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Lens crop and full frame equivalent flame
  • 40 Replies sorted by
  • vicharrisvicharris

    @artiswar+11111111111111 Yes, the first one who understands what the hell I'm saying and does not flame me off topic! And yep, you've probably opened a larger can of worms. Good luck with all these pro's with 40+ years of experience cutting you down! :)

  • artiswarartiswar

    @vicharris - I'm with you! All that it comes down to is that I can create my images for clients or myself much quicker than "sticklers". Either way, depth of field is going to be a bit different of you adjust lens length for matching FOV. For me, the difference in crop is minimal and many of my lenses achieve a nice middle ground between what I want, and referencing a certain aesthetic of a focal length. For example, my LOMO 28mm is one of my most used lenses along with a 14mm Lumix zoom. These hit pretty close to a 32mm and a 18mm on a RED, Arri, etc.

  • LPowellLPowell

    @vicharris

    This might be a dumb question but why the hell does everyone on all these boards compare every damn lens' focal length to full frame cameras?

    The reasons for this industry practice are largely historical. We're currently in a transition period marked by two major developments:

    1. The advent of digital still cameras: In the first generation of digital still cameras, the technology could not yet produce affordable digital sensors as large as the standard 35mm (full-frame) film cameras they were replacing. As a result, it was necessary for digital manufacturers to explain the lens FOV crop factors to ease the transition for still photographers. For example, Panasonic cites both inherent and "35mm equivalent" focal lengths in marketing its line of MFT lenses. Since a wide variety of photographic lenses are currently used to shoot DSLR video, the industry's full-frame comparisons are frequently used in video lens discussions.

    2. The advent of DSLR video: The first video DSLR to achieve widespread prominence was the Canon 5D MkII, which has a full-frame sensor. One of its most notable features was its ability to produce narrow DOF using relatively slow photographic lenses. Many in the industry associate this effect with DSLR video in general, and regard the 5D MkII as the default reference for DSLR video. As a result, full-frame comparisons are frequently used in video lens discussions.

  • vicharrisvicharris

    @LPowell Thank you very much for that response and understanding the post, which seems to be a little difficult for some to understand. And thank you for taking time gore the long statements. You're a gentleman and a scholar! @artiswar I'm doing the same thing. Going 1.5 and many of my glass is pretty damn closer to Red and Arri stuff. 24=35, 35= 52.4 and so on.

  • goannagoanna

    @Sangye

    Any cinematographer worth her salt should be familiar with the ratio of focal length to angle of view for the camera being used.

    Well, cinematographers working with one camera format do - but the rest of us only carry around a few benchmarks in our heads. When teaching media, if I told students to "set your zooms to a 50mm equivalent" we got lots of different FOVs, with people dashing around to squint into each other's viewfinders, gasp and come to me to ask which one's right.

    The reason why a change in jargon would be a wise thing now is that there isn't going to be a standardisation of sensor-size anytime soon.

  • MeierhansMeierhans

    Its all fine, no can of worms. This is just the kind of equation many are used to do, and in their mind they refer to FF. Refering to Arri or Super35 might make more sense, anyhow FF was chosen as reference once and adding a second reference won't make it easier..

  • sh1ggysh1ggy

    I think it is also important to mention that FF sensors don't have any crop at all, right? So in my opinion those comparisons do make sense, since the FF equivalent tells us what field of view a particular lens produces if it isn't cropped at all. To me it seems like a nice standard to compare with.

  • balazerbalazer

    What do you mean "doesn't have any crop at all"? A four-thirds sensor is not created by taking a full-frame sensor and cropping it. Sensors don't have crop. They just happen to be different sizes. We call them crop sensors because for a long time 35-mm was the standard in photography, and using a smaller sensor has the same effect as shooting with a full-frame camera and then cropping the resulting negative or print or digital image. "35-mm equivalent focal lengths" are just a frame of reference, for people who spent a lot of time in that one format. If you only deal with one format, the relationship between focal length and angle of view is constant, so people got lazy and started expressing angles of view as focal lengths. It's easy, because the focal length is printed right there on the lens, whereas the angle of view is something that you need to look up or calculate. But if you ever deal with more than one format, or if you ever crop, then the relationship between angle of view and focal length is not constant.

    A good first step would be for lens manufacturers to start printing the angle of view on the lens. Angle of view is an intrinsic property of every lens, just like the focal length or f-number. The lens's angle of view at least gives you an upper bound on the angle of view of the resulting images with any different camera, and a way to quickly estimate the angle of view using any particular camera.

    Don't confuse angle of view and field of view.

  • soundgh2soundgh2

    And to think at 5am every Monday morning after having a coffee with the loader and seeing which lens he'd popped on and guessing where I'd not be in shot, I should've got me calculator out ;p

  • SangyeSangye

    @balazer exactly what you said. And it would be great if manufacturers would print the angle of view on their lenses, together with the diameter of projection, so you can immediately know whether it will cover your sensor, and do a little math to figure out what angle of view it will have on your sensor.

    For example, a lens with a native 50 degree angle of view that projects a circle with a diameter of 40mm, will have a field of view that is approximately 25 degrees on a GH2.

  • RikerRiker

    I would agree wholeheartedly with @vicharris on this one and thank god I've found this thread, I thought I was the only one confused about the whole "full frame" calculations. Out of 270000 feature films listed on IMDB, 50 of them are shot full frame. 50. So this makes perfect sense.

    vic's logic makes perfect sense, at least on a forum like this one, which is really 99% about GH2's video mode.

    Just one thing, about going wide. When I say "wide" I think of 35mm eq of 25mm. That AOV is something I would consider wide. What lens would get that similar AOV in video mode on the GH2?

  • artiswarartiswar

    @Riker - The math is simple. If you like the AOV of a 35mm on a 135mm exposure area, divide the focal length by the crop factor. 35/1.86= ~18mm or so.

  • inqb8trinqb8tr

    @artiswar

    35mm on a 135mm exposure area

    You mean 135 film? No millimeters in it's name. Just 135 (or 120 for medium format etc). Just to prevent adding more mm's to the confusion :)

    @Riker

    I think of 35mm eq of 25mm

    It would be 25/2=12.5mm. So you need a 12mm prime lens, or wide zoom.

  • BurnetRhoadesBurnetRhoades

    @Riker "Out of 270000 feature films listed on IMDB, 50 of them are shot full frame. 50. So this makes perfect sense."

    How did you arrive at that number? 8-perf 35mm has been used internationally after VistaVision and Technirama were mothballed here, though they likely went under different branding.

  • MeierhansMeierhans

    GH2 has an oversized MFT sensor, so 1.86 is the right number. BTW, this turns a 28mm closer to "normal focal length" than a 25mm (52.08mm vs. 46.5mm). Anyhow I doubt one will really recognize the difference in a blindtest. ;-) And yes, its confusing if people doing motion pictures refer to a fullframe sensor. But thats the way it is, at least in my place. I doubt adding more parameters to the equation would make it easier. All I really need to know is the crop factor of the cam and the focal lenght printed on the lens. (If diameter of projection is to small you will recognize first time you plug this lens on you cam... hello C-Mount...)

    As rule of thumb just take original focal lenght by 2 and substract 1/10 of the focal lenght printed on your lens from your result. (f.e. 25mm * 2 - 2.5 = 47.5mm). This should be close enough. If you need to know more exact just half the last value in your equation and again substract it from your result (25mm * 2 - 2.5 - 1.25 = 46.25mm). As you can see we are only 0.25 mm away from the result the calculator spits out. I can do this in my head pretty quick unless its 6 in the morning and catering forgot about the coffee. ;)

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