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Full Frame 35mm VS APS-C


Jules Le Masson Fletcher

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Hi all,

 

So I'm running into a little problem, and am a little confused. Basically, I'm having trouble choosing between a FF 35mm DSLR (Canon 6D) versus APS-C DSLRs (Canon Rebels, Canon 7D). I'm very inclined into choosing the Full Frame format because of the of the 35mm mount lenses and the distortion factor problems with cropped sensors. But I'm still not sure, because, as I'm trying to match the film look, the S35mm format rings in my head and I get confused. What would be closer to what I want? Keeping the APS-C sensors size? or upgrading to FF?

Please excuse if my question seems ignorant to you, I'm only 17 and still in my first years as a student.

 

Thanks for your feedback,

 

- Jules.

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APS-C is closest to the size of Super-35 cinema / 3-perf 35mm (approx. 24mm x 13mm); Full-Frame 35mm is closest to the 8-perf 35mm VistaVision format (36mm x 24mm). So the focal lengths used in APS-C for typical field of view would be the same if shooting in Super-35, and if you used any PL-mount cine lenses, they would be designed to fill the APS-C sensor area, not the FF35 sensor area.

 

APS-C sensors vary in size from 20.7mm × 13.8 mm to 28.7mm × 19.1mm. The Canon 7D sensor size is 22.3mm x 14.9mm.

 

Generally the only difference in "look" is the typical depth of field because the larger sensor sizes use longer focal lengths to achieve the same field of view. Once you had matched field of view by using a lens that was about 1.6X shorter on an APS-C camera, you'd have to stop down a FF35 lens by 1.6-stops to match the depth of field. So FF35 cameras tend to produce a shallower focus look; however, they also tend to be more sensitive in low-light and thus it's not hard to rate them faster and stop down for more depth of field to compensate.

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My only real opinion on this revolves around the problematic nature of focus pulling on big sensors.

 

If you want to set up shots which use depth of field, which is currently fashionable and in any case always a nice choice to have, you will almost by definition be putting yourself in a situation where focus pulling matters.

 

Focus pulling HD video on 2/3" video cameras is difficult.

 

Focus pulling on 16mm film, micro four-thirds video, or something like a Blackmagic cinema camera, is very difficult.

 

On 35mm, APS-C or similar sensors, it's so hard they usually employ someone whose sole job it is, and give him a lot of time and technology to get it right, and still expect to blow one take in three when it gets particularly taxing.

 

On full-frame DSLRs, Vistavision, 65mm, or equivalent, focus pulling is a sort of Zen meditative pursuit that's been known to drive people completely underside pumpernickel intrinsic caboose caboose rumplestiltskin.

 

No, you don't want a full frame DSLR.

 

P

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  • 2 months later...

 

Once you had matched field of view by using a lens that was about 1.6X shorter on an APS-C camera, you'd have to stop down a FF35 lens by 1.6-stops to match the depth of field.

 

David, could you please explain how f stop and crop factor are related in a linear fashion. I am having a lil' confusion on that.

Thanks..

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I don't think I can give a full explanation, it's just a short cut to figuring it out that works.

 

Let's say we are talking about a 2X difference instead of 1.6X, to make the math easier.

 

Look on a Depth of Field chart and compare a 25mm lens to a 50mm lens focused at 7'. At f/8 on the 50mm, the depth of field is 6' 0" to 8' 5".

 

To get that same range on the 25mm at 7', you'd have to shoot at f/2.0. That's a 4-stop difference. But if you put that 25mm on a format that was half was wide as the one with the 50mm, to match the same field of view at 7', you wouldn't be able to use the same Circle of Confusion figure to calculate the depth of field because on the format that was half the size, the Circle of Confusion would be twice as critical once the image is blown-up to match the larger format. So that 4-stop difference between the 25mm and 50mm would be reduced to a 2-stop difference if the 25mm is on a format that is half the size.

 

So it works out that a 2X crop factor equals a 2-stop difference in effective depth of field once you match field of view and distance by using a focal length that is half as long on the format that is half the size.

