Auto Chinon m42 lens - auto versus manual question

[apragmaticoptimist]

As posted previously, I have inherited a Fujica ST605 with an Auto Chinon 28 mm

and Auto Chinon 200mm. These lenses have a switch to go from M to A (manual to

auto I must assume). Forgive my ignorance of traditional cameras, but I'm

guessing this is auto exposure... is that correct? Are there any user manuals

for these lenses or any online instructions? I'm not sure how to take

advantage of the "auto" feature of these lenses with the Fujica body.

 

When I search photo.net I get tons of forum posts but I haven't found

instructions for this topic yet. I may not be using the best search terms to

find them if they are out there.

 

Thanks in advance for your help.

[tjod]

For a suggested $3 donation, there is a downloadable manual here:

http://www.butkus.org/chinon/fujica/fujica_booklet/fujica_booklet.htm

[apragmaticoptimist]

Thanks, Tim. I do have that manual already, and it tells me all about the Fujica camera body. I should have been more specific in my post. That manual doesn't tell me how to use the A/M feature of the Auto Chinon lenses. So I'm not sure if the Fujica ST605 will work with Auto Aperture (assuming that's what it is) or how to properly use it if it will. Anyone know of any instructions on using the Auto Chinon lenses?

 

Thanks.

[15sunrises]

I might be able to help you out. When the lens is set to A, when you turn the aperture knob the blades don't close unless you press the "pin" at the bottom of the lens. This is used for cameras that have metering so that it will meter at wide open, you set your aperture, then when the shot is taken, the camera "presses" the pin in to close the blades when the shutter is open. Just put it into A, set the aperture, and press the button, you'll figure out what it does fairly quickly.

 

on the other hand, a few of my M42 lenses are "jammed" so the pin doesn't function as it should, if this is the case with yours, then you can just meter when wide open, set your aperture, and fire in M mode.

[paul_noble]

This is the auto-aperture pin. When in "A" mode, you should notice that, with the lens off the camera, when you rotate the aperture ring, nothing appears to happen. When you push the pin, the aperture will stop down to the aperture indicated on the ring.

 

In "M" mode, the aperture is always stopped down to the value indicated on the ring. This is useful for macro work. Some extension tubes and bellows don't have any linkage to operate the aperture on the lens. Without M mode, the lens would always be wide open when used on such devices.

 

Look at the bottom of the inside edge of the lens mount on the camera. There should be a flat plate, about 1/2 inch wide. When you trip the shutter, this plate will move forward to depress the pin on the lens. This stops the lens down to its working aperture for the duration of the exposure.

 

This doesn't really allow open-aperture metering. For that, there must be additional linkage that tells the camera what the indicated aperture is. The Pentax Super-Multi-Coated Takumar or SMC Takumar lenses had this extra linkage. The little pin at the bottom of the lens mount isn't sufficient.

 

I don't know if any camera manufacturer, other than Pentax, ever made an M42 camera that had open-aperture metering. Even Pentax only made three such cameras, the ES, ES-II and the Spotmatic F. By that time (early to mid-seventies), the screw mount had fallen out of favor. In 1976, Pentax switched to the k-mount system, with the K2 and K1000.

 

I'm not familiar with the Fujica. On my Spotmatics, from the same era, there was a meter switch on the side of the lens mount. You would focus the lens with the aperture wide open, the slide the meter switch up to the "on" position, which pushed the pin in and stopped the lens down. After adjusting the shutter speed and aperture until the meter needle was centered, you tripped the shutter. This turned the meter off and re-opened the lens to its full aperture. On successive shots in the same lighting conditions, it is not necessary to re-meter the scene. In this case, you focus with the lens wide-open, and take the shot. The camera automatically stops the lens down for the exposure and re-opens afterwards.

 

Stop down metering sounds awful when I describe it, but, back in the day, I could do all that in less time than a lot of people take today, with their automatic-everthing-point-and-shoot digital cameras.

