dear member

[nmanjunath]

I am an ameture photographer - wish to know what is DX format and Fx format, i have Nikon - D7000 camera, i would also like to know what is crop factor and how to calculate

[dubaiphil]

An FX camera is fitted with a 35mm film sized sensor.

A DX camera has a smaller sensor.

The crop factor is the ratio between FX and DX sensor size = x1.5 in the case of Nikon

Therefore if you use a 50mm lens on a FX camera, the equivalent focal length on a DX camera to record the same image is 50 / 1.5 = roughly a 35mm

(edited by a half asleep DX and FX owning dumb a@@!)

[Mike Buckley]

Therefore if you use a 50mm lens on a FX camera, the equivalent focal length on a DX camera to record the same image is 50 x 1.5 = 75mm

To record the same image using a DX camera, you would use a 33.5mm focal length (33.5 x 1.5 = 50).

[HaseebM]

Also note the 50mm on a DX camera though gives you a view equivalent to 75mm, it is only giving you the field of view of a 75mm on a full frame, not necessarily magnifying it.

[dubaiphil]

haha - I'm being a dumb a@@!

[mrinmoyvk]

No matter how much digital photography progresses, it is always compared to old 35mm films.
Sensor which resembles the size of 35mm film is full frame sensor also called as FX.
DX sensors are smaller in size. which means at a specific focal length, you will get wider angle of view on FX as compared to DX.
You know that all lenses are circular and hence capture circular image.
However sensors being rectangular in shape, store only rectangular part of that circle.

Consider a FX lens (circle) fitted on a FX sensor camera (will capture image equal to biggest rectangle drawn inside the circle, all 4 edges will touch the circle)
Consider a FX lens (circle) fitted on a DX sensor camera (will capture image equal to rectangle drawn inside the circle) but this time the rectangle will be smaller than that of FX sensor.

while reviewing the image you might think that you get you get more zoom on DX sensor camera but it is just the perspective of looking at the image with sides being cropped with some reduced mega pixels.

multiplication factor is by how many times the DX sensor is smaller than FX sensor. Nikon is generally 1.5 and Canon is 1.6
So if you are using FX lens on Nikon DX sensor (or DX lens on DX sensor)

50mm will work as (50 * 1.5 = 75mm FX lens fitted on FX sensor)

[rpcrowe]

Here is a graphic representation of the various formats of Canon cameras.

You can compare these formats to those of Nikon. The full frame is obviously the same as the Nikon FX while the Canon 1.6x format is very similar to the Nikon DX (1.5x) format. Canon doesn't produce cameras with a 1.3x format any longer; these were some of the earlier 1D (series) cameras. AFAIK: Nikon never produced a digital camera with a 1.3x format...

You will notice that a lens designed for full frame cameras will produce an image circle that is larger than that produced by a lens designed for a crop camera and will cover the entire full frame. The smaller image circle of the lens designed for a 1.6x (or 1.5x for Nikon) will not cover the entire full frame format. These lenses will (in most cases) also not physically fit on full frame cameras.



You will also notice that the size of the subject (in this case the mountains) is exactly the same for both full frame and for crop cameras. However the full frame camera will cover a greater area and include more information.

Here are the relative sizes of many common formats...



You could superimpose these cropped formats over the full frame image to see what area of the full frame that the cropped formats will cover.

[Nicks Pics]

while reviewing the image you might think that you get you get more zoom on DX sensor camera but it is just the perspective of looking at the image with sides being cropped with some reduced mega pixels.

I think one thing to note about this topic is that an image from the smaller dx sensor is not necessarily exactly equal to an image from a fx camera cropped to the same field of view, because pixel count can vary from camera to camera; therefore, the resolution between the two might not be equal. One thing to like about dx sensors if you usually shoot at telephoto ranges is that they might, (often, perhaps, but not necessarily) have a higher pixel density which allows you to get a higher resolution image per field of view than you would get from cropping a FX image to the same field of view.


One thing I have been wondering recently which might be relevant in giving Manjunath.N, more information about calculating lens length is when looking into lenses, should a lens labeled dx 400 mm, for example, be considered a 600 mm (magnification affect/field of view) on a dx camera? Or is the 400 mm given as an already calculated equivalent length?

Anyway, there is my two cents and my ignorance all in one post.

[rpcrowe]

One thing I have been wondering recently which might be relevant in giving Manjunath.N, more information about calculating lens length is when looking into lenses, should a lens labeled dx 400 mm, for example, be considered a 600 mm (magnification affect/field of view) on a dx camera? Or is the 400 mm given as an already calculated equivalent length?

A 400mm lens is 400mm whether it is used on a full frame camera, or on any of the crop cameras. The equivalent focal length is used only to compare the area captured by the sensor...

In other words, if I wanted to capture the same area with a crop sensor that I have captured with a full frame camera, I would have to do one of two things:

1. Use a wider lens
and/or
2. Shoot from a further lens to subject distance.

[Nicks Pics]

Thanks Richard,

should a lens labeled dx 400 mm, for example, be considered a 600 mm (magnification affect/field of view) on a dx camera? Or is the 400 mm given as an already calculated equivalent length?

That makes sense,
I guess I meant would the 400 mm label be given as an already calculated 35 mm equivalent, in which case you would be buying a 200 mm lens, labeled as 400 mm field of view effect for a crop frame? But I think the answer is no, as then they would have to specify which crop sensor it is for. The shopper should do the calculation themselves.

[xpatUSA]

I must congratulate Nikon whose effect in this thread is to somehow turn DX and FX into global terms even tho' they are only specific to Nikon products . . .

. . . so says the owner of a good few DC and DG lenses.