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?
- Thread starter James809
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n057
Veteran Member
Not sure who exactly said it was an advantage. Some THINK it's an advantage because you get (or SEEM to get) longer reach out of your lenses. But you can achieve the same thing by merely cropping the image taken with a full frame camera.
No it is NOT. The camera does not do any enlarging at all. All that is happening is that it is cropping due to the fact that the DX sensor is smaller than a full frame sensor.
Alex Permit
Senior Member
The effective size is magnification divided by the crop-factor. It's a normalized measure for the size of the viewfinder image. It's commonly used to compare viewfinder image sizes of cameras with different crop factors. You can read more at DSLR Viewfinder Sizes .
if you prefer, you can calcuate the actual size of the viewfinder image by multiplying the magnification factor by the dimensions of the sensor.
Viewfinder image (mm) in DX mode:
D500: 24x16
D5: 17.23x11.47
D810: 16.85x11.15
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Sometimes I think that anyone considering the purchase of a digital camera should be required to first purchase a 35mm film camera, a 2 1/4 film camera and a 4X5 film camera. In other words, while there are definitely some difference between film and digital, most of the underlying facts that apply to film sizes, lenses etc. still apply 100 percent.
If you shoot an image with a 50mm lens with a 35mm film camera you get a certain angle of view. A 50mm lens is considered a 'normal' lens for a 35mm camera. If you use that same lens on a 2 1/4 camera it becomes a wide angle. If you use that same lens on a 4X5 camera it becomes an EXTREME wide angle lens (plus you get an awful lot of vignetting because the image circle created by a lens designed for a 35mm camera won't be big enough to fit the larger format sizes.
Now go the other way...shoot with a 150mm lens on a 4X5 camera (this is pretty much a normal lens on a 4X5). Take that same lens and fit it to a 35mm camera. Being that 35mm film is much smaller, and thus "cropping" the scene, that 150mm lens now becomes a telephoto on the 35mm camera...but it's NOT a telephoto on a 4X5 camera. The difference is the result of the fact that the 35mm piece of film cropped the image with that same lens. The focal length did not change, there is no magic software inside the camera making it into a telephoto....the scene is cropped because of the smaller film size.
Now again, one may argue this or that in regards to DX and FX cameras having different pixel density and so on..and this is all true...but it has NOTHING at all to do with the reasons why the same lens gives more reach on a DX camera than it does on an FX camera. Put lens X on a DX camera and it will look more telephoto than that same lens will look on an FX camera...ONLY because the smaller sized sensor of the DX camera crops the scene making it APPEAR as that scene was shot with a longer lens.
Everyone should read the post above by Dogman Joe. He has it SOOO right.
If you shoot an image with a 50mm lens with a 35mm film camera you get a certain angle of view. A 50mm lens is considered a 'normal' lens for a 35mm camera. If you use that same lens on a 2 1/4 camera it becomes a wide angle. If you use that same lens on a 4X5 camera it becomes an EXTREME wide angle lens (plus you get an awful lot of vignetting because the image circle created by a lens designed for a 35mm camera won't be big enough to fit the larger format sizes.
Now go the other way...shoot with a 150mm lens on a 4X5 camera (this is pretty much a normal lens on a 4X5). Take that same lens and fit it to a 35mm camera. Being that 35mm film is much smaller, and thus "cropping" the scene, that 150mm lens now becomes a telephoto on the 35mm camera...but it's NOT a telephoto on a 4X5 camera. The difference is the result of the fact that the 35mm piece of film cropped the image with that same lens. The focal length did not change, there is no magic software inside the camera making it into a telephoto....the scene is cropped because of the smaller film size.
Now again, one may argue this or that in regards to DX and FX cameras having different pixel density and so on..and this is all true...but it has NOTHING at all to do with the reasons why the same lens gives more reach on a DX camera than it does on an FX camera. Put lens X on a DX camera and it will look more telephoto than that same lens will look on an FX camera...ONLY because the smaller sized sensor of the DX camera crops the scene making it APPEAR as that scene was shot with a longer lens.
Everyone should read the post above by Dogman Joe. He has it SOOO right.
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BirgerH
Veteran Member
Yes. Has it to do with "Reach"?
Yes. Again - don't the two images have the same "Reach"
Of course.
They'll have the same "Reach", wouldn't they?
What does that have to do with "Reach"?
Yes Seth absolutely.
Though you are not speaking about the "Digital Zoom" but about the image quality, when doing Digital Zoom.
That was not the OP's question - he asked, if the DX/FX advantage in "Reach" was simply "Digital Zoom". It is, whatever DX or FX he uses - he gets "Digital zoom" with more or less quality.
--
BirgerH.
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Tony Beach
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DX often is the sweet spot in terms of getting pixels on the target.
Equal pixel density equates to the same demand on lenses within a given image circle. The larger FX image circle often equates to more demand on lenses than the smaller DX image circle.
Don't, it's a waste of time.
According to DXO Mark, there are lenses that do better on the D750 than on the D800, which is demonstrably wrong.
Tony Beach
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I would look forward to picking up a lightly used D500.
