peteraitch

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Recently posted elsewhere on PN, but I think it qualifies...<div></div>

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<p>Currently "running up" my trusty old A-1. My first-ever very own camera body, it hasn't seen much use in the last decade, but its 30th anniversary is approaching and I'm now moving back into scanned B&W film (on an occasional basis). Still working through my expired unexposed film stock (the expired colour stock performed surprisingly strongly on the well-known auction site recently).</p> <p>So, taken last weekend, a low shot of some fairly up-market accommodation overlooking Liverpool's restored Albert Dock. Canon A-1, FD 50mm f1.8, 25A P-series filter, Kodak T-400CN (commercially C-41 developed), Minolta Elite II Scanner.</p> <div></div>

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<p>I use the Tamron 90mm macro which I've had over 10 years now. This lens has been around, in various iterations, for many years and is generally very highly regarded. My version, the 172E, or the following version (272E) would not be ideal for your camera as they will not autofocus on the D3100. The next model up, the 272EN II, would be ideal and according to Google is still readily available in the US from B&H for $499 or the low 400s from Amazon. Since there is now an even newer VR version on sale, the 272EN II is also available secondhand - but use a trusted source, with a clear returns policy.</p> <p>Although you do not <em>need</em> AF for macro, it <em>is</em> useful on this lens for conventional use. I use mine as much, or more, as a standard 90mm (on FX, admittedly) as I do for macro stuff. Incidentally, ultra-macro of the kind you have mentioned is really quite tricky and has quite a learning curve. I've never really done it: the depth-of-field and illumination issues put me off! Good luck - it sounds quite exciting, doesn't it?</p>

<p>I think it's a case of suck it and see, just remember that you are looking at emission lines and so need good contrast with the bright background, as viewed directly on negative film. How bright is your background? If it's bright then you probably need a longer exposure, if not I would reduce the time a bit.</p> <p>Looking on the web at the data sheets for both products, the extra sensitivity (aka speed) of Tri-X is obvious, but I also notice that it is much more evenly panchromatic than Plus-X and the spectral sensitivity graph shows it clearly and evenly extending well into the UV, right down to at least 300nm, but not really going into the IR at all (shame, but Plus-X is the same in this respect). Won't you have to calibrate a new emulsion at some point to help you with your quantitative data, or are you only doing qualitative analyses?</p> <p>Hope this helps - I've only ever used solid-state detectors for spectroscopy, a long time ago now. Did use film with X-ray diffraction, but that's a whole different ball-game.</p>

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