Mamiya 140mm Macro - advice needed (RB67)

[Rob MacKillop]

I got the Mamiya 140mm Macro C a few days ago, and am in the process of trying to figure it all out. I have the official Instructions booklet. And I also attached the No.1 extension tube when it arrived. So, I'm all set to go. I have the Pro SD.

I'm indoors, trying a close up of a flower.

1. I align the red dot on the green No.1 scale with the red triangle on the lens barrel

2. I focus

3. I read the bellows extension amount on the Distance Scale on the side of the camera. It reads 8mm. This is the total distance from the top right-hand corner to the visible top left-hand corner of the diagram.

4. I change the reading on the green No.1 scale to match

5. I set the aperture I want to use

6. I use a light meter on my iPhone (called Light Meter, of course!) to calculate the shutter speed. I set the shutter speed ring accordingly.

7. Double check focus

8. Fire shutter

Job done? What about the ring closest to the Depth of Field Scale, which has indications also for Magnification and Exposure Compensation?

9. I read the diagram on the side again, this time looking at the very bottom, and it tells me I've just crept over into +0.5.

10. I set the STEP value to match...but it covers every distance from around 0.85 meters to 2 meters. Do I set the distance more accurately? If so, where exactly am I measuring from?

11. Do I return to the light meter and increase the aperture by 0.5? From, say, 4 to 4.5? What if I had previously chosen 11?


I'm almost there. Familiarity will speed things up. With the mainly natural light and dull house lamps, I barely manage to get a shutter speed faster than one second. Thankfully I have a very strong tripod. I don't want to use flash.

Any help and or advice, gratefully received!

 

[Xmas]

There was an instruction booklet for the camera and another for the lens.
One of the rings on the lens is for the floating element.
It is set for tube and for extension, the scales are cryptic.

 

[Rob MacKillop]

Yes, I have the instructions for both, but they are not the most helpful I've ever seen.

 

[chrisaisenbrey]

It is easier if you know the function of the different rings:

The ring with the green No. 1 scale (the first ring on the rear end of the lens) is the floating element ring. It optimizes the lens for a certain magnification.

The last ring at the front of the camera has no real function it is simply a “calculator” for the depth of field and the magnification.

If you use an extension tube you can’t use the scale on the side of the camera for the calculation of the exposure correction. So you can use the values on the depth-of-field-calculator-ring if you set it to the right distance. .5 would mean to open the aperture by half a step. So if you measure 11 you have to put it between 8 and 11.

 

[Rob MacKillop]

Thanks, Chris. I get it now. Of course, I would have the choice of either changing the aperture, as you mention, or the shutter speed. Is that correct? If so...if my light meter gave a shutter speed of 1 second, what would an exposure compensation value of +0.5 be for the shutter speed?

 

[chrisaisenbrey]

Well can change the shutter speed only by full steps. (It is a fully mechanical shutter in the RB) So with a negative film you could double the exposure time (one step) and simply overexpose by half a step.
Or you double the exposure time and close the aperture by half a step.

However the mechanic shutter can’t control exposure time of more than 1s. So you could only use the “T” setting and push the release button for two seconds (or 1.5 s for half a step). But this is of cause not very precise.

Chris

 

[Rob MacKillop]

Thanks, Chris. Much appreciated.