M and X settings on YashicaMat

[Steve Smith]

We all know that the difference between the X and M settings is the relationship in time i.e. in M the contacts close a little bit before the shutter is open and in X it's more or less instantaneous.

What I thought I knew but I'm not sure about now is how that is achieved.

I was under the impression that the contact was either moved by the lever or a different contact was used when changing between M and X an the timing was just the point at which the two contacts touched.

There is an implication here though that suggests there is a delay mechanism which puts in a delay between pressing the shutter and the shutter actually firing with the flash contacts firing with the shutter button each time.

Although it doesn't really matter to me which way it works, it's one of those trivial facts which I like to know.... so I will wait to be educated!


EDIT: Pass me some of that Popcorn John!


Steve.

 

[BrianShaw]

EDIT: Pass me some of that Popcorn John!

I said my piece... I'll join you if you guys don't mind!

 

[JRJacobs]

I was under the impression that the contact was either moved by the lever or a different contact was used when changing between M and X an the timing was just the point at which the two contacts touched.

Yes, that is exactly the way it works. There is no "delay" in the shutter. The shutter is completely unaffected by the MX setting. All that happens is the contact point for the flash changes - the MX is nothing more than a slider contact. When switched to "M", the contact is shifted in position so that it connects slightly before the shutter opens. There is no delay in the shutter in either setting.

 

[paul ron]

Yeah yeah yeah... And 35 years of marrage has taught me... Yes Dear, you're right.

Pass that popcorn over this way Jack?

 

[Ian Grant]

Yes, that is exactly the way it works. There is no "delay" in the shutter. The shutter is completely unaffected by the MX setting. All that happens is the contact point for the flash changes - the MX is nothing more than a slider contact. When switched to "M", the contact is shifted in position so that it connects slightly before the shutter opens. There is no delay in the shutter in either setting.

And ignorance is bliss. I suggest you do some reading on the subject. Leaf shutters work by adding the delay for M flash synch. How on earth o you think the flash could be triggered before the shutter release is activated otherwise.

Ian

 

[2F/2F]

You can use either one for non-flash pix, as that switch simply sets the amount of delay before the shutter triggers the flash.

M synchs flash bulbs to your shutter. X synchs electronic flash to your shutter.

X trips the flash when the shutter opens completely, because electronic flash has such a short duration that it is effectively constant in output throughout the duration. M trips the flash before the blades are fully open. Flash bulbs take a bit of time to ramp up to their peak output (and ramp back down), so the bulb is fired so that it reaches this peak when the shutter is fully open.

As such, shutter speed does have an effect on exposure when using class M flash bulbs. Shutter speeds faster than the duration of the flash can be used, but they have the ramps chopped progressively as the shutter speed increases, so lose some guide number.

In short, if you ever want to use flash, you should tape, glue, rig the switch on X unless you are using flashbulbs. If you use electronic flash when the switch is set on M, the flash will fire before the shutter fully opens, and your shot will have practically nothing on it.

 

[Ian Grant]

You can use either one for non-flash pix, as that switch simply sets the amount of delay before the shutter triggers the flash.

Wrong way around

If the shutter was triggered before the Flash Bulb (on M) it wouldn't sync at all as the shutter would have already closed on any shutter speed over about 1/50th second. Flash bulbs have a time lag so this is why the typical delay between the shutter release being pressed & the shutter actually activating is around 20 milliseconds (1/50th sec).

On the Ilex/Acme Synchro shutters this mechanical delay can be set for 5, 20 & 23 ms, and it's and additional timing mechanism.

The M/X synch works as you describe on an camera with a focal plane shutter as you have the time of the first curtain opening which is sufficient to cope with the lag time of a flash bulb, and it's the X synch which is delayed & triggers when both curtains are open.

Very early bulb flash synchs on leaf shutters had to be used at speeds of 1/10 - 1/25 of a second to allow for the 20ms (1/50) lag time, that was the reason for introducing the M setting to allow faster shutter speeds to be used.

Ian

 

[BrianShaw]

And ignorance is bliss. I suggest you do some reading on the subject.

Ian... you have some extraordinary persistence in attempting education.

May I remind the kind readers that there are two links in post 14 that might help. It is about 1 page (per link) of reading required. Not much, but a bit of squinting might be needed since enlargement of the page doesn't seem possible. Both texts clearly speak to the point Ian and I have been making.

