So I finally pulled the trigger on the a7R V after saving up for months because I really wanted that 61mp detail for my portrait work here in Chicago. I have a big project for a local fashion boutique starting in about three weeks and I'm honestly lost on which lens is actually going to do this sensor justice. I spent a whole day looking at comparisons between the Sony 85mm f1.4 GM and that newer Sigma 85mm DG DN Art. People keep saying the Sony is a classic but it's getting pretty old now and I'm worried it wont be sharp enough when I'm cropping in on those high-res files... like is the purple fringing still a big deal on the newer bodies? The Sigma looks incredible for the price but then I read some stuff about the AF not being quite as sticky for moving subjects which makes me nervous. My budget is right around $1700-$2000 so I could go either way but I dont want to buy something that's gonna feel outdated in six months. Does the 50mm 1.2 GM make more sense for this sensor or should I just stick with an 85mm for that compression? Just curious what you guys think about what glass actually holds up to the 61 megapixels without looking soft.
Unfortunately, I had issues with the Sony FE 85mm f/1.4 GM being way too soft for 61mp. It isnt as good as expected for the cash. If you wanna save a ton, the Sigma 85mm f/1.4 DG DN Art is actually sharper for big crops. AF isnt perfect, but paying two grand for that purple fringing on the Sony feels like a mistake... anyway, I'd go Sigma.
It is pretty disappointing that the current Sony 85mm lineup is in such a weird spot for high-res users. I had issues with the Sony FE 85mm f/1.4 GM being way too soft for that sensor, unfortunately. It is definitely not as good as expected for a premium lens and that purple fringing is gonna drive you crazy in post-production... specifically for fashion stuff.
Building on the earlier suggestion, I've been very satisfied with the Sony FE 50mm f/1.2 GM on high-res bodies. It resolves that 61mp sensor perfectly and the AF is super reliable for fashion. If you really need compression, the Sony FE 135mm f/1.8 GM is another stellar choice that actually holds up to the a7R V sensor without looking soft... TL;DR: Buy the 50mm 1.2 or 135mm 1.8 for the best sharpness.