Is it .27 or .30 when figuring out a focal length - Which one do you use?

[jnantz]

sounds like your issue is that you think 50mm is the normal lens for 35mm film. it's not, 43mm is. 152mm=43mm, 175mm=50mm.

hi maltfalc

sorry to be a contrarian or seemingly problematic but while some folks go by the diagonal measurement to determine the "normal" lens, others just suggest whatever lens they use "normally" to give them the look they want. I have an uncle ( really he's my 2nd cousin once removed ) who did professional photography ( catalog work ) and his "normal" was something like a 210 shorter than that was too wide longer than that too narrow. maybe that's what's going on with EB ... ?

[maltfalc]

hi maltfalc

sorry to be a contrarian or seemingly problematic but while some folks go by the diagonal measurement to determine the "normal" lens, others just suggest whatever lens they use "normally" to give them the look they want. I have an uncle ( really he's my 2nd cousin once removed ) who did professional photography ( catalog work ) and his "normal" was something like a 210 shorter than that was too wide longer than that too narrow. maybe that's what's going on with EB ... ?

we're talking about equivalent focal lengths here. it's super common for people to mistakenly think 50mm is the normal for 35mm film. he specifically mentions normal lenses based on diagonals, the 4x5 normal lens being 150mm and being surprised that a 150mm lens looks wider than 50mm and that a 162mm lens doesn't look a touch longer than "normal"...

[EBJohnson]

sounds like your issue is that you think 50mm is the normal lens for 35mm film. it's not, 43mm is. 152mm=43mm, 175mm=50mm.

In fairness, I'm falling victim to the thing I'm calling out in the 150mm as "normal" argument for 4x5 and working off of those assumptions because that is what I've shot for over 20yrs... either way, per the numbers both "normals" are wrong, but are still used as.

Regardless, when I mount my 150 on my 4x5 it "feels" more like a 35mm than a 50mm... though it is closer to 40mm (per my arithmetic and judgement).

[Bernice Loui]

35mm being a 3:2 image ratio and 4x5 or 8x10 being a 5:4 image ratio does not direct translate to what is defined as a "normal lens".

Normal lens being defined as size of objects front to rear of the image perceived. Lens choice should be decided on image perspective then focal length needed to achieve this perspective in the print/image.

Typical "normal lens" for 4x5 would be 150mm to 210mm. Typical "normal lens" for 35mm still film would be 40mm to 60mm, but the aspect ratios are different.

Normal lens example, 40mm full frame digital (35mm, 3:2 aspect ratio), aprox diagonal Angle of view 57º. Note size of items in this image.




Wide angle lens example, 14mm full frame digital (35mm, 3:2 aspect ratio), aprox diagonal Angle of View 114°. Note size of items in this image (expansion).


Tele lens example, 300mm full frame digital (35mm, 3:2 aspect ratio), diagonal Angle of View aprox 8°. Note size of items in this image (compression).



Lens focal length should be driven by image perspective/size of objects "front to back" relative to how the "human eye" might see them in real time. Absolute focal length is not as important as lens/camera placement (height, distance to subject and LOTs more) which has a HUGE effect on the image being made.


Bernice

[Alan Klein]

If you're using a zoom lens, you wouldn't concern yourself with wide, normal or tele but what framing looks best. Then pick the lens that it works best with.

[Bernice Loui]

Zoom lenses can develop un-healthy habits due to their "lazy_ness" factor. Focal length alone should NOT be used framing-composition-perspective and what is and is not in focus, it is more a combo of lens/camera position + lens focal length + image recording lens aperture.

The overly common zoom lens on digital and 35mm film and lesser degree 120 roll film tends to develop the habit of being in one position then "zooming" as needed to "frame" the image. What should be done is know what the image needs to be, then figuring out lens/camera position + the lens focal length needed to achieve what was in mind. This begins to dip into personality types and how any given individual works the image making process. Essentially, not everyone can or have the ability to pre-visualize the image then apply the tools needed to make the image in mind.


Tends to favor fixed focal length lenses over zooms for digital and roll film cameras.
Bernice

If you're using a zoom lens, you wouldn't concern yourself with wide, normal or tele but what framing looks best. Then pick the lens that it works best with.

[EBJohnson]

If you're using a zoom lens, you wouldn't concern yourself with wide, normal or tele but what framing looks best. Then pick the lens that it works best with.

I mean... when I do use a Zoom lens, I 100% choose the lens based on where it's range falls within those guidelines...

[Oren Grad]

I learned from experience that the focal length that corresponds most closely to the way I see, and which serves best as a standard lens for me, is whatever I can get that's closest to 7/8 of the format diagonal. The exception is panoramic formats beyond a 3:2 aspect ratio, where I'm more comfortable with a focal length about 3/2 times the vertical dimension of the format. Operational definitions of "long" and "short" follow from that.

Of course, this isn't a universal rule. The point is to let your own pictures tell you what is right for you - pay attention to how you see and how your pictures come out.

[jnantz]

we're talking about equivalent focal lengths here. it's super common for people to mistakenly think 50mm is the normal for 35mm film. he specifically mentions normal lenses based on diagonals, the 4x5 normal lens being 150mm and being surprised that a 150mm lens looks wider than 50mm and that a 162mm lens doesn't look a touch longer than "normal"...

thanks !

like I said photography attracts all types of people. ... personally I don't even think I'd notice the difference between a 15O and 162 mm lens. but that's just me I'm oblivious... and im more interested in other things...

that said, good luck OP, EB and whoever else might be distressed
gotta do what makes you happy!
John

[maltfalc]

35mm being a 3:2 image ratio and 4x5 or 8x10 being a 5:4 image ratio does not direct translate to what is defined as a "normal lens".

Normal lens being defined as size of objects front to rear of the image perceived. Lens choice should be decided on image perspective then focal length needed to achieve this perspective in the print/image.

Typical "normal lens" for 4x5 would be 150mm to 210mm. Typical "normal lens" for 35mm still film would be 40mm to 60mm, but the aspect ratios are different.

Normal lens example, 40mm full frame digital (35mm, 3:2 aspect ratio), aprox diagonal Angle of view 57º. Note size of items in this image.




Wide angle lens example, 14mm full frame digital (35mm, 3:2 aspect ratio), aprox diagonal Angle of View 114°. Note size of items in this image (expansion).


Tele lens example, 300mm full frame digital (35mm, 3:2 aspect ratio), diagonal Angle of View aprox 8°. Note size of items in this image (compression).



Lens focal length should be driven by image perspective/size of objects "front to back" relative to how the "human eye" might see them in real time. Absolute focal length is not as important as lens/camera placement (height, distance to subject and LOTs more) which has a HUGE effect on the image being made.


Bernice

"normal" focal length equals image diagonal, regardless of ratio, period. that's what a normal lens is, that's what the term means. 152mm for 4x5 with a modern holder, give or take a mm depending on film holder variations. 43mm for standard 35mm cameras. crop factor is also based on diagonals, at least according to every camera manufacturer on earth.