Best way to test lens sharpness at home?

480sparky · Feb 12, 2015

FWIW, here's my method:

I go out on a sunny day to my back yard. I set the camera up on a tripod, and set it to Manual mode at ISO 100. I use a wired release to trigger it. I also focus manually, using 100% review to verify focus is good. I turn off any VR/IS/OS/VC the lens might have.

I take a JPEG with the lens wide open, then at each full aperture (4, 5.6, 8....) all the way down to minimum aperture. I repeat the process for each focal length marked on the barell if it is a zoom lens.

I then pixel-peep each image at 100%. I rate both the center and corner on a scale of 1-10. I create a small chart of these results to keep for handy reference, converting it to a .PDF so I can view it on my phone.

I don't bother with shooting charts as I don't shoot charts in the field. The trees and grass and bushes in my back yard are good enough for me.

unpopular · Feb 12, 2015

Take a picture, look at it. Is it sharp? Done.

I also have a bunch of primes, which one I use is not so much about sharpness, but contrast, color rendering, bokeh, etc. Sharpness is over-rated.

Buckster · Feb 12, 2015

I use the LensAlign, but it's really easy to build one at home on the cheap. All you need is a ruler and a printout of a target, then put them together, and you have the basic system, which is what I used to do before I got the LensAlign and, to be honest, it worked just as well for me. Go all out and glue the target to a piece of foam core or stiff cardboard or something like that, even build a platform similar to the LensAlign, and then it will last and be reusable.

What may not be obvious in the photo of the LensAlign is that there's a small hole in the center of the target, and a dot it lines up with on a target behind the front target. This is intended to make it easier to make sure that the target is square to the camera, not tilted in any way. However you do it, you'll want to keep that in mind.

After building, just focus on the target, and see which lines on the ruler are the sharpest when you view the image closely. If it's the line right next to the target, everything's right on. If in front of or behind, then you know your focus is off a little, and may need adjustment.

Here's an image to use as a template:

http://ecx.images-amazon.com/images/I/51oYu+OC9wL.jpg

See the other photos of it here: Amazon.com LensAlign MkII Focus Calibration System Camera Lens Accessories Camera Photo

Mach0 · Feb 12, 2015

tirediron said:
photoguy99 said:

Bar codes.

But don't. You typically don't get anything useful or very interesting out of it.

Been there. Done that.

Click to expand...

Useful to whom? I do home-brew lens resolution tests with all my lenses. My method: Cover a letter-size sheet of paper with 12pt, upper-case 'X's (preferably 'Arial' or a similar sans-serif font). Make sure it's edge to edge. Then, tape that piece of paper to a wall, and set up your camera so that it is perfectly level and the plane of focus is parallel the sheet of paper, and that it is close, but not at the minimum focusing distance. In other words, if the mnimum focusing distance for the lens is is 12", have the camera 14" away. Once everythings set up, tripod solid, release ready, exposure correct (aperture priority/Tv) shoot a frame of the paper wide open, and at whatever other apertures you're interested in. I find this an excellent way to show me approximate sharpness corner to corner, and most importantly where my aperture needs to be for maximum sharpness, where difractions starts to occur, etc... It may not be useful to you, but I consider it good infomration to have.

I do something similar and it allows me to dial any needed af fine tune and no issues thus far

Sent from my iPhone using Tapatalk

bratkinson · Feb 12, 2015

Performing tests to determine the sharpness of a lens can only result in your being disappointed, in my opinion.

One of the posters in this thread suggested performing your lens tests at a little bit further from the subject than the minimum focusing distance of that particular lens. Whether you focus manually (probably without the benefit of a split-ring focusing screen) or letting the camera auto-focus, the results will not likely be what you expected.

Regardless of the result you get, it applies only to that lens and camera combination AT THAT DISTANCE. I learned that lesson the hard way when performing micro focus adjustment using a target at the recommended distance of 50x focal length, as I recall. As a result, my target was in the range of 15 feet to perhaps 25 feet away. The problem was that was not the subject distance for 95% or more of my photography! When I performed my next shoot during a church event, everything, and I mean everything, was noticeably 'soft', in my opinion. In comparison to using the same lenses on a non-MFA capable camera, the MFA'd shots were softer still. My solution was to perform MFA outdoors on a sunny day with an long ruler-style tool located about 30-40 feet away, my typical indoor subject distance. The difference was like night and day. It also changed my EF 24-105 f4L from 'eentsy-weensty soft' to being as sharp as my EF 24-70 f2.8L mark i I previously owned, in my opinion.

The other side of the coin, to my way of thinking, is you're expecting to get $20,000 lens image quality from a $300 lens and an entry level camera. Again, you're setting yourself up for disappointment.

These days, the entry level DSLR gear provides images that are sharper, consistently better focused, and properly exposed than any of the 35mm film gear I ever owned, starting about 1970. Slides I took then, and I had maybe a 20% keeper rate that I was happy with, even when projected on a 10 ft x 8 ft screen were more than satisfactorily sharp. Images produced by my former 8mp Canon 30D and an EF-S 18-135 lens on it are every bit as sharp as what I could produce on film, and maybe a bit better. A couple of years and 3 months gross pay spent on camera gear later, my results are sharper still.

But...in addition to my higher-quality gear, my photography skills have improved as well. Regular readers of this forum as well as other photography forums will see threads where the poster is not getting the results they expect from their DSLR. In almost every instance, the problem is either missed focus, a too-thin DOF, or too-slow shutter speed. The last two are the result of not fully understanding and applying the exposure triangle.

In short, regardless of what you think is 'sharp enough', the results you get in your tests will disappoint. Then you'll end up spending a fortune (or a marriage, or a car, or whatever) buying the newest, latest, greatest gear, do the tests again, and still be disappointed. Oh...and one other thing about super-sharp pictures...On occasion, I've intentionally softened them during post processing due to the pores on the subjects face being too prominent in the picture.