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Thread: Stitching Question - Digital SLR vs 4x5

  1. #1

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    Stitching Question - Digital SLR vs 4x5

    I have followed the 2-3 threads in the last couple of days on the advantages of digital stitching to replicate using a 4x5 or 8x10 camera with film and have a couple of questions...

    If the desire for a stitched digital photograph is increased resolution to compete with 4x5 film resolution when scanned, won't you have to use a different lens for the multiple digital captures compared to what would normally be used for a similar field of view?

    For example, if I use a 180mm lens on a 4x5 camera I get 47 angle field of view (using the diagonal of the 4x5 film). For a single digital capture using a Nikon camera (1.5 crop factor) if I wanted a similar angle of view I would use a 35mm lens with gives me a 44 angle of view with the Nikon digital sensor. Pretty close to the 4x5 view. This is straightforward using the diagonals of both formats.

    Now is I want to increase the resolution of the digital by stitching several frames together then I will have to change the lens to one giving a smaller angle of view than the normal lens in order to get the same angle of view with the total stitched image.

    Is this thinking correct on stitching digital images for higher resolution. If you just pan left and right or even up and down using a normal lens giving a similar angle of view, then you would actually get a much wider field of view. Correct or am I off base here?

    I do see that if I use a much smaller field of view lens for the stitched image then I can increase the resolution of that image. For instance, a 135mm lens on a Nikon digital sensor gives a 12 field of view which is about 1/4 the field of view using a 4x5 camera with a 180mm lens. So using an double row of 6 digital shots (6 on top and 6 on bottom) to allow an overlap of the images would be an increase in resolution from about 12MP to 170MP.

    Am I off base with these calculations and the way to look at stitched digital photograph resolutions?

    Bill Nelson

  2. #2

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    Re: Stitching Question - Digital SLR vs 4x5

    With digital stitching you can use whatever lens you want. The key is to have about a 30° overlap in the framing, and have the camera pivot on the nodal point of the lens. Then you can match whatever angle of view that a film camera can produce on a 4x5, 8x10, etc.

    I simply do not let the comparison enter my head. I look at the scene I need to capture and use the tools at hand to do it. For me it's all about learning the gear so the choices become natural. This is how I work in 8x10, 4x5, medium or 35-mm format. I want my brain to know how each lens / camera combination sees before I look through the camera.

  3. #3
    Jack Flesher's Avatar
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    Re: Stitching Question - Digital SLR vs 4x5

    Bill, you are correct and it can be performed that way, though like Walter said, I usually don't think in terms of replicating 4x5 or 8x10 but rather in terms of capturing the image I want at higher or "high enough" resolution.

    What this means in practice is that I do often stitch with longer than normal lenses -- in fact the 90 Tilt/Shift on my 5D is a common choice. If I stitched to cover the full area of a 4x5 neg, I would need roughly 20 captures (5hx4w) allowing for enough overlap to stitch. In practice, the final result would match the AoV of a 90mm lens on 4x5, but my final resolution quality (about 100 MP) would meet that of having used a 180 on scanned 8x10. (BTW, this is where the disadvantages of a digital scan back start to become advantages -- capturing 20 DSLR frames for a tiered stitch [rows and columns] is a non-trivial exercise and requires adherence to process; the scan back does it for you.)

    Instead, I might capture 6 to 8 frames (2x3, 2x4) for about 50MP of final effective stitch and this AoV and resolution would more closely match say a 150 on scanned 4x5. Similarly used, my 45 Tilt/Shift might match a 75 on 4x5; my 24 an uber-wide 35 or 47 on 4x5. By adding my 2x converter to my 90 T/S, I maintain excellent optical performance and have what would amount to a 240 - 300 on 4x5. (IMO 6-8 DSLR captures is relatively easy to manage and is more convenient than using the scan back on a view camera.)

    Lens tilt for altering PoF becomes an issue with the multiple stitch -- it can be done with a T/S on a DSLR, but is quite complex in a tiered stitch -- but the shorter lenses generating more DoF mitigate this to some degree, though not enough for all images. Thus, there are still some advantages to using the view camera to begin with

    Cheers,
    Jack Flesher

    www.getdpi.com

  4. #4
    Kirk Gittings's Avatar
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    Re: Stitching Question - Digital SLR vs 4x5

    Here are some related articles. The first, in fact, is by Jack!
    http://http://www.getdpi.com/stitch.html
    http://www.outbackphoto.com/workflow/wf_58/essay.html
    Thanks,
    Kirk

    "When did photography become a desk job?" Kirk Gittings 2009

    KIRK GITTINGS
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  5. #5
    Jack Flesher's Avatar
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    Re: Stitching Question - Digital SLR vs 4x5

    Quote Originally Posted by Kirk Gittings View Post
    Here are some related articles. The first, in fact, is by Jack!
    http://http://www.getdpi.com/stitch.html
    http://www.outbackphoto.com/workflow/wf_58/essay.html
    And I wrote that long before CS3 was available!

