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How can MF bring greater resolution, don't diffraction limits apply?
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Barrie Davis
Forum Pro
Yes there is.
I'm afraid you are looking at the matter with the wrong object in view. You are not alone in this error.
The object of the game is not to demonstrate that large formats deliver the same quality as smaller formats, by reducing their light intensity per unit area until the TOTAL light is stifled down to the same total as the smaller format being compared.
The whole point of the larger format is that it be PROVIDED with the extra light it needs to outperform the smaller format... that its light volume per unit area be the same, NOT its total light per image.
It is better quality that the is the object of the large format game, not proving "equivalence" .
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Regards,
Baz
"Ahh... But the thing is, they were not just ORDINARY time travellers!"
Barrie Davis
Forum Pro
The smaller formats can be shot wider open, and still achieve the same DoF.What iso values do you typically use then? Just wondering...
So, where I typically used 100-ASA/ISO film, I also shot digital at the same sensitivity. The economy in light levels with digital was achieved by shooting at f/4, instead of f/16, say, with 6x9cm... or even f/22, if 5x4".
I didn't use 35mm film for serious work. Its quality was not high enough. 35mm transparency stock was used only for AV presentations (slide shows). Negative film was used more rarely... when requested by clients to cover a party on the cheap, or something.
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Regards,
Baz
"Ahh... But the thing is, they were not just ORDINARY time travellers!"
You dont seem to understand that there is no limitation preventing a smaller format from recording the same amount of light as the larger format unless you are already shooting at its lowest iso setting, why would you intentionally shoot pictures with lower quality settings than you want by using a smaller aperture on the smaller format if you would use a larger aperture with a larger format? Are you really saying medium format only has value below iso 200 compared to full frame?
John Sheehy
Forum Pro
I think that you have your terminology backwards. A larger aperture is a lower f-stop, and visa-versa, for a given focal length.
Aperture and f-stop are different things.
Aperture is the size of the opening. f-stop is the focal length divided by that aperture.
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John
Barrie Davis
Forum Pro
I am sorry, Malcolm, that is you not understanding.
Thing is, I do not know how you can NOT understand. It seems pretty obvious to me that a sensor such as the 2/3rds one (1/16th the area of a FF35mm film frame) is saturated by 1/16th the volume of light rays impinging on it as would saturate a FF35mm one.
And that I do not understand, because it doesn't seem to express a coherant idea. Sorry, but is that the actual word order you intended to use?
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Regards,
Baz
"Ahh... But the thing is, they were not just ORDINARY time travellers!"
So why is this the whole point? What makes the lowest iso setting so special that you have to use that setting to justify the format? When you can record at iso 10 on full frame, will medium format give no advantage whatsoever anymore to you? Or would you see the value in also using it at iso 10? What happens when sensors can record continuously and iso is no longer restricted at a minimum value? What would be the ideal sensor size then?
The only inherent benefit that larger formats have is higher resolution lenses. It used to be mainly the film that limited the quality of the smaller formats and sensor technology did so as well for a while and still does to a small extent but ultimately the only limitation that will be left limiting the quality of smaller formats will be the lens.
It does not make sense to state that pictures have to be compromised with less depth of field than desired simply because you are using a larger format. How is that different from saying you have to use a longer shutter time on the larger format because the larger sensor requires more light to reach its potential? I know that would require different settings with different number-tags instead of different settings with the same number-tags on the larger format which people would not automatically select by default... But what makes using a larger aperture inherently a better choice than using a longer shutter time? And of course unless you are limited to the lowest iso value on the smaller format you can also use a longer shutter time there to improve the quality in the same way. So i ask again: what happens when there is no more bottom iso limit on sensors? What sensor size is best?
I was using aperture as the size of the opening as you say not to refer to the f-stop, so by choosing the same f-stop on a smaller format you are using a smaller aperture as i said.
I explained before that unless you are shooting at a setting on a large format that has no equivalent setting on the smaller format there is nothing preventing the smaller format from shooting that equivalent picture. So rather than others limiting the quality of larger formats to prove equivalence like you suggest they do it seems you are actually limiting the quality of smaller formats to prove their inferiority. Any picture that is taken at iso 200 or above on medium format can be taken on full frame on an equivalent setting. The bigger light gathering ability of larger sensors is only being used when you use the lowest iso settings.
So you actually did shoot large format at a setting that has no equivalent setting available on full frame such as iso 10.The smaller formats can be shot wider open, and still achieve the same DoF.What iso values do you typically use then? Just wondering...
