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Author Topic: Bryce Canyon 125° stiched from 45 images  (Read 12882 times)
Dave Carter
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« Reply #20 on: March 27, 2007, 08:36:44 AM »
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Dave, I think if you make the stitched 180mm shot have the exact same Angle Of View and take it from the exact same position as the single 24mm shot, then the overall persepctive will be identical in both and in fact the only differences will be image detail...  It gets sticky with Depth Of Field, because we are using a longer lens, but also creating a larger net file, so the two factors kind of cancel each other out for any given aperture. (IOW if we used f8 on both lenses, the net DOF should be similar in both.)  Hence, neither image should have more or less apparant "depth" than the other due to perspoective or DOF.

HOWEVERBUT!  I think the added detail does in fact alter our sense of depth as we can see minute detail structure in every part of the stitched image, but cannot say the same thing for the single 24mm capture.  So perhaps that is what makes the stitch appear to have less depth?

Cheers,
[a href=\"index.php?act=findpost&pid=108918\"][{POST_SNAPBACK}][/a]

Thank you Jack.  And, yes I agree one has to be aware of using a higher mm lens with the 'Depth of Field' (focus) being less at the same f stop.  Usually I do increase the f stop used because of that.
Thanks again.
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Kirk Gittings
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« Reply #21 on: March 27, 2007, 10:24:47 AM »
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Julian,


You talk about two months of computer time assembling this image. How much time elapsed in the field making the 160 captures?
 
I routinely use stitching of 2-4 images to solve problems with commercial shoots, but for anything like your example I would go to Large Format in a minute. In retrospect, you really feel this is a superior method to shooting Large Format? I can see it for someone who does not own large format, but for me LF for this kind of image would be a no brainer for both capture in the field and image processing. Hours in the field become a few minutes. Months in front of the computer becomes a few hours.
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Thanks,
Kirk

Kirk Gittings
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julian kalmar
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« Reply #22 on: March 27, 2007, 10:49:06 AM »
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Julian,
You talk about two months of computer time assembling this image. How much time elapsed in the field making the 160 captures?
 
I routinely use stitching of 2-4 images to solve problems with commercial shoots, but for anything like your example I would go to Large Format in a minute. In retrospect, you really feel this is a superior method to shooting Large Format? I can see it for someone who does not own large format, but for me LF for this kind of image would be a no brainer for both capture in the field and image processing. Hours in the field become a few minutes. Months in front of the computer becomes a few hours.
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1: sorry! I do not have a larg format lens with 125 degree field of view. Do you?
2: Just believe me: I can get more detail with stiching 45 images and I needed the details for a 7 feet print, thatīs why decide to stich these image
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Jack Flesher
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« Reply #23 on: March 27, 2007, 10:53:10 AM »
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except the stitched image would be much sharper.
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Ray:  I'll give you everything except this last comment.  As I said above, I have 360mm LF lenses that can lay down over 60 line pairs at the film.

Cheers,
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Thomas Krüger
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« Reply #24 on: March 27, 2007, 11:46:55 AM »
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Julian, taking also images for stitching with a 5D I correct my source pics with PTLens (distortion, vignetting) and stitch them with Autopano, works great.
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Kirk Gittings
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« Reply #25 on: March 27, 2007, 12:48:27 PM »
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Julian,

So rent a view camera and do a 2x with 8x10 or 4x stitch with 4x5? The time involved is still a small fraction of the time you have expended here.

I do this professionally and do stitches from both DSLR's and 4x5 all the time for clients. To me, while your effort is an interesting exercise, it is not a viable routine technique for a variety of reasons.
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Thanks,
Kirk

Kirk Gittings
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LIGHT+SPACE+STRUCTURE (blog)
Ray
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« Reply #26 on: March 27, 2007, 07:59:46 PM »
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Dear Ray,
The answer is very simple. The top of the Canyon is not very distant. Look on the very left side of the image behind the Canyon. That is distant
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Dear Julian,
The top of the Canyon is as distant as the trees are small, relative to the closer figure lower down. The elevation of the camera seems to be about midway between the top of the Canyon and the bottom. For some reason, the distance between the small figure, lower right, and the trees on top of the ridge (with regard to depth rather than elevation), seems a bit odd.

