Remember the article I wrote in praise of kit lenses, including the Sony FE 28-70mm f/3.5-5.6? Yeah, about that…
I tested my lenses on the Sony A7RV body, to see if they’re up to snuff. Let’s just say that I’m starting to get what some people were talking about. The 28-70mm is consistently less sharp than all the other lenses I tested, and while in the centre I would say it meets the minimal requirements for resolution, toward the sides and especially in the corners it is much worse.
The cause of the problem is obvious. The new body magnifies the image more, demanding more resolution from the optics. It used to be that the 35mm format was very easy on the lenses, unlike the four thirds or APS-C, which basically pull the same resolution out of a smaller circle, and a lens needs to be really great to be critically sharp on a smaller format. Basically, an APS-C body with a 24MP sensor will pull as much information from the smaller APS-C circle, that a 24MP full frame body will pull from the bigger 35mm circle.
The Sony A7RV body with 61MP pulls 26MP from the APS-C circle alone, and continues to make those demands across the 35mm frame.
I’m usually not all that obsessed with image sharpness at 100% magnification; it’s like viewing film under a microscope. It is expected that the lenses won’t draw a perfectly sharp image from centre to corners at full magnification, so the criterion is image that is good enough for printing big enough. Basically, I decided that the 28-70mm lens is the only one of my lenses that would create problems when printing big, and since my use for a lens in this range is landscapes from a tripod, which means sharp stuff that is most likely to be printed big, I decided it’s time for an upgrade. The good news is that the FE 16-35mm f/4 Zeiss and the FE 50mm f/1.8 are just fine, even though I tested the Zeiss at 35mm, which is its “softest” focal length. I didn’t even test the FE 90mm f/2.8 G macro; not only is it one of the sharpest lenses in the world, but also the closeups are generally more tolerant of magnification, because they lack the high-frequency detail such as grass, leaves or pine needles, that require sharpness on the landscape shots.
The actual reason why I finally decided to replace the 28-70mm is not this test, but the results from the last time I used it to actually take pictures, and I was shocked to find that almost nothing was sharp, and that was on the A7II. It looked as if the image stabilisation introduced some kind of an optical defect that looked like some kind of haze that blurred out the high-frequency detail, and the photos were not usable. It performed much better on the tripod, but still noticeably worse than the other two lenses I compared it with, and I decided it’s giving me too much trouble with inconsistency and I’m just done with it. I can’t rely on it to just consistently produce images to a certain standard, and instead it varies between quite nice and fucking awful, and that is simply not acceptable.
What did I replace it with? Initially, I considered the FE 24-70mm f/2.8 GM II and the FE 20-70mm f/4 G, but then decided against them both. The f/2.8 GM is excellent, but its strongest point is versatility as an all-around lens for everything, and this makes it quite heavy and super expensive. I don’t need f/2.8 aperture for a landscape lens that will be used at f/8-f/16 apertures. As for the 20-70mm f/4 G, it is much better suited for my needs, but it tries to overlap with the 16-35mm too hard and I’m not sure I need that. I ended up going with the FE 24-105mm f/4 G, simply because this is an excellent range for the intended purpose, and it is widely used and highly esteemed by landscape photographers, so I don’t expect to have issues with the lack of resolution. Sure, something will always be sharper, but I don’t need this to be the sharpest lens in the world, I just need it to keep up with my other glass and not create a blurry mess at random unpredictable moments. The FE 24-105mm f/4G is a workhorse lens relied upon to produce predictable results by many photographers and that appealed to me, because I need something that just works, and not create problems.