bytesmiths

Besides @John Seaman's excellent answer, another thing to consider is what is called "reciprocity failure." That is the tendency for film to either over- or under-expose with extremely short or extremely long exposures. You say "the photo appears as if correctly exposed under the midday sun," so you probably are not experiencing reciprocity failure with that particular film. But be aware that other films may behave differently under extremely long exposures… the OM-2n can go well beyond 120 seconds, which is one of the reasons I got one in 1977! Here is an example of reciprocity failure with a very long exposure. This is probably what you were hoping for! But it was under-exposed without my trying to make it that way.

Fast forward fourteen years, and EX condition still fetches good money, but I'm a huge fan of KEH "UGly" rating. I bought one in March (2022) for $255.64. It arrived in a plastic bag, with no caps nor case, and some rather severe brassing on one 3mm section of the aperture ring. I have plenty of spare caps! I can live with that.

I have both. The Zuiko Digital 50/2 is outstanding optically, but it is "focus by wire." The film Zuiko is not, of course. Today, I reached for the ZD to put on my neo OM-1, and it didn't focus. At all. No AF nor MF. On two different adapters, and two different bodies (E-M1 Mark II being my backup.) DoF preview still works, so it isn't electronic communication with the lens. My guess is it's the focusing motor. So, I picked up the trusty OM 50/2 Macro and took a picture of it to send to Olympus to see if I can get it repaired. My guess is not… I think they've formally "sunset" all 4/3rds lenses. So, my alternative is to scour the Earth for someone who can repair it, get one of similar age and dubious quality on evilBay, or use my OM 50/2 Macro, which any camera technician with a decent tool set can overhaul and refurbish, for longer than I'm going to be around. So there's good reason to invest in a "forever" lens, versus one that you might not be able to get electronic parts for tomorrow.

Sorry for reviving a zombie thread, but I wanted to note that the Olympus OM Zuiko 135mm ƒ/4.5 Macro was designed for a prototype tilt-shift bellows that was never marketed, and has a huge image circle. I use it often on the Nikon PB-4, upon which it does focus to infinity. To be fair, I'm not sure what Dan considers a "short" lens; probably not 135mm. Just in case anyone winds up here from a search engine, like I did…

Sorry to revive a zombie thread, but I am in the process of making some of these filter holders. Please PM me if you'd like one or more. To dispel some of the misinformation here: standard 46mm filters will not work! The olympus filter that comes in the holder is slightly smaller, and has a different thread pitch, and is also way thinner than any filter available on the market. the holder is very different from the Nikon 300/2.8 holder. I bought one in the hope that it would work, but it is much thicker and has a different latch. as @skip_williams mentions, none of these lenses were ever produced in anything but the Olympus OM mount, although they work brilliantly with modern mirrorless cameras and an adapter. The holders I am making will have a standard 46mm x 0.75 thread, but because of the narrow slot, it will still not take the standard filters, none of which are 2.5mm thick or less. Rather, you will be able to disassemble your favourite 46mm filter, pop the glass element out, put it in my filter holder, then screw in the retaining ring. I am also working on a design for a rotating element filter holder that will at least work with a circular polarizer, graduated filter, or any other rotating filter that does not depend on two elements that rotate independently. Here's a shot from the 350/2.8 with the OM 1.4X-A teleconverter, for an effective 500/4, on the Olympus OM-D E-M1 Mark II. This lens also works wonderfully with the Metabones Speedbooster Ultra, yielding an effective 250/2.

Do what It takes. Second mortgage. Sell your children into slavery. Pimp your wife. Get the Zuiko! You won't be disappointed. Every time I buy a third-party lens, I wished I'd bought the equivalent Zuiko, instead. So now, the only non-Zuikos I have are things Olympus doesn't make. (Yea, I know: old thread, discovered while looking for Zuiko ultra-wides.)

Old stuff, replying to which, I am certain to be beat-up by self-appointed "old thread police" who don't have a life other than telling people who want to learn something that they are "foolish." Here is the pinout for Speedotron Blacklinke plugs (specifically, a 102): A: (thin white wire) trigger pulse B: (heavy black wire) flash tube anode (WARNING: 900+ VOLTS!) C: (thin brown wire) fan hot wire (WARNING: 120 VAC!) D: (thin yellow wire) model lamp (WARNING: 120 VAC!) E: (thin blue wire) fan/model common (WARNING: 120 VAC!) F: (heavy red wire) flash tube cathode (WARNING: 900+ VOLTS!) G: not connected H: not connected I: (heavy green wire) chassis ground, trigger return While I'm at it, here is the Brown Line pinout (specifically, a M11): A: (heavy red wire) flash tube cathode (WARNING: 600+ VOLTS!) B: (thin white wire) modeling lamp (WARNING: 120 VAC!) C: (thin brown wire) modeling lamp (WARNING: 102 VAC!) D: (heavy black wire) flash tube anode (WARNING: 600+ VOLTS!) E: (thin green wire) trigger pulse To repeat what others have mentioned: THE ENERGY AVAILABLE AT THESE PINS ON THE PACK CAN KILL YOU! EVEN WITH THE PACK TURNED OFF AND UNPLUGGED! If a strobe head is unplugged, it should not be dangerous at all, unless you whack one of the old-posting-police up the side of the head with it. There is a small (0.33 µF) cap in there that can give you a poke, but it cannot hold life-theatening energy. The original poster wanted to re-wire heads, which is not particularly dangerous, despite protestations from the fear-mongers. Here's some tips for re-wiring heads: NEVER, EVER work on a head that is plugged into a pack! Keep your solder joints smooth and round. "Pointy bits" can create discharge paths. No smoking within 24 hours; no alcohol within 50 feet. :-) Should be obvious, but don't work in explosive vapours. Tell your wife she has to apply toenail polish somewhere else. When you plug in your re-wired head for the first time, make sure the pack has been unplugged for at least 24 hours. Wear safety goggles, and turn your head away. Repeat these precautions when powering the pack on. You're not likely to have an explosion, but should there be arcing, you don't want to be looking at it. Needless to say, mis-wiring can damage or destroy your head, pack, or both. If you aren't comfortable and experienced with electricity, pick an easier "first project." :-) Happy hacking!

I signed up here, just to support Lon in this ancient posting. I find the comments here derogatory and demeaning. If you know something Lon doesn't know, why not just explain it, instead of calling it a "foolish endeavor" or "in over your head." (The latter from someone who had "never seen a Blackline head.") Notice that Lon didn't participate much longer. Too bad. Y'all might have learned something from him. Perhaps he was an electrical engineer or a ham radio operator. (Hams routinely work with much higher voltages and currents than EEs do.) I'm in the process of re-wiring a different manufacturer's ring light to a Blackline connector, and was seeking helpful information. I was intending to share what I learned here — along with certain DANGER! THIS CAN KILL YOU! caveats. But I don't think I will do that, now. (Please note: I am both an electrical engineer and a ham radio operator. I've built kilowatt linear amplifiers that had 1,350 volts on the plate at well over an amp. But you'd never have known that if I had just asked for a pinout, and then been shouted down.)