Help judging performance of my FE55z, FE35f2.8z horizon/infinity

Started Jul 5, 2016 | Questions thread
Nephi Contributing Member • Posts: 531
Re: Help judging performance of my FE55z, FE35f2.8z horizon/infinity

JimKasson wrote:

holin wrote:

JimKasson wrote:

Most people's difficulty in getting good MTF Mapper numbers is, I believe, the result of several issues:

  • Alignment
  • Getting a high-resolution target
  • Alignment
  • Getting the target big enough.
  • Alignment
  • Getting the target far enough away
  • Alignment
  • Lighting the target properly
  • Alignment
  • Vibration
  • Alignment
  • Field curvature

Oh, and alignment is important, too.

I would like to add flat target the above list. Folded and then straightened newspaper taped to a wall from two corners is not quite there. And alignment.

You are absolutely correct. I have found from experience that just dry mounting a target to a piece of foam core won't do it.

Jim

I printed 3 large ISF charts and posted them on foam core.  Despite all the effort a miniscule bend in a corner can give blurry false results.  Half the time you won't know if its the chart, your camera, or your lens.

I wish I could fine the link for a lens test I found earlier online.  Basically it is a $500 light box on a stand that has a test chart, perfectly flat, and perfectly lit.  While knowing if you are perfectly parallel could be a challenge at least you could rule out the target!

I'm still looking for a DYI centering test that is reliable and accurate enough to detect decentering.  I tried the flashlight test taking a shot of a test chart in each corner however I found the results be less than consistent and somewhat hard to interpret.

I've heard taking a shot at infinity and then flipping it upside down works however I'm not quite sure what you need to flip a camera and how in the world you would line it up upside down.

-Brian

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