lamiaceae Loc: San Luis Obispo County, CA

That is kind of the problem, it never should have been. One should learn the camera and lens(es) they have and master those before moving on to worrying about something they are likely not even using at the time.

John_F Loc: Minneapolis, MN

To me "crop" has always meant something 'thrown away.' As the optics equations show, it is only the angle subtended by the subject that changes as the 'sensor' dimensions changes. If the sensor dimension is d and the subject dimension is D, then D/d is the magnification factor which equals s/s' the distances of subject from len's front principle plane and rear principle plane. 1/s' = 1/f - 1/s we find D/d = s/f - 1, where f is focal length. It is but a few algebraic steps from the angle of view, adduced from D/s by the tangent law. What this means is that a scene width of D gets captured on a sensor of lesser width than 36 mm. But you do not 'lose' subject width which is what 'crop' implies.

ecurb1105

I shoot my 35mm f1.8 DX lens on my D600 in full frame mode and I like it. Mine covers the ff field with delicious vignette fall off in the corners. In the manner of the old 2.1 cm Nikkor.

BebuLamar

But obviously you do not have the same angle of view as if you use the 35mm FX lens.

Booker

I guess I'm an "old geezer." When I first converted to digital, I found the 1.5 factor useful and still think in those terms.

BebuLamar

I am an old geezer too but when I bought the Nikon Coolpix 5000 there is no crop factor listed for it. When I get a DSLR I bought an FX camera so there is no crop factor either. Actually this is the most important reason I bought an FX camera because there is no crop factor and all my lenses I bought for my film SLR works exactly the same way on my DSLR

ecurb1105

Correct. Every format has its own requirements. If you're shooting a view camera, you have to understand image circle as well. Thats an area often lost in the whole crap factor discussion. One of the first things I did as a photographers assistant, in 1971, was make a chart of camera formats and lens equivalents, 8x10, 4x5, 6x7, 6x6 and 35mm. Aspect ratios had to be considered as well.

BlackRipleyDog

Nikon made this exact same assertion about "reach" on the back page of the D300s brouchure when a wildlife photographer referred to it in his gushing blurb along with a photograph of him hanging out the window of a aircraft. The implication was obvious.
The sensor size does not change the optics of any lens.

ecurb1105

Yes, field of view is same as I am using the full frame, not DX mode.

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

You're clearly not a farmer or gardener....

BebuLamar

The vignetting narrows your field of view.

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

To paraphrase Stormy Daniels: Define 'old'! (See Jimmy Kimmel interview where she said "Define true")

If it helps you, then it is a good thing, but the issue is about conveying information in a useful way. That usually involves both the people providing information and the people receiving information. It is about a frame of reference. If your mindset is based on 35mm film, then the 'crop factor multiplier' may be useful. If your mindset is based upon a different experience then it may not be of any value at all. As others have accurately said, a lens is a lens, and each lens has a fixed focal length value or a range in the case of zooms. It is the camera sensor size (or film size) that is changing, and some users seem to have difficulty in adapting their mindsets or frames of reference.

So is the problem the lens focal length, what information is printed on the lens, the camera, the vendor information, or the person behind the camera?

I suspect that we all know the real answer.

Bobsphoto

Sounds like some "older" folks in this discussion. I am one of those and grew up with the concept of film size and lens lengths. But it was not just 35mm. There were a variety of cameras and films, ranging from the 110 or smaller to medium and large format, and the lens designations were also varied. While 50mm lens was normal for 35 mm film, it was wide angle for larger formats, and telephoto for small. But we did understand what normal meant in relation to the film size. Perhaps the designations or normal, wide and telephoto are not really relevant anymore. Resolution, or the quality of the image when printed, was related to film size and speed or ISO. (Anyone remember ASA for film speeds?)

I have a good Nikon compact zoom camera that I often use for hiking and other mobile activities. I accept its limitations and value its flexibility. I understand what the zoom ratio means in practical terms, but use no gray cells trying to figure out where in that focal length range is normal.

