Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

Started May 18, 2014 | Discussions thread
BobORama Senior Member • Posts: 2,553
Re: Please use better experiment protocol

Trevor G wrote:

jf_tea wrote:

shallow DOF at f/1.8

subject distance at left vs. right is significantly different.

Not a very good guess, jf. I'm sorry I didn't post the full image as well so that you could see the layout.

Samples shown earlier cropped from each side of this image...

Please use better experiment protocol. that you can see what I did, do you still feel the same way?

Yes.   Thanks for posting this.   Look at the central lamp post, you have adjusted you camera so that the lamp post is perfectly aligned with the window behind it.   And the vertical center line of the photo is aligned with the lamp post.    The upper and lower roof line of the colonnade ( the alternating cream and burgandy roof ) is in perfect horizontal alignment down to a pixel level.   So we have our coordinate system.

But the building is actually skewed with the left side further back than the right.

You can see this very clearly looking at the angle of the seams in the slanted cream-burgandy roof.     IF the building were parallel with the focal plane of the camera, AND the center of the image were centered on the vertical axis of symmetry of the building, the slanted roof lines would be symmetric from right to left.   They are not.   And they suggests the left side is father back.   So my diagram explains your observation entirely.

Your lens is fine, its your expectations that are off center.

 BobORama's gear list:BobORama's gear list
Pentax K-5 Pentax K-1 Sigma 10mm F2.8 EX DC HSM Diagonal Fisheye Pentax smc DA 18-55mm F3.5-5.6 AL WR Samyang 14mm F2.8 IF ED MC Aspherical +9 more
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