super 8 camera shutter speed and ASA

[jisimon]

I have a Chinon 674 Super 8 camera. I want to use it in manual mode so I want to know the shutter speed. The camera has a kind of stair stepped button inside that I suppose that adjusts the ASA with the cartridge hole....

The question is that I dont know if that ajustment is only for automatic mode or is ever.

I want to use kodakchrome asa 40 (25) film.

This adjustment regulates the shutter speed?

What is the shutter speed (really shutter time 1/40, 1/100 etc) with ASA 40 film. Is it the same at 18 fps than at 24 fps (the camera has two speeds)

I suppose that the calculations are the same as in photography with the relation between f, shutter and ASA...

Thank you very much!

[Nigel]

Exposure=(1/speed in fps)x(Angle of Shutter/360)

I would guess that you have an 180degree shutter.

Good Luck

[jisimon]

But then, how affect the ASA of the film?, I mean the hole in the cartridge . Only in the automatic mode? Or also in manual?

Ignacio Simon

[cameraguy]

Originally posted by jisimon:
I have a Chinon 674 Super 8 camera. I want to use it in manual mode so I want to know the shutter speed. The camera has a kind of stair stepped button inside that I suppose that adjusts the ASA with the cartridge hole....

The question is that I dont know if that ajustment is only for automatic mode or is ever.

I want to use kodakchrome asa 40 (25) film.

This adjustment regulates the shutter speed?

What is the shutter speed (really shutter time 1/40, 1/100 etc) with ASA 40 film. Is it the same at 18 fps than at 24 fps (the camera has two speeds)

I suppose that the calculations are the same as in photography with the relation between f, shutter and ASA...

Thank you very much!

<font size="2" face="Verdana, Helvetica, sans-serif">The adjustment you are referring to only sets the film speed (ASA) for the cameras built in light meter and it has no effect on the shutter speed. Changing from 18 fps to 24 fps definitely changes the shutter speed. The shutter is a circular disc with a "pac man" like cut out. The angle of the cut out is the shutter angle. The shutter rotates 18 or 24 times per second. Each time the cut out goes by a frame is exposed. Of course while waiting for the cut out to come by again the motor claw pulls down another bit of film to be exposed.

The shutter speed formula is better in this form

shutter speed = (fps X 360) / (shutter angle)

This way gives you a number like 40 which means 1/40th of a second.

So for example if your camera had a 180 degree shutter angle then the shutter speed at 18 fps would be 1/36 and at 24 fps its 1/48. The million dollar question is what is your cameras shutter angle? Don't know, but 180 is a good starting place to expirement with.