Doug Chadwick

Doug Chadwick

Joined on Dec 26, 2012

Comments

Total: 6, showing: 1 – 6
On The DSLR Field Camera article (180 comments in total)
In reply to:

Timmbits: Tell me if I understand correctly:
the reason the lens needs to tilt in relation to the sensor plane, is to bring farther objects into focus that would otherwise be out of focus, for a given aperture.
As I understand it, this would be the one and only benefit over "standard" panorama stitching (with standard (non-tilting) lens).
And if I understood correctly, do you need to increase or decrease the distance between lens and sensor for farther objects?

Most large format photographers use a bit of front tilt in most photographs. No, we don't put the plane of focus on the ground, but from the ground in the foreground to the subject in the top of the frame usually works best. D-o-f gets used from there. In a stitched image this might cause a bit of problem unless your tilt lens rotates on the nodal point of the lens, and many don't. I use rotating film cameras for that to eliminate the problem.

Direct link | Posted on Jan 3, 2013 at 19:40 UTC
On The DSLR Field Camera article (180 comments in total)
In reply to:

TimGarner: I have been stitching images since my first digital camera. I agree that the technique of horizontal shifting of the lens is problematic, and probably useful only for maintaining a rectilinear image. Using the extreme edges of the lens sacrifices image quality. One advantage of stitching is to be able to use multiple areas of highest lens sharpness to improve overall image quality. Many images are better with a cylindrical layout anyway. Landscapes typically won't matter so much.
I used a similar technique with my Canon 20D (8 Mpix) to make a 20 Mpix image of the Boulder Flatirons using three vertical format images with the 70-200 F4 L lens at 70mm. Stitched in Photoshop, you cannot find the seams, and the images is quite a bit sharper than a single image.
The T/S lens has one advantage not mentioned. The vertical shift is useful for keeping the camera image plane vertical while shifting the view somewhat up or down. This helps keep the image from shrinking at the edges when stitched.

The problem I have found is that most stitching software does very poorly with images made with shift lenses. I have found much better results with a regular lens and the camera pointed up or down.

Direct link | Posted on Jan 2, 2013 at 18:28 UTC
On The DSLR Field Camera article (180 comments in total)
In reply to:

Micky Nixgeld: @solarsky
Or medium-format like the Hasselblad. Digital "Large-Format". 50mp.
Canonusers are somewhat behind the time.

The Obama Gigapan was quite interesting. But if you saw it when it was first posted you would have seen hundreds of stitching errors. After a month or so they had been repaired, but to me it looks like at least 100 hours of work, and maybe a lot more. It makes film seem appealing though it would have taken a #16 Cirkut camera to match the resolution and that is one cumbersome beast.
For those who don't know about Cirkut cameras, a #16 shoots 16" film and in this case the neg might have been about 6 to 8 feet long.
I use a #10 Cirkut and get a 10" x 50"-60" neg and very sharp prints, contact prints of course, or scan and print digitally.

Direct link | Posted on Dec 29, 2012 at 01:48 UTC
On The DSLR Field Camera article (180 comments in total)
In reply to:

Roland Karlsson: For far away subjects you can use an ordinary lens and a modern stitching software without any problems. There is no need for a shift lens for this, nor is it any advantage.

If things are near, you need to rotate around the input aperture of the lens. That true for both an ordinary lens and a shift lens. So .. for the ordinary lens you need a tripod and panoramic head. But ... for the shift lens you need a tripod and a tripod thread on the lens. If you move the lens you only can use it for far away subjects.

If you have a tripod thread on the lens, then the only advantage is that you get a consistent focus plane. If you torn the entire camera, then you also turn the focus plane, which might be problematic.

So - except for the focus plane stuff - I see no advantage of getting any shift lens.

@ acidic, Roland is quite right. Of the photos with the story, the lead photo and the one under "metering" would have shown very distinct areas of "stitching errors" until worked over. That is if the lens were shifted and not the camera body. And finding the nodal point isn't all that hard, and it just needs to be done once and remembered or marked.
Plus you would end up with better edge sharpness since you would be using more of the center of the lens's image circle.
Admittedly I find stitching easy because I do a lot of it, and I have been shooting with rotating panoramic cameras for over 30 years.

Direct link | Posted on Dec 28, 2012 at 13:40 UTC
On The DSLR Field Camera article (180 comments in total)
In reply to:

Roland Karlsson: For far away subjects you can use an ordinary lens and a modern stitching software without any problems. There is no need for a shift lens for this, nor is it any advantage.

If things are near, you need to rotate around the input aperture of the lens. That true for both an ordinary lens and a shift lens. So .. for the ordinary lens you need a tripod and panoramic head. But ... for the shift lens you need a tripod and a tripod thread on the lens. If you move the lens you only can use it for far away subjects.

If you have a tripod thread on the lens, then the only advantage is that you get a consistent focus plane. If you torn the entire camera, then you also turn the focus plane, which might be problematic.

So - except for the focus plane stuff - I see no advantage of getting any shift lens.

I guess we should point out what the problem is with the use of a shift lens in this application. Because the lens nodal point moves between exposures the point of view changes and images don't line up in stitching because the foreground moves relative to the background. One can fix this in Photoshop but why bother? There is no advantage over turning the camera, only disadvantages.

Direct link | Posted on Dec 27, 2012 at 00:25 UTC
On The DSLR Field Camera article (180 comments in total)
In reply to:

Roland Karlsson: For far away subjects you can use an ordinary lens and a modern stitching software without any problems. There is no need for a shift lens for this, nor is it any advantage.

If things are near, you need to rotate around the input aperture of the lens. That true for both an ordinary lens and a shift lens. So .. for the ordinary lens you need a tripod and panoramic head. But ... for the shift lens you need a tripod and a tripod thread on the lens. If you move the lens you only can use it for far away subjects.

If you have a tripod thread on the lens, then the only advantage is that you get a consistent focus plane. If you torn the entire camera, then you also turn the focus plane, which might be problematic.

So - except for the focus plane stuff - I see no advantage of getting any shift lens.

Roland, Absolutely correct. I did all the tests and could see no advantages of a shift lens for stitching. A nodal bracket is much better and that point a shift lens is a hinderance, not a help.

Direct link | Posted on Dec 26, 2012 at 23:32 UTC
Total: 6, showing: 1 – 6