Does anyone have a portrait sample using 2 different lens like a f/1.2/1.4/1.8 vs. f/2.8?

[TrekRover]

I don't usually do portraits, but I was wondering how big the difference is between a f/1.4 and f/2.8 is? Is it just the bokeh is more smooth with a bigger aperture?

So far I only have mostly zooms (12-24 f/2.8, 24-70 g/2.8, and 70-200 f/2.8) and a 600mm f/4 prime. Wondering how big the difference is for a prime designed for portraits?

[tonygale · Accepted solution]

By coincidence I shot all these last week, not the exact same lighting setup, but same model and similar framing. The difference in f/stop will change how shallow the depth of field is and thus more or less bokeh. However the focal length will also have an impact, a longer lens with the same framing will have shallower depth of field. Then the lens itself will affect the character of the bokeh. The 100mm STF has smother bokeh by design, but the 135mm has shallower depth of field because it is a 1.8 and a longer focal length.

135 GM at f/1.824-70/2.8 GM2 at f/2.8100mm STF at f/2.8 (T/stop 5.6)

FE 135mm F1.8 GM (SEL135F18GM) FE 100mm F2.8 STF GM OSS (SEL100F28GM) FE 24-70mm F2.8 GM II (SEL2470GM2) a7RV

[tonygale · Accepted solution]

By coincidence I shot all these last week, not the exact same lighting setup, but same model and similar framing. The difference in f/stop will change how shallow the depth of field is and thus more or less bokeh. However the focal length will also have an impact, a longer lens with the same framing will have shallower depth of field. Then the lens itself will affect the character of the bokeh. The 100mm STF has smother bokeh by design, but the 135mm has shallower depth of field because it is a 1.8 and a longer focal length.

135 GM at f/1.824-70/2.8 GM2 at f/2.8100mm STF at f/2.8 (T/stop 5.6)

FE 135mm F1.8 GM (SEL135F18GM) FE 100mm F2.8 STF GM OSS (SEL100F28GM) FE 24-70mm F2.8 GM II (SEL2470GM2) a7RV

[TrekRover]

Thanks @tonygale this is exactly what I was looking for! I can definitely see the bokeh and depth of field difference between the 1.8 vs the 2.8

[LensBrew · Accepted solution]

To add to what Tony has mentioned above, the prime glass usually gives a smoother transition between and in and out of focus areas. This does give the image a more appealing look. There is also less glass inside, thus less optical defects, such as distortion and aberrations.

If you're on a budget, I suggest to get the 85mm 1.8, otherwise I recommend my favorite the 135mm 2.8 GM.

[TrekRover]

Thank you @LensBrew for the lens recommendations! After seeing Tony's photos, I want to get a portrait prime lens now 😄