FE SEL24-105 soft focus

Started 7 months ago | Discussions thread
havoc315 Veteran Member • Posts: 5,040
Re: FE SEL24-105 soft focus
1

JERumball wrote:

havoc315 wrote:

JERumball wrote:

No... these are all taken indoors (in an ice rink with great ambient lighting) shot at f/8 , ISO 200, 1/250s at 105mm on a tripod with three AD200 strobes lighting the subject.

so in good natural light at f4, the focus is fine?

I will have to review more closely some of the other images I've taken to see. Most of those have been for personal use and therefor haven't been as much of a concern for me as these team and individual photos are.

But that's how we need to identify the issue you're having.

If it's fine at F4 and natural light, then it's either a low light focus problem, and/or a focus shift problem.

If it's still front focusing at F4 and in good light, then something is wrong with the lens or the camera focus system.

If it's focus shift, the solutions are to shoot at F4, use DMF, or use AF-C (which forces the camera to focus at F8).

Problem is, it will be hard for the camera to lock focus accurately at F8 in low light. And yes, you're shooting in very low light. Even if your eyes are able to adjust and see everything, it's still a low light environment.

And I do wonder whether it's unique to this environment. Extreme contrast of the scene -- the white ice and dark background, then putting a dark jersey in front of the dark background, I do wonder whether the camera's AF system is struggling.

I wouldn't jump to the conclusion that your Zeiss 16-70 is focusing any better on the A7r3. When using the APS-C lens, you're shooting a much lower resolution image. If you're shooting 70mm F/8 on the Zeiss, you're also getting more DOF than 105mmF/8 with the entire full frame sensor.

From 10 feet away, with the full frame at 105/F8, you're getting 1.33 feet of DOF. When using the APS-C part of the sensor, 10 feet away, 70mm, F8, you're getting 2 feet of DOF.  So you're getting 50% more DOF with the Zeiss lens, on a much lower resolution image. So you're far less likely to notice the slightly missed focus.

I will say this for shooting F8 portraits with many Sony lenses on the A7r3 -- I often get missed focus with every lens at F8, I get much better focus with wide apertures. It's the cameras, not the lenses.

 havoc315's gear list:havoc315's gear list
Sony a7R III Sony a7 IV Sony FE 55mm F1.8 Sony FE 70-200 F4 Sony FE 90mm F2.8 macro +9 more
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