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Nikon "DX" format questions
I am trying to wrap my head around the terminology and meaning of "DX" format so that I can more intelligently purchase lenses for my Nikon D300 and get what I am expecting. My understanding is that DX means the sensor is 1.5 times smaller than a full frame sensor (FX?), and therefore, when the light from a lens is focused on the sensor, the light blankets the sensor and some of it falls off the edge and the sensor misses some of the image. The net effect is that of zooming, making the image appear closer and cropped vs what it would look like on a full frame sensor. Is that correct?
Then my next question, if I want a 35mm lens, for example, and I want the field of view to be that of the traditional 35mm film camera, then for a DX-format camera, I would need to actually use a 35/1.5 mm lens or ~24mm lens. And if I want a traditional 24mm lens, then I would need to purchase a 24/1.5 = 16mm lens. Is that correct?
If that is correct, then what about for "DX" labeled lenses? Are they "true" focal length for DX-format cameras, or does the above formula still apply? I.e., does a 35mm DX lens appear as a traditional 35mm lens, or does it appear as a 35*1.5mm = ~52mm lens?
What I mean by "DX" labeled lens is something like this: "AF-S Nikkor 35mm f/1.8G DX"
Would that lens appear to my DX format D300 camera as a 52mm lens, or as a traditional 35mm lens?
Finally, let's say, hypothetically (:D), that I recently intended to purchase a 50mm lens, specifically something like this "Nikon AF-S Nikkor 50mm f/1.4G Autofocus Lens", thinking I was getting a traditional 50mm lens, but in reality, because of my "DX-format", is it really equivalent to a 50*1.5 = 75mm lens?
I *think* I know the answer, but it would be great to get some confirmation from the experts. I am relatively new to all this and don't want to make too many (more) expensive mistakes as I am trying to understand what this stuff means.
Thanks!
Then my next question, if I want a 35mm lens, for example, and I want the field of view to be that of the traditional 35mm film camera, then for a DX-format camera, I would need to actually use a 35/1.5 mm lens or ~24mm lens. And if I want a traditional 24mm lens, then I would need to purchase a 24/1.5 = 16mm lens. Is that correct?
If that is correct, then what about for "DX" labeled lenses? Are they "true" focal length for DX-format cameras, or does the above formula still apply? I.e., does a 35mm DX lens appear as a traditional 35mm lens, or does it appear as a 35*1.5mm = ~52mm lens?
What I mean by "DX" labeled lens is something like this: "AF-S Nikkor 35mm f/1.8G DX"
Would that lens appear to my DX format D300 camera as a 52mm lens, or as a traditional 35mm lens?
Finally, let's say, hypothetically (:D), that I recently intended to purchase a 50mm lens, specifically something like this "Nikon AF-S Nikkor 50mm f/1.4G Autofocus Lens", thinking I was getting a traditional 50mm lens, but in reality, because of my "DX-format", is it really equivalent to a 50*1.5 = 75mm lens?
I *think* I know the answer, but it would be great to get some confirmation from the experts. I am relatively new to all this and don't want to make too many (more) expensive mistakes as I am trying to understand what this stuff means.
Thanks!
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You are correct
You don't take a photograph, you make it. ~Ansel Adams
Blue Moon Originals
So the 35mm DX lens has the same focal length as any other 35mm lens would: which is a 52.5mm FF equivalent field of view.
This is why it's so surprising that Nikon has yet to make a set of wide primes for DX.
$$$
Probably isn't much of a market for them
You don't take a photograph, you make it. ~Ansel Adams
Blue Moon Originals
Further more, why would they? It'd cost more to completely retool for dx lenses. As it is, they're shared with fx and film bodies.
No. I suspect there is plenty market for DX only lenses.
I've often thought if I were a Manufacturer/Seller of lenses I'd clearly state on the lens box; 50mm f/1.8 fov FX, 75mm f/1.8 fov DX. Yet. What does that all mean to the average consumer? I'd venture little. Oh sure some folks just love the technical aspects of lenses. But really unless you've shot 35mm (film) and know what that FOV looks & feels like, You'll never really get the FX/DX thing anyway.
Personally I think it is a mistake to label a lens DX and have it's FOV different from what it is advertised as: 35mm f/1.8 with FOV of 52mm? Weird~to me.
Couldn't disagree more with both of you. The market for them is as large as for any other DX lens at this point.
Here's an interesting read from Thom Hogan:
http://pomeroyphotography.smugmug.com
Universe halted: reality.sys not found (that's old school!)
"The net effect is that of zooming" isn't quite right. It is more accurate to say the net effect is that of cropping. The reason this distinction matters (to some, perhaps not to you) is that a 50mm lens used at a particular distance from the subject will provide the same depth of field on DX and FX cameras (if distance to subject is the same). In other words, the depth of field when it is used on a DX will not mimic a 75mm on FX.
Chooka chooka hoo la ley
Looka looka koo la ley
Historically speaking, with digital technology, progress has always been in the "direction of smaller". Pretty much every electronic device out there used to be a huge brick, and now it fits in the palm of our hand.
...So why is it so hard to fathom the notion that smaller sensors will eventually improve the point of being totally acceptable by the masses? Sure, full-frame sensors will always have an advantage. But as lens sharpness technology advanced, even in the days of film, "everybody" switched to 35mm for casual shooting. Smaller is always more convenient.
I'm looking forward to seeing what can happen with Nikon's DX format, in a professional or advanced amateur capacity. The D7000 has been an amazing camera with great DR and overall IQ, shutting up those who brag about how their full-frame body is so vastly superior. Maybe it's still superior in many ways, but that's not the point. The point is that each year, DX makes roughly the same amount of progress that FX makes, and it is providing a great new option to even the most demanding photographers.
Just my opinion...
=Matt=
My SmugMug Portfolio • My Astro-Landscape Photo Blog • Dgrin Weddings Forum
I don't believe anyone has addressed this question specifically, though you have probably figured this out by now. All Nikon lenses reflect their true focal length, so a 35mm DX lens has the same focal length as a 35mm FX lens. The only difference is that DX lenses cast a smaller image circle which is large enough for a DX sensor but not for an FX sensor. This allows Nikon to make the DX lenses smaller and lighter.
If you mount a DX lens on a full-frame (FX) camera, you will most likely see dark corners, or "vignetting" because of the smaller image circle.
Thank you, jthomas, for addressing that part in particular, and thanks to all who helped to explain the format and focal length effects so clearly.
Great distinction, I did not even think of that.