Lens Sweet spots

[thefibreguy]

Hi All,

I am a beginner, & new to this site, so sorry if this has been done to death, but I have the following glass:

Canon 70-200mm f2.8L IS
Canon 24-105mm f4L IS
Canon 50mm f1.8
Sigma 18-50mm f2.8

Can anyone recommend the 'sweet spot' for each lens?

I am not lazy, & would actually love to spend a few days experimenting, but alas, time is against me.

Thanks in advance,

Regards.

 

[RevOnline]

Dunno.
f8-f11
f2.8-f5.6
Dunno.

 

[thefibreguy]

Dunno.
f8-f11
f2.8-f5.6
Dunno.

Thanks pal.

Any offers for the other 2?

Regards.

 

[Tight Fart]

I wouldn't worry about a sweet spot on L lens they are pretty good at any aperture.

 

[HoppyUK]

Since you're using a crop format camera, the image centre will be sharpest with all your lenses around f/5.6. With the L's, the edges will be about the same.

With the 50 1.8 and the Sigma, edge sharpness will get better until f/8 or maybe f/11 on the Sigma, depending on the focal length.

 

[cuthbert]

it won't take that long to find out for yourself really - surely all you have to do is take 5 or 6 photos a stop stop apart with each lens at a stationary object on a tripod? 30 mins work?

anyway it's a general rule of thumb that most lenses are at their absolute sharpest between f5.6 and f11.

for example, i did some testing on my sigma 50mm 1.4 and whilst the test charts on the digital picture show an incremental progression in sharpness from f2 to f8, in real life, on non uniform backgrounds i couldn't really tell the difference between f2 and f4 (well in terms of sharpness... vignetting is another issue)

i think that if you have to view at 100% magnification to see a difference, there isn't really a sweet spot.

 

[woof woof]

You should test these yourself, there's a lot of fun in it.

I think people here are being a bit conservative with the aperture sizes as I think that some of the newer designs hit there maximum sharpness a little wider these days, at least in the centre anyway and all you gain by stopping down is corner sharpness.

Mark, I agree with you about the Siggy 50mm, great lens, and maybe proof that some lenses are really as sharp as they're going to get at wide apertures.