Focusing Issues A7RIV

[Madafied]

I bought a A7RIV a few months ago and I've gone out several times to go shoot. The first photo shoot (portraits) I had with it, the focus looked spot on in camera but wasn't in focus once I got it on the computer. I thought it might have been the lens I was renting so went out to shoot some landscape shots with one of my trusted lenses. The focus looked great in camera but off when I put it on the computer. I immediately took it back and exchanged the camera. I shot again with the newly exchanged camera and at first I thought the shots were okay, but I'm just not getting the sharp focus I expected it to have when I bought it. I own the A7III, A9, and now the A7RIV and the trinity of G Master lenses. I just cannot get what I want out of the camera no matter what settings I use. 

Is there any known problem with the camera? I can't seem to find anything online and I feel like I'm stuck with a very expensive lemon. Any suggestions?

[Pieter]

Madafied,

Are you certain the lack of sharpness is due to a focussing issue? Due to the high resolution, your A7RIV is quite a lot more demanding than your other cameras. There are some aspects that might cause unsharp photos that your other cameras are less picky about. You should adjust your habits to get the most out of the A7RIV's high-res sensor:

 - Subject motion blur (use faster shutter speed)

 - Camera motion blur (use faster shutter speed or tripod)

 - Lens unsharpness (use sharper lens)

 - Diffraction (don't close down the aperture too far)

 - Critical focus acquisition (depth of field is shallower so aperture not too wide either)

To be sure your problem is actually a focussing issue, try the following:

Shoot a photo of a stationary subject from a tripod. Use a lens that is known to outresolve the A7RIV sensor. For the GM zoom trinity I'm not quite sure that it will, best use a sharp prime. Select an aperture value around your lenses optimum (usually F/5.6 - F/8). Try two shots: AF on your subject with spot focussing and MF with maximum focus magnification.

If the AF shot is still unsharp and/or less sharp than the MF shot, there might indeed be a focussing issue. If the subject is sharp then your issue is likely caused by any of the points mentioned above.

Edited June 7, 2020 by Pieter

[Chrissie]

2 hours ago, Madafied said:

Any suggestions?

You have to be aware, that the viewfinder of A7R4 has 5.76 MPix, which is a considerable resolution, but still a factor of ten smaller than the sensor @ 61 MPix. The LCD screen has even less pixels: 1.44 Million.

When visually judging the sharpness of an image by either looking at the LCD-screen or through the viewfinder, you can only do so if any two adjacent pixels have a sufficiently large difference in hue and/or brightness. Sufficiently large means: no less than the smallest difference which your eye can discern. This is where any limitation of your eye comes into play.

Even if your eyes are in perfect shape and you fully exhaust their capabilities when using the viewfinder, tweaking the viewfinder-sharpness to the smallest recognizable difference between two adjacent pixels, this still translates to the tenfold amount of pixels on the sensor, which leaves plenty of room for any two adjacent sensor pixels to have a _smaller_ difference in hue/brightness, than your eye can discern. Which is what you perceive as "lack of sharpness". So what you are observing is an inherent limitation of using the viewfinder for judging the sharpness of the actual image when viewed  @100%. Which becomes more pronounced as the difference between viewfinder MPixs and sensor MPIxs increases.

What you can do is, in addition to @Pieter's suggestions:

• trust the autofocus / experiment with its settings
• if you want to manually interact with focus settings: use focus magnifier and/or focus peaking.