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XF 16-55mm - Do I have a bad copy?

Started Jan 17, 2020 | Discussions thread
Kenneth Almquist Regular Member • Posts: 164
Re: XF 16-55mm - Do I have a bad copy?

One thing that can make it easier to see what is happening it to shoot a point of light.  Here is the setup I used, drilling a hole through a thin piece of aluminum and placing it in front of a light bulb:

setup for photographing pinhole

I photographed the pinhole from a distance of 34 feet, placing the pinhole under either the center focus point or one of the four corner focus points. Below are 100% crops from the raw images (converted using dcraw), with the aproximate pixel location of the pinhole in parenthesis:

center (3016,2016)

top left corner (681,805)

bottom left corner (626,3215)

top right corner (5444,807)

bottom right corner (5434,3254)

You will notice that the center and corners on the right pretty much make the pinhole look like a pinhole, but on the left hand side it is smeared around.  That's probably astigmatism.  To rule out camera shake, I would have to take several images on the left side and verify that the smears are all the same.

I used manual exposure to take these pictures, which was necessary because most of the frame has to be black to avoid overexposing the pinhole.  In theory they should all be the same brightness (except that the corners might be darker than the center due to vignetting).  I'm guessing that the differences in brightness are a camera issue.

 Kenneth Almquist's gear list:Kenneth Almquist's gear list
Nikon D7200 Fujifilm X-H1 Nikon AF-S DX Nikkor 35mm F1.8G Nikon AF-S DX Nikkor 18-300mm F3.5-6.3G ED VR Fujifilm 16-55mm F2.8R LM WR +2 more
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