The biggest difference is the build quality.
IMO-unless you know why you need the f/1.4 or you have the budget to buy it right out the gate... go with the 1.8. You can't shoot effectively at f/1.8 let alone 1.4 99% of the time.
There is a difference in IQ, but for the price? the 1.8 is worth it's weight in gold. It's going to be sharper than any lens you've probably used to date by far.
I'd LIKE to have the 1.4 NOW, but I have 2 of the 1.8 and I don't NEED it enough to justify the cost over buying other lenses or equipment.
I do a LOT of teaching. It comes in handy to have multiples. It's a cheap lens and I bought a used one even cheaper than dirt! Plus my kids shoot too. So they need to have it
The aperture diaphragm in the 1.4 is better than the 1.8. Shot with both starting with the better mark I version of the 1.8, both are fine for most... the 1.4 for those with a more modest budget and certain tastes
^^^^^^^what they said. My suggestion with whichever you choose is to shoot initially around f4 to f8 and get familiar with the lens outdoors. Try to stay away from the urge to shoot at 1.8 indoors, a beginner first mistake. BTW the 1.8 is a good lens at a good price, the 1.4 is for the more serious imo.
Good Luck :thumbup:
I only own 3 1.4 lenses, an 85 af-d, a 28 af-d and a 35 Ai (not the best 1.4 ever made). These were acquired for other qualities besides being f/1.4, they are seldom used at f/1.4
Objective qualities like build and sharpness, and subjective qualities like bokeh, colour, ease of use, centre and off centre rendering, etc...