Body 501 CM - For what is that knob?

[flashmxfreak]

I can not realize for what is that knob marked with the rectangle.
Thank you.

 

[jarim]

By pressing that button the mirror goes up and "secondary shutter curtains" open. You'll then press the normal shutter button to fire the leaf shutter.
Doing this will reduce vibration if you are using a tripod.

 

[macmx]

Yes.

Try to take off you back and lens and press this button. Then you will see what it does.

 

[blowupster]

It this button does nothing, that means that the body was open and not correctly monted !

 

[chivers67]

By pressing that button the mirror goes up and "secondary shutter curtains" open. You'll then press the normal shutter button to fire the leaf shutter.
Doing this will reduce vibration if you are using a tripod.

Yep it's mainly for long exposures or when you don't want much noise like in a Church - by pressing during a hymn etc....

 

[jotloob]

To be precise , this button is called: the (mirror) prerelease button .

Have a look here :
http://hasselbladusa.com/media/1e3a6d2c-be58-4744-aaa5-e3eadbc1881f-503CW.pdf

 

[simonpg]

Yes, "pre-release" for the mirror to reduce vibration during exposures caused by the big mirror and secondary "blinds/curtains" getting out of the way before a picture is made.

Keep in mind that this feature is there for good reason in the pursuit of the sharpest possible images from the great Zeiss lenses!! Of course its only practical when the camera is not hand held.

I ALWAYS use it when shooting with the camera tripod mounted. Even when the exposures are not so slow - why not? Its there so I use it.

By the way, some people incorrectly refer to this feature as "mirror lock-up" in the MISTAKEN terminology / interpretation that the mirror is locked up. It is not. After the exposure, the mirror returns to its viewing position (and secondary blinds) as you wind on the film / re-cock the shutter for the next exposure. Therefore you must use the pre-release button again for every next image it is required.

I believe the 555 type motorised leaf-shutter cameras are the only Hasselblad V series cameras with TRUE mirror lock-up feature - where the mirror (and curtains) remains in the pre-release position for subsequent exposures unless / until you purposely "unlock" the mirror when you have no need for it in that position - logical feature in the motorised models when you think about it.

 

[polypal]

Mirror lock up.

The only cameras that have mirror lock up are the ones from the 2000 series.
Inside the wind knob there is a coin operated selector that enables this.

It is possible to set motordrive cameras to keep the mirror in the top position but during subsequent release teh mirror and auxilary shutter are activated.