Does your Contax RX underexpose

[jwalton]

In the early days, when contaxinfo was still a baby, I posted a thread about my RX underexposing. To compensate I've always set the film speed to 80 for a 100 speed film. Invariably that film has been Provia 100F.

Lo and behold, I've just tried the new Velvia 100F and, would you believe it, the darn thing now overexposes slightly.

So, is it the camera, is it the film, is it the photographer (surely not!). Interestingly I've continued to shove Provia 100F through my T2 and through a cheap Minolta autofocus SLR and they have always exposed beautifully.

Conclusion: it's not the photographer (phew!), it's a combination of the RX's meter and the fact that Provia's slower than 100. I haven't yet pushed Velvia through my other cameras so I don't know whether that's faster than 100, it certainly seems faster than the Provia however.

Anyone else had similar results?

 

[koed]

It might just be a trait of the Fuji film, I've read numerous reports about the Velvia 50 underexposing too. If the new 100 is just a slightly upgraded 50, it might not be that strange that it overexposes now.

I'm not an expert and it might be a coincidence, but I own two minolta's and for me, both always overexposed a stop.

Just my two cents.

 

[planar]

Hi John,I can agree that mine also underexposes slightly, perhaps only 1/3 of a stop.
I think you will find the reason to be a good one for the following reason.
Using positive film and printing from it renders better prints if the exposure is slightly underexposed while at the same time not harming the exposure to the slide film. Print or negative film however can be pushed 2 stops either way infact modern day emulsions boast up to 3 stops.
Slides are a different matter and if you use Cibachrome the results are just superb.
Bob.

 

[bobbl46]

About 5 years ago. I was engaged in a conversation with the Service Manager of Kyocera UK about the slight under exposure of my recently acquired AX. I had based my judgement of this anomaly on my previous experience with my 137MA, 167MT, 139Q, RTS II, RTS III.and ST (I know, strange order of ownership!).

I had suspected that the ST had been producing quite saturated slides … but perhaps slightly underexposed, and on projection, I thought they were OK. However, I somehow preferred, when I had bracketed, the ones that were 1/3rd or 1/2 stop “over-exposedâ€. The AX seemed to me, even slightly more “out†than my ST. He offered to check it out and I accepted his offer. On return, it did seem to be much more “in-line†with my ST and with perhaps with shots taken many years earlier with my 137MA, 167MT etc.

He admitted to me that the more modern cameras (I think he implied ST, RX, AX and Aria) were deliberately set to provide an exposure that looked more saturated than those cameras that had preceded them! I pressed him a bit more on this ... Along the lines that ... Correct exposure was correct exposure etc. You can imagine the debate that followed, 18% Grey, what is correct exposure when projection equipment varied from user to user, averaging meter patterns etc.! I got the impression from him that it was a high-level decision made at sometime by the Kyocera boffins to make a deliberate choice to alter the algorithms in the cameras electronics to produce what they thought were “more impressive†photos!

I accepted this and, more often than not, now set my daylight shots on the AX to +1/3rd. Strangely though, I find that the AX with a TLA30 gives pleasing results at 0 compensation than at +1/3rd.

I guess, he was right when he implied that it was more a matter of what you are “use to†and, certainly projection equipment does play a factor. BUT, I was left with a feeling that the backroom boys had made a decision to alter the “norm†to make an impression on saturation!

Briefly, we discussed print film ... but both of us accepted that the variables in producing a print were beyond the point were 1/3rd stop and 1/2 stop mattered due to film latitude and the “unknowns†of the typical high-street Processing Lab. I know that some will disagree!

I find it hard to draw a conclusion from this as I have only one (educated) man’s word on it ... and my own experience of Contax cameras since 1988!

Cheers, Bob.

 

[mikel]

Bob,

It's very puzzling. But I also have a question. How do you actually know that it's the camera's exposure meter that is "off" or it's the film that is under- or over-rated or it's the processing? I remember a lot of people using Nikon and Canon equipment were recommending to use Velvia at ISO40 and NPH at ISO320 (which was a curious thing to me, since it's a negative film after all).

