Is there any functional differences between sensor/film sizes and their lens equivalents?

[mr cheese]

To lay the groundwork for this question, lemme get a few things off the table. There are the obvious crop-factor things to deal with, e.g. 35mm APS-C ~= 50mm Full Frame, and of course the quality/grain scaling mostly upwards (alongside cost) in film, sensor quality, and lens selection. 

 

What I'm trying to figure out is if, all other factors removed, "crop equivalent" lenses on different sized mediums produce the same depth, framing, and field of view. I want to invest in a 6x9 medium-format camera with a 50mm lens, which obviously could have the arguments made for the quality and resolution of medium format film over digital (especially since I shoot on an 18MP Canon 6D mk. I) but I'm wondering if I can get the same framing and depth with a 24mm (the crop-equivalent) wide angle lens on my 6D and save myself the money for the time being to experiment with the focal length and framing. I make up in my head that there are differences in depth of field and framing just because you are dealing with a physically larger medium but I do wonder if you get functionally the same exact image from both arrangements all other factors removed.

 

Sorry if this is confusing

[porina]

If you want the "same" field of view and depth of field, apply the crop factor correction to both focal length and aperture. Rounding numbers for simplicity, the medium format is near enough 0.5x crop factor. If we say it is a 50mm f/4 lens on that, you'd need a 25mm f/2 lens to match it on 6D. With wide angle field of view, depth of field isn't usually that big a consideration. If that doesn't matter then you might ignore that part of equivalence. 

[mr cheese]

1 hour ago, porina said:

If you want the "same" field of view and depth of field

Thanks for the info, I'm strictly trying to figure out what the major differences would be between two images taken on two different formats with equivalent lenses. DoF I guess isn't a consideration (this is gonna be a landscape setup anyway) but I'm wondering if there's fundemental differences in the frame or FoV between two formats using "crop-equivalent" lenses if that makes sense?

 

TL;DR I'm aware of the crop factor rule but what are the real underlying differences in the images, quality aside

[porina]

17 minutes ago, DaJakerBoss said:

Thanks for the info, I'm strictly trying to figure out what the major differences would be between two images taken on two different formats with equivalent lenses. DoF I guess isn't a consideration (this is gonna be a landscape setup anyway) but I'm wondering if there's fundemental differences in the frame or FoV between two formats using "crop-equivalent" lenses if that makes sense?

Crop factor is a quick way to compare two formats, especially when looking at focal length and field of view. If you ignore depth of field/aperture equivalence, then things affected by that are similarly affected, like diffraction softening. The other thing to note is aspect ratio. If the medium format in question isn't 3:2 then are you comparing one axis or diagonal for example.

[mr cheese]

1 hour ago, porina said:

Crop factor is a quick way to compare two formats, especially when looking at focal length and field of view. If you ignore depth of field/aperture equivalence, then things affected by that are similarly affected, like diffraction softening. The other thing to note is aspect ratio. If the medium format in question isn't 3:2 then are you comparing one axis or diagonal for example.

thankfully, my affinity for wide angle views has me looking at 6x9 so it's a direct 3:2 aspect relation which makes things easy. I guess in these cases the only significant differences are those inherent to the medium. I thought there was an actual difference in the resulting images outside of that, so I'll try to snag a cheap 24mm

[Blue4130]

The tonality will be different, but the image geometry will be similar. Don't get too hung up on lens equivalent though. It's a useless exercise. Use each format to its potential or why even bother having two systems.

 

I have a vast range of cameras from aps-c all the way up to 10 x12 inch ultra large format film. One thing I never do is try to make my digital Canon look like my 10 x12.

[Zodiark1593]

On 1/21/2023 at 12:45 PM, mr cheese said:

Thanks for the info, I'm strictly trying to figure out what the major differences would be between two images taken on two different formats with equivalent lenses. DoF I guess isn't a consideration (this is gonna be a landscape setup anyway) but I'm wondering if there's fundemental differences in the frame or FoV between two formats using "crop-equivalent" lenses if that makes sense?

 

TL;DR I'm aware of the crop factor rule but what are the real underlying differences in the images, quality aside

Quality, and depth of field, are the two primary differentials between film formats, assuming the same field of view. In fact, depending on the situation, you may find the larger format more difficult to work with, as landscape shooting often demands a deep depth of field, meaning you'll be reaching for some pretty slow aperture values. (It's not uncommon for Medium Format shooters to go F22 or slower)

 

Crop factor is pretty much a made-up value for the sake convenience.

