M4-P Flash Sync Speed

[TJV]

Hello all.
I've found that my M4-P flash sync speed isn't what it's supposed to be. I'm getting 1/3 exposed frames when I set my camera to a 50th. Several months ago, after having a roll of half exposed frames, I sent my camera away to have the speeds checked on a proper machine and they all checked out in spec. I just assumed I must have mistakenly set the speed too fast or forgot to turn it to the flash symbol. Now I'm convinced either the selector isn't clicking into the 50th position (it "feels" like it does,) or, for some reason, and I'm not sure if it's technically possible, the shutter works fine on all speed EXCEPT a 50th - seeing as the others where apparently dead on when checked. Or perhaps the flash is firing too late?

All other frames are dead on, no sign of a sticking shutter or over/under exposed patches.

Is the sync speed able to be adjusted / tuned independently of the other speeds on an M shutter or is it only able to tweeked over all?

Any other ideas of what could be the problem?

Thanks.
Tim

 

[rlouzan]

Are you using the M socket or hot shoe?

 

[TJV]

Hot shoe with an SF20.

 

[Roger Hicks]

Dear Tim,

(a) is it synching at 1/30?

(b) how much are you losing at 1/60?

You needn't check with real film -- just with the lens off, back open/removed, and a sheet of white card in front of the camera.

Cheers,

R.

 

[rlouzan]

I´m not familiar with the SF20 workings, but it sounds like 1/50sec needs to be adjusted to tighter tolerances.

 

[TJV]

Roger,
good idea. I've loaded a roll of film already so when I finish it I'll check using your method. Most of the shot is unexposed when set at a 50th so I'm assuming a 60th will either be the same or totally blank. Doesn't make sense if the tech reckoned the speeds were all good.

 

[Roger Hicks]

Roger,
good idea. I've loaded a roll of film already so when I finish it I'll check using your method. Most of the shot is unexposed when set at a 50th so I'm assuming a 60th will either be the same or totally blank. Doesn't make sense if the tech reckoned the speeds were all good.

Dear Tim,

Or CAREFULLY wind off until the knob slackens (film off take-up spool); note the frame #; pull out film; test; replace film and wind on to frame # +2.

This is a bugger to think through, especially after half a bottle of Chilean Chardonnay with lunch (musk melon and air-dried Spanish ham). Speeds could (I think) appear to be OK with low shutter tension (slower traverse = more exposure) and premature release of second curtain (narrower slit = less exposure), but I don't know enough about shutter adjustment on Ms to be sure of this. Despite (or perhaps because of) using Leicas since about 1970, I've found it safest to leave repairs to those who do it for a living.

Cheers,

R.

 

[Trius]

premature release of second curtain (narrower slit = less exposure) ... I've found it safest to leave repairs to those who do it for a living.

Cheers,

R.

Where are the moderators when you need them?

 

[Roger Hicks]

also possibly, is your sf-20 not set to the right iso or aperture?

How will that affect the area exposed?

(Sorry, I know nothing about the SF-20).

Cheers,

R.

 

[TJV]

The SF20 is set properly. It works on my Mamiya 7ii and M7.
ISO and aperture settings won't effect this problem as it's to do with the shutter.

 

[TJV]

It seems that the speeds are perfect (my chromes are testament to it!) but, after finishing my last roll, I mounted the flash on the camera, opened up the back of the body and took off the lens. I then fired the flash attached to the hot shoe and it does not sync at any speed. It fires when the second curtain has traveled over halfway across. The 1/3 exposure is clearly seen. Now, the plot thickens. If I attach my Metz flash via a PC Sync cord to the X port on the camera it works perfectly. In case it was my Leica flash, I also tried mounting the Metz via the hot shoe and again, the fault reared its ugly head.
How is it possible to have a faulty hot shoe signal? Does anyone know how to go about fix this problem with a Leica? I'm assuming the triggering system is the same with all mechanical leica cameras other than the M7?

Tim

 

[Roger Hicks]

Dear Tim,

This is one for professional repair (or just using the X-synch port!)

An M4-P has both M and X synch, so clearly the synch is variable.

Plug the electronic flash into the M-synch port and see if you get the same problem. If you do, it's been mis-wired at some point, either deliberately or accidentally.

Or conceivably (though I don't know if this is possible) the X-synch on the shoe comes off yet a third contact.

'Anything that can go wrong will, and anything that can't, is just waiting for an opportunity.'

Cheers,

R.

 

[rlouzan]

I´ll second Roger on this one, the hot shoe is miswired :bang:- it´s set for flasbulb usage.