Amazing lens, incredible sharpness

markintosh13 wrote:

Great Bustard wrote:

c_henry wrote:

So, if I had my 75mm f1.8 on my E-M5 and was using a light meter which told me to set the aperture to f1.8, what would I set it to?

I'm sure I can't speak for what you would do. I could tell you what I would do, if you like -- let me know.

I'd like to know if you would be so kind.

Kind I am, sir!  An overflowing cup of human goodness, if you will. 

If I trusted that the meter would give me the exposure I wanted for the scene, and the meter recommended f/1.8, then I would use f/1.8 so long as it resulted in the DOF I wanted and a shutter speed that did not result in motion blur (unless I wanted motion blur for artistic effect).

If f/1.8 resulted in a too shallow DOF, for example, I'd consider using a more narrow aperture, fully cognizant that it would result in more noise unless I also lowered the shutter speed the same number of stops.  How I would choose to balance DOF, motion blur, and noise depends very strongly on the scene, so I can't be more specific than that without knowing the scene in question.  I could embed a few examples of different choices I made and explain why I made the choices I did, if you like.

Now, let's say I shot a scene at 75mm f/1.8 with my mFT camera 'cause that resulted in what I thought to be the best photo.  If I were using a FF DSLR with a 150 / 1.8 lens (no such lens exsits that I'm aware of, but just go with it for this example), would I shoot the scene at 150mm f/1.8?  Yes, if 150mm f/1.8 resulted in a better photo than another aperture.  Specifically, if the more shallow DOF of 150mm f/1.8 was more desirable than 150mm f/3.6 or the lesser noise of 150mm f/1.8 vs 150mm f/3.6 mattered more than the DOF.

If I've missed any important points, please don't hesitate to let me know, and I'll be pleased to answer in greater detail.