I've been kind of interested in comparing the same photo taken with two different lenses at the same focal length.
Let's say you take two lenses that cover the same focal length.
I've got an 18-135 IS USM lens and a 55-250 IS STM lens.
Let's say you set the focal length to 100mm. Take the same photo with the exact same settings for both lenses
Would you notice any appreciable difference?
Steve Thomas
You might see some differences when you shoot under labatory settings, I think in real world situations you will have to be an pixel peeper to see differences 😉
But it also depends on with of the versions you use, The first 55-250 wasn't the best, The latest does perform a lot better.
That also is the same with the 18-135 versions the latest (NANO-usm version) is the best of them
Stop both lenses down to f/22 and you probably won't see any appreciable difference.
You could answer your question and at the same time give also for us the comparison of those lenses.
Only shoot with both and post pictures here.
Don't stop to f/22.😎
[deleted]
Yes, there can be difference. See focus breathing and focal distance at closeup focus, sharpness CAN differ, as 55-250mm IS STM zoom is quite sharp, etc.
You can see global contrast, flare, bokeh, and distortion differences in a print the size of a credit card
Yes, "differences" is bit like "image quality" which is so often mentioned without qualification.
For sharpness, I would shoot a slant-edge and measure the MTF here and there.
then all I'd need is ...
Lateral Chromatic Displacement (LCD)
Color Uniformity
Local Geometric Distortion
Texture Blur
Visual Noise
Chroma Level
... but Imatest is not cheap ...
MTF Mapper is free.
I knew that.
I use QuickMTF.
The reference to Imatest was about the other quality measurements that I mentioned which are also incorporated into Imatest.
To save you another one-liner I know that they refer to CPIQ.
How do you use MTF mapper? Do you use the patent information for a lens to build a model? Do you disassemble a lens and measure the parts?
Thanks in advance.
I shoot targets and use MTF Mapper under the control of Matlab programs to analyze the results. No lens modeling involved.
I only use MTF Mapper if there's a fair amount of data involved. For more casual testing I use Imatest.
