Teagueia zeus orchid, simple manual stack-and-stitch

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Lou Jost
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Teagueia zeus orchid, simple manual stack-and-stitch

Post by Lou Jost »

The simplest and most economical way to increase the resolution of photos is to stitch them. Ray, Mike, Rik, and many others have discussed these techniques. Even the simplest stitch of two photos doubles the pixel resolution over a single photo with the same FOV, and such small stitching projects are really easy.

Here I stitched two stacks to make a 10000 x 7000 pixel image of the center of a small orchid. I used a telecentric 5x Nikon MM objective, and processed the stack in Zerene with scaling turned off. That is important; with scaling turned on, the outline of the flower is slightly different, and the two image tiles don't line up perfectly. With scaling turned off, the two image tiles could be stitched together perfectly in Photoshop with absolutely no adjustments to angle or scale. It was really neat to see that work out so well.

Image

Here is detail at 100%, not as sharp as one might wish, but not bad:
Image

This is the manual x-y stitching device (with different lens set though):
Image

I used a FF camera, even though the Nikon 5x MM objective is usually rated only for APS sensors. The only problem was a very slight darkening of the extreme corners, which were not needed in this particular simple stitched image. I used the Photoshop Camera Raw filter to remove the vignetting, and made sure I overlapped the tiles enough so that the corners were unneccessary.

I have done this also with the 10x Nikon MM objective, and there is virtually no vignetting on FF. The Gigapan website says that the 20x MM objective does not vignette at all on FF.

One surprise for me was the lack of purple fringing. These objectives often do produce purple fringing, but I am beginning to think this may be due to using them at a different extension than they are designed for. I spent a lot of time getting the extension just right to obtain exactly 5x, and maybe this is important. Some Nikon literature gives the recommended extension for these lenses to tenths of a millimeter, as if that amount of accuracy matters. Maybe it really does matter.

This orchid was under water during the photography, to keep it from wilting. The NA of this objective ( 0.13) is low enough that spherical aberration due to the several millimeters of water (maybe 5mm) did not affect the image much if at all.

This is an extremely rare orchid, Teagueia zeus, which only exists in and around my foundation's Rio Zunac Reserve, in very wet cloud forest.

The cloud forest habitat of this orchid:
https://ecomingafoundation.wordpress.co ... at-last/[i][/i]
Last edited by Lou Jost on Sun Apr 21, 2019 8:41 pm, edited 2 times in total.

ray_parkhurst
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Post by ray_parkhurst »

Lou,

In one of my shootouts I showed that the 3x objective has coma effects when not at its rated mag. This led to "star" patterns in the corners. I also saw much less purple fringing when exactly at 3x. I see a similar thing with the 5x and 10x. Seems they all have best performance right at their rated mags.

Lou Jost
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Post by Lou Jost »

Ray, that's interesting. With my 5x and 10x objectives (both bought from you--thanks!!) set exactly to their rated magnifications, I have not seen any coma even in the corners of FF sensors.

elf
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Post by elf »

Can you show more of the water setup?

Lou Jost
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Post by Lou Jost »

Sure. I am away from home now but will show you when I get back.

JH
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Post by JH »

Nice picture - thanks for showing this orchid!

Just tested my own 5x MM objective under different dry conditions. It works well - even tested it with a tube lens, the ITL 200. With my Canon 6D I could not find a set up that did not have some blue and little green CA.

Best regards
Jörgen Hellberg
Jörgen Hellberg, my webbsite www.hellberg.photo

Lou Jost
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Post by Lou Jost »

Thanks Jorgen. I did not notice any blue or green fringing on my FF camera, but blown highlights had purple ghosts. I found it important that the extension was exactly right: the distance between the Nikon camera flange and the rear edge of the fat objective segment is 162mm.

What were the results of using the tube lens? I have been meaning to try that.

JH
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Post by JH »

Lou Jost wrote: What were the results of using the tube lens?
Thansk for asking! Made a short post here; https://www.photomacrography.net/forum/ ... 418#248418

Best regards
Jörgen Hellberg
Jörgen Hellberg, my webbsite www.hellberg.photo

Lou Jost
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Post by Lou Jost »

Great, thanks! I've asked a few questions there....

apt403
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Post by apt403 »

Beautiful shot, Lou! I've come back to this post a few times to look at it.

