Help wanted breaking thro the High Magnification Barrier

[Chris S.]

[Craig Gerard]

Leica Z6 APO and Z16 APO User Manual

http://www.leica-microsystems.com/products/stereo-microscopes-macroscopes/quality-control/details/product/leica-z16-apo-a/downloads/



Craig
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To use a classic quote from 'Antz' - "I almost know exactly what I'm doing!"

[Chris S.]

Craig,

When I first saw your links, I thought, "Been there, read that." But then I saw that the user manual you linked to has about twice as many pages as the one I have on my computer. Perhaps it's a newer version? Anyway, page 58 of the user manual you linked to has some interesting information about compatible cameras that my copy lacked.

The cameras Leica sells for this system have very small sensors--6.5mm x 4.92mm through 8.8mm x 6.6mm. The smaller sensors use a 0.5x optic in the camera mount, the larger sensors, a 0.63x optic. A standard DSLR is also said to be useable, apparently without optics in the mount.

Extrapolating from the numbers on this page (and I may very easily be doing this incorrectly), it appears to me that the "acceptable" image circle for an optic-free camera mount would have a diameter of 13-14 mm, with a higher-quality image circle of 10-11 mm.

This seems way too small for the long axis of the Canon 50D (22mm) that Bob used, so I'd repeat my question: Bob, did the image vignette on your 50D? If my extrapolated dimensions are correct (a very big if), the image circle for this system would vignette strongly on either Canon or Nikon crop frame sensors (Nikon DX is 24mm on the long axis). It would also vignette strongly on a micro 4/3 sensor (18mm long axis). Not until one gets down to the very small dimensions of a point-and-shoot sensor (or a machine vision sensor) would it appear not to vignette.

Tonight I spoke with a researcher who recently purchased a Leica compound microscope, Leica camera, and related software. I asked what the camera cost, and, as far as she could recall, she thought it was about $2000 USD. Egad--this camera seems like a point-and-shoot, priced absurdly high.

If any of my musings are correct, this Leica zoom resembles the Navitar zooms available for Mitutoyo optics. The zoom capability would be nice, but the image circle is impractically small.

Cheers,

--Chris

[Charles Krebs]

Chris,

The 10X eyepieces for this Z-series have a field number (FN) of 23mm which should indicate a "normal" size intermediate image.

With a 2/3"sensor camera and the Leica 0.63X C-mount adapter (Part #10 447 367) the camera is recording an intermediate image of 17.5mm diagonally. (In the 35mm camera days, the "standard" was a 2.5X magnification to the camera, which then recorded a 17.2mm portion of the intermediate image across the diagonal... so this is about equivalent). For the Z6/Z16 Leica offers a T-mount adapter with a 1.6X factor, which would take that same intermediate image size and place it perfectly on an APS-C sensor... very nice!

What I am not sure about is the intermediate image size obtained with the "HR" microscope objectives shown as accessories. This which is why I suggested contacting and checking with Leica before shelling out big bucks for one of these objectives. (The "HR" designation makes me cautious, since I believe there are some other non-Leica "HR" objectives that yielded smaller image circles than normal as they were to be used primarily with small sensor devices).
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http://www.krebsmicro.com

[MacroB]

Happy New Year Charles,

I tried replicating the conditions but without the Einstein Flash, using the modeling light - not powerful enough. There are 21" from the front lens to the focal plane mark. Then tried the 430 EX II speedlite as a slave - angle of flashes from the MT 24 EX would not fire the slave.

Only one thing to do, I raised the power of the MT 24 EX to full and just shot off 11 exposures with that and the modeling light.

Admittedly, the foreground is not so cluttered but for a short stack I was concentrating on the apex. Pretty miserable photo.

Could this all be down to exceeding the optimum magnification?

If the 5x objective reduced the effective aperture to f32, might that help??

Best Wishes for the New Year,
Bob

[MacroB]

fault

[MacroB]

Hello All,

Here's a photo of my Z-16 set-up, Graphomya maculata and actual pixel shot.

