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Author Topic: Stitched Nikon to emulate medium/large format capture?  (Read 22814 times)
elliot_n
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« on: November 05, 2010, 08:29:13 AM »
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Hi

I've recently started exploring the world of stitching. I'm attempting to achieve the resolution and image quality of a medium format digital back and/or large format film with my humble Nikon D700.

I'm interested to hear the experiences of others who have gone down this road.

My subject matter is urban - interiors and exteriors.

I like moderately wide angle views (90mm lens on 4"x5", 24mm lens on single frame Nikon). (I've no interest in wide-aspect ratio panoramas, 360VR tours, or distant landscapes.)

To achieve this I've been shooting multi-row stitches (3 rows of 6) with D700 + 50mm prime + Manfrotto 303 Pano Head + PTGui Pro.

The pano head (borrowed from a friend - I've just ordered a Nodal Ninja 5) made the world of difference - totally seamless stitches from PTGui Pro in easy (automated) mode.

I've had some problems with the geometry of the final stitch, and at the moment I'm finding it essential to take a preliminary single frame wide-angle reference shot of the whole view, framed to my liking, so that I can locate my intended centre point in the final stitch. (Anyone else do this?)

I'm interested to know how closely this technique can emulate a single medium format or large format capture?

Seems to me that one essential difference is that with stitching the plane of focus is spherical (there's no way you can get a sharp picture of a brick wall at f5.6). I like deep focus, and have found that shooting at f16 is the best compromise (f22 is too mushy).

Any thoughts

Elliot



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ternst
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« Reply #1 on: November 05, 2010, 08:46:45 AM »
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I went through this process a couple of years ago Elliot using a D3x and Phase P-45+ (on controlled landscapes). I tried every way I could think of to make the Nikon stitches look as good, but it never did and I ended up selling the Nikon and keeping the Phase. I'm sure many others have come to the opposite conclusion though (especially with the X) - it really is what you want to see and believe and you could go either way...
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elliot_n
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« Reply #2 on: November 05, 2010, 12:46:02 PM »
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I'm interested in what ways the D3X, stitched, failed against the P45. I'm thinking it would only take 3 vertical frames from the D3X to match the P45's resolution, so a simple stitching operation (compared to the multi rows I'm stitching).

I'll soon be digging out my 4"x5" camera to do a direct comparison of stitched D700 against a sheet of large format film. Both techniques seem about equally fiddly (if you include the hassle of scanning and retouching the film).

(I should have mentioned in my original post, that this is for big (minimum 30"x40") exhibition prints.)
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ternst
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« Reply #3 on: November 05, 2010, 12:56:30 PM »
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There is a lot more to it than just resolution (discussed to death here and elsewhere), otherwise you probably already answered your own question, know what you are going to do, and don't need any more info. Like I said, it really has a lot to do with what you want to see...
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elliot_n
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« Reply #4 on: November 06, 2010, 09:15:43 AM »
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There is a lot more to it than just resolution

Yes, that's what I'm interested in discussing here.

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(discussed to death here and elsewhere)

So far, I've found relatively little about using stitching to emulate a large format film workflow. This article goes into some detail: http://www.scotthendershot.com/Example01.aspx

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otherwise you probably already answered your own question, know what you are going to do, and don't need any more info

Hmm, I'm new to this. Whilst I've got some things resolved - e.g the necessity of using a spherical panorama head and good stitching software - there are other issues that I'm only just learning about. For example:

- The focal plane in a stitched shot is spherical.

- As you increase resolution (by adding more images to the stitch), you lose depth of field. No problem if your shooting a giga-pixel view of the city from your balcony, but limiting if you're photographing an interior. By my calculations (allowing for a 30% overlap between frames), a 3x3 vertical frame stitch from a D700 has an effective sensor size of 56mm x 84mm, and a 5x5 stitch has a sensor size of 88mm x 132mm (about the same as 4"x5" film).

- Geometry. I've been overlaying my stitched shot on an uprezzed single frame capture. There are geometrical differences that I haven't fully understood. Some are good - no vignetting or barrel/pincushion distortion - but sometimes horizontal or vertical dimensions seem squashed. (This is using PTGui at its default settings - except for setting a centre point of the image. PTGui is obviously capable of infinite variations in rendering, but I'm wary of tinkering too much. I just want the straightforward (?) view of a single frame capture.)

- Dust. A 5x5 stitch means 25 times more dust from a dirty sensor.