Of course, I've never visited this location. That might be exactly how it looks. Perhaps also, on a small jpeg vital clues as to depth are missing. Perhaps the stitching program has distorted the size of certain elements. I just mention it as an impression I get. Impressive image though   .
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Ray
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« Reply #27 on: March 27, 2007, 08:21:12 PM »
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Ray:  I'll give you everything except this last comment.  As I said above, I have 360mm LF lenses that can lay down over 60 line pairs at the film.

Cheers,
[a href=\"index.php?act=findpost&pid=108981\"][{POST_SNAPBACK}][/a]

Jack,
That is indeed impressive. Are we talking 4x5 or 8x10? And what film and at what MTF?

I believe T-Max 100 (is it still available?) can (could) record 50 lp/mm at 100% MTF and 100 lp/mm at 60% MTF. I guess it could record 60 lp/mm at about 85% MTF. A good 360mm lens for 35mm format should be able to deliver 60 lp/mm to the film at 50% MTF.

50% of 85% is 42% MTF. I suspect those 60 lp/mm from your LF 360mm lens are barely discernible; 10% MTF or less. Am I right?
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Jack Flesher
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« Reply #28 on: March 27, 2007, 09:59:52 PM »
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Jack,
That is indeed impressive. Are we talking 4x5 or 8x10?
~~~
I suspect those 60 lp/mm from your LF 360mm lens are barely discernible; 10% MTF or less. Am I right?
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Ray:

All of the LF 360's I've owned will cover 8x10, so we're talking 8x10   I did not measure contrast, but the line-pair divisions were clearly visible (no guessing), so I'd estimate more like 25% or 30%. And admittedly, film grain adds to one's ablity to distinguish detail.  Regardless of whatever the contrast was, there was a clearly visible distinction on the line pairs -- just like what I'd look for to determine "real" detail in an image.  This was in the central area of the IC, and using the same arbitrary yet "clearly visible distinction," the lenses made over 50 at the extreme corner of the 8x10 frame WITHOUT re-focusing to compensate for field curvature.  

FWIW, I also tested several different 4x5 lenses when I had my Betterlight scanning back.  Here, many of the contemporary pieces of glass equalled the resolution limits of the sensor, about 54 line pairs.  Even some old lenses from the early 1930's through the 1950's got very close to that, though many tapped out at around 30 line-pairs.  Surprised me actually to discover that as a group, the contemporary large format lenses were that good...  

Cheers,
« Last Edit: March 27, 2007, 10:11:24 PM by Jack Flesher » Logged

Ray
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« Reply #29 on: March 27, 2007, 10:53:02 PM »
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FWIW, I also tested several different 4x5 lenses when I had my Betterlight scanning back.  Here, many of the contemporary pieces of glass equalled the resolution limits of the sensor, about 54 line pairs.  Even some old lenses from the early 1930's through the 1950's got very close to that, though many tapped out at around 30 line-pairs.  Surprised me actually to discover that as a group, the contemporary large format lenses were that good...   
[a href=\"index.php?act=findpost&pid=109071\"][{POST_SNAPBACK}][/a]
 

Yes, it is surprising. I still think, though, that the MTF of those 60 lp/mm is critical for real world images. Even cheap 35mm zooms can deliver 60 (and more) high contrast line pairs which are still easily distinguishable even though they might have lost 80 or 90% of their original contrast by the time they are recorded.

What happens if those line pairs are not high contrast, say medium to low contrast? A camera like the Canon 20D, although its sensor is capable of recording 60 lp/mm, simply wouldn't be able to record them using a cheap zoom. But it probably would when using a good prime, provided the contrast of the target wasn't t too low.

