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Large-ish Format w/ Digital Back and Stitching
Today I finally got around to trying a technique I've been meaning to play around with. I used my digital back with an adapter on my P2, set up and composed a still life on the ground glass, and then made a series of digital exposures of it in pieces using the rise, fall and shift on the rear standard. Once everything was stitched together (which took a while), I ended up with an image with an effective sensor size of about 3.2x3.5 inches, although I ended up cropping in significantly from there to get my final composition (went from ~200MP to ~100MP in cropping). So I'm not exactly using the full capabilities of the 4x5 camera, but I'm getting a lot closer than I've ever been with a digital camera. The biggest limiting factor is just how much movement I can get out of the bellows, since trying to translate the center of the frame out to the edges is a pretty extreme movement, and doubly so if I used any movements to begin with. I might get a sliding adapter at some point to give me some more flexibility on that front. I tried to do everything I could with front standard movements so I'd still have room to move around on the rear standard. And of course I have to avoid using tilt or swing at the top of the rear standard in order for my movements to stay in the same image plane, but if I really need to I can use the coarse tilt, since the rise/fall and shift dials are above it.
Here's the final composition in full size: https://www.flickr.com/photos/tehbie...posted-public/
Just ignore the horrifically posterized preview image Flickr made. The download sizes all seem to be pretty decent though. I'll attach some very down-rezed versions of the original stitched image and the final composition here, too.
Attachment 178257
Attachment 178258
Re: Large-ish Format w/ Digital Back and Stitching
Anddd, of course the forum software also posterized it to hell and back
Edit - Actually, I guess it's my browser. Renders fine everywhere in Firefox.
Re: Large-ish Format w/ Digital Back and Stitching
Which lens did you use? A wide angle bellows would solve the problem with restricted movements.
Kumar
Re: Large-ish Format w/ Digital Back and Stitching
I just have a 150/5.6 for now. I didn't really need any more area for what I was shooting this time, but I do have a bag bellows and I'm thinking about using it next time I try this. On left/right shift I can actually hit the limits of the camera pretty easily, my P2 is only marked for 3cm left shift, and it won't physically go much farther than that.
Re: Large-ish Format w/ Digital Back and Stitching
A WA bellows is perfectly usable with a 150mm lens. You can also combine front and rear movements for even greater coverage, but since the lens position changes, perspective also changes. That will probably result in weird artifacts in a studio setting.
Kumar
Re: Large-ish Format w/ Digital Back and Stitching
Yeah, for stitching I need to keep the lens fixed throughout the different exposures, so I'm just sampling different parts of the same image circle. I do make sure to do whatever compositional movements I can with the front standard though, so the rear one has as much room as possible to move around
Re: Large-ish Format w/ Digital Back and Stitching
Bieber,
I am currently experimenting with this as was well. What back are you using?
-Joshua
Re: Large-ish Format w/ Digital Back and Stitching
I'm using the credo 40. One of these days I really want to get my hands on one of the leaf or phase one 50mp backs with the CMOS sensor though, the double shot process really shows off all the flaws of the CCD sensor. In particular I've been getting some noticeable centerfold artifacts, so I try to make sure I get some overlap in my images and hugin does a pretty good job of blending everything smoothly
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Re: Large-ish Format w/ Digital Back and Stitching
I was shooting with an extra bellows and intermediate standard today just for the magnification, but it turns out that also helps a lot when it comes to having some freedom to move around. Even with the front standard tilted all the way forwards, I was able to get a really wide range of movement on this one. 3cm left, 4cm right, 3cm down and 4cm up, all without really straining the bellows. That got me pretty darn close to 4x5 in the original capture, although I lost some of my edge room to stitching artifacts. Ended up with a usable area of about 4.25x4.1 inches, which I'm not complaining about: https://www.flickr.com/photos/tehbie...posted-public/
Attachment 178439
Large-ish Format w/ Digital Back and Stitching
For reducing fixed pattern noise, dark frame subtraction is a technique astrophotographers have been using since the dawn of digital imaging to remove this..essential when all your information is in the lower 25% of the histogram. You may want to check that out.