 

For another interesting tidbit, the F value represents the focal ratio, or the quotient of the focal length, divided by the aperture diameter (in mm). Both focal length, and aperture diameter, influence the light allowed through. A longer lens requires a larger aperture diameter to achieve the same exposure, and vice versa. The F value serves to condense these into a single value that photographers can easily use.

 

However, depth of field is controlled by the aperture diameter, and distance to subject, but actually not by the focal length. F values being equivalent however, longer lenses have the larger apertures, giving the perception that longer lenses achieve shallower depth of field.

 

In the same vein, a larger format alone doesn't make for a shallower depth of field. However, it does increase the field of view for a given focal length. A 50mm F2.8 on a FF will have exactly the same depth of field as on a Medium Format (all else being equal). However, you're capturing a much wider field of view on Medium Format. To achieve the same composition requires a longer lens, and with it, a shallower depth of field (for the same F-value). This is what provides Medium Format with it's distinctive "look".

[wseaton]

Used to shoot macro work with my Mamiya 6x7 and extension tubes. While a royal pain sometimes having to sling a rig the size of an RPG through a field of flowers the results could be astonishing. 35mm has always been a toy format in my opinion.

 

Once films scanners got competent my combo of choice was Provia 100 (hand processed myself vs lab). 

 

I've shot pretty much every dSLR on the market, and nothing I've used matches those 6x7 Provia drum scans. Detail isn't the problem. Digital wins hands down. Digital wins when it comes to low noise detail as well. Where Provia wins out easily is high saturation gamut range, particularly reds and oranges. Medium format digital capture gets close with 48bit raw aquisition, but I've never come close with cropped sensor.

 

I've been griping for years that digital sensors need to dump RGB and opt for for four if not five sensor sites. Maybe go for 6 sensor sites with 4 devoted towards chroma and two for luma. Red needs to be split between 650nm and yellow, and cyan and deep blue (450nm) need their own sensor site. This would dramatically increase dynamic range and decrease the need for high color depths, which only help at the extremes anyways.

[mr cheese]

Spoiler

23 hours ago, wseaton said:

Used to shoot macro work with my Mamiya 6x7 and extension tubes. While a royal pain sometimes having to sling a rig the size of an RPG through a field of flowers the results could be astonishing. 35mm has always been a toy format in my opinion.

 

Once films scanners got competent my combo of choice was Provia 100 (hand processed myself vs lab). 

 

I've shot pretty much every dSLR on the market, and nothing I've used matches those 6x7 Provia drum scans. Detail isn't the problem. Digital wins hands down. Digital wins when it comes to low noise detail as well. Where Provia wins out easily is high saturation gamut range, particularly reds and oranges. Medium format digital capture gets close with 48bit raw aquisition, but I've never come close with cropped sensor.

 

I've been griping for years that digital sensors need to dump RGB and opt for for four if not five sensor sites. Maybe go for 6 sensor sites with 4 devoted towards chroma and two for luma. Red needs to be split between 650nm and yellow, and cyan and deep blue (450nm) need their own sensor site. This would dramatically increase dynamic range and decrease the need for high color depths, which only help at the extremes anyways.

I really want to shoot film, while I still think you can get close enough to a filmic look with Lightroom/DaVinci and a digital sensor I think MF is the one place where it makes sense to shoot film and get results unique to the medium. I've got my 6D mk I and I love it to death, but no matter how much I toy with my images I can't quite match Portra 400, and since I don't have $1k+ to spend on a FF mirrorless with higher sensor resolution, lower noise, and higher dynamic range, I'm gonna settle on a 6x9 Mamiya Super 23 since I can get those sub-$400 on eBay with a 50mm (24mm equiv in 6x9) and get quality 2:3 shots and even incredible resolution landscapes if I wanna adapt 35mm.

 

The original intent of this post was to establish if there was a noticeable-enough difference between a 24mm on FF and 50mm 6x9 on a MF camera, inherent film differences aside, which for my purposes there isn't much of, since in framing the images would be roughly the same. However, EF lenses for my 6D run easily $250+ on eBay used, relegating me to expanding my inventory of old film era lenses to afford the landscape views I want. At that price point, I'd rather, at least for now, invest in Medium Format as those images can be sharp, high resolution (for prints and for client photo-shoots where they agree to a film premium), and have that unique film look that takes far too long to replicate in digital tools on a digital sensor. At the cost of film (even though lately it's been steep) and scanning at my local darkroom (until I can invest in an Epson V600 and develop my own film, since my 20.2MP digital certainly won't be doing me well) I have a very large threshold before it would have made more sense to invest in a higher resolution full frame digital mirrorless camera.