May I also suggest looking at some shutter guts. Daniel Mitchell's site shows and describes the parts of many shutters. I direct attention to the Copal MXV since that is the shutter in Yashicamat (does anyone remember the question when this thread started?)

http://pheugo.com/cameras/index.php?page=copalmxv

Picture 3 shows the three escapement mechanisms in the shutter. The text helps you locate them. The first escapement is the shutter timing (slow-speed retardment) delay; the second escapement is the self-timer (V) delay; and the third escapement is the M-synch delay, which is in the "11 o'clock position". It is the part that looks like a gear with corwn points. What can't be seen is the lever-like part that ratchets against that wheel, making a svery, very fast ticking sound... a quick buzz.

One will find the same/similar in a Sychro200, Synchro Compur, Rapax... Daniel Mitchell has these on his site if anyone cares to do further reading.

Hasn't anyone listened to their shutter in both positions? The very quick buzz heard when the switch is in the M-synch, but not heard in the x-synch, is that escapement, AKA delay, mechanism. Try it! It is quite apparent on the SynchroCompur; less so on Copals but after a couple of times your ear will be tuned.

As said before, there are a variety of ways that have been concocted to sequence flash bulbs with shutters. Some may have used physical distance of a metal contact to do the same, but one can not deny the "retardment method" given both testimony and evidence presented several times in this thread.

peace, out.

p.s. If anyone wanted to join in on yesterday's popcorn offer, I'm finished with mine and will gladly pass it along.

 

[removed account4]

LOL

this thread is kind of funny.
the op's question was answered by the first reply
and then 4 pages of arguments on how a shutter mechanism works


:munch:

 

[paul ron]

Have any of you actually seen the insides of a shutter?

Inside a leaf shutter there is a cocking ring (that ring in the center attached to the main spring) that controls everything n how the shutter sequence is determined. On this ring are cams n tabs that control when the iris is opened n closed n when in relation to the shutter blades being open n closed. It sets how fast the shutter opens n closes via govonors that slow the ring down, all in exactly the correct timing at an exacting sequence.

On this ring is a tab which hits the shutter blades at a certain point, regardless of what speed it is set for, the shutter will be full open, exposing the film plane with the iris set to the set F stop. At this exact moment another tab hits the flash contacts... X. If you want to delay the flash to compensate for a bulb you simply set the synch lever to M. That lever moves the contacts back at an exact distance... physically moves the contacts, to hit by the tab just before the shutter is full open causing the bulb to fire first then the shutter is fully opened.

Now what's the beef about? The original question simply wanted to know if the shutter should be set to X or M. The simple answer is keep it on X, if you advance the self timer by accident in M, you will lock up the shutter n need repairs.

Now pass the popcorn. sheesh!

 

[BrianShaw]

Have any of you actually seen the insides of a shutter?

Yes, dear... including a Retina Syncro Compur that you declared dead but I fixed by simply turning a spring around into the correct position.

Now that we have that out of the way perhaps we can dispense with the posturing and condescending responses... okay?

So are you saying that all of the cited sources are incorrect? What shutter, specifically, are you talking about? I'm eager to learn more than I already know.

EDIT: I'm not saying you are totally wrong, Paul... some work that way... just not ALL leaf shutters, and specifically not the shutter in the Yashicamat.

 

[BrianShaw]

this thread is kind of funny.
the op's question was answered by the first reply
and then 4 pages of arguments on how a shutter mechanism works

It is, isn't it... but sometimes it is interesting to know what's behind the answer.

Rather than just throwing shells from the peanut gallery maybe you can join in. How do you think M-snch works?

EDIT: I must be going now, boys and girls, to bury an old friend. Have fun, if you must, in my absence.

 

[Steve Smith]

I'm watching this thread now to learn what actually happens. I assumed that for X the contacts closed when the shutter blades were fully open and for M the contacts closed as the shutter blades started to open.

I'm still not certain what actually happens!


Steve.

 

[BrianShaw]

Read some of the links Steve!

 

[Q.G.]

I assumed that for X the contacts closed when the shutter blades were fully open and for M the contacts closed as the shutter blades started to open.

I'm still not certain what actually happens!

The shutter blades take about 1 - 2 ms to open. Much too fast for Medium speed flash bulbs.
Hence, M-synch makes the contact, starts firing the bulb, about 17 ms before the shutter is open, allowing time for the bulbs to ignite and reach full output.
(Actually, the M-synch contact doesn't close sooner, but rather the opening of the shutter is delayed by said amount of time when set to M-synch.)

Electronics flash units ignite and reach full output much faster, so the X-synch contact makes much later, fractions of a ms before the blades are fully open.

P.S.
You can tell that i hadn't read the entire thread before posting. Brian is absolutely right.

 

[Ian Grant]

Have any of you actually seen the insides of a shutter? . . . . .

. . . . . The simple answer is keep it on X, if you advance the self timer by accident in M, you will lock up the shutter n need repairs.

Now pass the popcorn. sheesh!

