Talk:Minolta Hi-Matic 7s

Does anyone have some more detailed information on this camera? Specifically, what was the automatic exposure profile, because the user manual includes a graph that suggests intermediate f-stops and shutter speeds were set (automatically) to replicate EVs. This seems unlikely, and is something the marketing of this camera would have surely bragged about. Also, there's the CLC system. I do not understand what this was, since it would be impossible to detect contrast in a scene using only one light cell. Other Minoltas of the time with a CLC had two light cells, and so could provide a bottom weighted exposure reading. I haven't finished yet! There's the SLS which apparently checks film advancement and correct alignment (according to the manual), but it's a mechanical flag connected to the spool, so it might show advancement, but how can it show alignment? I get the feeling this camera was pretending to do things it could not, and the CLC, SLS names were just hype. --Johnbear (talk) 10:33, 13 March 2017 (CDT)

Johnbear, you might be able to get more answers from someone who owns this model by posting the question on the wiki Flickr group discussion board. Posting here, it might only be seen by three or four wiki editors.

While acknowledging that camera marketers always overhype whatever features the engineers came up with, maybe we can shed light on a couple of these questions by looking at the US patents assigned to Minolta.

Yes it does seem credible that the 7s programmed auto-exposure was stepless, because patent 3,309,974 talks about an improvement to the "trapped needle" method of autoexposure where the trapping mechanism was a rubberized gripper rather than a toothed one (which would result in stepped exposure settings).

You seem to be right that the SLS mechanism just indicates "film is winding onto the takeup spool" as seen in patent 3,335,695. Charitably we might take the word "alignment" to mean the toothed advance spindle is correctly engaged with the film sprocket holes.

There seems to be some confusion and even some "wishful thinking" about what Minolta's CLC metering system did, even in the better known, dual-CdS-cell cameras. The description here is not entirely helpful, but I interpret it to mean that two meter cells look at slightly different parts of the scene; and the total series resistance is dominated by whichever meter cell sees less illumination. In practice that's typically the one aimed at the lower half of the frame (assuming landscape orientation).

Patent 3,286,609 indicates a much simpler method to have the meter cell favor the lower half of the scene: just offset it from the axis of the meter lens! This patent does seem to be the one relevant to the 7s and you're right that it's even more simplistic than "regular" CLC.

--Vox (talk) 08:53, 16 March 2017 (CDT)

Vox - Thank you very much for this information. I have posted this question on a couple of forums, but got no answers or opinions.

I've looked at the trapping mechanism info., and don't pretend to understand it all, but I agree it does point towards step-less transfer of a trapped needle's position, which we must suppose to have a tangible benefit on exposure settings. I appreciate that setting an intermediate aperture may not be too problematic, but I don't know if the Seiko LA shutter (apparently designed for auto exposure cameras) is capable of intermediate speeds (and neither have I been able to find out). But the graph showing the auto-exposure profile definitely suggests both intermediate aperture settings and shutter speeds, and I'd like to think it's not Minolta fibbing.

I agree that my criticism of the SLS was harsh, and if a film is winding it will likely be aligned, but I was ruffled by alignment being the primary claim (and fuelled by other anomalies).

I have since found Minolta's Technical Bulletin A, and read how the CLC works in the SRT 101. This clarifies that the Hi Matic's single cell cannot detect contrast, and I have concluded CLC was just a name - as with Agfa's sensor button which could be a membrane over a mechanical switch, or an electro-magnetic switch (that actually required a membrane). The off the axis meter lens is interesting, and my camera does indeed appear to have a lens with fixed top and bottom blind behind. However, I took test meter readings of a high contrast sunset, taking care with my framing, and changing the orientation of the camera (upside down, side ways, etc.) I got exactly the same readings, so couldn't detect any bias in the orientation or screening of the meter's view point that would favour the foreground.

I've trawled for advertising literature, and have noticed the Hi-Matic's CLC is very played-down, and at times strung into a sentence that describes automatic exposure compensation when filters are fitted.

At the end of the day, I am simply curious, and surprised all the authors of Internet sites that report the Hi-Matic 7s, 9 and 11 have a CLC which is two cells in series, have never noticed (over 50 years) the cameras have one cell, and have not reasoned this cannot detect contrast differences because it has a single perspective. I guess more than anything I'm looking for someone to recognise the problem more than offer the absolute solution. --Johnbear (talk) 12:04, 16 March 2017 (CDT)