28mm 1.8 sharpness
/forum/topic/833002/1

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Will Patterson
Registered: Nov 06, 2006
Total Posts: 4064
Country: United States

also 1.8



Dudewithoutape
Registered: Oct 07, 2009
Total Posts: 430
Country: United States

Ah, yes, recompose, DUH. I feel the center focus shot is very sharp, but the thing is you have to recompose to find out if the lens is sharper further away from the center or if its an AF point problem. Some lenses just need to be stopped down in order to get sharpness through out the frame, center sharpness is easy to obtain in most lenses (even the 18-55 IS is known to be sharp wide open at the center). Thats why you have to recompose. Lets see a shot that way, yeah?



Will Patterson
Registered: Nov 06, 2006
Total Posts: 4064
Country: United States

Dudewithoutape wrote:
Ah, yes, recompose, DUH. I feel the center focus shot is very sharp, but the thing is you have to recompose to find out if the lens is sharper further away from the center or if its an AF point problem. Some lenses just need to be stopped down in order to get sharpness through out the frame, center sharpness is easy to obtain in most lenses (even the 18-55 IS is known to be sharp wide open at the center). Thats why you have to recompose. Lets see a shot that way, yeah?





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fmikio
Registered: Aug 12, 2008
Total Posts: 213
Country: Canada

I'll try some "in the field" tests with MA set to 0. Having an idea of your nice pictures at 1.8, it will be easier to know if mine is at least acceptable.

Thanks !



fmikio
Registered: Aug 12, 2008
Total Posts: 213
Country: Canada

So I couldn't go out so decided to run some more tests in my christmas decor.
Again, all those straight out of the body with MA set to 0 and the focus in the Post Office.

@1.8


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@2.0


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@2.2


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@2.5


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@2.8


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Ivor Karabatko
Registered: Oct 04, 2007
Total Posts: 325
Country: United States

wow, you can definitely see a jump from f/1.8 to 2.0. Fascinating. It seems like once you get to 2.0 it gets decently sharp, and 2.2 seems pretty darn good.

Do the exposures and the bokeh at f/1.8 and f/2.0 differ that much? I've pushed and pulled many times with film and with the digital cameras as well, so I can't really see why someone would want to shoot at 1.8 if the sharpness is that much greater at 2.0...if the shutter speed doesn't really change much.



digimies
Registered: Oct 21, 2003
Total Posts: 196
Country: Finland

My copy of EF 28/1.8 was very soft indeed. No matter if stopped down to f5.6 and focused from tethered computer. Even with relatively 'low resolution sensor' like in 1DMKIII the result was very disappointing.

As a background I have owned the following Canon lenses: 17-40/4L (twice), 28/2.8, 35/2 (twice), 50/1.8II, 50/2.5 Macro, TS-E 90/2.8, 300/L IS (twice) and 500/4L -> they all have been miles better with image quality than my EF 28/1.8 was.



fmikio
Registered: Aug 12, 2008
Total Posts: 213
Country: Canada

Ivor Karabatko wrote:
wow, you can definitely see a jump from f/1.8 to 2.0. Fascinating. It seems like once you get to 2.0 it gets decently sharp, and 2.2 seems pretty darn good.

Do the exposures and the bokeh at f/1.8 and f/2.0 differ that much? I've pushed and pulled many times with film and with the digital cameras as well, so I can't really see why someone would want to shoot at 1.8 if the sharpness is that much greater at 2.0...if the shutter speed doesn't really change much.


True... big difference between 1.8 and 2.0.
And the exposure changes 1/3, so, I can consider no changes at all...
As for shooting at 1.8, it's really to see its limits, and for me, I think my copy is acceptable.

Thanks !



David Tognazzi
Registered: Dec 08, 2006
Total Posts: 241
Country: United States

I have a 28mm f/1.8 as well. Mine seems not-so-good compared to the christmas still life examples here. Also, mine is loaded in CA when used to take landscape shots. It's been a nice paper weight for about 2 years now.



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