Mamiya 1000s Prism?

[p_nislson]

I have a question about the digfferent types of prisms that can be had for the

mamiya 1000s, and what other modles they would be compatible with. what I am

most interested in is what do the different prisms do, and how they doo it. I

am gettin a PD and from what i have read so far it seems like a pain to use!

[dan_mcclain]

I don't know much about the PD prism, but I use the PDS prism on my 1000s, and it works great. Accurate, easy to change shutter speeds, LEDs are simple to use in the dark. What specific problems do you expect from the PD?

[p_nislson]

I rread that you have to set the shyutter speed on the finder as well as on the body to get the metter to read. I heard that their was a match needle finder, do you know what that one is?

THank you

[custom film holders for fl]

The PD/PDS (vs. the CDS) is a simple finder to use. You don't set the speed on the body each time. You just set the body speed to the red dot and then set the shutter speed via the prism dial or adjust the aperture ring.

<p> Doug<p>

<a href="http://www.betterscanning.com">BetterScanning.com</a>

[p_nislson]

Thank you, doese anyone know what teh other prisms do?

[frank_patrick]

Any info on the AE prism for the M645 would be appreciated as well.

[custom film holders for fl]

Download the .pdf manual for the 1000s from the Mamiya website. It shows three of the different finders and discusses their features/use (must look in two sections to find all of the discussion).

 

<p> Doug<p>

<a href="http://www.betterscanning.com">BetterScanning.com</a>

[jack_varney]

Preston, I can forward a Mamiya publication with brief descriptions of the Prism finders, including the AE Finder, for the Mamiya 645 1000S. There's not much else to know once you put it to your eye. Unfortunately the 1000S manual has no information about the AE Finder and I have never seen a manual for it. I also have a system guide that may prove helpful if you should look for attachments in the future.

 

The Mamiya site has a download for the 1000S here http://www.mamiya.com/cservice.asp?id=3&id2=115&id3=117&id4=361 in case you need one.

 

Send me an email at jv-1gator@varney.clearwire.net and i will return the publications via email.

 

Regards,

Jack Varney

[ondebanks]

Preston,

 

I think the only Mamiya metering prism that could be described as "a pain to use" is the CDS one. The PD prism is wonderful, in contrast.

 

(1) CDS (Cadmium Sulphide) cells are inferior metering technology to the excellent Silicon cells in the PD (photo-diode) prism (btw, I have never seen it called "PDS" - just PD). Silicon photo-diodes are much more sensitive in low light; this baby goes well into negative eV territory...as in 8 seconds at f1.9 - it is able to accurately meter in near-darkness! Just compare the specs for the two prisms in the M645 1000s user manual (PDF file on the Mamiya website). As well as the wider range, Silicon metering is also quicker to respond, more linear, and has no "memory effect" (whereas CDS can take a while for the meter to "recover" from very bright light).

 

(2) The CDS prism needs its own battery - the PD does not: it draws its power directly from the camera's battery.

 

(3) The PD prism is switched on by a touch to its side button; it remains on for ~15 seconds, then automatically switches off. The CDS prism has a lever-switch, and if you forget to switch it off while it is mounted to the camera, it keeps draining the battery.

 

(4) The CDS prism has a match-needle system, which does not show the degree of over- or under-exposure (up to +/- 2 stops) all that clearly. The PD prism has 7 LEDS - green for correct exposure, 3 red ones for up to +3 stops overexposure, 3 red ones for up to -3 stops underexposure. Half-stops and third-stops are indicated by pairs of LEDS lighting by various proportions. You really know exactly where you are with the LEDs; so much so that Mamiya recommend using the red LEDs if you want to do deliberate exposure compensation. Also, the LEDS are of course visible in the dark - the match needle is not.

 

(5) Although both prisms are aperture-coupled to the lens, only the PD prism is shutter-speed coupled to the body. You do NOT have to transfer the shutter speed from the PD prism to the body's dial. You just turn the shutter speed (or aperture) until you get the green LED to light, then take the picture. This is very simple and very fast.

 

The AE prism is of course by its nature somewhat faster to use than even the PD prism - just set the aperture and fire away. But beware! Although the AE prism was a very late addition to the M645 line (late enough that it does not feature in any of the user manuals I've seen), THE AE PRISM DOES NOT USE SILICON METERING: IT USES CDS CELLS! This, for me, is a major disadvantage - and a rather inexplicable design decision by Mamiya. (This information comes from a Focal Press book I have on the Mamiya 645/645J/645 1000s line).

 

Ray

[refinder_refinder]

thank you Ray!

 

your answers are always detailed, complete, and well structured. great post!