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Misconception: Using an FX lens on a DX camera "extends the reach" of the lens

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Austin Li said:
Austin Li said:
A Nikon D70 with a 300mm f4 lens gives EXACTLY the same photo results
as a Nikon D90 with 300mm f4 lens.
The same composition, same depth of field, same reach towards the
subject.
Click to expand...
So you are saying they have the same reach. I would agree that the
reach of the lens is the same apparently, but the D90 offers more
reach. Because if you print large enough, which one will give more
detail?

Calm down, buddy, we are discussing and learning, not really arguing
or fighting.
Click to expand...
So you print large enough, and hang it on a wall. And when you stand close you see the detail. And when you take distance from the photo hanging on the wall... the reach lessens??

Or when you downsize a photo to share with your buddies... the reach of the lens somehow gets less?

No, of course not. Resolution has nothing to do with "reach", only with detail.
 
Austin Li said:
Austin Li said:
A Nikon D70 with a 300mm f4 lens gives EXACTLY the same photo results
as a Nikon D90 with 300mm f4 lens.
The same composition, same depth of field, same reach towards the
subject.
Click to expand...
So you are saying they have the same reach. I would agree that the
reach of the lens is the same apparently, but the D90 offers more
reach. Because if you print large enough, which one will give more
detail?
Click to expand...
They are both DX cameras. The D90 does not offer more reach - it offers more resolution.
Austin Li said:
Calm down, buddy, we are discussing and learning, not really arguing
or fighting.
Click to expand...
--
'87.6% of all statistics are made up on the spot'

ShutterBugin
http://www.exposureproductions.smugmug.com

 
What is happening in this thread, honestly? WHO CARES what anyone else's perception is about FX versus DX "reach"? If someone wants to smugly sit there with the knowledge that his 50mm lens is nothing more than a 50mm lens on a DX camera, just with greater pixel density that increases the perceived focal length blah blah blah, then I'm very happy for them, but how about we all agree to stop making threads about it?

Brightcolours, my hats off to alienating a whole group of photographers. Tell me, does a SERIOUS photographer, a true artist, obsess over utterly meaningless semantics like you do? But hey, who cares what I think, I've taken a few bird pictures in my day.
 
Only a lens designer cares about focal length. Aside from that it's useless, just an optical design parameter. The only thing a photographer cares about is field of view and aperture, both of which have a direct relationship to photography.

When all cameras had the same 35MM sensor size FL and FOV had a meaningful relationship, so photographers started using FL. Today they don't.

So, don't use obsolete terms. FOV is what's important, and FOV is what changes when you change sensor size. If you must use FL, then you need to correct it to an equivalent FL for your sensor size. That's a workaround designed to deal w/years of accumulated intuition

Nobody really cares whether true FL doesn't with sensor size, because true FL has nothing to do with photography. End of story.
 
I don't think you get the concept, even though a bunch of well meaning people are trying hard to explain it to you.

Take a crop and FF photo with the same lens. Out of camera, no retouching, the subject will appear closer with the crop camera. No confusing pixel stuff, no magnification, no crop. The subject is bigger, because the FOV is smaller. Simple

OK, lets try again. I have a camera w/a 7.4 to 88.8 mm lens. What does that tell you about the images? Absolutely nothing, I have to tell you the sensor size. Now, knowing that its a 4.7 crop, so that's to 35MM to 420MM equivalent, not quite what you expected?

Do you think this camera will look, smell, taste, or act like a wide angle? Do you think a 100MM lens on a FF camera will out reach it for a distance subject, even though 100MM is greater than 88.8 MM? Do you think you can ignore crop factor?
 
Let us first agree a couple of constants. First we are going to compare the full frame camera and the crop camera with the same lens and lens settings, the same subject distance and finally the same MP density of sensor and the same print size and resolution.

i.e. the only difference is the full frame or crop sensor.

Because the part of the image being measured is smaller in the crop camera, the circles of confusion in the image the lens projects onto the sensor are smaller, to keep everything else equal.

So in effect the crop sensor has the lower depth of field. Do not believe me, go try some calculation through an on-line Depth of Field calculator for the D300 and D700 with all parameters equal, except for the camera body.

Next if you set the two camera up with the same subject distance and same lens aperture, but run the crop camera with a wider angle lens to get the same field of view, the crop camera has greater depth of field.

It is true the lens parameters are not changing as you use different camera bodies, but the measurements performed on what the lens projects does.

It is all in the end maths. In reality you learn what a lens does on your chosen camera and adapt to it.
 
Correct..it has an angle of view and a circle of coverage!! The rule of thumb remains of course that the"standard" lens is equivalent to the diagonal dimension of the format...35mm for DX, 50mm for FF/35mm, 70+mm for MF and up to 150mm for 5x4, etc...

Each will record the same amount of scene.....given that of course the formats are not all identical proportions...
 
It depends on how you define "extend the reach" . . .
ChicagoNikonGuy said:
Please forgive me for repeating this thread but the misconception
continues to be propagated.

Using a lens designed for an FX size sensor on a camera with a DX
size sensor DOES NOT "extend the reach" or change the effective focal
length of the lens.
Click to expand...
--
Take a look at my album . . . http://www.F1Album.com
 
Thank you, that is actually a very good, valid point . . as far as I am concerned.

:-)

--
Take a look at my album . . . http://www.F1Album.com
 
Well, if you take an photo with the 6Mpx D70 and the same with the 12 Mpx D90, both using the same lens, then you crop the D90 image to get an 6Mpx resolution, your image will contain an smaller part of the image which you could only get with an longer tele lens on the D70.

Sure, it would mean that the cropped image is only 6 Mpx and the pixel advantage of the D90 is not there anymore (if you crop), but compared to the D70, the pisel density gives you an crop possibility that changes the field of view compared to an equal sized sensor with less amount of pixels.

--
Rickard Hansson
Sweden
 
I think you'll find that the widths, heights, areas and pixel densities should refer to mm not cm. A 24cm x 36cm sensor might be a bit large for a D700, or even for a Hasselblad. But I'll bet the noise performance of a 12M pixel sensor that size would be super.
 
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