75/1.8 vs 40-150 A Comparison

Started Sep 3, 2012 | Discussions thread
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Clayton Jones Contributing Member • Posts: 866
75/1.8 vs 40-150 A Comparison

I purchased the 75/1.8 primarily as a portrait lens, but have been wondering whether to take it on an upcoming landscape trip to Arizona and Utah in October. That focal length might come in handy out there. Since I also have the 40-150 I wondered how it compares to the 75/1.8 at that focal length and with relatively distant subject matter. So I did some test shots today with both lenses.

Subject matter was some boats docked at about 1/2 mile distance looking NE across the intracoastal waterway from West Palm Beach toward Palm Beach, Florida. The zoom focal length ended up being 78mm (the camera does not show the focal length, even in view mode after taking a picture, and since the lens is marked at 70 and 100, I had to guestimate)

Camera was a GH2 on a sturdy tripod, manual focus, 2-sec self timer, Aperture Priority, +1 EV.

First up, here is an uncropped version (75/1.8 @ f/5.6). All others are 100% crops from the center. All are unsharpened from raw in CS5/ACR, no added PP (except the last two, explained below).

Next, here are the 75/1.8 versions. They begin at f/2.8 (couldn't go wider due to max shutter speed). I also shot at f/16 and f/22 but they aren't shown here because they just get softer. It's apparent where it's going by f/11.

And here are the 40-150 shots at 78mm. This isn't a perfect comparison because the sun is brighter in this set. Unfortunately the camera was metering mostly on the water and didn't change exposure enough, so the white boats are over exposed. More on that below...

These last two are the best from each group (the 75 @ f/4.0 and the 78 @ f/4.7) with some sharpening and minor PP. Each raw file was reopened and processed again. The 40-150/78 version had Recovery=100 applied to bring down the over exposed white boats. Both files have very slightly increased contrast, and the same USM applied:
Amount = 250
Radius = 0.4
Threshold = 1

It's pretty clear that the 75/1.8 is resolving finer detail, plus there's a clarity in the rendering (both lenses have a 58mm filter ring and both were using the same lens hood without any filter). However the 40-150 isn't bad and has some pleasing characteristics (warmer color and renders contrast nicely). Interesting also that it's best resolution is f/4.7, it's largest aperture at that focal length.

I hope this is helpful to other readers.


Info on black and white digital printing at
I-Trak 3.0 http://www.cjcom.net/itrak.htm

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