Does medium format have a negative crop-factor?

[HeWandersAround]

Forgive the probably dim question, but I was just thinking - I'm used to doing the maths in my head for my MFT (2x), my APS-C (1.6x) and not having to do any for my full frame (hoorah!), but then, going by that pattern... do medium format cameras have a crop factor that takes the focal length down?

For instance, is a 25mm medium format lens actually 25mm, or is it (for eg.) 20mm when you take the sensor size into account?

 

[grsnovi]

On MF, an 80mm is approx. = to a 50mm on 135 (aka. FF).

 

[HeWandersAround]

On MF, an 80mm is approx. = to a 50mm on 135 (aka. FF).

Ah, interesting, thank you!

 

[robert1955]

Really

 

[tbcass]

Forgive the probably dim question, but I was just thinking - I'm used to doing the maths in my head for my MFT (2x), my APS-C (1.6x) and not having to do any for my full frame (hoorah!), but then, going by that pattern... do medium format cameras have a crop factor that takes the focal length down?

For instance, is a 25mm medium format lens actually 25mm, or is it (for eg.) 20mm when you take the sensor size into account?

A 25mm lens is always 25mm regardless of the sensor format. You are talking about field of view. A 25mm lens on a MF camera will have a wider field of view than on a Full Frame camera. Personally I think we should be using field of view instead of crop factor.

As a side note this was switched from the Open Talk forum to the Medium Frame forum while I was composing my answer. That's a first. Write while in Open Talk and post while on Medium Format. This is my first and possibly last post in this forum.

--
Tom

 

[SrMi]

On MF, an 80mm is approx. = to a 50mm on 135 (aka. FF).

On MF, an 80 mm is approximately 63mm in FF (per Hasselblad brochure).

The horizontal factor is 1.22, and the vertical factor is 1.38. Typically, factor 1.25 is used to "translate" an MF focal length to FF focal length

P.S.: I am talking about the corresponding FOV, as focal length does not change.

 

[David Kieltyka]

Multiply the focal length of a lens used with a 44x33mm sensor ("medium format") by 0.79 to get the approximate 35mm format equivalent. Note: focal lengths don't change with sensor size but coverage does. The bigger the sensor (or film format) the wider the coverage for a given focal length.

Example: my Pentax 75mm lens used on a Pentax 645z camera with its 44x33mm sensor gives me coverage equivalent to a 59–60mm lens used on a "full frame" camera.

-Dave-

 

[grsnovi]

...instead of equipping your MF with a 50mm "standard" lens, you will more likely get an 80mm lens as your "standard".

Both my 645 and my 6x6 have 80mm lenses.

 

[dbateman]

Forgive the probably dim question, but I was just thinking - I'm used to doing the maths in my head for my MFT (2x), my APS-C (1.6x) and not having to do any for my full frame (hoorah!), but then, going by that pattern... do medium format cameras have a crop factor that takes the focal length down?

For instance, is a 25mm medium format lens actually 25mm, or is it (for eg.) 20mm when you take the sensor size into account?

--
HeWandersAround
Come join me on BlueSky? - https://bsky.app/profile/hewandersaround.bsky.social

You actually have two questions here.

First is about field of view and second is about medium format.

For the first, all medium format cameras have a field of view multiple less than 1 to be equivalent to the field of view for a 135 (full frame) camera.

Second question is there isn't just one sensor size for medium format. Most here use the 44x33mm digital sensor. Some use 56mmx56mm film, some 7x6 format, others around these sizes. So there isn't a specific medium format field of view factor, it depends on the final capture size.

 

[Doppler9000]

Forgive the probably dim question, but I was just thinking - I'm used to doing the maths in my head for my MFT (2x), my APS-C (1.6x) and not having to do any for my full frame (hoorah!), but then, going by that pattern... do medium format cameras have a crop factor that takes the focal length down?

For instance, is a 25mm medium format lens actually 25mm, or is it (for eg.) 20mm when you take the sensor size into account?

You actually have two questions here.

First is about field of view and second is about medium format.

For the first, all medium format cameras have a field of view multiple less than 1 to be equivalent to the field of view for a 135 (full frame) camera.

Second question is there isn't just one sensor size for medium format. Most here use the 44x33mm digital sensor. Some use 56mmx56mm film, some 7x6 format, others around these sizes. So there isn't a specific medium format field of view factor, it depends on the final capture size.

This!

 

[Stan Disbrow]

Hi,

Yep. Medium Format covers everything between 24x36mm and 4x5 inches.

And film is still as valid as digital. Heck, the digital cameras are often used as scanners for film.

But the bulk of the medium formats are the ones which used the 120 film, which is 6cm wide. But it gets a little confusing with the image area since some of the roll film width is used by the film rails.

Anyway, the bulk of the digital sensors revolve around the 645 size systems. And those systems have lenses designed to go with. And now the most common size sensor is 44x33mm and we have a crop factor to think of again with those lenses.

So we had the Normal lenses as 75mm or 80mm but the smaller size of the sensor means Normal is now more like 63mm. Which explains the Fuji GF 63.

Stan

 

[Rand 47]

Forgive the probably dim question, but I was just thinking - I'm used to doing the maths in my head for my MFT (2x), my APS-C (1.6x) and not having to do any for my full frame (hoorah!), but then, going by that pattern... do medium format cameras have a crop factor that takes the focal length down?

For instance, is a 25mm medium format lens actually 25mm, or is it (for eg.) 20mm when you take the sensor size into account?

