Low light capability relative to film size...

[Patrick]

I have a theory that I have often wondered about but strangley, I have never seen it discussed in any photography books. I am wondering if cameras that use larger format film have an additional advantage when filming in low light situations as compared to smaller formats. Obviously, with any format that you use, the first thing you do is open the aperture right up to allow as much light in as possible. Though cameras that have a larger gate area would theoretically allow an even larger amount of light to pass through to expose the film. Hence, a 16mm camera with a mirror shutter would be more efficient in low light than a super 8 camera with a mirror shutter. A 35mm still camera would fare even better. Though the comparison between the two cine camera formats (s8 and 16mm) could only be accurately made if both cameras shared roughly the same shutter speed and used the same ASA film speed etc. Does anyone know this theory to be actually true?

[rhcvatni]

The amount of light should be the same either way. If you were to have the exact same framing for the different formats(with a equally light sensitive lens, same apparture, whatever) the exact same amount of light would hit the film. The bigger formats would only have a bigger area to "record" that light. You would get more detail, but I can't see that it would be any brighter. Why would it? And that's my take on this. Anyone else?

[Patrick]

I guess with my way of thinking, the gate would act like an additional 'aperture.' The gate of a 16mm camera is about twice the size as the gate of a super 8 camera. Hence, wouldn't twice as much light pass through that larger gate size?

[BK]

Hello Patrick,

Nice theory! And one that actually 'baffled' me for a few minutes. And I couldn't find any info on the net that explains this.

Like rhcvatni said, the light is the same, you are just having a larger area to record your image.

However, I think it is true for projection, you are having a larger light source and lots more light going out from a larger gate with a same wattage bulb projecting onto a same size screen.

I think if the light transmission is any different between different formats then our light meters would have some extra dials for working out exposures. For 35mm, 6X6, etc, and for 8mm, 16mm, 35mm cine.

Bill

[Patrick]

Good point, Bill! Actually, I was just thinking the same thing myself now. I use the light meter in my 35mm SLR for my Krasnogorsk 3 and the results are always correctly exposed. Maybe, I was wrong after all.

[christoph]

I guess with my way of thinking, the gate would act like an additional 'aperture.' The gate of a 16mm camera is about twice the size as the gate of a super 8 camera. Hence, wouldn't twice as much light pass through that larger gate size?

unfortunately, that's not true... the only factor that matters is the aperature of the lens (well, to be bit more precise, the T-stop and of course the shutter speed and the viewing system of the camera).

if you take a 35mm lens and put it on a 16mm camera, exactly the same amount of light will fall on each square mm of the negative, thus the density of the negative will be exactly the same. the only difference of a 35mm lens is that it will cover a bigger total area -- just think of an enlarger projecting a negative to the size 30x40cm.. whether you put a 20x30 paper under it or a 10x15 doesnt matter, both prints will have the same brightness.

so, the main difference of low light capability is in lens and film stock.
larger formats allow you to use film with higher ASA rating because the picture doesnt have to be enlarged that much, thus showing less grain.
but on the lens side, the larger the film format, the more difficult is it to build a lens that will fully cover it on low f-stops (not to speak of the fact that depth of field is becoming a problem).

with all those factors in mind, 35mm is probably the best format for low light use, having a lot of high speed lenses and a reasonable film area to use film with high EI.

as for projection, the difference why larger formats are brighter is because you can use a lamp with higher output without melting the film. again, it's a function of light per square mm (same amount of light per square mm -> more square mms = more light).

sorry for the somewhat dodgy terms, but i hope the main idea got through
++ christoph ++

PS: as i'm doing some reseach about this myself, does anybody know of a *very* high speed lens that will cover super16.. i'm thinking about f=1:1,0 here or preferably even less (f=1:0,8 anyone? ;).
to make thinks even harder, it should be in a reasonable (for 16) focal lenght, between 12mm and 25mm and fit on a PL mount of an SRIII in someway. i wouldn't mind a bit of vignetting, but it's got to be faaast ;)

[istvan]

Sorry if reposting, reading in a hurry, but the larger the gauge, the bigger the latitude, so apart from fast lenses/less of a grain problem, 35 will beat 16 just out of sheer size, as will 16 beat s8.

