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[pri]

i have a crown graphic.in the schneider 135 lens there are 2 word, X & M.what those?you can put on the x position or on the M position.thanks

[wkjagt]

If I remember correctly:

X is for electronic flash
M is for flashbulb

[ImageMaker]

Correct. The M stands for "Magnesium" wire inside a flashbulb (burns in pressurized pure oxygen to make the brief, intense light), while X stands for "Xenon", the gas inside the tube of an electronic flash, which emits light when an arc passes through it.

_________________
Is thirty-five years too long to wait for your first Speed?

[clnfrd]

I had never realized the X stands for xenon (makes sense) and the M stands for Magnesium. I always assumed the M stands for Medium speed (20 ms or so delay) and the F on some synched shutters stands for Fast speed (usually gas-filled lamps) with about 5 ms delay. Thanks. Fred.

[Dan Fromm]

[clnfrd]

When I was a kid and only had a cheap Ansco Flash Clipper camera, shutter speed about 1/30th or so, I used the gas-filled "F" lamps, because of their short flash duration,estimated at the time at about 1/200th-sec. (5 ms), to shoot action at local sporting events. This stopped the action pretty well. The low light output, however, required souping up the film with longer development times to get a usable neg. Fred.

[Doug Kerr]

Greetings,

[Doug Kerr]

Greetings,

[/quote]According to the bible, 10th edition:

Class F: Very rapid-burning. Time to peak, 5 milliseconds, flash duration 5 milliseconds.

Class M: Medium-burning; time to peak, 20 milliseconds, duration 12 to 20 milliseconds.

Class S: Slow burning: Time to peak, 30 milliseconds, flash duration about 30 milliseconds.

Class FP: Very slow-burning for use with focal-plane shutters. Time to peak, 20 milliseconds, duration 25 to 60 milliseconds.

Thus spake the prophets Morgan and Lester. Who here dares disagree with them? Come on Les, here's a good opportunity for a cheap shot.

Elsewhere I've seen reports that "X" stands for instantaneous, 0 milliseconds delay.[/quote]

Hark, ye faithful, for Holy Scripture is in all the above chapters and verses wholly inerrant.

Thus saith the telephone engineer.

Note that "F" is in fact mnemonic for "fast" (burning). These lamps were mainly invented for use in cheap cameras where having any sync timing was too expensive. Thus they were often fired without any delay at all (although 5 ms is optimim).

The Graphex/Rapax full sync shutters usually have a single sync setting for F and X, and it is of course zero delay (contact perhaps actually closing when the shutter is fully open).

_________________
Best regards,

Doug

[ImageMaker]

Actually, there was also an MF class of bulbs, which included M2 (but not M3), AG-1, and AG-3 (the Phillips baseless PF-1 was also in this class). These had a nominal 15 ms time to peak instead of the 20 ms of M type, and then a burn time of 15-25 ms; they could be used with X synch at 1/60 without much loss of guide number (about one stop off from a full burn shutter duration), which made them useful with 35 mm focal plane shutters that, by the late 1950s, synched at 1/30 and 1/60 but had only X and FP synch.

_________________
Is thirty-five years too long to wait for your first Speed?

[essessem]

"Those shutters also offer "F" synchonization, for Class F ("fast") lamps. Those require only a 5 ms delay for optimium operation, and zero delay is workable. (Often the "F" sync setting is the same as the "X".)"

Just posted to Flash help, but I see I may be able to piggyback onto this posting. Wondering if the F sync on my Flash Supermatic (you have to cock a separate lever to fire the flash) work with electronic flash at a lower shutter speed? Only other option on this shutter is M sync, which I know is only used for bulbs.

[Dan Fromm]

[essessem]

Alas, Dan, this isn't the case (at least in my case). I tried firing the flash without cocking the sync lever on M, F and in between the two, to no avail. It does make the little ready light blink when I trip the shutter, though.

[Dan Fromm]