For a rough equivalent, the factor is 0.79

Rand

 

[NAwlins Contrarian]

Forgive the probably dim question, but I was just thinking - I'm used to doing the maths in my head for my MFT (2x), my APS-C (1.6x) and not having to do any for my full frame (hoorah!), but then, going by that pattern... do medium format cameras have a crop factor that takes the focal length down?

For instance, is a 25mm medium format lens actually 25mm, or is it (for eg.) 20mm when you take the sensor size into account?

For the math-averse and/or hazy on specification history, here's a little chart with the crop factors for a bunch of common digital sensor and film sizes. These factor apply both to equivalent focal length and equivalent aperture (f-stop). To covert from 35mm or 'full frame' to the equivalent in some other size, you divide by the crop factor; to convert from some other size to full frame, you multiply by the crop factor.



Some notes

* Obviously when the two sizes don't have the same proportions, the effective crop factor changes depending on the proportions of the final use of the photo.

* The 'average' crop factor is based purely on the diagonal. It only applies to final uses equi-proportional to the two capture sizes. That condition is met when printing borderless on ISO paper sizes like A4 and A2 and comparing 3:2 captures like full frame with 4:3 captures like GFX.

* Many full frame cameras are a hair smaller than nominal than FF. For example, this site reports that my Sony A9's sensor, or at least the normal effective image capture area, is 35.6 x 23.8 mm. That's about a 1% difference. Likewise, among 'APS-C' sensors, even in the same brand, they vary slightly. As a practical matter, you can probably ignore this.

* Some film sizes were standardized more than others. Most '645' film was 56x41.5, but IIRC some Pentaxes were 56x42mm. So-called 6x7 film was mostly 56mm on the short side, but varied somewhat on the long side. The 69.5mm that I used is the specified size for the camera I really wanted, the Mamiya 7-II.

 

[SeeingSomeThingsMissingMany]

If digital certainly a negative crop on our wallet.

I was looking at Hassy H6D 100C which at approx £$7K body only used 2nd hand ain't too bad for a 53x40 sensor approx X0.65 fov compared to 35mm.

--
Photography after all is interplay of light alongside perspective.

 

[DavidMillier]

The term "crop factor" is fascinating in the way that it has taken on a life of its own way beyond its original meaning.

It started as a term when DSLRs first became consumer products. The original models aped the form factor of 35mm film SLRs, used the same mounts and lenses but used sensors smaller than 35mm film. It made sense to think of such cameras as being 35mm film format with a smaller 'cropped' sensor.

I suppose the rationale for this is at the time the 35mm format was easily the most common in use and more people had memorised the range of focal lengths used for different fields of view with this format. Early digital came in a variety of sensor sizes and no one wanted to bother to memorise all the focal lengths for each particular sensor size. So using 35mm as a common reference with a multiplier allowed you to calculate the equivalent focal length for any sensor size as long as you knew the relevant "crop factor" multiplier.

But it stopped making sense as soon as manufacturers started to bring out new mounts and lens ranges dedicated to the sensor size they use.

For example 4/3 sensors were launched as a dedicated range of cameras with their own sensor size, their own mount and their own range of lenses designed to that sensor. 4/3 and the successor m43 were never in their history a crop of anything, but they are still labelled as "crop sensor" cameras in a way that diminishes the format.

This makes as much sense as calling 126 or 110 film "crop film". Likewise saying that a sensor that is larger than 35mm should be called a 0.79 crop sensor is ludicrous.

The original use of the term "crop" made sense in a temporary way; the continuing use of "crop" makes no sense at all. What it does do is put the 35mm format on a pedestal, gives it a special "Full frame" status, makes it seem as if somehow 36x24mm is a "natural", "normal" size for a film or a sensor, and everything else is a crop (or a fractional crop in the case of medium format) of the perfect, mythical "Full frame" format.

Very annoying historical development.

 

[robert1955]

I suppose you are a micro 4/3 user?

 

[Stan Disbrow]

Hi,

Well, yes. 24x36mm *is* the natural size. At least for a long time. This comes from Kodak. They used, save for two models, film camera bodies which were of the 135 format and grafted their digital backs onto them.

Kodak set all this up for years, make that decades, before anyone else decided to play. And then the others did the exact same thing. Smaller digital sensors inside what was essentially a 135 format film camera.

The two Kodak models which were different used Nikon Pronea 240 format film bodies. So, they were APS-C film cameras with APS-C sensors and their own APS-C lenses.

Nikon and Fuji did something odd to begin with. They used internal relay lenses to force a 135 lens image onto a smaller sensor and so no crop factor. It stunk.

Stan

 

[DavidMillier]

I suppose you are a micro 4/3 user?

2/3" sensor, 1" sensor, 4/3" sensor, 1.7x "crop" Foveon sensor, APS-C sensor, 35mm full frame sensor, 44x33mm sensor user, it depends what I'm doing. No allegiance to any particular sensor format.

 

[Stan Disbrow]

Hi,

Right now, in use here are APS-C (microscope), APS-H (copy stand), Full Frame and 44x33mm MF. And I am used to how they all work that I never think of Focal Length Multipliers....

Stan

--
Amateur Photographer
Professional Electronics Development Engineer

 

[SrMi]

Hi,

Right now, in use here are APS-C (microscope), APS-H (copy stand), Full Frame and 44x33mm MF. And I am used to how they all work that I never think of Focal Length Multipliers....

Stan

I use everything from m43 to "superMF," but because of my long usage of FF, I always translate to FF focal lengths to imagine the FOV.