So, where I typically used 100-ASA/ISO film, I also shot digital at the same sensitivity. The economy in light levels with digital was achieved by shooting at f/4, instead of f/16, say, with 6x9cm... or even f/22, if 5x4".
Those must be some powerful lights if you cant use them at f/4 on iso 100. So you have no use of faster shutter speeds or more depth of field to take advantage of the lights?
Yet 35mm sensors are good enough? That was my first reply to you, it is the higher quality of digital sensors that allows you to use less light, not the fact that it is a smaller format.
Barrie Davis
Forum Pro
Yes there is.
The point of larger formats is to yield higher quality. They do it by using more light. If they don't get the extra light, we don't get the extra quality.
(Please don't tell me why this is such a problem for you, because, frankly, I don't give damn.)
You keep making some point about ISOs. I don't what the point is, and I don't know why you keep making it.
Huh?!!
I don't know where you are headed with that, either. What's more, I'm getting the feeling you don't know yourself.
As it happens, larger format lenses have lower resolution. Perhaps this is news to you? Well, you know now.
Where did that one come from...? (...nothing to do with anything I have posted). [shrugs]
Very often one does. Naturally the extra light needed by larger formats is delivered by the least inconvenient means, but because one has to stop down to higher f/numbers, larger formats often are exposed at longer shutter speeds, or by more powerful lighting.
You lost me. I don't know what you mean by number tags, and I don't know what you are trying to say about them. Your whole posting seems to be increasingly confused.
I dunno, Malcolm. You tell me. Or maybe don't bother, huh?
Sorry. Again I find your reasoning doesn't hang together and and I find myself completely at a loss to understand what point you are trying to make.
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Regards,
Baz
"Ahh... But the thing is, they were not just ORDINARY time travellers!"
Barrie Davis
Forum Pro
No. 100-ASA/ISO was just the slowest Daylight Ektachrome reversal film available in any format, at the time... (still is, as far as I know. I have not bought film in a long time.)So you actually did shoot large format at a setting that has no equivalent setting available on full frame such as iso 10.The smaller formats can be shot wider open, and still achieve the same DoF.What iso values do you typically use then? Just wondering...
So, where I typically used 100-ASA/ISO film, I also shot digital at the same sensitivity. The economy in light levels with digital was achieved by shooting at f/4, instead of f/16, say, with 6x9cm... or even f/22, if 5x4".
Huh!? (For some reason or other seems you cannot understand a single thing I write.)
They were tungsten lights, right? I got the DoF I needed on small format at f/4, so I SHOT at f/4... the shutter speed was adjusted accordingly.
I could just as easily have been shooting by studio flash, because I DO have a set of lights that screw down low enough to suit the small formats of digital.
I told you. I got the DoF I needed at f/4, so stopping down anymore was pointless. The subjects were typically still life interiors, and any shutter speed was fine.
Yes they are. They are terrific. But I don't use FF-sensors.
Wrong!
- It is their high quality that makes them able to replace larger film formats.
- Whereas it is their small size that makes them require less light than the formats replaced, because they give same DoF at lower f/numbers.... Note that this is equally true of small film formats, of course. So, it is a FORMAT thing, NOT a digital thing!
Regards,
Baz
"Ahh... But the thing is, they were not just ORDINARY time travellers!"
Because it is only at the lowest iso's that smaller format have no equivalent settings, how more obvious can this be? When you are using higher iso's than the lowest on smaller formats for shots that you would take at the same iso on the large format you are unnecessarily limiting the quality of the smaller format, apparently just to force a false quality advantage of larger formats.
iso 10 on full frame would be equivalent to iso 25 on medium format, seems easy enough to understand... Basically what you consider to be the quality benefit of larger formats is then also available on full frame which is currently restricted to higher equivalent iso's.
The more limited equivalent iso range of smaller formats is the only factor that can justify your argument that larger formats have to be exposed with more light to realise their higher quality potential.
I actually suspected this was coming and added that i meant full image resolution and not linepairs per mm resolution but deleted it again because i felt it would be stating the obvious. Note that the linepairs per mm resolution you are getting on the objects in the scene is increased, if you have to use that kind of measurement... You are trying to take pictures of something outside of the camera and not a macro shot of the sensor itself using another sensor i assume?
Same number tags such as f/8 and iso 400 which happen to be different actual settings on different format camera's. They are just named the same. It is strange that everyone understands the point of equivalent focal length but this just seems to be lost on many.
The only quality advantage of larger formats you are arguing for being higher light gathering ability would be gone as there would always be an equivalent iso on smaller formats.
Oly Canikon
Senior Member
Malcolm, when you find yourself in a hole - stop digging.