Younger folks growing up in the digital age are not burdened with those memories. They are used to the new language. Instead of film size, we talk sensor size, which probably really means resolution. Perhaps what confuses us is that we get different sensor sizes in the same SLR style camera body, so our thinking tries to translate from film to digital. I have never thought much about "crop factor". The type of photography I do lends itself to using zoom lenses, but that is me. Regardless of fixed or zoom, the key to good photography is to use the lens that works for what you are doing. When you think about it, that was true with film.

amfoto1 Loc: San Jose, Calif. USA

Your first point is incorrect. There were many different formats during the film era, too. Personally I used 35mm SLRs (24x36mm image, which was originally called "miniature format"), medium format TLR, rangefineders and SLRs (60x45mm and 60x70mm image), and large format "view cameras" (4x5 inch, or approx 100x125mm image). Now in my collection of vintage cameras I also have "half frame" (18x24mm on 35mm film), "spy" cameras using 14mm and 17mm wide film (images approx. 8x12mm), "APS" or "Advanced Photo System" (16.7x30.2mm image on 24mm wide stock), "110 Instamatic" (16mm wide film, image 14x17mm), "126 cartridge" (26.5x26.5mm image on 35mm wide stock), unperforated 35mm (image 30x36mm) and more. There are many others... See https://en.wikipedia.org/wiki/Film_format

What you may not be aware of is that much roll film for still cameras started out as movie film.... long rolls 70mm wide. That's simply respooled in shorter lengths for "medium format", most of those use the full 70mm width. "Miniature" roll film that came to be known as 35mm was simply the same film split down the middle. Later "Hit", "Minox" and other "spy" camera 17.5mm 17mm and 16mm sizes were 35mm split down the center once again. In fact, common 16mm movie film was created the same way, while for 8mm movie film it was split lengthwise once again.

Blame Kodak to a large extent for the vast number of different film types. They deliberately designed and patented cameras to require unique patented films that required special rolls that only they offered or that they licensed to other manufacturers. For example, there are dozens of different film types that use full 70mm width roll film.... but use different size spools or other slight variations done deliberately so that Kodak could patent the design, control manufacture and profit from it. Early on Kodak even controlled much of the film processing and printing. It also gave them a means to encourage user upgrades due to forced obsolescence. Their final attempt to use this market strategy with film was the APS format, introduced in 1996 and lasting about 8 years, due to that rapid dawning and development of digital.

We actually had to do "lens factor" calculations back in the days of film, too... My 35mm SLRs used a 50mm "normal" lens, while my medium format cameras used 75mm and 90mm lenses (6x4.5cm and 6x7cm, respectively) and my large format's "normal" was a 180mm lens.

I do partly agree with you... folks who never used film, aren't making a transition from one format to another so don't need to figure out "equivalent lenses", and are simply looking to buy a DSLR don't really need to get into all this discussion of "crop factors". They just need to know what constitutes "wide", "normal" and "telephoto" on their particular camera. The problem is that there are a lot of different digital sensor formats, too. In addition to "APS-C" and "full frame" (both of which are somewhat ironically based upon film formats), there are also moderately large "APS-H" (another film reference), smaller m4/3 and 1", and ridiculously small 1/2.3", 1/2.7"... as well as "medium format" digital (once again, a film format reference). Depending upon the user, "crop factor" calculations can be important. But probably for a lot of users it's just unnecessary confusion.

srt101fan

Rich, I think I agree with you almost 100%.

Trying to wrap my “crop” brain around this issue leads me to the following regarding practical applications of “crop factors”:

(1) With my 35mm film SLR, I knew roughly the angle of view I would get from my lenses and selected them accordingly. When I migrated to a “crop sensor” Nikon DSLR, I found the equivalency numbers based on the “crop factor” very helpful. For example, if I wanted to get the angle of view I was getting with my SLR camera and 28 mm wide angle lens, I would need a 19mm lens on my Nikon DSLR. I wouldn’t call these equivalency numbers a “crutch”; maybe more of a “transition aid” in going from film to smaller-sensor digital cameras. But this applies only to long-term film shooters with pre-visualization anchored to lenses used with 35mm cameras. As time goes by, there will be fewer and fewer of us old geezers and less and less of a need for this equivalency aid.

(2) “Crop factors” may be significant in assessing the difference in images when you use a lens designed for a crop-sensor camera (e.g., Nikon DX) on a full-frame camera, or a lens designed for a full-frame camera (e.g., Nicon FX) on a crop-sensor body. I’m not sure I understand all of that, but I don’t really care, since I only have a crop-sensor Nikon DSLR and Nikon DX lenses made for these bodies.

(3) Most everything else addressed in the responses to your post seem to be technical aspects of optics and lens design that may be of great interest to some but would seem to have limited practical application in the pursuit of photography as a hobby.

What am I missing?