 

Paul Noble

[winfried_buechsenschuetz1]

There were at least two other manufacturers of M42 camera systems with open aperture metering: VEB Pentacon and Zeiss-Ikon/Voigtlaender. The Pentacon Super used an additional tab outside the lens mount, the Voigtlaender a recessed pin inside the lens mount.

 

Both systems were compatible with any M42 lenses, they worked with stop-down metering. The Pentacon Super lenses could be used on any other M42 body since the extra tab could be recessed. I think the original Voigtlaender modified M42 lenses were backward-compatible, too.

 

Anyhow, to answer the original question, usually you set the switch to "auto" and use the meter button on the camera body to close the aperture to the selected value when metering.

[tlr]

Mamiya MSX and DSX, Olympus FTL and several models of Fujica like the ST-801 and ST-901, also have open aperture metering, all incompatible with all the others. Also from Pentacon, the Praktica LLC has open aperture metering via electrical contacts.

[walter_degroot]

I believe mr butkus said the chinon m42 cameras would use ordinary screw-thread lenses and would meter when the lens was stoipped down at the time of exposure. and he commented that ONLY these cameras would do so when used with a m42 lens with only a single pin that closed the diaphragm.

 

Pentax had another mount, still m42, they called ES, not sure how it worked.

 

I am not familiar with the other lens mounts mentioned.

But think it is likely that there was some other arm or contact or something.

 

" the wonderful (or amazing)" chinons camera bodies mr butkus refers to did it electronically, not mechanically.

 

I also think there was at least one bayonet mount bodiy , by a company that previously made m42 camera, that had a rare manufacturer's adapter that allowed auto diaphragm operation with m42 lenses.

[paul_noble]

I'm not familliar with the Pentacon or Zeiss/Ikon cameras that were mentioned. I am familiar with the Pentax lenses.

 

The first Pentax camera to allow open-aperture metering was the Pentax ES (electro-Spotmatic). This was followed by the ES-II and the Spotmatic F. I've never heard of any name specifically for the mount, other than M42. The Super-Takumar lenses of the Spotmatic era did not support open-aperture metering. With the ES, ES-II and SP-F, they introduced the Super-Multi-Coated Takumar lenses, which, in addition to improved lens coatings, had extra linkage to tell the camera what position the aperture was set at. Later, they shortened the name to SMC Takumar.

 

This linkage was very similar to that used on the k-mount bayonet lenses. It consisted of a lever that protruded from the back of the lens and traveled in a circular arc around the rear element.

 

I wasn't aware of any other makers that supported open-aperture metering, but I'm not surprised that there were a few. Even Pentax, however, abandoned the screw-mount after only a few years of support for open-aperture metering. I think it only lasted from 1971 until 1975 0r 76, when the k-mount was introduced.

 

Paul Noble

[JDMvW]

Perhaps your confusion is at a more basic level? If not, ignore my efforts to make it even simpler.

 

As several people have pointed out, the "automatic" here refers to the operation of the aperture blades or "diaphragm" NOT to automatic exposure or focus. Those came much later in the development of cameras. The M setting, as said, is to use the lens in 'stop-down' mode on cameras lacking the automatic feature.

[apragmaticoptimist]

Thank you for all of the responses. I do have an exposure meter button on the Fujica ST605. When I set the Chinon lenses to Auto, the aperture is fully open. I can then use the meter button to set the appropriate shutter speed and aperture to the point where the needle in the viewfinder is centered. When I press the meter button, it definitely changes (darkens) the view in the view finder when the lens is in Auto mode. Once I have everything set per the meter, then I can take the photo. I haven't gotten the film developed yet, so we will see if these shots come out correctly exposed or overexposed. Then I will know if the Fujica is supporting the Auto mode of the Chinon lenses.

 

Thanks again!

[donnie_strickland]

Andrea -- what you have just described, is the correct procedure.

[apragmaticoptimist]

I'm happy to report that the auto aperture on the Chinon lens seems to be working fine with the Fujica ST605. No over exposures in the film I developed. Thanks everyone for your advice.

 

Best,

Andrea