3 Kommentare

1. 
   sharpwaveripple · 2018-05-08 15:45

   Stunning image! I love the focal point, and mood of the scene. Have you calibrated the rangefinder of the Graphic, or was this composed via the ground glass? I have just constructed a Burnett Combo of my own, stripping the AE from a Kodak K-24, but I haven't yet calibrated the rangefinder accordingly.

2. 
   aeroektar · 2018-05-09 14:46

   @sharpwaveripple Thanks for the very kind comments. The Burnett Combo is a strange beast - easily the most challenging piece of kit I've ever handled. I actually bought the lens in the 1980s, long before I had any other LF gear, intending eventually to put it on a Speed. As a bonus, someone had built it a m42 adapter, so it would function as a (pretty good for 1950 but no great shakes now) very fast 35mm telephoto. Some observations that might help:
   General: It's hard to use for exactly the reason you'd want to use it - extremely tight DOF. 35mm full frame equivalent is about 50mm f0.7. I love the "painterly" bokeh from the AE - to me it suggests a charcoal sketch. In theory, you could use it to get great action shots, but focusing that accurately on-the-fly would be tricky - you'd get a lot of pretty expensive out-of-focus shots, but the occasional "hit" would be mind-boggling to look at. It's ok at medium apertures, but for those, you're better off with a Tessar or etc. At f16, there is a noticeable bright spot in the middle of the shot - it can be effective if you want it, but obtrusive otherwise. All of this means that I use the AE wide open almost all the time.
   Bleaching: Easy to do with a compact fluorescent "blacklight" right next to the rear element for a few weeks. I gained a full T stop; the lens runs (for me) at T=3.5 or so. A sunny-16 exposure on ISO 100 for T=3.5 is around 1/3000, so I've occasionally wished for a giant ND filter. In other words, for B&W, bleaching may not be that important, and could occasionally be counter-productive.
   Rangefinder: That would have to be a holy king-hell of a precise rangefinder calibration. The gig pictures I posted were all pre-focused on the ground glass before the performance. I was maybe 14 feet from the subject, and the DOF was just the width of your hand. I focused before the performance by suspending a flashlight where I wanted the plane of focus to be. Then I just waited for the shots. I also got three times more misses than hits. With the AE, I always pre-focus on the ground glass.
   Camera: Large format cameras (except a very few specialized ones) were never built for a lens like this, and the AE runs hard up against some limitations. Film flatness and manufacturing tolerances in film holders mean that your plane of focus may not actually be a plane, and may be shifted a little from where you thought you'd put it. This would make a difference it you were taking a critically focused picture of a perfectly flat subject, but why use an AE to do that in the first place?
   - The velodrome shot was taken with tilt to exaggerate the impression that the subject is tiny.

3. 
   sharpwaveripple · 2018-05-09 18:04

   @aeroektar Many thanks for the detailed reply and advice! I've been doing some test shots with it, and I see what you mean regarding the difficulty in getting sharp focus; this has been perhaps exacerbated by the fact that most of the shots so far have been macro! The results have been broadly close enough, though, which suggests to me that the graflok back on my SG is reasonably well adjusted. I've only shot wide open so far, but I'm interested to see this F16 bright spot as well.
   Regarding bleaching, so far I haven't thought about it too much. My example doesn't seem to be too discoloured (it definitely is slightly), and I understand that this can be quite variable. It's from 1945, but I don't know if the thorium content varied much over the production run, or of any other change that may account for such differences. I've shot a couple of test sheets of Velvia though, just to see how dramatically the discolouration affects the colour balance, so it will be interesting to see how they turn out..! From my black and white tests, it does seem to be just under a stop slower than expected, but I haven't formally measured it with a densitometer or anything like that.
   I'll get round to calibrating the rangefinder soon. Hopefully it will be adequate at some distance and a little stopped down, but it's likely that the precision will be insufficient for shooting close at 2.5... Thanks again for your help!