Zhongyi (Mitakon) Super Macro Lens (1 - 5x)

[ray_parkhurst]

That's a much bigger file! But it looks better, less CA and I don't see any stitching errors. It does look less saturated though, but my computer complains when I try to compare the images...

[mjkzz]

If you are trying to compare the two images, they will not match -- different stitching algorithm will yield different result for SURE.

As for less CA, like I said before, if part of tile happen to be shot and stitched with most part in the center, then it will have less CA for this lens.

I did not add any saturation to the finished image, the only adjustment was adding 25% unsharp masking (I think I did it twice, so more than 25%), I think maybe my monitor is playing tricks on me again -- it tends to display with higher contrast and saturation.

My next test is to use APSC mode of the Sony A7 III so that most images acquired will have less CA overall, and maybe compare it with a 5x Mitty + 100mm tube lens in the same mode.

[Lou Jost]

different stitching algorithm will yield different result for SURE.

I think a truly telecentric lens will produce tiles that need no modification by the stacking algorithm, so I think all good algorithms should give the same result with such tiles. My experiment using Nikon MM telecentric objectives did not require any scale change or rotation in order to match tiles. I did the stitching manually in Photoshop so I could see what transformations were required.

[mjkzz]

different stitching algorithm will yield different result for SURE.

I think a truly telecentric lens will produce tiles that need no modification by the stacking algorithm, so I think all good algorithms should give the same result with such tiles. My experiment using Nikon MM telecentric objectives did not require any scale change or rotation in order to match tiles. I did the stitching manually in Photoshop so I could see what transformations were required.

I do not think the lens is a TRUE telecentric lens, this is why I added suggestion to them to TRY to make it more telecentric by moving the aperture (vs changing optical path)

With any algorithms, it is rather hard to get EXACTLY same result, ie, pixel to pixel match, when approaches are different.

In my algorithm, though still buggy, I do not see much rotation nor scaling. The algorithm is a simple one, my intention is to let user do a sweep scan (where the video was shot) and produce a preview. This is rather helpful for planar subjects before a full SnS stack. But looks like this feature will be dropped as it is too difficult to implement.

[ray_parkhurst]

I do not think the lens is a TRUE telecentric lens, this is why I added suggestion to them to TRY to make it more telecentric by moving the aperture (vs changing optical path)

Is telecentricity a desirable quality in a general use lens? I'd also expect the aperture needs to be smaller to achieve telecentricity, smaller than f2.8, so not a great move for marketing purposes.

BTW, what aperture did you use for the SnS?

[Lou Jost]

I think it is a nice feature for making stacked scientific imaging, even when not stitching, because it allows accurate measurements that do not depend on the z-coordinate. This is of course why the major objective manufacturers make telecentric objectives.

I remember some discussions here about scale bars. Telecentric lenses resolve all those ambiguities.

[mjkzz]

I do not think the lens is a TRUE telecentric lens, this is why I added suggestion to them to TRY to make it more telecentric by moving the aperture (vs changing optical path)

Is telecentricity a desirable quality in a general use lens? I'd also expect the aperture needs to be smaller to achieve telecentricity, smaller than f2.8, so not a great move for marketing purposes.

BTW, what aperture did you use for the SnS?

I think it is, the more telecentric, the better. Whenever you have scaling factor not being one, no matter how good your stacking algorithm is, there ought to be some "guess work" (for example, when scaling up, interpolation will be used, this is just one example), and these "guess work" are part of computer generated, "artificial" ones, ie, in my opinion, these are distortions.

So, yes, telecentricity is very important, particularly when stitching stacked images.

I used f/2 mark which seems to be the sweet spot of this lens.

[ray_parkhurst]

I think it is a nice feature for making stacked scientific imaging, even when not stitching, because it allows accurate measurements that do not depend on the z-coordinate. This is of course why the major objective manufacturers make telecentric objectives.

Yes, but what % of folks are doing stacked scientific imaging? My point is that the mfr is probably looking at the lens to replace the MPE65, so in this context is telecentricity a desirable property?

[mjkzz]

I think it is a nice feature for making stacked scientific imaging, even when not stitching, because it allows accurate measurements that do not depend on the z-coordinate. This is of course why the major objective manufacturers make telecentric objectives.

I remember some discussions here about scale bars. Telecentric lenses resolve all those ambiguities.

Sorry, this might sound nitpicking , but I would characterize telecentricity as a property of an optical system. A feature sounds like something you can add instead of "being"?

[ray_parkhurst]

So, yes, telecentricity is very important, particularly when stitching stacked images.

I used f/2 mark which seems to be the sweet spot of this lens.

What % of folks buying this lens are going to do Stack and Stitch? Probably < 0.1%. So indeed telecentricity may be important to you, but is it to the manufacturer, especially if it causes a reduction in performance for other purposes?

You mention f/2 but I think this is an f2.8 lens? Do you mean stopped-down 2 stops?

[mjkzz]

So, yes, telecentricity is very important, particularly when stitching stacked images.

I used f/2 mark which seems to be the sweet spot of this lens.

What % of folks buying this lens are going to do Stack and Stitch? Probably < 0.1%. So indeed telecentricity may be important to you, but is it to the manufacturer, especially if it causes a reduction in performance for other purposes?

You mention f/2 but I think this is an f2.8 lens? Do you mean stopped-down 2 stops?

But I think this lens is so close, moving the aperture MIGHT work, so why not?

I set the aperture at f/2 mark on the lens.

[Lou Jost]

Sorry, this might sound nitpicking, but I would characterize telecentricity as a property of an optical system. A feature sounds like something you can add instead of "being"?

You're right, that does sound like nitpicking to me. Anyway I think if one is assembling an optical system, telecentricity is indeed a feature that can be designed into the system if one wants. If we had two competing optical systems, one telecentric and the other not, I think it is quite natural to say that the telecentric system has a feature that the other does not have.

[ray_parkhurst]

So, yes, telecentricity is very important, particularly when stitching stacked images.

I used f/2 mark which seems to be the sweet spot of this lens.

What % of folks buying this lens are going to do Stack and Stitch? Probably < 0.1%. So indeed telecentricity may be important to you, but is it to the manufacturer, especially if it causes a reduction in performance for other purposes?

You mention f/2 but I think this is an f2.8 lens? Do you mean stopped-down 2 stops?

But I think this lens is so close, moving the aperture MIGHT work, so why not?

I set the aperture at f/2 mark on the lens.

So this is actually an f/2 lens, not f/2.8?

[ray_parkhurst]

Sorry, this might sound nitpicking, but I would characterize telecentricity as a property of an optical system. A feature sounds like something you can add instead of "being"?

You're right, that does sound like nitpicking to me. Anyway I think if one is assembling an optical system, telecentricity is indeed a feature that can be designed into the system if one wants. If we had two competing optical systems, one telecentric and the other not, I think it is quite natural to say that the telecentric system has a feature that the other does not have.

But it also has limitations on size of objects being imaged. I'm not sure if the front lens is large enough for telecentricity across the full mag range, but if not this might be a problem. Plus won't the lens need to be stopped-down a bit to be telecentric?

[Lou Jost]

Sure, Ray, the limitations you mentioned are potentially serious with this lens.