Re: RF35mm f/1.8 IS STM MACRO AF and Resolution performance.
Thanks @Martin_99. Please find the answers below.
1. You are looking at 100% magnified photos in the center.
2. I use the electronic levels to judge horizontal and vertical tilts of the camera. I also used a laser distance measurer from the target to check distances of the camera from the target. The images I had attached were taken at about 2 ft. All results were reproducible at ~4ft, ~8ft.
3. Thank you for the note on decentering. I have never done this before. I will check this.
Given 1 and 2, any thoughts on the results? Thank you!
Martin_99 wrote:
bharathmsk wrote:
Thanks all.
@Martin_99, following your link to opticallimits, I read through the review and I had some hope instilled in me. I repeated the resolution chart experiments (attached pictures, I have concatenated images, use Dpreview loupe).
On what are we looking at actually? 100% magnified photos in center?
To my dismay, the lens gets sharpest at f/11-f/16! And the resolution drop from f/1.8 -> f/2.8, f/4 and the recovery thereafter at around f/5.6 is also very clear. These results were highly reproducible.
Hard to judge. If somebody tell me such result, my first thought is user testing error. What is your distance from target? Are you sure that camera is perpendicular to test chart?
So the lens is poorer than I had originally thought (I should have taken the time to sweep through the entire aperture range). At this point, I certainly feel like this lens is a lemon. And the poor optical performance could have lead to a poor AF performance like the opticallimits review indicate. I think I should contact the manufacturer. If you all have other insights to add, please, I would greatly appreciate them!
What I mostly do - testing decentering based on below link:
https://phillipreeve.net/blog/how-to-check-how-decentered-your-lens-is/
Conclusion is not allways easy though.
To answer your question @Martin_99 on the AF settings, when I photograph family, these are left at eye tracking & servo. For these resolution chart pictures, they were left at single point AF on the target.
RF 35mm f/1.8 IS STM MACRO
Thank you for your help and support!