Bob

[Craig Gerard]

Bob,

Could you provide some specific details regarding the rail directly beneath the StackShot in the image of your setup?

How is the camera supported when using this particular setup?


Craig
_________________
To use a classic quote from 'Antz' - "I almost know exactly what I'm doing!"

[MacroB]

Hello Craig,

The Cognisys rail is attached by screws to two metal saddles that sit astride a 3" wide rail from comaroptics.com.

Camara screws on to metal tube circa 21/4" x 91/2".

Bob

[Craig Gerard]

Bob,

I must admit to having no knowledge or experience with the particular optics in your setup. I have seen a Z16 in operation, but it looked more like the model in the previously linked User Manual. Does your arrangement have a specific Leica designated identity? Suffice to say, it's not what I expected to see.

One aspect which concerns me is the camera attachment (and the overall length of extension). Connected, in the manner you've indicated, I would anticipate vibration problems. I believe we need to look at that area of your setup and see if we can formulate an alternative solution applicable to your equipment.

When looking at the LCD in magnified Live View do you see much vibration in the displayed image? I am curious as to whether the proximity and position of fiber optic illuminator may be contributing to vibration concerns.

Do you have 'Silent Shoot' enabled and Mode 2 selected via the Live View function settings in the 50D menu?

Thanks for the information regarding the Comar rail



http://www.comaroptics.com/pdfs/Comar_rails_and_carriers.pdf



Craig
_________________
To use a classic quote from 'Antz' - "I almost know exactly what I'm doing!"

[MacroB]

Hello Craig,

I only use the fibre optics for focusing due to the vibration from the fan - just this moment struck me. That for starters could mess up the sharpness of my focusing. Though usually I place something to redirect the current of air away from set-up.

I do not use it when shooting a stack, primarily due to the warm air from the fan moving everything. Did try this morn' to direct the Einstein flash through the fibre optics via the snoot, but too much light spillage and not enough reaching target to illuminate.

Have used flash thro the fibre optics at lower magnif. but the light from a small source played up with all the small hairs causing specular effects. In that case one can of course turn off the fan as not using the in-built light.

Also tried a Cyberlite 360 this morn' with constant illumination. Not powerful enough to give me a picture at 30X.

Regards Silent Shoot, yes this is great for focusing on large screen, but I had not turned on mode 2 as the Hbook says it will disable 1 & 2 if using flash. Will give it a try, however.

Yes, when looking at Live view & magnified, it does jump around. If I turn off the fibre optics I have not got a strong enough light source to enable focusing.

Right, I will put some shock absorbing material under feet of F/O unit and see if that improves focussing. As mentioned that is turned off when shooting.

Regards,
Bob

[Charles Krebs]

Bob,

Is the camera attached about as shown below. Does the red line indicate the only support point for the microscope/camera?


If so, then (in addition to the "overmagnification" initially discussed) this is almost certainly another problem source that must be addressed.


First let's backtrack a little...

[MacroB]

Hello Charles,

Yes, of course, you are right. I've lowered the speed and got a picture with the modeling light.

Unfortunately, I had put the rig away and in doing so lost the mounted fly. Everything set up but now its one of the complex eyes. Probably as sharp as I have seen it using just the Einstein. Will wait and see how it turns out.

With Live view running and 10X zoom there was no movement because I was using the Einstein model lamp rather than the F/Optics with fan.

I will post some photos in the next couple of days.

Regards,
Bob

[MacroB]

Hello Charles,

Hope I have got this right. One slice with the model lamp only and one with flash, both 30X of a somewhat different Max palp.

I did notice that with Live view and zoomed in 10x the heat from the Einstein model lamp had the picture jumping around a bit, so I went and prepared my meal. By the time I came back the lamp had cooled down and the picture seemed more stable.

Can see now, just how vibration will move that camera around. First slice with model lamp only, no ancillary flash or diffuser.
Again 30x with Einstein flash only, no MT-24EX to illuminate underneath ( both slices upside down)

Bob

[Charles Krebs]

Bob,

Thoughts after looking over this thread form the beginning...

