Digital Large Format

[Paul Kay]

I've been building a step and repeat back for a 10" x 8" Gandolfi. First attempts to use are both encouraging and surprising. This image of a 5" x 4" Welsh made Nesbitt camera (~1990) and 1970s Welsh made PPE lenses, is made up from a number of full frame 35mm sections and was taken on an 1860ish simple cemented two element lens.

 

[David M]

That looks very impressive.
May I ask why you are doing this? I'm very curious.

 

[Paul Kay]

Because its the easiest/cheapest way to find out the performance of very old large format lenses. I'm researching into old lenses and the cost of using 10" x 8" and larger film is prohibitive for what I need to do, especially as the washer stops are in 1/8" increments so working out exposure would be hard work. Whilst 'step and repeat' has many limitations, its actually very useful for testing and I can even assess image field curvature with a bit of messing around. Here's another 6 image stitch:

 

[David M]

That's very interesting. Thank you.
I know that "can't see the join" is a cliché, but it seems appropriate here. Will you be posting pictures of your mechanism?

 

[Paul Kay]

Once my 'mechanism' is as I intend it to be I will post pix. In the meantime here's another 'stitch' (its effectively a simple stitch so no join should be visible) of 12 Sony A7II files or the equivalent of about 108MPixels on a 8 1/4" lens for 1859/60. I need to make some more washer stops as it only had one (of 4 originally) when I bought it. The image on the ground glass was about 3" wide and the camera is about 5" long so magnification was ~0.6x.

 

[David M]

This kind of thing is all terra incognita to me. As a compliment, may I say the dust is excellent?

 

[Paul Kay]

I use the 35mm Summilux a lot of the time (it was designed almost exactly 100 years after the lens I took its photograph with) - the dust is gathered whilst out and about not from sitting around doing nothing! At the moment I'm limited to a 6" x 6" format image but this will change .....