Istvan

[christoph]

Sorry if reposting, reading in a hurry, but the larger the gauge, the bigger the latitude, so apart from fast lenses/less of a grain problem, 35 will beat 16 just out of sheer size, as will 16 beat s8.

i don't know who came that in the first place (it was mentioned in another thread) but i'm afraid it's simply not true, 16mm and 35mm strips are basically cut from the same sheets of film (and so are pro8mm). kodak in fact has a combined data sheet for the 35/16mm variants of their film.



that's from the tech sheets of 5279/7279
http://www.kodak.com/US/en/motion/16mm/ ... 10.4&lc=en
http://www.kodak.com/US/en/motion/produ ... 5279.shtml

the reason why you might get away with underexposure on 35mm is that the grain doesnt show up as fast...
++ christoph ++
(edit: corrected errors)

[mattias]

the reason why you might get away with underexposure on 35mm is that the grain doesnt show up as fast...

correct, but that's what latitude in practical terms means. you will in fact get slightly more shadow detail with a larger negative, even if the measurable latitude of the emulsion is exactly the same. it's easy to see the logic if you extrapolate this thinking into an extremely small negative area which has no latitude whatsoever since it only contains a single grain, and thus can only be on or off, nothing inbetween.

/matt

[Pedro]

I think the latitude only takes effect, when having hi contrasts or wrong exposure. For comparing the discussed light issue, it would be better to stick with picturing inside the contrast range of a material. The latidude is an add to this discussion but not the point.
For my opinion, Christof is totally right. The bigger the format, the bigger the lens diameters have to be for providing the same light outlet. For small formats, you can easyly built highspeed lenses, like 1:1,0. A Canon S8 camera has a 1:1,0 zoom lens and a Elmo projector has a 1:1,0 zoom lens, too. Bigger formats would need lenses with much more glass and size for the same maximal opening. 16 mm lenses which compare in weight and size to S8 lenses, only open to about 1:2,8 or less. Zoom lenses for 35 mm mostly start at 1:4.
The better low light ability of bigger gauges is only a result of the bigger area, allowing to use a type of film with more grain and more sensibility.
If we use a 40 ASA film in a S8 and in a 16 mm camera, and the S8 camea has the 6-80 Angenieux lens (F=1:1,2 - T=1:1,4) while the 16 mm camera can only take the Angenieux 12-120 lens with F = 1:2,8, the S8 is more than one stop better. But when you load a 200 ASA stock, or even the new 500 ASA stock and still get reasonable results while S8 with 160 ASA just looks grainy, you see why larger gauges are better in Lolight.
Pedro

[MovieStuff]

you will in fact get slightly more shadow detail with a larger negative, even if the measurable latitude of the emulsion is exactly the same.

100% correct, Mattias. The larger the format, the better it handles low light/contrast issues. The difference between 16mm and 35mm isn't as noticable as the difference between super 8 and 16mm but there is a HUGE difference between the latitude of super 8 and 35mm, even when shooting the very same emulsion under the same lighting scheme. The more grain that the image is spread across, the more latitude it will have, to a point. Obviously, there is a point where both 8mm and 35mm would fall off to black but long before that point the 8mm image would be judged unusable, asthetically, while the 35mm image under the same lighting conditions would still exhibit usable shadow detail.

A good example of the power a difference in format size can make is when I shot my daughter's 5th birthday this weekend on a Pentax 6x7. I used some 800 ASA negative while other's around me used 35mm with the same ASA. The difference between the two formats was stunning. The 6x7 had a full range of grey scale in all tones while the 35mm counterpart (under the same light) was so contrasty that it looked like underexposed reversal in some shots. Amazing difference. Also, I have found that I can shoot motion pictures by available light far more often on 35mm than on smaller formats.

Of course, the trade off is that the larger the format, the less depth of field so there is sometimes the notion that larger formats are worse for low light because of the higher f-stop needed to maintain depth of field. However, the ability to use higher speed film without building up objectionable grain generally offsets this.

Roger

[Patrick]

I can recount an example from my experience too. A few years ago, I was photographing a waterfall in Canada near the Banff springs golf course. It was an awsome sight, even for a small waterfall - white, frothy water being churned out amidst the thunderous roar. The sun was shining nicely on the water and the rocky surroundings. With my 35mm Canon AE1 camera loaded with Fujichrome Sensia 100, I took a light reading from the mid-toned rock and got a few shots of the waterfall. My Canon 1014 movie camera was loaded with K40 and with this camera, I also took a light reading from the same rock and filmed a selection of shots of different angles and distances of the waterfall and the general surroundings.

After the slide film and movie film were both developed, the 35mm frames all showed good exposure in all areas of the image - the rock, the blue water and there was still nice detail recorded in the white water generated by the waterfall. With the super 8 frames however, the rocks and the blue water were correctly exposed but the white water was grossly overexposed and lacking in detail - washed out. Of course, this says as much about the difference in exposure latitide between Fujichrome Sensia 100 and Kodachrome 40 film stocks then about the expanded number of grains present in 35mm and super 8 film frames.