Canon MP-E 65 versus 10X Mitutoyo Plan Apo At 5x

[ray_parkhurst]

Another important variable is that some lens tests (those that look at single images) will not distinguish between field curvature and always-mushy corners. A lens can be sharp in the center at one focusing distance, and sharp in the corner at a different focusing distance. That kind of lens would be fine for us stackers. But someone testing single shots focused at the center will not realize that the corners would also have been sharp if the lens had been focused on them instead of on the center.

This is another good reason for a full review. Does anyone know how flat the field is for the MPE65 at various apertures and magnifications?

[JohnKoerner]

Another important variable is that some lens tests (those that look at single images) will not distinguish between field curvature and always-mushy corners. A lens can be sharp in the center at one focusing distance, and sharp in the corner at a different focusing distance. That kind of lens would be fine for us stackers. But someone testing single shots focused at the center will not realize that the corners would also have been sharp if the lens had been focused on them instead of on the center.

Lou, I would suspect 99% of lens testers fail to factor this in.

Fascinating point.

[Lou Jost]

Yes, I have hardly ever seen this treated carefully by testers. And I think no quantitative automated lens testing pays attention to it.

[ray_parkhurst]

When testing lenses for my own use, I check both the field curvature and the quality of corners both with and without stacking. For my coin photography, given that coins are fairly flat (typically only a few hundred microns of topography), there is an advantage to a lens having sharp corners with no curvature in that single shots can be sufficient at lower magnifications. But at higher mags, and lenses with wide apertures, there is no debating the need to stack.

I published a test of a few objectives for field flatness a while back. My method was to focus stack a flat surface, then use 3D rendering to show the shape of the in-focus field. It was fairly instructive, though I have not used the method lately.

[Lou Jost]

I wish everyone did that, Ray! I gather most testers don't come from a stacking background. I suppose that is ok since most of their readers also aren't stackers.

[RobertOToole]

I would like to see a modern, full review on the MP-E 65, on a modern sensor, to see where it really stands (resolution, contrast, bokeh, CA, etc. ... at 1x, 2x, 3x, etc.) ... so I could interpret the data myself, for my purposes, without a reviewer's personal spin on anything.

I am not aware of any such review however.

Testing my MPE65 again in a shootout is on my 2017 to do list as a matter of fact.

My busy spring and summer season is over now I will have some time and best of all I have a source of any Canon, Sony, or Nikon body that I need to borrow.

Other than time one of the things keeping me from starting is the question of target? Any good ideas, let me know.

Robert

[Lou Jost]

Although USAF targets are nice, they don't show all the problems a lens has. I like butterfly scales in a mix of colors, at least blue and red or orange, with some pure white ones hanging against black space on the edge of the wing. The difference (or lack thereof) in sharpness of a blue scale and a red scale tells us whether the lens is nearing diffraction territory. The white edge scales often reveal color aberrations.

And more specifically, my preference is for the dorsal surface of the Painted Lady or its relatives (Vanessa cardui and its relatives). These are found all over the world and make a nice standard target. They have fine hairs overlaying some of the scales and this adds another test. The ridges on the blue scales in the eyespots are also good indicators of resolution and are probably the same size in all members of the genus.

[ray_parkhurst]

And both butterfly wings and USAF targets fall short in showing the effects of specular highlights. Pretty much each time I publish a lens comparison test using a coin as subject, I get folks asking "why didn't I use a butterfly wing?". Well, it's because they don't tell me all I need to know about the lens performance under my use conditions.

[Lou Jost]

Actually the blue scales in the eyespot do seem to have some specular reflections and are the bane of my existence. Though Urania moths are worse. But of course the best test subject is the one you intend to use the lens on in real life.