You asked
Is the sony fe 40mm f 2 5 g worth it?
Here is what the site says about that.
From Sony FE 40mm f/2.5 G: Sony FE 40mm f/2.5 G: A prime lens by Sony for Full frame cameras, 40mm f/2.5. Tiny and sharp: a lovely everyday lens on the compact bodies. Specs - Maker: Sony - Focal length: 40mm (prime) - Maximum aperture: f/2.5 - Made for: Full frame sensors - Mounts: Sony E - Stabilised: no - Autofocus: yes What it frames like - On full frame (Sony E): as marked, 40mm. - On APS-C (Sony E): like ...
From Sensor sizes: Is full frame worth it?: For low light, events, and portraits with very shallow depth of field, yes. For travel, street, wildlife on a budget, and most hobby photography, a good APS-C camera with good lenses is enough, and you'll carry it more. Lenses and light matter more than the last stop of sensor performance.
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