[Foto - Dino]

Hi to all Members of the Forum.

I have recently read Online that the Asahi Company changed the internal light metering system of the Pentax Spotmatic camera from a "Spot Metering" evaluation to a "Center Weighted" (?- Average) system, just prior to the launch of the camera, due to concerns about the consumer public being incapable of correctly using the system. Is this factually correct ?

I purchased the original Asahi publication; "The Pentax Way", when I bought the camera New in the Mid 60's and the book refers specifically to the internal light meter being of a Spot Meter system.

It has occurred to me that it would have been a gross misrepresentation of the product upon it's release, if the claim is indeed true.


Would any Member be able to shed some light on this subject, and possibly describe what was changed in the camera design that was implemented just prior to the camera's release, please ?

Many thanks to all Members for any insight and information that may be offered.

Thank you.

[arnold]

I think they just made the spot bigger. Just what size is a spot limited to?

[stevebrot]

It has occurred to me that it would have been a gross misrepresentation of the product upon it's release, if the claim is indeed true.

To the best of my knowledge all production Spotmatics were sold with center-weighted averaging meters. If there was ever an attempt to pass any of those off as having spot metering, that also would be a surprise. See the article below for a detailed history.

http://camera-wiki.org/wiki/Pentax_Spotmatic


Steve

[sergysergy]

CenterWeightedMatic was not as catchy

[Lord Lucan]

I think they just made the spot bigger. Just what size is a spot limited to?

It was a radical change, and I don't know why they kept the Spotmatic name, I don't find it attractive.

I understand that the prototype had the photocell on a moving arm which only came into the centre of the viewfinder when you asked for a reading. I guess you moved a lever, but, outside Asahi's development workshop, the one-and-only prototype was only ever demonstrated briefly (and unofficially?) to a few journalists at the 1960 Photkina, so perhaps we will never know for sure how it worked. It possibly still exists somewhere. The photocell was small - hence spot metering. The production models had fixed photocells by the side of the viewfinder giving a more diffuse but centre weighted reading - the standard arrangement in many cameras ever since (with exceptions like the Pentax LX).

[Foto - Dino]

Thank you so much to All who responded to my query with your thoughts and knowledge, and for the Link to the Wiki site, which I was unaware of.

I have been able to gather far more information about the camera I have owned for so long, than that which was detailed in the original Asahi Book publication of the time, and has filled in some of the gaps in my current knowledge.

I expect that the Manufacturer's decision to change the metering from their Spot-metering prototype to Center-weighted was probably made hastily after a late review of the camera's functions and the possible Warranty implications that may have occurred with a more complex electro-mechanical system. I wonder why they didn't consider mounting the Cd Cell embedded into the apex of the Penta-prism, directly over the center spot of the focusing screen, that may have allowed spot-metering as was originally intended.

Once again, thank you for all of your responses.

[Lord Lucan]

Warranty implications that may have occurred with a more complex electro-mechanical system. I wonder why they didn't consider mounting the Cd Cell embedded into the apex of the Penta-prism

I have read that spot metering was dropped because Asahi thought that users would not understand the principle of it, for which you almost first have to read Ansel Adam's books on the subject of exposure. II the user takes a picture of a guy in a dark suit, the spot is likely to be on his chest so the shot will be over-exposed, and many (or most) users would not understand what had happened. Asahi and their dealers did not want all those complaints, or to need a call centre to educate users about spot metering

I don't think the electro-mechanical aspect would have been a problem, it was just a swinging arm, possibly moved directly by a simple external lever. I am surprised however that they could make a small photocell sensitive enough at that time. The meters of production Spotmatics (alsocarried forward into the KM and K1000) was rather slow as it was.

[stevebrot]

I have read that spot metering was dropped because Asahi thought that users would not understand the principle of it

A problem that continues to this day! I can't count the number of help requests regarding poor exposure where unschooled use of spot metering was the culprit.


Steve