a very large project

[Bruce Watson]

Good on ya, Amanda. It does sound like a great challenge, and great fun. Enjoy it.

When you get this done, how about start a new thread and tell us about it? And do tell us how to see it - even if only from a web site.

[Evan Ayers]

Dear Amanda,

I have made a few "stiched" images from multiple large format negs. The advice from others on this thread is absolutely correct. If I may add a few tips that have not yet been mentioned.

>> i'd rather stay away from digital--but i'll definately end up dividing the wall into multiple images and "stitching" them together. how large can you go, yet retain sharpness, with a large format?

Very Large :-) I use TMax 100 8x10, and Bergger "18" 16x20 and get wonderful detail. The trick, of course, is just how sharp is "sharp enough" for _your needs_ :-) Here's the way I do it.

I go on location and test shoot the scene using TMax100 in 35mm. I mark the location from which I want the final shots to be taken from, let's call this the "eyepoint".

Carefuly looking at the scene I find the smallest detail that I want to come out sharp in the final image. I move my 35mm camera to a position 1/10 the distance to that detail from the "eyepoint" and take a test shot of the detail. Then I move the 35mm again to a position 1/20 the distance and take another test shot.

I then develop, scan and blow up those test shots. The initial pics from "eyepoint" give me a rough idea of the perspective, and of the total number of large format negs I'm going to need. The 1/10 shots show me the approximate sharpness I will get if I take the final shots with an 8x10. The 1/20 shots for a 20x24.

If the 1/20 shots are not sharp enough, then I'm out of luck because that's the biggest camera I have :-) It's time to move the "eyepoint" closer :-)

The next set of decisions are based on the perspective and "stiching" needs. When taking multiple images the tendency is to park the camera on a tripod and rotate the tripod head from side to side, taking images at every "X" degrees. The problem with this approach is that the detail at the outermost edges of the frames is very small, so when you stich the images this detail requires the most enlargement and will be the least sharp. You either get a "fisheye" effect at the edges of the "stiched" frame, or you get a slight "vigneting" of sharpness.

You can compensate for this perspective induced problem by using the movements of a view camera. i.e. "enlarging" the outermost edges of each image by fiddling with the swing of the back board. The catch to this is that getting the image edges of two adjacent negatives to align perfectly when using this technique is mighty close to imposible. The resolution of the ground glass is simply not up to the accuracy that is needed. I've done the math, and the accuracy of the various markings on the knobs of a view camera are not equal to the task either. A high-end Sinar comes pretty close.

That's for _three_ images. One in the center and two to either side. If you need more than three there's the additional challenge that you have to match _two_ edges on two of the images.

There's a much easier solution :-) Move the camera.

I mark off a line on the ground parallel to the scene I am photographing. As long a line as the geography of the location allows. I then move the camera for each image, keeping the film plane as close to parallel to the image plane as possible. This greatly reduces the need for micron precision alignment of the camera movements. Naturally, if you can move the camera the complete length of the image plane you would need no movements at all :-)

Nevetheless, even with the above "cheating" and the use of fine Sinar's and plenty of careful calculations I have yet to create a _perfect_ set of negatives where the "stich edges" were sufficiently aligned to make a good "giant" image. The problem is that as you take an image and "expand" one edge to align with another image, the opposite edge "shrinks". In order to make _perfect_ negs that would all stich together you need to either use a zoom lens (with a vernier zoom dial :-), or move the camera along the camera axis to compensate for the "shrinking" distal edge, or modify a camera back to swing on the outer edges of the negative instead of in the middle.

I don't have such a lens (maybe I'll make one :-), I haven't yet had a commision where this solution was workable given the geometry of the location, and my "edge swing" camera is still in pieces in my garage :-)

What I do is cheat again. I take my multiple negs with as much compensation as I can with back movements. Then I scan said negs and stich them digitally :-) The digital file is then printed on a large carriage printer or LightJet. I get the wonderful detail of the large format negs, with the ease of digital.

As an example of the above, see my website image http://www.platinumlegacy.com/AboutPrime.html?tp=1&id=1

I have added an additional image in a hidden directory on the website which you can see here

http://www.platinumlegacy.com/Images/Stiching/LampCloseup.tif

This image is an un-retouched close-up of the building taken from the original tango scan of a TMax100 8x10 at 300dpi. In the full building picture, note the lampost on the front porch. The lamp atop the lampost is reflected in the glass of the front door. In the close up image you can see the reflection of the lamp, as well as the fluting of the column.

I'm not very good at explaining things in text over the web. I'm a visual kind of guy :-) So if I completely muddled it all up feel to write me at

Evan@PlatinumLegacy.com

Evan :-)

[Øyvind Dahle]

If you are in a hurry, do it digitally whit a Canon 1Ds and stich, else, do it the way explained above

Øyvind

[tor kviljo]

Biggest thing I have been into is a 10 by 15 feet color print which were produced as a curved landscape-picture for a montage of mounted reindeer. The customer (taxidermist) being tired of undetailed photos - (probably of 35mm or MF originals used for backdrops) which he had been forced to use before, were hapy when I showed him 8"x10" fuji trannis (taking with a Sinar P/P2 & Nikkor W 360mm). One of the pictures were selected, drum scannet to a file of about 1 GB and output in strips by a printer doing five feet wide at max. (don't know the brand of the printer). Customer were very satisfied, and we have later worked out several other background - photos, also using 4"x5" trannies taken with camera rotated around nodal point, and put together as panorama pictures in mac (didn't find a pano-tool working with mac, but manual fitting were very successful once pictures were produced correctly). Biggest problem is maybe finding a mac operator dealing with the 2 GB files..