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BartvanderWolf
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« Reply #5 on: November 06, 2010, 10:20:32 PM »
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Hmm, I'm new to this. Whilst I've got some things resolved - e.g the necessity of using a spherical panorama head and good stitching software - there are other issues that I'm only just learning about. For example:

- The focal plane in a stitched shot is spherical.

Ah, a grand disclaimer, which isn't necessarily true. As a relative newbie, you're forgiven Wink

You mentioned "good stitching software" (the spherical panorama head is only needed to avoid parallax issues). Good stitching software knowns how to deal with the effects of re-focusing. By checking the "focal length" parameter in a "good stitching software" as a part of the optimization, the magnification differences due to re-focucisng will be reduced. 

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- As you increase resolution (by adding more images to the stitch), you lose depth of field. No problem if your shooting a giga-pixel view of the city from your balcony, but limiting if you're photographing an interior. By my calculations (allowing for a 30% overlap between frames), a 3x3 vertical frame stitch from a D700 has an effective sensor size of 56mm x 84mm, and a 5x5 stitch has a sensor size of 88mm x 132mm (about the same as 4"x5" film).

In fact, the DOF of a larger format "sensor" is also 'limited'. The general explanation is the larger maginification by the longer focal length.

Quote
- Geometry. I've been overlaying my stitched shot on an uprezzed single frame capture. There are geometrical differences that I haven't fully understood. Some are good - no vignetting or barrel/pincushion distortion - but sometimes horizontal or vertical dimensions seem squashed. (This is using PTGui at its default settings - except for setting a centre point of the image. PTGui is obviously capable of infinite variations in rendering, but I'm wary of tinkering too much. I just want the straightforward (?) view of a single frame capture.)

This is related to the "projection" one chooses for the final stitch. The current champion of projection methods is PTAssembler (for Windows only).

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- Dust. A 5x5 stitch means 25 times more dust from a dirty sensor.

A decent Raw converter allows to duplicate the "spot" corrections (which are the same for a number of images).

Cheers,
Bart
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elliot_n
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« Reply #6 on: November 07, 2010, 07:59:57 AM »
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Ah, a grand disclaimer, which isn't necessarily true. As a relative newbie, you're forgiven Wink

You mentioned "good stitching software" (the spherical panorama head is only needed to avoid parallax issues). Good stitching software knowns how to deal with the effects of re-focusing. By checking the "focal length" parameter in a "good stitching software" as a part of the optimization, the magnification differences due to re-focucisng will be reduced. 

Thanks for the reply.

I've been doing my tests with a demo version of PTGui Pro.

I've been following what I think is the orthodox method of not changing focus between shots. I'm using old Nikkor A-iS primes, so I don't think PTGui Pro would have any focus information to read if I decide to change focus between shots. But it's a technique I should look into.

I guess another option would be to focus stack and then use Helicon Focus - but I think number of images would become unwieldly.

Actually I did another test shot of an interior earlier today - 3x3 grid with a 50mm lens to emulate the view of a 24mm lens - and with the 50mm set at f16, with the focus set a third of the way into the room, the overall depth of focus was quite acceptable.
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BartvanderWolf
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« Reply #7 on: November 07, 2010, 09:01:26 AM »
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I've been following what I think is the orthodox method of not changing focus between shots. I'm using old Nikkor A-iS primes, so I don't think PTGui Pro would have any focus information to read if I decide to change focus between shots. But it's a technique I should look into.

PTGUI or PTAssembler or Hugin don't need focus information, it's automatically derived from the parameter optimization. By allowing the optimizer to also optimize focal length, differences in image magnification can be resolved. That way one can keep the focus on a plane.

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I guess another option would be to focus stack and then use Helicon Focus - but I think number of images would become unwieldly.

Focus stacking is also possible, and there as well one needs to allow the focal length parameter to be optimized. The number of images does grow, and then one can also add HDR exposure bracketing. Programs like PTAssembler can do it all, stack, fuse exposures and focus layers, and stitch it all together.

Cheers,
Bart
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Kumar
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« Reply #8 on: November 07, 2010, 07:06:30 PM »
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Look for Bernard Languillier's posts. He does a lot of stitching with a Nikon.

Kumar
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elliot_n
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« Reply #9 on: November 08, 2010, 08:03:55 PM »
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Look for Bernard Languillier's posts. He does a lot of stitching with a Nikon.

Kumar

Yes, his posts here and elsewhere put me on to the idea of stitching Nikon files for high res images.