Tony Beach
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You need a wider lens for DX to get the equivalent FOV, then you need a larger aperture with DX to also get the equivalent DOF. Actually, if you use the same focal length and the same aperture from the same distance then DX actually has a shallower DOF:
[IMG width="400px" alt="Same shot cropped to DX on the right and both enlarged to 800 pixels width. Note when viewing the "Original size" that the area just beyond the "1" (front and back of the DOF scale) has more clarity on the FX version than on the DX version."]http://photos.imageevent.com/tonybeach/mypicturesfolder/sharing/_AB25079.jpg[/IMG]
Same shot cropped to DX on the right and both enlarged to 800 pixels width. Note when viewing the "Original size" that the area just beyond the "1" (front and back of the DOF scale) has more clarity on the FX version than on the DX version.
You can also consult DOF calculators about this. Mine shows the following:
Simply changing the amount of enlargement as expressed by the CoC shows that the DOF has narrowed on the DX enlargement versus the FX enlargement.
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http://imageevent.com/tonybeach/twelveimages
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Tony Beach
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The question has already been answered, but many refuse to recognize it. It's not about DX or FX, it's about pixel density and and cropping. If one sensor puts 1000 linear pixels on a subject and another shot puts 1500 linear pixels on that same subject, then everything else being equal you have more resolution with the 1500 linear pixels than with the 1000 linear pixels.
cosmicnode
Veteran Member
For me everything comes down to this. The shot is full width of a DX sensor trimmed at the top, shot at 200mm. I would have needed to shoot at 300mm using full frame, I cannot move forward there is a fence in the way,
This is DX cropped from a 200-500mm shot at 500mm, I would have needed 750mm on FF to get this shot. Once again against a fence. Call it reach or magic, its simply common scense for me
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Tony Beach
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The D500 will do better below ISO 1200. See here:
http://www.photonstophotos.net/Charts/PDR.htm#Nikon D5(DX),Nikon D500
BirgerH
Veteran Member
Yes - and if you are shooting OOC jpg and send it to the printer, the camera software enlarge the image to be same printing size, no matter if you are shooting DX or FX.
The same, if you review the image on the camera screen, the FX image is same size as the DX image on the same screen - who is making that enlargement of the DX-crop, if not camera software.
You can do the same thing in PP software if shooting RAW.
If you don't do the enlargement, you are just cropping without getting more "reach". That's possible as well, of course - but was not the OP's question.
briantilley
Veteran Member
You're not wrong, but your definition of "reach" differs from the other responders in this thread. You're using "more reach" to mean "the subject fills more of the frame", others are using it to mean "the subject covers more pixels". Either is valid, but to have any sensible discussion, we need to decide which we want to use.
TacticDesigns
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+1
That is the way I interpreted it when I got back into cameras in 2011/2012.
I could afford (and was willing to carry) a Nikon 80-200mm f/2.8 zoom to my daughter's gymnastic competitions. But couldn't find / afford and be willing to carry a 120-300mm f/2.8 lens. LOL.
And so I got the 80-200mm f/2.8 lens.
At the time, the most affordable full frame camera was the Nikon D700. (This was before the Nikon D600 came out.)
So, do I stick that 80-200mm f/2.8 on a Nikon D700 with it's 12MP full frame sensor, and then end up cropping into that image, because I'm a parent, shooting from the stands?
Or do I get a Nikon D7000 with it's 16MP cropped sensor and have more pixels on subject?
At the time, my choice seemed pretty easy to make.
The "extra reach" of the DX was beneficial to me.
I think, now-a-days, with lower cost full frame cameras with 24MP and higher sensors, the choice is becoming a lot less clear.
Take care & Happy Shooting!
BirgerH
Veteran Member
Not sure I understand.
How can "reach" be considered more pixels behind the subject. In my book, that's resolution.
According to that definition, my D800 would have "more reach" than a D750.
"Reach" defines a distance, doesn't it?
This is an example from the English Dictionary: "Someone's or something's reach is the distance or limit to which they can stretch, extend, or travel."
How will that fit - even in English - "the subject covers more pixels"?
n057
Veteran Member
briantilley
Veteran Member
My point is that a discussion of the "reach" advantages of a format can only be effective if the participants have a common understanding of the term. The problem arises because, unlike photographic terms such as "f/stop" or "pixel count", "reach" does not have a single, universally-agreed definition.
My impression is that the most common definition of "reach" as it applies to digital image capture is that of "pixels on the duck", because that determines the maximum print or display size, but as this thread has shown, others have a different view.
Leonard Migliore
Forum Pro
Exactly right. My intuitive definition of reach is that it's the field of view you get with a specific lens. By that definition, any crop sensor camera has more reach than any full-frame camera.
But wildlife shooters care about getting good quality images of objects that are hard to approach. So they're more concerned with resolution. To a wildlife shooter, a D810 has more reach than a D300 because they can get a higher-resolution image out of it, never mind that they have to throw most of the frame away.
O
OlyPent
Guest
But, is it enough to overcome a resolution advantage? Nothing is 100% absolute, you'd have to compare the lenses and cameras on a one to one basis.
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