buckscop Loc: Bucks County PA

I just completed taking focus test shots for 2 of my lens, f/5.6 up through f/40, and downloaded them into my computer. My camera shot in RAW. Do I keep them RAW unedited and just look for sharpness, or edit them in some fashion to compare them (I have LR)? Should I have shot them in JPG as the would have been cleaned up somewhat exposure wise? Is MS File Explorer good enough to look them over (therefore un edited)? Thanks in advance.

CHG_CANON Loc: the Windy City

RAW files, depending on the software used to view the files, either has no (zero) sharpening, or has the camera's (or the software's) default sharpening applied. For the purposes of your described experiment, you probably want to look at the "raw" RAW files, as in: use an editor that applies no sharpening.

one_eyed_pete Loc: Colonie NY

What CHG_CANON said. RAW is what you start with. I'm assuming you want to compare the "lenses" at each f stop. Unless you want to compare something other than the Lense's performance such as editing capability of software.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

My advice, since your asking. Forget trying to do a focus test on your own. Many others who have attempted this end up more confused and the results are far from conclusive.
Most lenses are sharpest stopping down two to three stops from max. So if your lens is a f1.8 lens, then the sharpest f stops for that lens should be around 2.8 to f4.
Generally speaking the further you stop down your lens the less the desirable sharpness. I personally would not shoot above f16, and that would be a stretch for me.
Good luck and keep on shooting until the end.

DirtFarmer Loc: Escaped from the NYC area, back to MA

What is your plan for determining sharpness? Are you going to compare two photos for relative sharpness or are you going to do a numerical measurement somehow to determine sharpness. What sort of subject are you using? Something like a focus test image?

Comparing images side by side can be tough. You have to move your eye from one image to the other while remembering the first image. Sounds easy but it can be surprisingly tricky. I recommend using a blink test. If you open two (or more) images in an editor using layers (e.g. Photoshop or GIMP) you can align the images, then turn the top layer visibility on and off. That allows you to look at a particular spot and see quickly what the difference is between the two images without having to move your eye. If your editor is capable of saving an animated gif you can use that to make a comparison that you can save and/or send to someone else. https://www.uglyhedgehog.com/user-page?upnum=3016

DirtFarmer Loc: Escaped from the NYC area, back to MA

Don't limit yourself (never say never). F/16 and above is not that bad and sometimes DOF trumps sharpness. My diffraction study has a chart showing how sharp an image is as a function of f/ number. Admittedly it is for a single lens, but I don't believe there will be large differences among different lenses.

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imagemeister Loc: mid east Florida

If I were doing an "f-stop focus test" I would be doing it as it relates to large prints made from JPEG. To that end, I would want to do the evaluations with normally processed JPEGS at print magnification - but maybe that is just me ! ?? But, I am not sure of the exact reason for your "f-stop focus test" .....either
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MJPerini

You don't say what you photographed. The first rule of any kind of Testing is to isolate variables to be tested and eliminate variables that are not being tested
So, Camera on a tripod, release with self timer , remote or MLU (mirror lock-up
Same distance from the target and be sure the sensor and the target are plane parallel and centered.
Even illumination of the target. and bright enough that you can use moderately fast shutter speeds.
There are lens testing targets on line that you can print (Targets have both gross & fine detail) and arrange on a brick wall (to also check for barrel & Pincushion distortion) or a blank wall indoors. Arrange in a rectangle at least 4x6 feet
If you shoot RAW, any application that allows you to view the file will be displaying a JPEG, either the embedded one (part of the RAW file) or created by the raw converter of the application. In Lightroom's case Camera RAW
Most cameras have an AA filter that blurs the image slightly to avoid moire', so all RAW files need some sharpening. I am not a lightroom user so I cannot say with any certainty if Camera RAW sharpens on conversion.
But, since this is a personal test, as long as you are consistent with all things tested you are ok.
Personally, since all files Raw or JPEG get some sharpening, I would probably make a very basic preset in lightroom and view the JPEG there.
To have real value any kind of testing requires some rigor, otherwise your results have much less meaning than they otherwise could, and could even be misleading. I would also make 2-3 exposures at each setting so that if you see an anomaly you can check the other frames (the camera could get bumped etc)
I would also think you could safely eliminate f/32 & f/ 40 on crop cameras.

I hope this helps a bit

OldCADuser Loc: Irvine, CA

When you say 'focus test shots', are we talking about where is the image the sharpest or how does this effect depth of focus? And note that as you step down, the depth of focus will of course get broader, which might make it harder, if you're just doing visual comparisons between shots using different f-stops, to see differences in sharpness.

I've tried this a couple of times using one of those DSLRKIT targets and while I've learned a few things, it's a lot more tricky than you'd first expect.

buckscop Loc: Bucks County PA

My test was for focus/sharpness purposes, the supposed 'sweet spot'. This started with my taking images of fallen trees along an abandoned RR line, of which I took similar images at different f/stops with my Canon R7, and 18-150mm shot at 76mm on a monopod. When in LR post, and looking at 100%, I noticed that one particular image at f/9 looked a lot sharper than its twin image shot at f/16. In the screen shot attachment of them both together, f/9 is on the left. I did the test inside on a tripod, with 2sec shutter. My target was a glossy mail ad with some good fine print in different sizes. I did different zooms and at each f/stop. I back button focused, took a picture, then moved the f/stop, focused again, picture, etc etc on both lenses.

While far from perfect, I was happy enough with my process, but was asking how best to view the images as they were RAW. My thought was, is comparing the RAW images without any post editing the right way to compare them. Or, should there be a least some minimal (common to all the images) edit in LR to be able to better compare them.

Thanks for all your responses so far. I have been looking at them without any edit, and it is pretty apparent that the F/7-11 range shots are sharper than the ones at f/16-40 range

Side by Side comparison. Left f/9, right f/16

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EJMcD

While I've never made such comparisons, it seems odd to me that the f16 image is that much softer overall than the f9 image. I assume the ISO was the same for both shots but the shutter speed would of course have to be slower for the f16 image which may account for the softness?? Or is f9 really that much better than f16?

imagemeister Loc: mid east Florida

Ever heard of DIFFRACTION ??

TriX Loc: Raleigh, NC

Diffraction.

If you really want accurate acuity testing of your lenses, let me suggest investing in a copy of Riekan Focal. I bought it to do microfocus adjustments on my DSLR, but I found that the lens/acuity test to be even more useful. Not only will it tell you where your lens is the sharpest (all lenses are NOT sharpest at 2 stops down, some are sharpest wide open), but it will tell you instantly if a lens isn’t up to par, and best of all, there’s nothing subjective such as comparing images - you get a repeatable graph of fstop vs acuity.

DirtFarmer Loc: Escaped from the NYC area, back to MA

What I see is the f/16 image is significantly noisier than the f/9 image.
Also, the images are aligned very slightly differently. Below are two blink gifs so you can see the difference. The second one has been enlarged by about a factor of 3.
For sharpness tests I would recommend the use of a focus target. You will have a subject with really crisp sharp edges. I would also recommend use of a tripod rather than a monopod,.

EJMcD

Thanks but I don't spend time "testing" lenses. If it looks good to the naked eye, it's good enough for me. I don't view my images (prints/enlargements) with a microscope but thanks again for the suggestion.