NikonGear'23
Gear Talk => Lens Talk => Topic started by: Frank Fremerey on January 30, 2024, 20:47:29
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has anyone ever heard of or tried the
AstrHori 25mm f/2,8 2-5X Nikon Z?
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It is a copy of the Laowa 25mm f/2.8 Ultra Macro lens.
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There are several YouTube reviews by the well known Macro YouTubers. The preproduction lenses they were sent were dogs, but apparently the production versions are better … Internal reflections and ‘macro creep’ were the issues.
https://youtu.be/wKoblJgUmXA?si=Zht-txf50YJmPZJr
https://youtu.be/0oSODOa57A4?si=gWgrSwer2R_mKJZG
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The Laowa 25mm f/2.8 has none of the mentioned flaws. I have shot thousands of frames with it for making stacked photomacrographs for my Aquatic plant project the last 5-6 years and in general the Laowa has turned in excellent performance. It is not perfect -- what lens is -- and if I would suggest any improvement, that would be getting the last vestiges of chromatic aberrations squished for good. Probaby would entail an additional ED element or two.
I purchased the Laowa for F mount in order to put a CPU in it, instead of going directly with a Z version. This despite I intended to deploy the lens on my Z7 cameras only.
The first image shows the general setup with the Laowa 25/2.8 on my Z7, the next a typical outcome (seed pods of Zannichellia palustris ssp. pedicellata at 2.7X). Do note the gear image is IR thus the lens barrel looks brighter than it really is in visible light.
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Simple setup and impressive result there ;)
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Yeah great stuff!
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Yes, impressive !!
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Certainly a very impressive setup - is it a motorised rail?
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Certainly a very impressive setup - is it a motorised rail?
Yes. Stackshot by Cognisys. The entire contraption is an old Nikon Multiphot stand, made in an era when all plugs were pulled to get top quality.
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Just curious: how do you get a scale on the photo?
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I have a set of "master rules" with either 10 or 100 divisions, as separate b/w files. A stacking sequence is always ended by shooting a suitable ruler or measuring tape to allow precise determination of scale. After the stack has been processed into the final image, I just add a layer in Photoshop with the captured ruler and another layer with one of the master rulers. Then it is simple to resize the master ruler to match the actual shooting scale. I usually add the scale unit as a text layer if the image is to be published to avoid repeating this information in the legend. For the Zannichellia fruit, the scale is 1mm long.
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Thanks a lot for the detailed explanation.
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I have a set of "master rules" with either 10 or 100 divisions, as separate b/w files. A stacking sequence is always ended by shooting a suitable ruler or measuring tape to allow precise determination of scale. After the stack has been processed into the final image, I just add a layer in Photoshop with the captured ruler and another layer with one of the master rulers. Then it is simple to resize the master ruler to match the actual shooting scale. I usually add the scale unit as a text layer if the image is to be published to avoid repeating this information in the legend. For the Zannichellia fruit, the scale is 1mm long.
Please help me: if you use a step motor, the scale changes with the movement. As I understand you explanation you scale for the last picture's magnification, while the stacking software scales for pattern matching, not for any particular scale
Is this systematic scaling error small enough to neglect?
Love
Frank
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Nope. The scale changes with magnification only, which is held constant here. It is the plane of focus that moves (slightly in the range of a few tenths of a mm).
There are other posible modes of stacking in which the magnification changes (for example, a camera uses built-in AF-based stacking), and then the scale, if required, has to be computed from the main plane of focus for the subject. Typically those approaches are used when you stack a large scene to get excessive depth of field, such as in a landscape. I don't think the 'image scale' concept is of much importance in such circumstances. If the scene is a "miniature landscape", however, then one might put a scale bar into the scene as a final step.
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Yet another review by Christopher Frost.
https://www.youtube.com/watch?v=9OV9Ut1Kki8
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That review wasn't very exciting -- to put it mildly. Plus his strange way of thinking that diffraction is linked to focused distance ..... People tend to twist and bend in every possible manner just to avoid talking about what magnification does to your image and photographic techniques.