Testing recently bought SEL24105G lens

[João André]

Dear SonyAlpha members,

Hello from Lisbon by a newbie in this forum and in photography.

The reason I'm uploading this post is that quite recently I had the chance of purchasing a A7iii+SEL24105G combo. I had read very exciting reviews from both the camera and the lens as a nice 1st setup to start in enthusiast photography.

Disclaimer: My background on photography basically comes from Youtube videos.

My experience with the camera+lens has been somewhat unsatisfying since I struggle often with lack of focus, producing unsharp, blurry all round photos. This happens even mounting the camera in a sturdy tripod and shooting indoors in very well lit conditions. The image quality does not match my lowest expectations.

So given the above I spent the last days trying to understand how to identify the cause of this apparent problem. Since I only own one lens I figured that I could only test if the lens could be the problem. So I searched around the web and found this page https://www.lensrentals.com/blog/2014/02/setting-up-an-optical-testing-station/.

I tried to follow the procedure and test the lens by taking photos of test images PDFs displayed in my Sony 4k 49'' TV, using various focal lengths (24, 70 and 105), the widest aperture of the lens (f4), centre focus area, manual focus with focus peacking, camera centred with the image centre, AF-lock off, face-eye priority off, neutral creative style, camera on the tripod, 2sec timer.

I attach the images I got in result. I think for the Siemens Star Chart I cannot see any decentering so I think the test is OK. However, the sharpness of the photos is mediocre, or at least below my lowest expectations from the reviews I've seen for this camera+lens.

Considering the ISO 12233 chart, I got these images full of chromatic effects.... not sure if they are to be expected since I was shooting a screen (although the star chart images are also from the same tv screen). That apart, the sharpness at centre is again, in my opinion, poor, but I cannot perceive any issues by looking at the corners. Just the sharpness issue brings me doubts.

I also made the sony back and front focus test (https://www.sony.com/electronics/support/articles/00018293) and I also attach some images. Sharpness aside I see no issue.

I would really appreciate if you can give me your opinion about what might be causing my bad experience. What should I correct in my shooting, how should I do further testing, should I go to the Sony local repair shop to get the lens/camera checked?

I was not sure if I should attach jpegs or RAW files, so I upload the latter which can be downloaded using a wetransfer link (due to size limitations):

https://we.tl/t-Afs5fYZybU (warining large file ~700MB. Please tell me if this is too large. I can provide a link to just the jpegs).

Thank you!

Kind regards,

Joao

[Pieter]

Did you disable steadyshot when taking these pictures? Steadyshot will negatively affect sharpness if your camera is mounted on a sturdy tripod: it will attempy to counteract movement while there isn't any.

Also: don't blindly trust focus peaking as it's often too forgiving in focus identification. Use maximum magnified live view instead to confirm critical focus.

[João André]

Dear Pieter,

Hello and thank you for your comment and suggestion.

I tested with and without lens steadyshot ON and in my experience it seems that there's almost no perceptible differences between photos. I might be leaned to say that with steadyshot ON seems a bit more sharp.... at least through my eyes.

One thing I tried was to add much more light into the subjects I was using in the test. This allowed the ISO to come to 200 instead of 6400 or higher. This made a significant difference in terms of overall sharpness.

I have to do some more testing but as of now I do think ISO played a big role in the image quality I was having up to now.

Thank you once more for your time and support!

[Pieter]

ISO 6400 will indeed result in blotchy/grainy images with little sharpness. Since you were shooting in a controlled environment off a tripod, I kind off assumed you were at ISO 100 and let the shutter speed be as slow as needed for proper exposure.