I've been doing test stitches for the last few days and I'm finally getting the hang of it.


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JohnBrew
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« Reply #10 on: November 09, 2010, 06:00:36 AM »
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I do stitching with a D700, Zeiss 50 Makro combination. Works great. You do end up with some quite large files, though.
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adrian tyler
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« Reply #11 on: November 10, 2010, 12:43:21 AM »
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hi

i use a D3X with the 24 45 and 85 PCE lenses, using the shift makes stiching quite easy, i use a linhof multiview finder on top from my 4x5 which i have set up to show 3 frames stitched on the 45 and 85 (3 frames on the 24 goes too wide for the finder).

the quality is very good (even without stiching...), i didn't go down the MFDF route so i can't compare but i've made exhibition prints up to 2,66 meters wide using this technique and if properly treated they are really very good.

adrian
http://adriantyler.net/
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elliot_n
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« Reply #12 on: November 10, 2010, 09:38:41 AM »
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Yes the D3X sounds like the ultimate stitching camera. On a D700, shifting the lens won't give me the resolution I'm after, so I'm stuck with multi row panos. Pre-visualising the shot is important for me. I'm shooting standard aspect ratios (2:3, 4:5), so I use a 20-35/2.8 on my D700 to find my frame, and then either a 50/1.8 or an 85/1.8 to shoot the stitch.
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Peter McLennan
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« Reply #13 on: November 10, 2010, 11:57:44 AM »
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I've stitched for years and love the creative freedom and image quality that it provides.
I have recently begun stitching with an old 55mm 3.5 Nikkor macro.  I had no idea that my D300 could produce images so rich in laser sharp detail.  Highly recommended.
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hjulenissen
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« Reply #14 on: November 10, 2010, 01:09:29 PM »
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It seems that all stitching is done taking pictures from a single vantage point, presented as some projection? Is this the only interesting way of doing things?

I imagine taking images along a line, projecting the resulting images "planar"(?) to the output. That way, "wide scenes" could be captured even when it is impractical to back up a lot, and I am curious as to what it would look like.

-h
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Peter McLennan
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« Reply #15 on: November 10, 2010, 04:25:07 PM »
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National Geographic Magazine did exactly that, only vertically.  It's difficult to get a top-to-bottom shot of a very tall tree in the forest.  By the time you get far enough away to see the entire tree, it's hidden behind other trees.

Their solution was to hoist a camera up the side of the tree, shooting successive images which were stitched in to a complete whole.  Very successful, IMHO.

http://www.npr.org/blogs/pictureshow/2009/09/redwoods.html

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adrian tyler
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« Reply #16 on: November 11, 2010, 12:17:10 AM »
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National Geographic Magazine did exactly that, only vertically.  It's difficult to get a top-to-bottom shot of a very tall tree in the forest.  By the time you get far enough away to see the entire tree, it's hidden behind other trees.

Their solution was to hoist a camera up the side of the tree, shooting successive images which were stitched in to a complete whole.  Very successful, IMHO.

http://www.npr.org/blogs/pictureshow/2009/09/redwoods.html


that must have been a REALLY calm day, the first breeze will make stitching very hard...
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elf
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« Reply #17 on: November 21, 2010, 11:31:20 PM »
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It seems that all stitching is done taking pictures from a single vantage point, presented as some projection? Is this the only interesting way of doing things?

I imagine taking images along a line, projecting the resulting images "planar"(?) to the output. That way, "wide scenes" could be captured even when it is impractical to back up a lot, and I am curious as to what it would look like.

-h

That's called orthographic stitching and is much harder to do well.  Most software is optimized for spherical stitching. 
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BernardLanguillier
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« Reply #18 on: November 25, 2010, 03:31:58 PM »
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That's called orthographic stitching and is much harder to do well.  Most software is optimized for spherical stitching. 

Haven't tried yet, but the beta2 version of Autopano pro is supposed to now be able to handle these cases also.

Cheers,
Bernard
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A few images online here!
BernardLanguillier
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« Reply #19 on: November 29, 2010, 04:08:10 AM »
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This isn't really it, but the 140 megapixel image below was stitched handheld yesterday with a 100mm lens, I was probably standing 10m away from the store. Autopano pro 2.5 beta2 had no problem whatsoever dealing with it.

http://www.flickr.com/photos/bernardlanguillier/5213556089/sizes/o/

Cheers,
Bernard
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A few images online here!
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