Originally posted by cameracravings Shutter speed is irrelevant. It is mirrorless digital camera mounted on a rock solid tripod and a 10-second timer triggered it.
Well, I guess you have it pinned down, though your mirrorless camera does have a shutter and rock solid is always relative in the world of tripods, particularly when using the center column as a horizontal arm. Leveling the camera for copy work generally requires a small carpenter's level at the lens front bezel and is a pain without a geared head. Sorry if that sounds snarky, but I have done a fair amount of lens testing and copy work and that sort of thing is a common source of poor results. Assuming the setup is rock solid and true to the subject, three more questions:
- How sharp and/or contrasty is the sheet music? Is it an original or a photocopy? I was struck by the low contrast.
- Are you certain your adapter positions the lens at right angles to the sensor. I don't use your tools, but have read multiple reports of adapter issues that include poor alignment.
- What is the physical condition of the lens? Specifically:
- Is there evidence of internal fungus, crazed rear or internal elements due to botched cleaning
- Is there evidence the lens has been subjected to amateur service? (This would include scratches on or around screw heads or bunged screw heads.)
It is quite likely that your lens has a problem traceable to physical damage and/or foreign substance on the optical path. The image of the staple at center (point of focus?) on the f/5.6 example was my first clue. It simply looks yucky. The ST 55/1.8 is a very fine lens and while it a bit of an antique, it is not a macro lens, and has some field curvature, it is still suitable for general copy work. Below is a test image I did with my ST 55/1.8 and a setup similar to yours.*
Pentax K-3, 1/10s, f/5.6, Super-Takumar 55/1.8, in-camera JPEG (highest quality)
The full-resolution JPEG may be downloaded (12.5MB) from:
https://farm1.staticflickr.com/953/40211014180_d5c9a7de2f_o_d.jpg
Here is a full-resolution snippet from near the bottom edge of the APS-C frame
I deem the results adequate and much better than what you got from your lens, though if I were working from RAW, I would have applied a little sharpening and correction for the very slight chromatic aberration present towards the edges. If I were to do it over, I might also give it at least an additional 1.0 stops exposure and a tweak to white balance, but I was in a hurry. If it were a copy for my own personal purposes, I would also be at f/8 to defeat whatever field curvature might be lurking.
Since your lens is new to you, I might suggest contacting the seller.
Steve
* Subject (back of computer power supply box) on floor, natural window light, Giottos 9360 tripod with center column configured as horizontal arm, focus using magnified live view.