Yes, I've seen inside shutters.

On the Yashicamat 124 I have you can't physically set M & the Self timer at the same time, I tried yesterday . The reason is the M synch use part of the same escapment as the self timer..

If M is set the self timer won't set, if the self-timer is set on X then you can't switch to the M setting. Force either one and you'd damage the shutter.

Hasn't anyone listened to their shutter in both positions? The very quick buzz heard when the switch is in the M-synch, but not heard in the x-synch, is that escapement, AKA delay, mechanism. Try it! It is quite apparent on the SynchroCompur; less so on Copals but after a couple of times your ear will be tuned.

Yes again however the Yashica shutter is quite quiet so you don't hear it but on older Synchro Compurs etc it's noticeable, & even more so on the Acme's.

Leaf shutters are designed to work best on the X sync, so why add the unnecessary 1/50th delay by using the M sync if it's not being used properly.

Like Brian suggest perhaps people should read the links posted earlier in the thread, and try listening to the difference for themselves. There's plenty of other information in books & on the internet explaining how the M setting works on leaf shutters.

Ian

 

[removed account4]

SNIP

How do you think M-snch works?

i would guess that the switch changes the position of the contact a smidgen
to allow for the several fraction of a second delay that is required for the bulb to be
illuminated at full intensity.
so it goes: trip shutter-contact made-bulb fires - then .. shutter opens/closes.
instead of trip shutter-contact made flash fires shutter opens/closes.

it is probably similar to firing a modern flash using the rear curtain ...
i would guess, that at slow shutter speeds (dragging) there wouldn't really be that much of a difference shooting on M or X ...

 

[Ian Grant]

SNIP


i would guess that the switch changes the position of the contact a smidgen
to allow for the several fraction of a second delay that is required for the bulb to be
illuminated at full intensity.
so it goes: trip shutter-contact made-bulb fires - then .. shutter opens/closes.
instead of trip shutter-contact made flash fires shutter opens/closes.

it is probably similar to firing a modern flash using the rear curtain ...
i would guess, that at slow shutter speeds (dragging) there wouldn't really be that much of a difference shooting on M or X ...

Add your name to the list of those who need to read the links

and eat some pop-corn while reading them

Ian

 

[removed account4]

Add your name to the list of those who need to read the links

and eat some pop-corn while reading them

Ian

LOL

why is it i am reading the links ...
i didn't realize i was in class and i was being quizzed ..

:munch:

 

[BrianShaw]

why is it i am reading the links ...

I say this with kindness in my heart...

The reason is so you don't need to use the following phrases, abstracted from post #42:

"i would guess that"
"a smidgen"
"the several fraction of a second delay"
"it is probably similar to"
"i would guess, that"

The good news is that it will be an open-book quiz

 

[Steve Smith]

The reason is the M synch use part of the same escapment as the self timer..

Is this also the reason why my Rolleicord has M, X and self timer on the same lever?

I had assumed that it reverts to X sync if using flash and self timer. Is this correct?


Steve.

 

[Ian Grant]

Is this also the reason why my Rolleicord has M, X and self timer on the same lever?

I had assumed that it reverts to X sync if using flash and self timer. Is this correct?


Steve.

It will be the reason they are on the same lever, my only Rolleicord didn't have flash synch so I can't tell you, why not try seeing if it returns to X synch after using the self timer, fire the shutter with no film/ the back open and a flashgun hooked up.

Ian

 

[John Koehrer]

SNIP


i would guess that the switch changes the position of the contact a smidgen
to allow for the several fraction of a second delay that is required for the bulb to be
illuminated at full intensity.
so it goes: trip shutter-contact made-bulb fires - then .. shutter opens/closes.
instead of trip shutter-contact made flash fires shutter opens/closes.

The only correction I would make here is in the second sequence
trip shutter/shutter opens fully/closes synch switch,flash fires/shutter closes.

The M function allows the flash bulb to ignite & burn so when the shutter is fully open, the bulb has reached it's peak. IE: synch switch closes FIRST.

 

[removed account4]

The only correction I would make here is in the second sequence
trip shutter/shutter opens fully/closes synch switch,flash fires/shutter closes.

The M function allows the flash bulb to ignite & burn so when the shutter is fully open, the bulb has reached it's peak. IE: synch switch closes FIRST.

thanks john!

 

[paul ron]

Brian Shaw? I don't seem to have any receipts for any Retinas that come into my shop from you in the past 45 years. How did I miss that spring? What did you pay for that camera n where did you buy it? ummmm... the obvious is never very obvious is it Mr Shutter wizzard? Wax on, wax off my boy!

Now as for going up one floor in an elevator... does the building move or the elevator?