Pixel Peeping Pros: Lens Sharpness?

Started Sep 28, 2022 | Discussions thread
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Tilt Fishy New Member • Posts: 2
Pixel Peeping Pros: Lens Sharpness?

Hi fellow photographers,

Note: Cross-posted in Sony SLR forum. Just realised this is the place for E-Mount questions.

I have recently upgraded to Sony Alpha ILCE-7 IV + Tamron 28-75mm f2,8 G2, and I'm still learning to master it. Many of my initial photos appears soft and out of focus and I'm in doubt if it is due to the shallow depth of field, and lack of skills, wrong settings etc. - or if the lens is misaligned.

To understand if the lens has issues I looked up a two test in regards to "decentering" and "corner sharpness".

1: For decentering i printed a Zeiss circle chart and manually put the image out of focus to see if the center dot would shift to the sides.

2: For corner sharpness I put the camera on a tripod in uniform lightning and shot jpegs at 4 focal lengths (28mm, 35mm, 50mm and 75mm). All focus lengths at full open aperture (f2.8). I used countdown triggering to avoid bumping the camera.

I did this exercise twice. In the first run i was at 86 centimer distance from the wall. In the second run I was at 25 cm distance from the wall. The images appears softer when I'm closer to the wall, so I tried to lookup the DOF.

To my understanding when I'm at 25 cm distance at 75mm f2.8 the DOP appears to be less than 1mm to each side of the plane. Hence I am a bit in doubt if the longer distance shot (86 cm from the wall) are more representative of corner sharpness than the shorter distance (25 cm from the wall)?

3: For corner sharpness I also tried a sharpness chart printed out in A4, but I had to step very close to cover the full frame at 28mm (approx 15 cm distance from the wall) and I got very bad results. For that reason I didn't' complete this test. Should I have done that instead?

4: Can any of you pixel peeping pros out there help determine if my lens is sharp or not? Any help would be much appreciated, so I can learn if it's me or my gear that needs a fix

Straight out of camera jpegs below - Thank you so much!:


Panasonic Lumix DMC-G2
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