Oly Canikon
Senior Member
touche
Thats exactly what i said, the equivalent setting of the large formats at iso 100 is not available on full frame being something around iso 10.No. 100-ASA/ISO was just the slowest Daylight Ektachrome reversal film available in any format, at the time... (still is, as far as I know. I have not bought film in a long time.)So you actually did shoot large format at a setting that has no equivalent setting available on full frame such as iso 10.The smaller formats can be shot wider open, and still achieve the same DoF.What iso values do you typically use then? Just wondering...
So, where I typically used 100-ASA/ISO film, I also shot digital at the same sensitivity. The economy in light levels with digital was achieved by shooting at f/4, instead of f/16, say, with 6x9cm... or even f/22, if 5x4".
You stated your lights were too powerful to be used on the digital camera's and you had to use less of them or turn them down which i find surprising at iso 100 f/4. That is all i meant to say there.
Seems you didnt need those powerful lights for your large format camera's either then.
Whatever format you use it is smaller than you used with film. Judging by the fact you stated you use f/4 where you used f/22 on 5x4 that means you use an aps-c camera now?
No it is the fact that you are using higher equivalent iso settings that makes them require less light. The reason you can now use higher equivalent iso's is because digital sensors are better than film.
Barrie Davis
Forum Pro
.... which is to say that equivalence doesn't happen, isn't it? Your concept of "equivalence" only happens in the land where imaginary sensors reside, ones that are not saturated by gross overexposure.
Electronic flash lights need to be turned down to accommodate the smaller digital formats, which many of the previously produced units could not do. With continuous lighting it's a matter of using a shorter exposure, or of using fewer lights and the same exposure. The latter meant humping a lot less equipment around, so that is what I did.
It also meant that my same lights were now much larger relative to the sets being illuminated, which is, of itself, a benefit. It greatly simplifies the lighting operation. It means you are not using multiple lights across a set, whilst trying to make it APPEAR as if only one light has been used, for instance.
On the contrary. With film, exposure times cannot be allowed to grow too long. The reciprocity of extending exposure duration to compensate for lower light levels at the image plane, breaks down, and the film loses sensitivity. This is called Reciprocity Law Failure.
It isn't just a loss of sensitivity, which is inconvenient enough, because you CANNOT fix it by simply giving longer exposure times, of course.... but it screws up the colour as well, because the three layers in the film are not affected equally by Reciprocity Law Failure....
.... and the use of colour correction filters doesn't help, either. They further reduce the light entering the camera. It is a lose-lose downward spiral situation. The only way out of the cycle is to add more light .
The failure of Reciprocity Law doesn't happen with digital, which is a blessing, but with long exposures we tend to get noise instead.... (which could be considered analogous to loss of sensitivity, since we also get noise when underexposing.)
(sigh) When "equivalence compatible" sensors of 10-ISO make their appearance, you call me. Until then, you are talking about something that does not exist. :-|
It seems you are besotted by the "equivalence" idea. This is a shame. It is slewing your understanding of what are pretty basic facts.
- Larger formats need more light ... (and smaller formats less). More light is needed because larger formats have greater areas of sensor to illuminate to adequate exposure level than have smaller formats. This means a 10x8" film needs 4x as much light to illuminate it as does a 5x4" film. This isn't hypothetical, it happens in practise.
- It is precisely the same with lighting. If large subject areas need lighting, more light will be needed to do it. That is why Shea Stadium cannot be illuminated by a pop-up flash, despite the huge number of people who earnestly believe that it can.
- It doesn't MATTER that underexposure on larger sensors can yield results similar-looking to correct exposure on smaller formats. It is just a curiosity. It is not the function of large formats to duplicate the results of smaller formats. ... they are there to be better . The price of improvement is the requirement for more light.
Good luck, Malcolm.
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Regards,
Baz
"Ahh... But the thing is, they were not just ORDINARY time travellers!"
Equivalence does happen when equivalent settings are available on the smaller formats. Are you really going to pretend you meant that medium format should only be used at iso 100 to take full advantage of the format? It is pretty clear to me that you were suggesting that a particular picture taken at for example iso 800 on full frame should also be taken at iso 800 on medium format because it should be exposed with the same amount of light per unit area. It does not take any imaginary sensors to take that particular shot at iso 320 on full frame to get the equivalent exposure.
Do you know that most people do not take all their photographs at iso 100? By your logic any shot at higher iso might as well have been taken by a smaller format since you are not taking advantage of what you consider to be the only purpose of the larger format.
Barrie Davis
Forum Pro
Good luck, Malcolm..... (message ends)
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Regards,
Baz
"Ahh... But the thing is, they were not just ORDINARY time travellers!"
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