b top gun wrote:
Finally a break in the gloomy weather so I could set up a test of my copy of a Nikon 24-70 f/2.8 non VR lens. Primary reason for testing, check lens performance primarily at the 24mm setting from f/2.8 through f/16 in whole stops. Have questioned the image sharpness of the corners of this lens since I got it. Test target, my back fence, 5 foot high wooden privacy type with lots of detail; target chosen because of the detail available. Lens on my D850 on a tripod. Distance to the target, about 8 feet; D850 as square to the fence as possible; 2 second exposure delay selected to minimize camera shake. Shots were taken in sets of 6 exposures; one set in color, a second set in monochrome for extra detail. 24mm starting at f/2.8, about 65% of the image had acceptable sharpness from the center out. Did not get acceptable image sharpness until f/11 at 24mm and even then not sharp all the way to the corners/edges. Same lens, same string of shots except at 28mm; immediately better results. Did not shoot beyond 28mm by choice. All this with the camera and lens set for auto focus.
For comparison sake, switched to live view, full manual focusing, and used in camera focus peaking option available in the D850. Manual focus shots gave better results especially at the wider apertures almost immediately. From experience I know not to shoot this lens at 24mm and forget f/2.8 at pretty much all focal lengths. I start at 28mm, have learned the sweet spot of this particular lens is f/5.6 or smaller. When shooting landscapes and seascapes I have come to prefer f/6.3-f/7.1 minimum aperture and a tripod whenever convenient. Will try some 'scapes using live view next. I have been researching 24mm primes and lenses like the Nikon 14-24 f/2.8 to renew my faith in the 24mm focal length; want to use it for low light and night time shooting as well. All this for me begs the question...."Why would you make a lens with a max aperture of f/2.8 if said lens does not yield sharp images to at least 80% of the image from the center out???" Using my copy of the 24-70 f/2.8 is like shooting through a tunnel at times. One option is to select the 1.2 crop factor available in the D850 menu, however that crop factor computes to around 28mm soooooooo, just set the lens there and shoot away, which I have been doing. Another option is to put this lens on my D7100 and get something else wide angle for my D850. Note: I am not looking at third party lenses, Tamron in particular; have owned four Tamron lenses, returned two to B&H a week after getting them, dumped my 150-600 due to auto focus issues; still have the 18-270 but should have sent it back because it is softer than my Nikon 18-200 VR.
Finally a break in the gloomy weather so I could s... (
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A good friend of mine, another commercial photographer, had exactly the same problem with his Nikon 24-70 non vr lens on the D850. It just wasn't really sharp at the wide end. He borrowed a Nikon 14-24 f2.8 from NPS and tested them side by side in his studio. He found that the 14-24mm was much sharper at 24mm than the 24-70mm at 24mm at all aperatures. Needless to say he got rid of the 24-70mm. The D850 really demands great glass.