I'll also add my name to the list of people interested in your water technique. Flowers are my primary imaging subjects, and the process of keeping them turgid throughout the process has been a tricky one.

Lou Jost
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Post by Lou Jost »

Thanks for the kind words. My water technique isn't very complicated. I learned to cut glass so I have made a variety of glass receptacles suitable for different sizes. Some are for horizontal shots, and they have one side made of a cover slip, or a camera filter. Cover slips can be cut like butter using a glass cutter.

Bubbles are a big problem. My solution has been to first dip the flowers in water mixed with a very small amount of liquid dishwashing soap. After they have soaked in that soapy water, I take them out and drop them gently in distilled water for photography. I use the minimum amount possible, so as to minimize spherical aberration. It is of course important to check (by looking closely at surface reflections) to make sure some part of the flower is not deforming the flat water surface.

Water greatly reduces reflections from things like hairs. This can be good or bad, depending on what you want.

My orchids bleed color fairly quickly; I have about half a day at best to work with them. Still, they'd be curling withing minutes if they were not under water. I am experimenting with Peltier coolers to extend their lifetime in either air or water.

Another approach is to use oil instead of water. This gives a slightly glistening effect to floral surfaces, and the pigments don't dissolve into the oil, so colors stay vivid. I use light cooking oil.

I am working on defeating spherical aberrations at higher NA. One way would be to use lenses corrected for shooting through a thick medium. Many x-ray lenses fall into this category, as do the Mitutoyo LCD and G objectives, and some Reichert objectives designed to image hot metal behind a thick window of quartz glass. I will build a"boat" of coverslips that will attach to the front of such objectives, and that will move with the objective during the stacking. so that there is always exactly the right amount of water between the objective and the flower parts being imaged. This will of course limit the thickness of the flower to less than the thickness of the medium that the objective is corrected for.

Spherical aberration can be completely eliminated by using water-dipping objectives. Their only problem is a generally short working distance and lack of telecentricity. They are ideal solutions for single stacks, but they can't produce a stitched image of a highly irregular object like the flower in my picture.

Here's an example of a single shot in water. I took this with a FF Pentax K-1 (modified to Nikon mount) either with a Dimage 5400 scanner lens or a Lomo 3.7x, I don't have my notes at hand. This is a new species I discovered here some years ago, Teagueia anitana.


Image

100% crop of lower left of flower:
Image

apt403
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Post by apt403 »

Thanks for the write up! I'm going to have to give this a try myself. Working w/ some Erodium cicutarium at the moment, and the reflections from the trichomes are proving problematic at times.

Based on the photos in the first post, it looks like you're using continuous lighting from fiber optics?

Lou Jost
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Post by Lou Jost »

apt403, yes, I use continuous light, but not fibre optics. I use a diffused Cineo Matchbox 5600k panel illuminating both the subject and a 45 degree mirror under the subject, to provide transilllumination and top illumination.

It's almost 3am here, I got shaken out of bed by an earthquake and the shaking woke up my sleeping computer too. I am still a bit shook up....it was so bad the water came out of my toilet bowl and got the bathroom floor all wet. Worst earthquake I've ever experienced.

ray_parkhurst
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Post by ray_parkhurst »

Lou Jost wrote:apt403, yes, I use continuous light, but not fibre optics. I use a diffused Cineo Matchbox 5600k panel illuminating both the subject and a 45 degree mirror under the subject, to provide transilllumination and top illumination.

It's almost 3am here, I got shaken out of bed by an earthquake and the shaking woke up my sleeping computer too. I am still a bit shook up....it was so bad the water came out of my toilet bowl and got the bathroom floor all wet. Worst earthquake I've ever experienced.
You must be fairly close to the epicenter. 8.0 is a big earthquake! Hope all is OK for you. Let us know when you can.

Lou Jost
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Post by Lou Jost »

Ray, thanks for your concern. Yes, I see now it was an 8.0 (some sources now revise that to 8.2). It knocked over my stacks of books and put some new cracks in my floors, but nothing else. I am amazed at how well everything in the neighborhood has withstood the tossing around. Main thing: my lenses are safe. But I am going to have to rethink my lens storage methods so they don't go flying off the shelves if this happens again.

The amazing thing to me is that I am more than 500km from the epicenter and it still bounced me around a lot. It was a very deep quake which was good for the places near the epicenter. If this had been near the surface it would have flattened cities.

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