Mamiya Macro 140mm F/4.5

Rob MacKillop

Rob MacKillop

Edinburgh Correspondent
This is the Mamiya-Sekor Macro C 140mm f/4.5 lens, purchased for £100 on ebay. Seems in very good condition, and the optics look very clear.


rings by RobMacKillop, on Flickr

And in situ...magnification lens up in the viewer:


above by RobMacKillop, on Flickr


side by RobMacKillop, on Flickr

This lens is more complicated than the ones I am used to. So, from top down we have:

1. Depth of field of scale
2. Distance Scale - this relates to the diagram on the side of the camera, which obviously changes as you extend or contract the bellows for focussing:


distance scale by RobMacKillop, on Flickr

On the lens ring, distance is notated in meters and feet (yellow). But this ring also has details for Magnification - the white number 3 = 1/3 its size. And also info for Exposure Compensation in Green. I can't quite get my head around why you would want to change the exp comp by, say, +1, when this would change the distance?

3. Shutter Speed
4. Aperture
Then there is a synchroflash terminal (I have the booklet of basic instructions!), the M-X selector (I assume this has something to do with flash?), and (far left) the Mup - mirror up knob, which I will be using.

Then the floating ring, which really comes into play when using extension tubes, and is otherwise set to infinity.

I don't have any film at the moment, but have ordered some HP5 and some Fuji Velvia...

Looking through the lens surprised me - doesn't look like macro to me...I imagine that is what the extension tubes are for. I've read, though, that at close focus you get a lot more clarity and detail. I'm curious as to how 'macro' this will be without the extensions. Many regard this as the finest of the RB67 lenses.
 
This might not mean anything to anybody here if you don't have this lens and camera, but I'll post it anyway as you are a resourceful and knowledgeable lot! I've also posted it to the medium format forum on apug (so sue me :eek: )

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!
 
You don't need to reset the distance after step 7 but you do need to take account of the exposure compensation. You just need to make sure that the aperture you have set gives you the depth of field you want in the image. The lens extension scale on the side of the camera indicates a compensation of 0.5 and so if your meter tells you that you should be using say 1 second at f/11 then you should use an exposure of 1.4 seconds to compensate for the extension. The manual is not especially clear but it also looks to me that you also need to compensate for the presence of the extension tube and from that table, for an extension of up to 27mm you would use +1 as the compensation (i.e. 2 seconds). I would always change time rather than f-stop as the latter will affect depth of field. You may need to take account of reciprocity failure as exposure times start to increase (for example beyond 4s) but that will depend on the film.

http://www.mamiyaleaf.com/assets/files/documentation/Mamiya-Sekor_Macro_C_140mm_f4.5.pdf
 
Thanks, Pete. I have that instruction booklet, and, somewhat predictably, find it hard to follow.

Where do you get the figure of 1.4 seconds from? Not that I'm capable of counting that accurately! I'd be using the T stop, and counting roughly one to two seconds. How important is accuracy here?
 
More tables, figures and formulas! OK, I guess I need to understand this better, so I'll light another candle and sit with it into the wee small hours. Hopefully by the morning I'll know something useful ;)

Another related thing...

The iPhone light meter I'm using allows me to click anywhere on the screen to get a local reading. So if I have a shaded area for the most part but also light streaming through the window in the corner of the frame, I can get two or more readings for the image. Do I add them up, then divide by the number of readings, find some kind of average? Is this similar to the zone system?
 
Aha, so the application is a reflected light meter. Yes, this is a bit zone system like and the readings will tell you the range of brightnesses in the scene. Your actual exposure will render some part of that scene as 18% grey. You need to decide what should be such a mid tone and which bits should be totally without detail either because there is too much light reflecting from them or too little. So, not the average but something that would encompass the range that you encounter.

You really didn't expect a straight answer did you?! ;)
 
It'll all be second nature by 2015 Rob! :D

Lovely looking bit of kit - love all of that quality engineering
 
OK, Pete. Thanks. I kind of get it. Depending on the light, I can have detail in the shadows or in the clouds (say) but not both to the same degree - and that is an aesthetic judgement on my part, realised through a judicious choice of exposure values. BTW, the app does both reflected and incident metering - seems quite useful.
 
From APUG...this guy clearly doesn't know me o_O But I thanked him kindly for it.

Bellows compensation for any camera & lens
I use the same bellows compensation for view cameras, and roll film cameras and don’t bother with the specific scales and so forth that only apply to one make of camera and lens. It requires a cheap handheld calculator with the natural logarithm function on the keyboard.

The distance the lens is displaced from its infinity focus position by the bellows is b. The extension is E = f + b. Then the required extra exposure is

Δf = 2*ln(E/f)/ln(2)

For example, if you’re using the RB67 with 140mm lens and the lens is extended 8 mm. Then E = f + b = 140mm + 8mm = 148mm.

So Δf 2*ln(148mm/140mm)/ln(2) = 0.16 stops greater than the hand held meter reading. This is such a small difference that it’s not worth bothering to correct it. It you did, you’d obtain the correct exposure by opening the aperture about 0.16 of the distance from the stop it was set to towards the next larger stop (next smaller f-number).

On the other hand, suppose you used the 45mm #1 tube and the bellows was extended 8mm.

In that case E = 140mm + 45mm (extension tube) + 8mm (bellows) = 193mm.

Then Δf = 2*ln (193mm/140mm)/ln(2) = 0.93 stops. That’s nearly 1 stop and that’s the amount of correction I’d use.

The advantage of this is that it works the same for ALL cameras and lenses, not just the RB67.
 
Rob MacKillop said:
From APUG...this guy clearly doesn't know me o_O But I thanked him kindly for it.

Bellows compensation for any camera & lens
I use the same bellows compensation for view cameras, and roll film cameras and don’t bother with the specific scales and so forth that only apply to one make of camera and lens. It requires a cheap handheld calculator with the natural logarithm function on the keyboard.

The distance the lens is displaced from its infinity focus position by the bellows is b. The extension is E = f + b. Then the required extra exposure is

Δf = 2*ln(E/f)/ln(2)

For example, if you’re using the RB67 with 140mm lens and the lens is extended 8 mm. Then E = f + b = 140mm + 8mm = 148mm.

So Δf 2*ln(148mm/140mm)/ln(2) = 0.16 stops greater than the hand held meter reading. This is such a small difference that it’s not worth bothering to correct it. It you did, you’d obtain the correct exposure by opening the aperture about 0.16 of the distance from the stop it was set to towards the next larger stop (next smaller f-number).

On the other hand, suppose you used the 45mm #1 tube and the bellows was extended 8mm.

In that case E = 140mm + 45mm (extension tube) + 8mm (bellows) = 193mm.

Then Δf = 2*ln (193mm/140mm)/ln(2) = 0.93 stops. That’s nearly 1 stop and that’s the amount of correction I’d use.

The advantage of this is that it works the same for ALL cameras and lenses, not just the RB67.
Click to expand...


Well it all seems clear to me - Exposure = spending too much time in overly hot or cold conditions without proper attire.
 
Is there an App for all that Rob?

Seems like it would be something App worthy
 
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