Sony Lens Selection for Wedding Photograohy
I prefer shooting with primes, but sometimes frustratingly inaccurate autofocus when I shot with Canon and Nikon led me to gradually drift toward a "zooms by default, primes only when needed" method of lens selection. I longed for the creamy look of f1.4-f1.8 lenses, but very often simply could not trust them to focus correctly. Even wide-angle primes at longer shooting distances (like a wide shot from the back of the church), where there should have been ample depth-of-field, would often front-focus for no apparent reason, requiring me to overshoot just to ensure I got a usable image or two.
Sony's accurate and reliable focus system has enabled me to get back to shooting with primes almost all the time, which I am really happy about. Generally speaking, my default lens choices for weddings are the 24mm f1.4 on one A9 body, and the 55mm f1.8 on another.
The 24mm f1.4 GM is quite a bit more compact and light than you would expect an f1.4 prime to be, such as compared to the popular Sigma Art 24mm f1.4. Yet it's amazingly sharp, even when shooting wide open, and is fast-focusing as well. It pretty much never comes off the camera unless I specifically need the 16-35 f2.8 for some reason. For the first half of 2019, this lens was quite hard to obtain, with backorders taking a few months to be fulfilled. Availability has since stabilized though.
I started out with the Sony 28mm f2 as my wide prime, though it hasn't seen much use since I added the 24mm f1.4 to my kit. Still, I found it to be a wonderful lens to use for almost all phases of the wedding day, and I still keep it in my bag just as a backup or for those rare instances when I need a wide prime on another body. Very small, light, and with a reasonably fast aperture, it's a good focal length that falls between 24mm that sometimes feels too wide, and 35mm that quite often isn't wide enough, especially during receptions. Just be careful, as the lens hood on this one has a tendency to pop off if it happens to bump against something while the camera is slung over your shoulder and down by your side. It's a good alternative if you need a wide angle prime lens but are not quite ready to fork over the fairly hefty price of the 24mm f1.4.
The Sony/Zeiss 55mm f1.8 is an absolutely amazing lens... compact and light, yet sturdy, fast-focusing, and with uncompromising image quality, it's by far my favorite lens I've ever shot with, and it's pretty much always on one of my cameras unless I have a specific reason otherwise. Yes, the $1000 price tag might seem a bit on the high side for an f1.8 normal focal length prime, but if you enjoy shooting at this focal length, it's absolutely worth every penny, and if it were lost, stolen, or damaged I would immediately replace it with the same lens without hesitation.
Of course, I do vary from these lens selections when appropriate. For instance, during a large church wedding ceremony I'll usually replace the 55mm with the 70-200 f2.8 (which is razor-sharp even wide open), while for ceremonies in courtyards, hotels, and other medium size spaces I may choose the 85mm f1.8 (which I selected over the f1.4 GM version primarily due to focus speed) depending on the size of the space and the lighting conditions. This lens is also handy even for large churches, if you need a fast lens during the processional if the lighting is too dim. I also sometimes use the 85mm during portions of the reception when I want a little more reach than the 55mm offers, such as capturing candids of guests mingling, or the couple's first dance if I have adequate space to work with. And during the later portions of receptions, it's occasionally necessary to swap out the 24mm for the wider view of the 16-35mm f2.8 when the dance floor gets really packed or otherwise when shooting in tight spaces. I also often photograph my group formals with the 16-35mm.
A Note about Autofocus
It should be mentioned that the effectiveness of the Sony autofocus system in dim light depends greatly on the maximum aperture of your lenses. For instance, during wedding receptions, when the venue staff turns the lights down very low, you might find it difficult or impossible to get a focus lock when shooting with an f4 or even an f2.8 zoom lens, but an f1.4 or f1.8 prime locks on just fine. This differs from my DSLR experience, where zoom vs. fast prime didn't seem to make much difference in AF performance in low light.
Also, when shooting in continuous focus mode (AF-C), if you are shooting at, say, f4, the aperture will not open up to the lens's maximum when focusing then stop back down to f4 when you shoot, instead it will just stay at f4 the whole time. But it will momentarily open up for AF if you are in single focus mode (AF-S). But because continuous focus works so well, I'm almost always shooting wide open in low light situations anyway, only stopping down when I need the depth-of-field (like for group shots).