Help please: 75/1.8 instead of 35-100?

I understand your indecision, both are great in IQ. The prime should have a bit more resolution, but not much.

The point here is versatility, and here the zoom wins, beside that we are talking about what I consider a high grade zoom very well built, and the AF speed maybe faster on the zoom.

On the other side has already mentioned the prime is a diamond. If you are a fan of good primes, get the 75mm, is not go for the 35-100mm.

Anyway any you choose will be a fantastic lens. I guess the aperture difference is not much a decision point, you can raise the ISO a bit without loosing IQ. Only if you take pictures in very low light the prime wins. You have to think what you really need.

--
Simplicity is the ultimate sophistication.
Pure logic is the ruin of the spirit.
Imagination is more important than knowledge.
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