Tammy,
I have an M645, but it's the generation before yours (before removable film backs). With the "leaf shutter" lens, it will X-sync at any speed you set the leaf shutter for. That's one of the reasons for making the leaf shuttered lenses.When you put a leaf shutter lens on the camera, you now have *two* shutters operating. One is the focal plane shutter inside the camera body and the other is the leaf shutter inside the lens. How it all works: (a) When you're focusing and composing the photograph, the leaf shutter in the lens is open, even when cocked. If it weren't, you wouldn't be able to see through the lens when you put your eye to the viewfinder. The focal plane shutter in the camera body is closed. If it weren't, otherwise the film would be exposed (completely fogged). (b) The following is the sequence of shutter events with both shutters when you trip the shutter release:
1. Lens leaf shutter closes
2. Body focal plane shutter opens
3. Lens leaf shutter opens (film exposure begins)
4. Lens leaf shutter closes (film exposure ends)
5. Body focal plane shutter closes
6. Lens leaf shutter opens again (c) The M645 Pro camera body should "automagically" set its body focal plane shutter to 1/8th second as soon as you put one of the "new" leaf shuttered lenses on it. Both of the lenses you have are the "new" style which will do this and you shouldn't have to set anything on the camera body to make this happen. [There are "old" style lenses such as the 70mm f/2.8 that won't do this.] If you want to though, you can set the shutter speed on the camera body for 1/8th. [The reason is the body focal plane shutter must open before the lens leaf shutter does for the exposure, and it must stay open until after the lens leaf shutter closes.] (d) The shutter speed for the body's focal plane shutter is set using a knob on the top right side of the camera body. As stated, as soon as you put a "new style" leaf shuttered lens on the body, the setting of this is ignored and it automatically switches to 1/8th second. (e) The shutter speed for the lens leaf shutter is the first ring just behind the front of the lens. You will also see a white index line next to the ring. The numbers on this ring are the shutter speeds and the speed used will be the one set to the index line. (f) When using the leaf shuttered lens, connect the flash sync to the *lens* and *not* the PC connection on the camera body! (g) Other notes: 1. There should also be a colored "F" marked on the lens shutter speed ring.
F = Focal Plane Shutter
If you set the lens shutter speed ring to this position, it disables the lens leaf shutter. The camera will use the body's focal plane shutter for making the exposure instead, and the shutter speed use will be the one set on the body, not the lens (it's set to "F"). 2. With *non* leaf-shutter lenses, or if you set your lenses to "F" the X-sync for electronic flash is 1/60th second. If you ever get any lenses without shutters in them, remember you must set the shutter speed to 1/60th when using a flash (including studio strobes). 3. A good habit just after you mount a lens on the body is rotating the aperture ring from widest aperture to narrowest one and back again to wide open. This *ensures* the forked tab on the lens aperture ring has engaged the metering pin on the camera body properly! This is how the body knows the aperture you have the lens set to. Occasionally, the pin may not engage into the center of the forked tab as you mount the lens, but stay next to it. If this happens, it will throw your metering off. 4. A-M switch on lens is used for depth of field preview. In the "A" position (Auto) the lens aperture stays wide open until you trip the shutter, then it stop down to the aperture you have set on it. After the exposure, the lens opens up again. In the "M" position (Manual stop-down) it stops the lens down to the aperture you have set so you can check the depth of field. You should *leave* your lenses in the "A" position and use it for focusing and setting exposure using the camera's metering. If you switch it into the "M" position to check depth of field, remember to switch it back before metering the exposure (or releasing the shutter if you have an AE prism)! If you don't have it in the "A" position when metering, it will throw exposure off. I've done this a couple times with grossly overexposed results. 5. The meaning of the "cryptic lens letters" for Mamiya Sekor M645 lenses:
C: Multi-coated. Leading edge of focus ring is beveled and chromed.
N: Newer than the "C" lenses with redesigned (new) barrel; also multi-coated. All black, no chrome on edge of focus ring.
L: "C" lens with leaf shutter.
N/L: "N" lens with leaf shutter.
S: Short barrel lens (e.g. 45/2.8 S). Both of your lenses are N/L. -- John
March 23, 2002
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