flyboy61 Loc: The Great American Desert

I am confused! I am looking to buy a Nikon DX 35mm f/1.8 lens. I have always been under the assumption that 35mm is 35mm...a mild wide angle lens. The exception is an FX lens on a DX camera, where the smaller APS C sensor size, using the central portion of the lens' coverage circle, gives an equivalent angle of view of about 52mm.

I see statements..."35mm is the new 50", and the information printed with the lens description;"52.5mm 35mm equivalent".
I've been of the opinion that nobody that knows anything uses a DX lens on a FX or 35mm film camera, due to extreme vignetting. It seems to me that a 35mm lens, designed for the FX sensor or film should give a 35mm angle of view, while a 35mm lens designed for the APS S sensor should do the same. Where is the error in my understanding?

BobPeterson Loc: Massachusetts

Even a 35mm DX lens on a DX camera has the same field of view as a 52 on a FX camera. The 35mm is distance to focal plane it is not a measurement of the width of the lens. Some DX lenses will work on some FX cameras with very little vignetting.

CHG_CANON Loc: the Windy City

Keep in mind, most (all?) Nikon full-frame DSLRs and MILCs will detect a Nikon-brand DX lens and crop the resulting image. So, there is no evident "extreme vignetting". Also, for a high megapixel camera like the 45MP D850, that 1.5 DX crop factor yields a 19MP image, maybe useful when a current DX camera like the D500 yields 20MP images.

You didn't identify the fool making statements about 35 is the new 50, so we can't identify the context of the statement. If you shoot a cropped sensor camera with a 1.5 crop factor (Nikon / Sony) or 1.6 (Canon), the 35mm lens is the equivalent field of view of a 50mm ish full-frame lens. But, the focal length is still 35mm.

To your confusion, your final two sentences:

It seems to me that a 35mm lens, designed for the FX sensor or film should give a 35mm angle of view, while a 35mm lens designed for the APS S sensor should do the same. Where is the error in my understanding?

A 35mm lens designed for the APS S sensor still experiences that crop factor. The lens is 35mm focal length, just like it says on the side of the lens. It's the sensor's crop factor that causes the equivalent field of view yielding images that seem 35mm x 1.5 = 53mm.

R.G. Loc: Scotland

If you keep the focal length the same but change the sensor size, how much you see (the angle or field of view) will change - the field of view is wider for a larger sensor, narrower for a smaller sensor. And don't forget that a DX lens will not give full sensor coverage on a FF camera.

Bill_de Loc: US

One thing you should know about this lens.
It is incredibly sharp!
If the 'equivalent' focal length works for you, you won't regret the purchase.

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DirtFarmer Loc: Escaped from the NYC area, back to MA

That is an option in all the Nikon bodies I have. It can be turned off, but the factory default is ON.

BobPeterson Loc: Massachusetts

No option to turn it off on the z full frame cameras.

BebuLamar

While a 35mm lens is a 35mm lens it's not always a mild wide angle lens. It's about normal for APS-C and a telephoto for M4/3. The 35mm is focal length and not angle of view of the lens (or more accurately angle of coverage. The angle of view depends on both the angle of coverage and the sensor size). The 35mm FX lens has wider angle of coverage than the 35mm DX lens.

PHRubin Loc: Nashville TN USA

A 35mm lens projects the same image no matter where it is used. HOWEVER, how much of that projection is used varies. The DX sensor sees a smaller part of it than an FX sensor, by an amount equal to 1/(the crop factor). Thus the angle of view seen by the sensor is different by the crop factor.

User ID

There’s no error in your understanding.
I read the other replies but they address only facts that you already understand according to your opening post.

The only possible glitch is your take on the talk you’ve heard that “35 is the new 50.” That is an old occasionally repeated remark that is not related to “DX vs FX”.

It dates back to predigital 35mm film camera users. It’s like those remarks about human health that say “40 is the new 35”. The meaning is merely that many users are adopting 35mm as their normal lens instead of a 50mm. Again, nothing to do with DX. It just says “Many users have adopted a bit wider view than 50mm as normal”.

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FWIW, 50 was always more narrow than the usual normal lenses for roll film and cut film cameras. I suspect 50mm was originally favored for rendering details a bit larger, way back when 35mm film was rather mediocre at resolution.

24x36mm is 3:2 which is a bit of “pano” compared to older formats that were 5:4 and 4:3. I had an old Nikon that was 24x32mm, the “old normal”. When you print 8x10 or 16x20 you are using that “old normal” and the “classically correct” normal lens for that is 40mm. 35mm lenses are simply more readily available than 40s. Acoarst I have two 40s ;-)

larryepage Loc: North Texas area

The notion of "equivalent focal lengths" is an unfortunate reference that dates back to marketing materials that were issued when the DX format was invented. It has been unnecessarily confusing photographers for too many years.

The only pertinent answer to your question is that you will get exactly the same results with a 35mm DX lens and a 35mm FX lens on a DX camera. Same field of view, same exposure, same everything. There is no difference, and there is no downside.

And yes, I do have a couple of DX lenses that I use fairly regularly on my FX cameras. They will all cover a 24x24mm square format. A couple of them come very close to covering the full frame. Different camera models offer different options for using them. Blanket statements on the issue tend to be very uninformed and just "sort of" true.

flyboy61 Loc: The Great American Desert

Or on my D 7100, which also has an additional 1.3X crop factor on top of the 1.5, which works out to ~15 megapixels resolution...and 409mm for my 70-210 FX mm lens.

My D90 had 12mp, and I never found it wanting.
Ah, well...I'll read the rest of the posts, and see...

flyboy61 Loc: The Great American Desert

O.K., larryepage and USER ID...Thank you, as well as all others who replied.
I think I am beginnning to understand, particularly about the statement;"35 is the new 50."
So far, the conclusions I have reached are:
Yes; 35mm is 35mm, no matter the format. DX lenses are designed with a circle of coverage to fit film or full frame sensors, to give (hopefully) sharpness to the corners of that format. Lenses for the smaller formats...APS C or 4.3 can be designed with coverage circles for the smaller sensors, which is why most don't produce stellar results on FX sensors, absent the in-camera wizardry that adapts them to the larger formats. By the same token, most FX lenses do well with smaller sensors, because only the center of their coverage circle, the portion that is the sharpest and most highly corrected is used.

Am I on the right track, here? it seems an old Harry Belafonte song could fit...; "It was clear as mud, but it covered the ground, and the confusion make me head go 'round..."

Thanks, all!

User ID

Amen to “very uninformed”.

Bill_de Loc: US

I think you meant FX.

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