However, the point is, what makes you sure that Velvia's sensitivity isn't rated ISO50, after all, they use *ISO* procedure to determine it! Ilford is different in this respect. As far as I can tell, in real world, variation of "proper exposure" can be related to lighting conditions, emulsion you're using and even processing. So, technically I wouldn't believe that 1/3 stop difference in exposure as measured using your built-in exposure meter in the camera is a big deal. I don't it's even possible to design a camera that will be always accurate, because again, you're using ISO-rated film, where ISO was determined using some standards that don't necessarily reflect every possible real-life situation. I think that the best way is to simply experiment (as usual) and determine what works best for you.

Mike.

 

[mikel]

Oops, accidentally erased one word when typed the previous message:

"I don't it's even possible to design"

should read "I don't think it's even possible to design"

Mike.

 

[mikel]

Wow, Bob. I see your point, but then here is a question - how possibly Agfa's emulsion couldn't have changed at all over all these years? And let's say it didn't, then indeed there could be a problem in the new exposure meter of new Contax bodies.

But then again, all the people that use Nikon and Canon swear that it's Velvia that isn't properly rated, while their exposure meter is correct!

So, although I definitely understand your point (not even arguing about it), but could it be that this change in "exposure philosophy" is explained by changes to "exposure philosophy" by film manufacturers as well?

And then another galon of oil into fire - how accurate the shutters are on the older Contax bodies? Could it be that they're actually SLOWER than rated and thus overexposing the film all by themselves, whereis exposure meter has nothing to do with it? While the modern ones are accurate and thus appear to be underexposing while using the same exposure meter?

As far as I know, even most of modern bodies have variation in their actual shutter speeds up to 1/3 of stop easily. Some are as far off as 1/2 of stop.

For instance, if I remember correcly, Germany's Foto Magazin tested shutter speeds of Pentax PZ-1P a while ago. And again, if my memory serves me right, they found out that 1/8000sec shutter speed was actually 1/6000sec speed, while some slower speeds were faster than they were rated (don't remember numbers for slower speeds, my memory isn't what it used to be).

Now, here is a bombshell. Years later, Pentax releases MZ-S with shutter based on PZ-1P with some modifications. Top shutter speed? 1/6000sec!

So, certainly, if many users can detect that their RX (or whatever else camera) is "off" a little bit, it's obviously nice to know, but it may involve many more factors than we know about, so why really worry? If we know the workaround and it's acceptable - hakuna matata!


Mike.

 

[swoolf]

> But then again, all the people that use Nikon and Canon swear that> it's Velvia that isn't properly rated, while their exposure meter is> correct!

I think alot of people other than C and N users rate Velvia at 40 , certainly I do fairly often when I use it , which is infrequently . Mainly because its a very contrasty film and given the VERY bright contrasty light we get down here in the land of Hakuna Matata , it works fine used this way ..... Steve

 

[mikel]

Stephen,

True, and there are others that use it at 50 and are happy with results (and I guess that means, often outside of Land Of Hakuna Matata

). I was only bringing that in as an ex&le.

My point here was that despite being rated ISO50, a lot of people use it at ISO40. Why? Because people like it and because some people say that ISO50 isn't Velvia's true speed, while ISO40 is its true speed. And yet, Fuji still labels it as ISO50 all these years. So, who would be right here - exposure meter of your camera (or the results you're seeing) or Fuji that follows ISO guidelines? Strictly speaking, if that film's labeling as ISO50 falls within guidelines defined by standard - Fuji is correct.

So, what I'm trying to say is, that I believe the best exposure in any case depends on many factors and for that reason 1/3 stop (or even 1/2) difference in exposure on one camera compared to another is nothing to be concerned about. It can be considered as salt and pepper that are always added according to your personal taste

Mike.

 

[nicolas]

I've also had the same experience of underexposure with the RX. I attributed it to light coming in from the eyepiece. eg. my back to the sun, etc. Someone once told me its due to the RX's sensor being placed above the prism (instead of the behind the mirror in the old cameras).