I would find it difficult to believe, if I were to use my modestly okay Canon 100-400 IS zoom at 400mm and f16 on my 5D, and take a mosaic of around 64 images which, when stitched, would have the same FoV as a single shot with an LF 400mm prime, that the single 8x10" shot at f16 would even be nearly as sharp, assuming you didn't use shift movements.

I could be wrong, though. Would someone care to do the experiment   .
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julian kalmar
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« Reply #30 on: March 28, 2007, 02:21:28 AM »
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Yes, it is surprising. I still think, though, that the MTF of those 60 lp/mm is critical for real world images. Even cheap 35mm zooms can deliver 60 (and more) high contrast line pairs which are still easily distinguishable even though they might have lost 80 or 90% of their original contrast by the time they are recorded.

What happens if those line pairs are not high contrast, say medium to low contrast? A camera like the Canon 20D, although its sensor is capable of recording 60 lp/mm, simply wouldn't be able to record them using a cheap zoom. But it probably would when using a good prime, provided the contrast of the target wasn't t too low.

I would find it difficult to believe, if I were to use my modestly okay Canon 100-400 IS zoom at 400mm and f16 on my 5D, and take a mosaic of around 64 images which, when stitched, would have the same FoV as a single shot with an LF 400mm prime, that the single 8x10" shot at f16 would even be nearly as sharp, assuming you didn't use shift movements.

I could be wrong, though. Would someone care to do the experiment   .
[a href=\"index.php?act=findpost&pid=109079\"][{POST_SNAPBACK}][/a]
Donīt missanderstand me I didnīt whant to start those redicolous debate if film or digital is better. Iīm still using my sinar 8x10 and have wonderful lense ( 121mm super Angulon, sironar 240mm  Apo sinaron 360mm) Of course I know that you canīt stich everything. But to be honest : Pano shooting is not a domain for 8x10 inch ( you always have problems with contrast and I know no Pano had which can hold my camera and I know no computer which is able to stich a scanned 8x10 slide. If you donīt whant to loose detail you have to scan it with high resolution and 16 bit and you get a 2GB file for each image)
What I like on film (8x10) is that you have to compose your picture wheras with digital you just click it. I mean no one can "compose" a 45 image stich made of more than 160 images you never no if it works in the end.
Now the resolution debate:
The best lenses for 35mm are able to repoduce 135 line pairs per mm in resolution charts. This would result in a 5940 x 9180 pixle image. 54 MP!!!
Everyone knows that this is nonsense!! You have to be glad if you get 12 MP in real world photography ( normaly 8-10 MP) So you only get one fourth of the resolution the chart shows. Why? The answer is simple: you normaly donīt make photos from linepairs which have a contrast of 1:1000 and you loose this resolution very quickly with decreasing of contrast because film grain whips it
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Ray
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« Reply #31 on: March 28, 2007, 11:48:19 AM »
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Now the resolution debate:
The best lenses for 35mm are able to repoduce 135 line pairs per mm in resolution charts. This would result in a 5940 x 9180 pixle image. 54 MP!!!
Everyone knows that this is nonsense!! You have to be glad if you get 12 MP in real world photography ( normaly 8-10 MP) So you only get one fourth of the resolution the chart shows. Why? The answer is simple: you normaly donīt make photos from linepairs which have a contrast of 1:1000 and you loose this resolution very quickly with decreasing of contrast because film grain whips it
[a href=\"index.php?act=findpost&pid=109088\"][{POST_SNAPBACK}][/a]

That's true, but we've been talking about 60 lp/mm. These figures are not nonsense.

Also, there are parts of many images that do have high contrast material, such as leaves against a sky, trees on a horizon, car number plates, signs and billboards in cities etc.

The general principle is, a line pair specification is meaningless unless it's associated with an MTF percentage.
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