 

I once measured the difference in depth of field between 2/3" video and Super-35, which is a 2.5X crop factor... and guess what? Once I used a lens whose focal length was 2.5X shorter on the 2/3" camera compared to the one on the Super-35 camera, and set the distance to be the same, I was able to match depth of field more or less when I stopped down the Super-35 camera by 2.5-stops.

 

So it just works out that the crop factor is the same as the effective difference in stops you need to adjust to match depth of field more or less, though this assumes the same display size for the final product no matter what the origination format is. It's not a scientific explanation though and probably modern depth of field calculators may give you different results but this rule of thumb works for all practical purposes.

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  • 4 months later...

This discussion has been really helpful to me. However, I'm a bit confused about when people refer to specific field of views for different focal lengths for still photography and motion picture photography.

 

For instance, if I'm shooting on a 50mm lens on a cropped body sensor, it would give me the field of view of an 80mm lens. Is this the same case for using cinema lenses on super 35mm film? If so, would this mean when a still photographer talks about the field of view that a specific focal length produces on a 35mm still camera he/she is referring to something different than a cinematographer shooting on a super 35mm motion picture camera?

 

Maybe another way of asking my question is: is there any difference in the field of view between a 50mm cinema lens and a 50mm still lens? Do cinematographers need to have wider lenses than still photographers to produce shots with a wide field of view?

 

Additionally, when Bresson says that he used 50mm lenses, does he mean they actually had the field of view of an 80mm lens on a full frame sensor or does he mean that they had the field of view of 50mm on a full frame sensor?

 

Sorry if I asked the same question four times. I was just trying to make it as clear as possible. Thanks.

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A 50mm is a 50mm is a 50mm. Doesn't matter if it is on a Super-8 camera or an IMAX camera, it's still a 50mm. One has to stop thinking of these focal lengths as having a specific view outside of the size of the target area that the image is projected onto. Even on a FF35 camera, the image projected from a 50mm lens is "cropped" -- it's cropped from a circle to a rectangle.

 

Yes, a still photographer generally is referring to the field of view of certain focal lengths on a FF35 camera, whereas most cinematographers think of the field of view of certain focal lengths in regards to the Super-35 frame, what still photographers used to call a "half-frame" (4-perf instead of 8-perf.)

 

Bresson used a FF35 still camera, 8-perf 35mm horizontal, with a 50mm lens... you'd need to use something more like a 32mm lens on a Super-35 camera to get a similar field of view.

 

Stopping thinking of it as "a 50mm becomes an 80mm on a cropped camera" because that just leads to confusion. A 50mm stays a 50mm on any camera. It just has a narrower view on a smaller format. Or to put it another way, the 50mm has a more telephoto image on a smaller format, a wider-angle image on a larger format. But it is still a 50mm.

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  • 2 months later...

Sorry to necropost but sort of a thread of interest for me.

My only real opinion on this revolves around the problematic nature of focus pulling on big sensors.

 

If you want to set up shots which use depth of field, which is currently fashionable and in any case always a nice choice to have, you will almost by definition be putting yourself in a situation where focus pulling matters.

 

Focus pulling HD video on 2/3" video cameras is difficult.

 

Focus pulling on 16mm film, micro four-thirds video, or something like a Blackmagic cinema camera, is very difficult.

 

On 35mm, APS-C or similar sensors, it's so hard they usually employ someone whose sole job it is, and give him a lot of time and technology to get it right, and still expect to blow one take in three when it gets particularly taxing.

 

On full-frame DSLRs, Vistavision, 65mm, or equivalent, focus pulling is a sort of Zen meditative pursuit that's been known to drive people completely underside pumpernickel intrinsic caboose caboose rumplestiltskin.

 

No, you don't want a full frame DSLR.