You have some excellent equipment in the Z16. But any optical set-up that works in high magnifications, even if it is of the highest quality, will have its resolution limited by the numerical aperture of the optics. (In photographic terms it is possible to translate that into an "effective aperture" if that is a more familiar concept). Photography is pretty unforgiving when it comes to diffraction. When you approach the upper limits, you often find that magnifications that seem perfectly acceptable visually when you are looking at a subject through the eyepieces, seem too "soft" when you closely examine a single image at 1:1 on a computer screen. There are a couple ways you can determine what this photo magnification "limit" might be. You can get a good idea by "running the numbers" (if you have them!), or you can do practical testing and make a determination looking at the actual images.

The zoom component of the Z16 provides settings from 0.57X to 9.2X

With the 2X Apo, the Z16, at the lowest zoom setting yields a magnification of 1.14X (2x0.57). At the highest zoom setting you will have a magnification of 18.4X (2x9.2)

You are using an APS-C sized sensor. The parameters will vary depending on image usage and personal taste, but generally speaking I think it is a good idea, especially when you are going to stack images, to keep the effective aperture below f/22 on that size sensor. (If you are not stacking but going after a single image with great DOF, you might need to accept smaller effective f-numbers. You would have greater DOF, but lower resolution).

The Z16 with the 2X Apo gives a NA of 0.034 at the lowest zoom setting (0.57X zoom setting, 1.14X overall magnification from zoom unit) and a NA of 0.224 at the highest zoom settings (9.2X zoom setting, 18.4X overall magnification from zoom unit).

Based on the NA, it means that with the Z16 and the 2X Apo, you would want to limit the magnification on sensor to 1.5X at the lowest zoom setting, and 9.8X at the longest zoom setting. Any higher magnifications on camera sensor would result in images that appeared less "sharp" due to diffraction.

Since your initial spider palp was at a magnification of 31X on sensor, you were definitely into a magnification where you would feel that the images were "soft". Photographing at 31X with a NA of 0.224 produces a very small effective aperture of f/69. Relationship is: 31/(2*0.224)

I do not know what camera connection/optics you use. It would be best if you could keep any additional magnification provided by the camera connection (that is... any additional magnification after the zoom component), to a minimum. Since I am not familiar with the Z-system components, I don't know if "direct projection" or a 1X projection is possible. And if it is, I don't know if it would cover an APS sized sensor, with a diagonal of about 28mm. What does seem clear is that it would be best to keep any additional enlargement magnification (after the zoom unit) as low as possible.

(Leica provides NA info for the two extremes of the zoom range. It would be nice to know how that NA changes with intermediate zoom settings,. I t would also be really nice to know the size (diagonal) of the intermediate image that is produced by the objective (the 2X Apo) and the zoom component. If it were greater than 28mm diagonal...I doubt it, but you never know... it might even be possible to apply some optical "reduction" onto the camera sensor in order to avoid over magnification).
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Looking at the physical arrangement of your set-up, and some of the observations you have made, show other areas where things might be improved.

Your observations of vibration from the fiber optic illuminator, and also the observation of "heat' movement due to the modeling light indicate problems that need to be avoided or eliminated.

The extremely large overhang of your equipment... front and back... with a single mounting point on the StackShot is a real invitation to vibration problems. Not that it would be impossible to handle with great care, but it sure looks to be unstable and problematic. (As mentioned earlier, it might be better to lock-down the camera/optics and use the StackShot to move the subject).

The issue of subject movement due to the studio type flash should also be examined more closely. The last comparison you posted seem to be at slightly different focus, but do not seem to show a problem. Just to be sure, I would check a few more times, trying to keep focus and lighting identical. (And avoiding any heat movement issues from the modeling light).
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I hope this analysis is accurate. (If anyone sees flaws in my observations or conjectures please jump in).

I have seen some stunning stacks made with the Leica macroscopes, but they were at more modest magnifications than 31X. Never having used one, I can only look at the specifications of the equipment, and the examples and descriptions you provide.
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