James809
Senior Member
Question as posted; what's the magic "reach" people talk about as an advantage or DX over FX? Angle of view is narrower, but what exactly is going on, and why is it considered "more reach?"
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Supposed "reach" advantage for DX vs FX; is it just the equivalence of digital zoom?
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JohnnyLuddite
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To throw something else into the equation - the lens.
There's obviously a number of features of lenses which affect what you'll see between fx and dx. Some fx lenses have vignetting to varying degrees, this won't be visible much in dx. Lenses may not resolve that well (as the sensor), and do not always do so evenly. Diffraction limits etc. So these may limit your "crop" independent of the sensor.
The f-stop is the f-stop for light gathering, but from a depth-of-field perspective, you lose some dof control with dx, or need a wider lens for the same dof effect.
There's obviously a number of features of lenses which affect what you'll see between fx and dx. Some fx lenses have vignetting to varying degrees, this won't be visible much in dx. Lenses may not resolve that well (as the sensor), and do not always do so evenly. Diffraction limits etc. So these may limit your "crop" independent of the sensor.
The f-stop is the f-stop for light gathering, but from a depth-of-field perspective, you lose some dof control with dx, or need a wider lens for the same dof effect.
Vince P
Senior Member
Exactly the size of the sensor is irrelevant. I can equally say that my D810 has a "Reach Advantage" over my D5s. What a DX camera can have is more viewfinder magnification which could be a factor.
R
Robert Soderlund
Guest
Reach depends largely on the lens, DX 24mp vs FX 24mp, you got higher pixel density on the DX, demanding more from the lens, so what you end up with it a lousier image, if the same lens is used.
For example, Micro 4/3 lenses resolve nearly twice as much as equivalent FF lenses to make up for their higher density, if one adapts a mediocre full frame lens on a high res micro 4/3, the sharpness becomes lousy instead of mediocre.
All these things need to be considered when comparing whether the 1.5 crop factor actually yeilds more detail or just more reach.
For example, Micro 4/3 lenses resolve nearly twice as much as equivalent FF lenses to make up for their higher density, if one adapts a mediocre full frame lens on a high res micro 4/3, the sharpness becomes lousy instead of mediocre.
All these things need to be considered when comparing whether the 1.5 crop factor actually yeilds more detail or just more reach.
Alex Permit
Senior Member
I agree they need to but I think in general they do not. Could you provide examples of MFT lenses that have double the lpmm of their FF equivalents?
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R
Robert Soderlund
Guest
From the Lenstip.com tests:
Here is the Olympus 75 1.8
Here is the Sigma 150 2.8
As we can see its not double, but there is a significant MTF difference.
Here is the Olympus 75 1.8
Here is the Sigma 150 2.8
As we can see its not double, but there is a significant MTF difference.
briantilley
Veteran Member
Yes, it is true.
That has no impact on the number of "pixels on the duck" (as explained earlier).
Yes, but when those 20.9MP are concentrated into the smaller DX area, there will be more of them on any given subject that there would be when the same lens is used on a 20.9MP FX camera. The duck will occupy more of the print.
True, but not relevant to the discussion on "reach".
Also true, and also not relevant.
AwesomeIan
Senior Member
There is nothing "supposed" about this. If you take a photograph with a full frame camera in 'DX' mode you are cropping off the edge of the picture and throwing away pixels. On a DX camera you are not throwing away any pixels because the image isn't being cropped. So if all things are equal (i.e. both cameras have the same number of megapixels) then the DX will have higher resolution.
Don't forget that the lens is a variable here as well. Bad glass won't resolve a lot of detail but the actually number of pixels doesn't change. So even though a DX camera could be putting more pixels on a target than a full frame that doesn't mean you will end up with a more detailed picture. I find this to be especially true at 600mm.
wasserball
Senior Member
NT
James809
Senior Member
I'm not asking about DX-mode vs DX, but DX vs FX.
I really think you guys are complicating this more than need be.
Taken at face value the OP asks a very simple question about the "more reach" of a DX camera. While I do not dispute the talk about pixel density and everything else that has been discussed here, really the answer is that there is no magical reach of a DX camera but merely the fact that the sensor being smaller than a full frame sensor means that you will end up with a cropped version of the scene compared to a full frame camera.
