hello I do hope some one can help me I'm torn between the to top lens in the photo the sigma 35mm 1.4 or the Sony 35mm 1.8 the Sony is sharper and cost 1/2 the price and the chr. aberration is less. but everything else is better on the sigma higher score too. my gear is a Sony 77ii I'm look at doing more portrait and street shooting as I'm going on a trip shortly so any help would be amazing thanks for your time.
2What is stopping you from making this decision? What would you need to learn in order to make it?– OnBreak.Jan 29, 2019 at 2:20
I wonder what that score compares: Most f1.4 will indeed be less sharp and have more CA than a f1.8 when both are shot wide open, both at f1.8 might tell the opposite story. Also, for portrait it is arguable whether you need much sharpness, for street you might or might not PREFER a lens that is very center sharp but not in the corners....– rackandbonemanJan 29, 2019 at 8:45
1Roger Cicala has coined a term for the practce of comparing the slightest differences between lenses' ability to sharply render flat test charts at relatively short distances: measurebating. It's important if you intend to use a lens to shoot flat test charts or other two-dimensional documents at close distances. Not so important if you use the lens for other purposes.– Michael CJan 29, 2019 at 22:10
This is pretty much a personal decision that you're going to have to make on your own. Here are some things to consider:
It's easy to make images blurrier. It's hard to make them sharper. I'd prefer the sharper lens.
How "unhappy" will you be if your lens isn't sharp enough? I had a 35/1.2 with lots of flaws that basically made it unusable. Was very unhappy with it. I have a 35/1.4 (not Sigma) that's very sharp, but if it weren't, I would be pretty unhappy with it.
Based on comparisons between f/1.4 and f/1.8-2 versions of lenses by the same maker, reviewers often seem to conclude that the f/1.4 lenses are less sharp at the same apertures. It seems to be part of the trade off for the wider aperture.
Do you need f/1.4? It isn't as great as I thought it would be, and I'd likely have been equally happy with the 35/2 version. I also have a 50/1.4 lens that gets more use as a loupe than on a camera because I simply don't need f/1.4.
Even if the lenses were rated equally on every metric, you still don't know what the images they produce look like. Simply having a larger aperture does not automatically mean "better" bokeh or subject-background separation. I had a 35/2.8 that was very good at separating subject and background at F5.6. I've used zooms that produce very nice bokeh at F3.5, and I've used primes that produce very messy bokeh.
Do you need a 35mm lens? Do you need either of these particular lenses? Maybe a different lens would fit your needs?
Distortion and vignetting add to the character of the lens and are easy to correct in camera or post. I personally do not even consider these when choosing lenses, unless I specifically need a particular feature. For instance, I would consider distortion if I intend to use a lens primarily to photograph documents.
Mild chromatic aberration adds character to the lens and isn't too difficult to correct. Usually it improves when stopped down. As long as it isn't distracting, I don't worry about it too much.
If you're short on cash, you can consider getting a used copy.
If you are really undecided, you can flip a coin. As long as they're both reasonably good lenses, you'll probably be equally happy with either.