p.1 #1 · can you help me check if I got a good copy?
I recently got a used RF50/1.2 and I'm wondering if it's as sharp as it can be. If I send you a couple of RAW files can you pixel peep and check if it matches the sharpness you get with yours? I'm also new to lightroom and my 5K apple monitor so there's too many variables for me to make sure...thanks in advance
p.1 #4 · can you help me check if I got a good copy?
Get one of these. https://www.edmundoptics.com/p/1x-i3aiso-12233-resolution-test-chart/12905/
You can mount it on a rigid board and then use hinges to swing it down into your shooting place for testing. over the years it pays for itself on dozens of lenses. (A smaller one is good for long lenses.)
Make sure you test for symmetry by taking the same image right side up and then upside down. All corners and sides should be the same. If the results shift 180° about the center when flipping the camera, the lens is probably misaligned or decentered internally.
p.1 #5 · can you help me check if I got a good copy?
EB-1 wrote:
Get one of these. https://www.edmundoptics.com/p/1x-i3aiso-12233-resolution-test-chart/12905/
You can mount it on a rigid board and then use hinges to swing it down into your shooting place for testing. over the years it pays for itself on dozens of lenses. (A smaller one is good for long lenses.)
Make sure you test for symmetry by taking the same image right side up and then upside down. All corners and sides should be the same. If the results shift 180° about the center when flipping the camera, the lens is probably misaligned or decentered internally.
EBH
But, how will it tell you if you have a good copy of the lens unless you test it against other copies?
p.1 #6 · can you help me check if I got a good copy?
Do you need to compare it to bunch of other copies of the same lens? For starters it should be compared to a reasonable standard. Once you see what a good lens looks like it is up to you to decide if any sample is good enough. Obviously there are plenty of medicore zooms with mushly corners and edges and you can test a dozen copies with similar results. It can help to read some lens test and check the MTF up front, but that would usually be before getting even one copy.
p.1 #7 · can you help me check if I got a good copy?
EB-1 wrote:
Do you need to compare it to bunch of other copies of the same lens? For starters it should be compared to a reasonable standard. Once you see what a good lens looks like it is up to you to decide if any sample is good enough. Obviously there are plenty of medicore zooms with mushly corners and edges and you can test a dozen copies with similar results. It can help to read some lens test and check the MTF up front, but that would usually be before getting even one copy.
EBH
If you want to know if it is as sharp as it can be, which is what the OP asked, then you have to test it against other copies of the lens. Otherwise as imagemaster wrote, are your images good enough for your purposes, and if they are that is good enough.
p.1 #8 · can you help me check if I got a good copy?
No, a sample should be tested against a standard not other random samples. Not having access to test equipment, the consumer can use a consistent target and/or some of the other methods linked above to get some idea of lens performance.
The easiest thing the OP can do is to send the lens to Canon so that they can test it to confirm if it is spec or needs adjustment.
p.1 #9 · can you help me check if I got a good copy?
EB-1 wrote:
Get one of these. https://www.edmundoptics.com/p/1x-i3aiso-12233-resolution-test-chart/12905/
You can mount it on a rigid board and then use hinges to swing it down into your shooting place for testing. over the years it pays for itself on dozens of lenses. (A smaller one is good for long lenses.)
Make sure you test for symmetry by taking the same image right side up and then upside down. All corners and sides should be the same. If the results shift 180° about the center when flipping the camera, the lens is probably misaligned or decentered internally.
EBH
Anyone with a quality photo printer can download it as a .TIF or other, for free.
p.1 #10 · can you help me check if I got a good copy?
EB-1 wrote:
No, a sample should be tested against a standard not other random samples. Not having access to test equipment, the consumer can use a consistent target and/or some of the other methods linked above to get some idea of lens performance.
The easiest thing the OP can do is to send the lens to Canon so that they can test it to confirm if it is spec or needs adjustment.
EBH
It’s very likely a waste of time and money sending it to Canon because most of the time they just say it is within specification, which spans superior and inferior copies. And what is the point of spending $466 on your suggested chart if that is not going to answer the OPs question and they have to send it to Canon? I test lens all the time using charts, but like the previous post, I print them myself. My favourite is one on the Bob Atkins site. Usually looking at one or two other copies is enough to satisfy me that my lens is typical and not an outlier, rather than it is the best possible.
