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11-14-2021, 09:54 AM   #1
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Pixel peepers wanted...

Hi all,

I got a K-3 mk III a few months back and it's so good it inspired me to pick up the new DA* 16-50 to get the most out of it.
I have a 30-day return policy but I'm not experienced with evaluating imperfections.

Can you take a look at this one? It was shot at f8 and 1/100 sec so it should be sharp pretty much everywhere.
I see some unsharp area in the upper left but not all the way in the corner. Perhaps it is just that on pine branch was moving...I don't know.
What do you think?

p.s. I'll post a couple more shots too.

https://www.flickr.com/gp/89237167@N02/B2Mg74

---------- Post added 11-14-21 at 11:58 AM ----------

This one also at f8.
It is "in camera" HDR but still came out pretty sharp with three images combined

PTX_3180.jpg | Vince Mokry | Flickr

---------- Post added 11-14-21 at 12:01 PM ----------

Also at f8


PTX_3159.jpg | Vince Mokry | Flickr

11-14-2021, 10:13 AM   #2
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About the first photo, a 50mm lens at f8 on 24mp apsc doesn't have that much depth of field as you'd think. All images look good to me, if there's softness it's not looking like a lens issue just out of focus. Do you remember where you focused for each image?
11-14-2021, 10:20 AM   #3
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QuoteOriginally posted by aaacb Quote
About the first photo, a 50mm lens at f8 on 24mp apsc doesn't have that much depth of field as you'd think. All images look good to me, if there's softness it's not looking like a lens issue just out of focus. Do you remember where you focused for each image?
Thanks for the help.

I was using AF-S and the max number of points. Is decentering best evaluated with max aperture which for this lens is f2.8???
11-14-2021, 10:20 AM - 1 Like   #4
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Nothing in any of those images look killingly sharp at 100% view, as is often the case. At normal size they look great.

Your best bet for testing a lens for sharpness is to do a brick wall test. Use a tripod to get the camera absolutely square to the subject and use the Electronic shutter to avoid any possible shutter shock.

The first picture I am assuming you were about 40 feet from the building, and that you focussed on the building ? At f8 that will give you acceptable DOF from about 20 feet in front of you. I am not surprised the big tree, extreme left is not sharp.

11-14-2021, 10:25 AM   #5
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QuoteOriginally posted by aaacb Quote
About the first photo, a 50mm lens at f8 on 24mp apsc doesn't have that much depth of field as you'd think. All images look good to me, if there's softness it's not looking like a lens issue just out of focus. Do you remember where you focused for each image?

Also, on the first picture,it just seems odd that the pine needles in the upper left are fuzzy but the rest of the picture seems decently sharp.
It is possible that the camera focused on the leaves by the ground. Those little red AF points sure were nice on my old K-3 mk 1.
11-14-2021, 10:30 AM   #6
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QuoteOriginally posted by Lloyd_Christmas Quote
It is possible that the camera focused on the leaves by the ground. Those little red AF points sure were nice on my old K-3 mk 1.
The red AF points must be visible in the K3 III ? Have you checked the menu ?
11-14-2021, 10:32 AM - 1 Like   #7
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QuoteOriginally posted by Lloyd_Christmas Quote
I was using AF-S and the max number of points. Is decentering best evaluated with max aperture which for this lens is f2.8???
Because of high resolution and large aperture, the safest is to refocus of every part of the image where you're checking sharpness. And to have an "easy" subject like a brick wall with the setup pschulte js describing. Tedious, but eliminates questions about whether it the problem is misfocus.


Last edited by aaacb; 11-14-2021 at 10:46 AM.
11-14-2021, 10:33 AM - 1 Like   #8
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QuoteOriginally posted by Lloyd_Christmas Quote
Also, on the first picture,it just seems odd that the pine needles in the upper left are fuzzy but the rest of the picture seems decently sharp
I imagine they in front of the DOF
11-14-2021, 10:35 AM   #9
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QuoteOriginally posted by pschlute Quote
The red AF points must be visible in the K3 III ? Have you checked the menu ?
Hi, the K-3 mk III has little LCD boxes that don't show up well.
They do flash a red light but it's still hard to see them.
If I hold down the AF button when I take the shot, you can see them in the review process.
I had move the pictures off of the camera.
I'll try to move them back to see if I can review them now.

---------- Post added 11-14-21 at 12:42 PM ----------

Here's one I took about a week ago of a brick wall. It's not optimum and I was not perfectly square.
This time f6.3 and it was hand held with shake reduction enabled:


https://www.flickr.com/gp/89237167@N02/308CJ5

Last edited by Lloyd_Christmas; 11-14-2021 at 10:46 AM.
11-14-2021, 10:55 AM   #10
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QuoteOriginally posted by Lloyd_Christmas Quote
What do you think?
You get the kind of sharpness that is expected from an APSC format camera. The sensor is no larger 16x24mm, prints no larger than 16"x24" should be fine.
11-14-2021, 11:12 AM   #11
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QuoteOriginally posted by Lloyd_Christmas Quote
I was using AF-S and the max number of points.
With an f/2.8 lens, limit yourself to center points only if you want accuracy and precision.

BTW...Pixel peeping at full resolution defeats DOF. As screen magnification increases, DOF approaches zero.


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11-14-2021, 12:02 PM - 1 Like   #12
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QuoteOriginally posted by Lloyd_Christmas Quote
...Can you take a look at this one? It was shot at f8 and 1/100 sec so it should be sharp pretty much everywhere....
No it shouldn't, you're shooting digital at 26MP, not 35mm film, and digital is much more exacting. Depth of field also refers to what's acceptably sharp either side of the distance focussed on. You don't mention what it's focussed on and I think you might not even know. In any event, I don't see what there is to complain about, but if you're still unhappy I'll take the thing off your hands – camera and lens!

Learning to ignore 100% magnification for most purposes was something I took a while to learn: look at the whole picture and enjoy what you shoot.
11-14-2021, 12:17 PM   #13
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QuoteOriginally posted by StiffLegged Quote
look at the whole picture and enjoy what you shoot.
That's good advice for sure. I don't have the focus point from that first shot I posted. If I remember to hold the AF back button it will keep them for me to review in camera later.
It just looked odd that there was only one part of the photo that was fuzzy... but appears that was a portion that was out of the DOF.

Didn't mean to say I'm not happy with the camera or the lens. Looks like a winning combo!
11-14-2021, 12:20 PM   #14
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I find the Zeiss Siemens star chart great for a more controlled, but still easy, lens test.

No need to buy it - just open it on your computer screen (it's on Flickr) and follow these instructions:

https://thecameraforum.com/test-decentered-lens/
11-14-2021, 12:40 PM - 2 Likes   #15
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QuoteOriginally posted by Lloyd_Christmas Quote
Here's one I took about a week ago of a brick wall. It's not optimum and I was not perfectly square.
You need to do that again to be able to read anything from the shot

---------- Post added 11-14-21 at 07:44 PM ----------

QuoteOriginally posted by stevebrot Quote
With an f/2.8 lens, limit yourself to center points only if you want accuracy and precision
First thing I do with a new camera is to change the number of AF points to the minimum (excepting single).....usually centre 9.

I want to be in control of what the camera focusses on, not leave it to the camera to decide.
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