    ,
    Jack Flesher

    www.getdpi.com

  6. #6

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    Re: Stitching Question - Digital SLR vs 4x5

    Great articles!

    Jack the flat stitch with the RRS rail looks to be really intriguing with a shift lens and quick as well but this approach changes the format of the photograph from the original to a slightly panoramic view. Correct?

    If you wish to retain the original aspect ratio and only increase the resolution how would you do that?

    Bill

  7. #7
    SatinSnow
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    Re: Stitching Question - Digital SLR vs 4x5

    Okay,

    I have worked with a few digital solutions over the years, so I may be completely wrong and I am not trying to start anything, just get some information....

    My questions is if you take ten images with a 10 megapixel camera and stitch them together, how are you increasing the resolution? I have seen claims of say 100 mp? But even if you stitch 10 10mp images together, you have a larger 10 mp image, are you saying if you stitch these together your multiplying 10 x 10 to come up with 100mp? I don't understand, total over all resolution doesn't increase because you lay them end on end?

    And like I said, I am really not trying to start anything, just trying to gather some information...

    Thanks in advance for any help.

    Dave

  8. #8
    Jack Flesher's Avatar
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    Re: Stitching Question - Digital SLR vs 4x5

    Quote Originally Posted by AlaBill View Post
    Great articles!

    Jack the flat stitch with the RRS rail looks to be really intriguing with a shift lens and quick as well but this approach changes the format of the photograph from the original to a slightly panoramic view. Correct?

    If you wish to retain the original aspect ratio and only increase the resolution how would you do that?

    Bill
    Yes, this method changes aspect ratio. If you stitch three horizontal frames you get essentially a 2:5 aspect ratio with a 2:3 sensor DSLR. If you stitch three frames horizontally with the camera placed vertically, you get about 3:4.

    The only way to maintain aspect ratio would be to stitch multiple rows. The good news here is I don't find 2:3 a particularly rewarding aspect ratio to constrain myself to, so simple three-frame flat stitching as described in the above article adds some creative freedom

    Cheers,
    Jack Flesher

    www.getdpi.com

  9. #9

    Re: Stitching Question - Digital SLR vs 4x5

    The more common stitching creates a spherical view of a scene. An extreme example would be a straight road rendered as a curve. Imagine the effect that a mild fisheye lens would give you. Of course, with so much information, you could correct that in post processing. The other advantage over using a single shot and single lens is there is less light falloff at the edges of the image.

    The other way to do this is with a stitching back mounted on a view camera. These are not very common items, and only a few companies make them. Most do not allow a large number of captures. If you have a view camera with a great deal of shift capability, then you could combine that with a stitching back to get many captures. The disadvantage of this approach is you would have even more equipment to drag on location. The main advantage is avoiding a spherical result.

    Kaidan also make some interesting tripod mounts to make spherical panoramas easier. However, with some software packages you could literally just shoot handheld with the motordriven frames overlapping, then put that together in post. I have seen this done a few times, though obviously it involves more effort to get a smooth result. The best spherical solution would be a motorized tripod head that auto-indexes to each position, cutting down the overall time needed for capture.

    I feel this is more a different approach than a substitute for a view camera. If you want to print really large images, stitching is a way to accomplish that. I know a local artist that uses a variation of stitching to create lenticular images, which is another approach; the results are 3D images that changes depending upon what angle you view them.

    Ciao!

    Gordon Moat
    A G Studio

  10. #10
    Jack Flesher's Avatar
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    Re: Stitching Question - Digital SLR vs 4x5

    Quote Originally Posted by Dave Parker View Post
    Okay,

    I have worked with a few digital solutions over the years, so I may be completely wrong and I am not trying to start anything, just get some information....

    My questions is if you take ten images with a 10 megapixel camera and stitch them together, how are you increasing the resolution? I have seen claims of say 100 mp? But even if you stitch 10 10mp images together, you have a larger 10 mp image, are you saying if you stitch these together your multiplying 10 x 10 to come up with 100mp? I don't understand, total over all resolution doesn't increase because you lay them end on end?

    And like I said, I am really not trying to start anything, just trying to gather some information...

    Thanks in advance for any help.

    Dave
    Hi Dave:

    I understand your question I think... The simple answer is you do lay the frames end-to-end (or rows x columns) and thus the resolution for each frame is additive to the total finished image. In a strict sense, ten 10MP laid end-to-end would generate a 100MP final image. However, since we do need some overlap to generate a good seam (read invisible), we lose say 30% to 50% of the overall image data on the stitch. So with ten 10MP frames we might end up with a 50 to 70 MP final image.

    Hope this helps clarify the concept,
    Jack Flesher

    www.getdpi.com

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