Thread Rating:
  • 1 Vote(s) - 2 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Do-it-yourself centering sanity check
#31
Well, there is a margin of error that you have to accept.

The first image indicates that full focus is achieved - plus/minus a little.

It is not a perfectly centered lens though.

I am not sure whether Fuji would replace a lens like this.

Looking at the characteristic of the blur I would check the lower right corner for asymmetry vs the others (in real life images).

#32
Thanks for your feedback, that's a relief to hear.

 

A cursory look through some shots seems to indicate no apparent asymmetry among the four corners. They all seem to match up.

 

If you're not sure Fuji would replace it then that's fine by me. I'm happy to accept this, as it doesn't seem to be affecting my shots. I'm glad it's within the margin of error and I needn't go through the bother of exchanging it and the potential saga that may ensue.  

 

Excuse me now, I have to go and take some photos  ^_^

#33
Well in fact I'm a Pentax user and it seems that I cannot do this test, however I use infinity focus on distant views of landscapes/trees to ascertain whether a lens is decentered, shot wide open at all focal lengths, it has never let me down so far!

Dave's clichés
#34
Well, you can do the test. Just take a shot with AF and then switch to MF, defocus slightly and take another shot. Then compare. That's assuming you don't have live-view.

#35
To: PZ crew,

 

Is it possible to create file with above pattern and instructions, available for download to PZ members?

#36
Quote:It's probably too late but if this lens was mine I would return it for sure.
Klaus, how did you determine this? My eyes are not as well trained as yours.
#37
Well, these are CENTER images (referring to the December samples by stoppingdown).

In the center these edges should have an absolutely symmetrical sharpness (it's different in towards the borders). 

The left and bottom edge transitions are sharper than the top and right ones.

This is more apparent in the slightly defocused image but in this case this is also just visible in the focused one.

Please note that if this is already visible in the center, it'll just be worse in one of the corners or sides.

#38
Now that you said it I see the difference. So it has to be really really perfect in the center.
#39
Am I understanding the distance correctly?  For a standard 50mm prime I would need to be at least 9.8 feet away, correct?  Obviously the image only fills a small portion of the frame at that distance.

 

I also would like to test an 85mm prime I have but I can only get 9 feet back without hitting the wall.  Do I really need to be over 16.7 feet away?  That would mean I would need to move my computer and use a hallway.

 

How important is distance?

 

Thanks!

 

-Brian

#40
Where do we get a copy of the image ? If I download quad.jpg in first post it is pretty small on my monitor. I'll be posting my test results soon (I hope I am not too unhappy).

  


Forum Jump:


Users browsing this thread:
7 Guest(s)