sigma would be a better investment.  The guys have told you its not a good idea.  But its your money.    

 

Sounds like a reasonable battery of tests.  The seller should not mind you bringing your laptop along to pixel peep.  I'd bring a good tripod along too, but for the record, I wouldn't be buying this lens.   

 

Hope it works out.

~Rick
Bay Area - CA
~6D2 ~Many Lenses ~DxO PhotoLab Elite ~Windows10 Pro ~EVGA RTX 2080 FTW3 Ultra ~Pixma Pro-100
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VIP
Posts: 12,744
Registered: ‎12-07-2012

Re: Best way to test used lens is working

"A Tamron 150~600 or even Sigma would be a better investment.  The guys have told you its not a good idea.  But its your money."

 

Bingo! Smiley Frustrated

 

There is no good way to "test" a lens at a point of sale pick up place.  Make sure the AF is working and the IS works. Take it home and use it.  Don't look back, you made the deal now work with it.

EOS 1DX and 1D Mk IV and several lenses!
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