Author Topic: Best solution at 3x for image-pan stitching  (Read 535 times)

ray_parkhurst

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Best solution at 3x for image-pan stitching
« on: February 28, 2019, 06:48:47 »
I'm trying to decide the best solution at 3x magnification for panoramic stitching through camera movement. In this application, I will be imaging a field of ~19mm x 19mm, so need an image circle of ~82mm. My 95mm Printing-Nikkor does well at 3x but I expect at most a 62mm image circle, and likely less, though this is untested. I have a Linos 105mm f4 Inspec.x L 3.5x which also does well at 3x, but its f4 aperture is going to limit the resolution due to the f16 effective aperture at 3x. I have been Can anyone suggest a solution at 3x magnification which has 82mm image circle and an aperture larger than f16?  I have a Minolta 5400, which is a good performer at 3x but the image circle is in question. Same goes for the Lomo 3.7x 0.11 objective. Robert OToole has tested the Qioptiq Mag.x 5x objective at 3x, and it won over the competition, but the image circle is "only" 57mm. Plus, that objective is made of unobtainium. I've been searching for a 75mm Printing-Nikkor, but again it "only" has 62mm image circle, so would suffer in the corners of the panorama. And again, it's another lens from the unobtainium vault.

So what am I missing?

Erik Lund

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Re: Best solution at 3x for image-pan stitching
« Reply #1 on: February 28, 2019, 07:54:47 »
Why don't you move camera and lens for the stitch? Like you would in an ordinary panoramic stitch
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Bent Hjarbo

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Re: Best solution at 3x for image-pan stitching
« Reply #2 on: February 28, 2019, 09:34:03 »
Why this give any inspiration
http://microsculpture.net/

Erik Lund

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Re: Best solution at 3x for image-pan stitching
« Reply #3 on: February 28, 2019, 09:44:38 »
Yes I also saw this, very dedicated work! The results speak for themselves - Impressive
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Birna Rørslett

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Re: Best solution at 3x for image-pan stitching
« Reply #4 on: February 28, 2019, 10:18:46 »
Seen this before but it really bears repetition :D a good illustration of the opportunities offered by infinity-corrected optics as well.

Erik Lund

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Re: Best solution at 3x for image-pan stitching
« Reply #5 on: February 28, 2019, 12:25:34 »
As far as I remember he moves the subject to stitch, up down and to the sides - then moves the camera/lens on rails for depth stacking
10.000 frames per image  8)
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Dr Klaus Schmitt

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Re: Best solution at 3x for image-pan stitching
« Reply #6 on: February 28, 2019, 15:56:31 »
How about a line scan lens, there are some with around 80mm image circle...?
formerly known as kds315

ray_parkhurst

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Re: Best solution at 3x for image-pan stitching
« Reply #7 on: March 01, 2019, 01:56:20 »
Why don't you move camera and lens for the stitch? Like you would in an ordinary panoramic stitch

I am doing this now (pan subject in X and Y, move camera in Z) at 2x with the 95PN, and indeed it works reasonably well, but lighting must move with the subject in order for the stitch to go together without visible stitching artifacts. This is highly constraining, and requires very large working distances to get lighting between lens and subject. The lens also should be telecentric to minimize distortions and light angle errors. The 95PN is not, and about half or more of my panoramas must be re-done due to noticeable lighting shifts.

Panning the camera in X and Y and subject in Z allows me to keep the lighting fixed and optimized. There is essentially just a single image to work with, and if I had a big enough sensor I could shoot it all at once, but alas 60x60mm sensors are not readily available.

Ultimately I don't know if this method will do any better than moving the subject. There is also a subject size limitation with this method, though for larger subjects I can just reduce the magnification, assuming I have suitable optics with sufficient image circle at that mag.

Why this give any inspiration
http://microsculpture.net/

Wonderful video, thank you so much for sharing that! Also it is a huge amount of work for each final image, much more than I'm willing to put in. I currently am doing 2x3 panoramas, with each tile composed of 10-12 shot stacks, for total of 60-72 images. At 3x I will need to do 4x6 panos due to overlap inefficiency, and depending on the quality of the objective I may need to do up to 20 shot stacks, so 480 total images. This is getting big, but still not the 10k+ as shown in the video.

How about a line scan lens, there are some with around 80mm image circle...?

Yes, most likely this is the best source for such optics. In fact the Rodenstock 105mm f4 Inspec.x L 3.5x that I am currently planning to use was specifically designed for 82mm line scan applications. The reason I'm looking further is that at f4 its NA is still fairly modest at 0.1, which is the same as the 95PN at its optimum f3.3. Thus in theory I won't be getting much more information than I am getting now with the 95PN.

ray_parkhurst

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Re: Best solution at 3x for image-pan stitching
« Reply #8 on: March 26, 2019, 04:57:00 »
Well, it looks like I am back to Nikon land, and my quest for the ultimate 3x lens may be over. For years I have been searching for a unicorn...the 75mm Printing-Nikkor. Nikon stopped making this lens long ago (can anyone verify they EVER made them?) and when the Tochigi-Nikon factory re-branded to Nikon-RayFact, they changed the design to a much longer and larger lens targeted for Line-Scan sensors...the RayFact 3.5x. I've been searching as well for this lens for nearly as long as the 75PN, and when one finally showed up on eBay, I bought it. And what a lens it is!

I published a brief report on Photomacrography forum, see it here: http://www.photomacrography.net/forum/viewtopic.php?t=39328

In summary:
- Sharp wide open (f2.4) all the way out to edge of 82mm image circle
- CAs are present but minimal. Not an apochromatic design, unlike the 1x and 2x
- Has intermediate stop at ~f2.8...still need to determine if f2.4 or f2.8 is the optimum
- Slightly sharper than the Rodenstock 105mm f4 Inspec.x L 3.5x lens at f4, and significantly sharper at f2.4

I had to build a custom stand to test it. It requires 650mm subject to image distance! Gave me a chance to build a system that could pan the camera/sensor to more effectively determine the image circle. Nikon RayFact rates the lens to 62mm, but indeed it holds up well out to 82mm, which is more than I need for the sensor-pan method.

Now to build an automated system to take advantage of this gem!

Edited to add: I have attached the specifications for the RayFact 3.5x lens in case anyone is interested.


Dr Klaus Schmitt

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Re: Best solution at 3x for image-pan stitching
« Reply #9 on: April 01, 2019, 18:30:13 »
WOW, very exciting news Ray! Too bad it is not apochromatic, would have hoped that...

Looking forward to seeing some results!
formerly known as kds315