 

P

You wouldn't happen to be a focus puller would you? :D I get that focus pulling is hard but as David said you can stop down and up the ISO on something like a 5D Mk.III or D800....ISO 6400 on those cameras is pretty dang clean...besides focus pulling doesn't HAVE to be hard, I mean sure if you have some crazy shot where the camera operator and focus puller are on a track following a fight sequence moving back and forth with a one shot deal exploding car while using a 24-290 wide open at T/2.8 simaltanously doing a hitchcock zoom then yes you might just want to jump off a bridge or rent an Epic/Scarlet for the day :)

 

 

but I mean a full frame DSLR isn't that bad, the first time I used one I remember being at 28mm ƒ/4 and thinking "Holy crap this looks allot more than ƒ/4".

 

Maybe you or David could correct me but I think if you wanted to go for an anamorphic look without anamorphic glass you'd be a step ahead of APS-C/Super35 sensor cameras since you have 36mm horizontal which comes closer to 22mm 2x (for 2x anamorphics on Super35) vs 22-28mm APS-C shooting flat...Correct me if I'm wrong but the part I mentioned about anamorphic being 22mm x2 would mean that anamorphic 35mm has the equivelent DoF of a sensor/film plane that is 48mm horizontal? It would seam correct since a 2x 100mm anamorphic has the horizontal view of a 50mm but vertical view of a 100mm.

 

A 50mm is a 50mm is a 50mm. Doesn't matter if it is on a Super-8 camera or an IMAX camera, it's still a 50mm. One has to stop thinking of these focal lengths as having a specific view outside of the size of the target area that the image is projected onto. Even on a FF35 camera, the image projected from a 50mm lens is "cropped" -- it's cropped from a circle to a rectangle.

 

Yes, a still photographer generally is referring to the field of view of certain focal lengths on a FF35 camera, whereas most cinematographers think of the field of view of certain focal lengths in regards to the Super-35 frame, what still photographers used to call a "half-frame" (4-perf instead of 8-perf.)

 

Bresson used a FF35 still camera, 8-perf 35mm horizontal, with a 50mm lens... you'd need to use something more like a 32mm lens on a Super-35 camera to get a similar field of view.

 

Stopping thinking of it as "a 50mm becomes an 80mm on a cropped camera" because that just leads to confusion. A 50mm stays a 50mm on any camera. It just has a narrower view on a smaller format. Or to put it another way, the 50mm has a more telephoto image on a smaller format, a wider-angle image on a larger format. But it is still a 50mm.

 

I think this post should be stickied. I don't think people had this issue when they shot on Super16 or Super8 but then again I never shot on those formats when there was not digital around. Regardless I think it would be weird if for example Zeiss DigiPrimes put a FF35mm or S35mm equivelent on the barrel unless they already do that and I'm crazy. Generally speaking what I would use as a basis is whatever the diaganol size of the sensor is in milimeters should be the approximate "normal" lens on the format no?

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APS-C is already about the same size as Super-35. Anamorphic 35mm has less depth of field because the lenses have double the horizontal view so you'd have to use a focal length twice as long to get the same horizontal view as a spherical lens in Super-35. So to get the shallower depth of field of anamorphic while using spherical lenses, you'd either need to use really fast lenses or go to a larger format like Full-Frame 35mm.

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APS-C is already about the same size as Super-35. Anamorphic 35mm has less depth of field because the lenses have double the horizontal view so you'd have to use a focal length twice as long to get the same horizontal view as a spherical lens in Super-35. So to get the shallower depth of field of anamorphic while using spherical lenses, you'd either need to use really fast lenses or go to a larger format like Full-Frame 35mm.

 

Comparing anamorphic to Super 35 (or FF35 for that matter) is often limited to their horizontal FOV context but it's really the difference in vertical FOV that matters in this case, no? Because anamorphic uses the full sensor/negative height you're always closer to a subject with anamorphic, at a closer focus distance, than you would be on the same lens in a Super 35/APS-C situation. DOF is usually a factor when filming people and this has more of a vertical context. Once you're framed vertically for a CU or MCU or Medium shot your extra width becomes more of an aesthetic concern than a technical one.

 

Anamorphic 35mm is effectively a larger format than FF35 if you're masking the spherical footage to a "scope" aspect ratio. I think that aspect is largely overlooked when folks try to decipher its aesthetic.

Edited by Sean Cunningham
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