Is my thinking about equivalence right?

Started 3 months ago | Questions thread
ahaslett Veteran Member • Posts: 8,872
Re: Is my thinking about equivalence right?

Muster Mark wrote:

Just look at the lenstip data. The Sony 50mm 2.5 has vignetting of 2.29 stops in the corners. The olympus 25mm1.2 has at most 1.3 stops of vignetting. Th Sony GM 50 1.2 has almost 3 stops of vignetting wide open.
Normal equivalence would say FF at 1.2 is gathering 4x the light as m43 at 1.2. That's not true if it's falling off so much more. Is the difference big? No I don't think so. I don't think most people care so much about vignetting, but it makes the "total light" calculation rather different.

As vignetting is so important to you, can I mention that the Lenstip reviews are based on JPEG’s, so the measure shows how much vignetting is left after in body corrections.  Many reviewers look at uncorrected RAWs to show the actual lens performance.

I’m struggling to accept that you can compare two camera systems based only on a limited number of lens comparisons, especially a high price lens for one system against a budget lens for the other.

How about comparing the Olympus 17mm Pro against the Tamron 35/1.4 SP, with the Tamron stopped down to f2.2 to match the Olympus?  The Tamron is a bit less than three-quarters of the price at market rates.


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