Take an 8X10 inch print and cut it to a 5X7 inch print. You end up with a cropped portion of what had been in the 8X10 inch print. Not only is it cropped but it also looks like it may have been taken with a longer lens (which would give more reach). The duck in the center of the image which had a lot of foliage around it in the 8X10 now appears in the 5X7 inch print by itself instead...just as if you had shot it with a longer lens.
There is no magic here, the smaller sensor is just cropping the scene. So if you print the images, one shot with a full frame camera with foliage surrounding the duck as an 8X10, and then printed the shot done with a DX camera with no foliage surrounding the duck as an 8X10 print also, the DX one looks like it was shot with a longer lens (more reach).
Again, yes, pixel density is different in the two cameras and as a result other factors may come into play, but quite simply to answer the OP, it's considered "more reach" because cropping the scene by using a smaller sensor makes it look like it was shot with a longer lens.
My apologies if the OP already knew this and IS actually asking about the other factors of pixel density and such.
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AwesomeIan
Senior Member
Lets say you shoot in full frame mode and crop in post to match the same picture taken with a DX camera. This is the exact same scenario as shooting dx mode on full frame. You reduce the resolution of the image to match the picture taken with a DX camera.
AwesomeIan
Senior Member
SethG
Senior Member
Alex Permit
Senior Member
Thank you. Yes, not quite double but certainly in the ballpark (at least in the center).From the Lenstip.com tests:
Here is the Olympus 75 1.8
Here is the Sigma 150 2.8
As we can see its not double, but there is a significant MTF difference.
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Assuming you are using the same lens, the DX camera will provide more "reach" than the FX camera will. And this happens very often because there really aren't that many DX lenses available compared to the number of FX lenses made. The idea is to make you buy FX lenses so you can someday upgrade to an FX camera, and then Nikon will not have to produce very many DX lenses for DX camera users.
This is due to the smaller sensor size.
If you really want to see some "reach" then get a Nikon 1 camera and an adapter, then slap on an FX lens! Your cheap 50mm f/1.8 lens will now become a fast 135mm telephoto lens, and a 70-200mm lens is now a 189-540mm super telephoto zoom lens!
This is due to the smaller sensor size.
If you really want to see some "reach" then get a Nikon 1 camera and an adapter, then slap on an FX lens! Your cheap 50mm f/1.8 lens will now become a fast 135mm telephoto lens, and a 70-200mm lens is now a 189-540mm super telephoto zoom lens!
AwesomeIan
Senior Member
Please watch the video. It should help illustrate the concept of APS-C vs Full Frame:
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www.slrlounge.com
James809
Senior Member
So if this is true (asking the question, not taking a position) how is this considered an advantage in DX vs FX, unless the point is that you don't need to crop out the foliage surrounding the duck? And if that's the true advantage, I can buy into that. And I can see why folks sometimes put "reach" in quotes, since it's not really reach, but cropping.
BirgerH
Veteran Member
Leonard Migliore
Forum Pro
The advantage is that you can often get greater pixel density in crop-sensor cameras than in full-frame cameras. To match the reach of a 20MP D500, you need a 45MP full-frame camera, which will be much more expensive.
Dogman Joe
Active member
The problem is with the use of the word "reach." It seems to imply, at least to me, that the DX sensor provides greater magnification than an FX sensor. This is simply not true.
When you put a 300mm full-frame lens on a DX body, because of the 1.5 crop factor, the image has the framing that you would expect from a 450 mm lens on an FX body. However, the key point is that a 300mm lens is essentially a lens that has a 6x magnification factor, i.e. 50mm lens is normal view and 300mm lens is 6 times closer than the normal view. When you put a 300mm lens on a DX body, you don't get nine times closer. You still have only a 6x magnification factor - the image just seems bigger because it take up more room on the cropped sensor.
Hope this helps.
When you put a 300mm full-frame lens on a DX body, because of the 1.5 crop factor, the image has the framing that you would expect from a 450 mm lens on an FX body. However, the key point is that a 300mm lens is essentially a lens that has a 6x magnification factor, i.e. 50mm lens is normal view and 300mm lens is 6 times closer than the normal view. When you put a 300mm lens on a DX body, you don't get nine times closer. You still have only a 6x magnification factor - the image just seems bigger because it take up more room on the cropped sensor.
Hope this helps.
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