Mamiya 645 AF question

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Donna and Dan Stanger - 30 Jun 2006 01:06 GMT

Does anyone know how difficult it is to use non AF lenses on a autofocus
body?
What problems will I encounter.
Thanks
Dan Stanger

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no_name - 30 Jun 2006 02:31 GMT

> Does anyone know how difficult it is to use non AF lenses on a autofocus
> body?
> What problems will I encounter.
> Thanks
> Dan Stanger

According to Mamiya's FAQ ...

Q. What accessories and lenses from my manual focus 645 system may I use
with the 645AF or AFD?

A. You may only use the lenses. However, they will not stop down
automatically the same way they do on the other cameras. When using the
manual focus lenses on the AF do the following. . .1-Set "A/M" switch on
lens to "M". 2-Rotate f/stop ring to maximum aperture for composition
and focusing. (Focus confirmation in finder will work) 3-Set desired
aperture and release shutter.

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Donna and Dan Stanger - 30 Jun 2006 03:42 GMT

The reason I brought this up, is that I bought a 70-150 Mamiya Sekor
zoom, which weighs about 2.3 lbs.
This is the lightest zoom I have seen in MF, and is the right range for
my wife who shoots events.
However, the Mamiya 645M has a maximum sync speed of 1/60th of a second,
which is too slow to capture dancing without bluring.
Does anyone know if its possible to convert a 645 non auto focus camera
to use a autofocus shutter
to get the higher sync speed of the auto focus units?
Or can the AF cameras be modified to handle non autofocus lenses,
automatically?
Thanks,
Dan Stanger

>> Does anyone know how difficult it is to use non AF lenses on a
>> autofocus body?
[quoted text clipped - 13 lines]
> composition and focusing. (Focus confirmation in finder will work)
> 3-Set desired aperture and release shutter.

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David J. Littleboy - 30 Jun 2006 04:01 GMT

> The reason I brought this up, is that I bought a 70-150 Mamiya Sekor zoom,
> which weighs about 2.3 lbs.
> This is the lightest zoom I have seen in MF, and is the right range for my
> wife who shoots events.

Get a Canon 30D and the Tamron 28-75/2.8 and forget about medium format. (Or
the 5D and the 24-105 IS, if you feel like spending the money.)

Medium format is about image quality, shooting events is about getting the
image. (And the 5D will get the image better than 645 film, and have far
better image quality if you are using ISO 400 or above.)

> However, the Mamiya 645M has a maximum sync speed of 1/60th of a second,
> which is too slow to capture dancing without bluring.

If you use a brighter flash and a smaller aperture, the ambient light will
be to dim to contribute to the exposure. (A 1/60th sync speed would only be
a problem in outdoor daytime events; indoor you should be fine.)

> Does anyone know if its possible to convert a 645 non auto focus camera to
> use a autofocus shutter
> to get the higher sync speed of the auto focus units?

In the Mamiya 645 cameras, the shutter is in the body (it's a focal plane,
not leaf, shutter). So the higher shutter speed of the 645AF is due to the
body, not the lenses.

> Or can the AF cameras be modified to handle non autofocus lenses,
> automatically?

In most cases, using manual focus lenses on an AF camera is a major
disaster. Manual focus lenses tend to have mechanical linkages for aperture
control, and AF cameras use electronic control of the aperture. At which
point, you lose aperture control and have to meter (and compose) at the
stopped down aperture, which you have to set manually. It's really not nice.

And since the lens doesn't have the electronics and motors, it's not
possible to modify it for AF.

David J. Littleboy
Tokyo, Japan

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