Crop Sensor to Full Frame?

PapaST

Senior Member
I think I know what you're asking, but then again I think a lot of things. Say you took a full frame 50mm photo. If you wanted the equivalent photo from a crop sensor then use a 35mm lens. Does that make sense/answer your question?
 

StrepoD7000

New member
So I would need a 35 mm lens on my camera to get the widest and fullest photo without any fish eye effect? I just want to be able to take the same size pictures a full frame produces on my D7000
 

BackdoorArts

Senior Member
The "size" of a photo has to do with sensor resolution, not sensor size - though they can be related. The D7100 is a 24MP DX camera, and the D600 is a 24MP FX camera. The size of the photo you get from each camera is for all intents and purposes the same. The difference lies in the density of the pixels on the sensors (which effect the amount of light information gathers) and the observed focal length of the lens used. A 35mm on a DX camera has the equivalent focal length of a 52mm on a FX camera. Were you to shoot the same photo from the same location with a 35mm on a D7100 and a 52mm on a D600 the photos would be virtually identical.
 

fotojack

Senior Member
This is how the Nikon crop works: for instance, take the 50mm lens. Half that number = 25mm. Add the two numbers together = 75mm. That would be the mm size of a full frame camera (roughly).

Let's do the 35mm lens: half that number = 17.5mm. Add the two numbers together = 52.5mm. Close enough to the 50mm lens of a full frame camera. Understand now? :) That's the way it works for all DX lenses on Nikon DX cameras.
 

WayneF

Senior Member
This may be a stupid question, but is it possible to put a lens on a crop sensor camera to have it come out as a full frame sized photo?

There are two ways to do it.

Use a focal length 1.5x longer on DX than on FX. For example, 35mm on DX or (35 x 1.5 = ) 52mm on FX would show the same view if standing in the same location. The DX frame is just cropped smaller, so it needs a wider lens to compensate.

Or with the SAME lens, you can back away, and stand 1.5x further with the same lens on DX as is also on FX. The views will be the same (but perspective could be slightly different). It is the same lens then, which does the same thing, but the DX frame is just cropped smaller, so it needs to stand back farther to compensate.

Normally, the concern is not so much to make them equal as to use their advantages.
With a similar lens, then:
The DX shows a 1.5x longer telephoto view, considered good for sports or wildlife.
The FX shows a 1.5x wider view, the only way to get real wide angle.

The only factor is that the DX sensor simply sees a smaller cropped area than the larger FX sensor sees.

See FX - DX Lens Crop Factor
 
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eli

Senior Member
I have heard, however, that the crop sensor (I use a D7000) cannot give you the same bokeh as a full frame, even after compensating for the crop sensor and the focal length. Is that correct?
 

Rick M

Senior Member
I have heard, however, that the crop sensor (I use a D7000) cannot give you the same bokeh as a full frame, even after compensating for the crop sensor and the focal length. Is that correct?

Yes, out of focus elements are very slightly different, but also dependent on the distance to subject. For practical purposes, the smaller the sensor, the wider the aperture needs to be to produce the same results. This is why point and shoots have a hard time with bokeh.
 
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eli

Senior Member
thanks RIck, for confirming the differences about bokeh. The degree of bokeh i find attractive probably necessitates that i move from my D7000 to a full frame. I have considered the 610, canon 6D and now the sony A7. have you been pleased with your D600? Maybe this is beyond this threads subject matter, but do the 39 focus points clustered so close to center of the frame work well for you using your D600?
Any advice?
 

BackdoorArts

Senior Member
I have heard, however, that the crop sensor (I use a D7000) cannot give you the same bokeh as a full frame, even after compensating for the crop sensor and the focal length. Is that correct?

Bokeh is a function of two things, aperture and lens focal length (actual focal length, not effective focal length). Bokeh increases as aperture widens and focal length increases, since both of those factors decrease depth of field (i.e. more stuff is out of focus). Cropped sensors, because of their reduced size and increased effective focal length, lose about 1 stop's worth of depth of field.

For example, an FX camera with 50mm lens and a DX camera with a 35mm will take pretty much the same photo from the same spot since the effective focal length of the 35mm is ~52mm. Because the FX camera has a longer lens, the depth of field at the same aperture setting will be smaller. A 50mm lens at f/2.8 shooting a subject 6 feet away has a total depth of field of about 9 inches, while a 35mm lens at f/2.8 shooting a subject 6 feet away has a total depth of field of about 11 inches, so you lose 2 inches of bokeh. To match the photos the 50mm will need to be set to f/4 where it will also have 11 inches of depth of field, or the 35mm will need to shoot at f/2.

Whether or not and bokeh difference will be perceptible depends mostly on what elements are in the photo to actually render the bokeh. In other words, if the out of focus elements are largely nondescript then you will likely not even notice. But if there are many elements to be seen then you will lose some level of bokeh on the DX camera. That said, it's possible for lens used on the DX to render more pleasant bokeh if the lens is of sufficient quality, particularly when compared to the lens used on the FX.

One more thing to point out. The same lens used on both cameras will produce exactly the same level of bokeh at the same settings, but your effective focal length will increase, so that 50mm at f/2.8 will act like a 75mm at f/2.8 - same bokeh, but you only get the middle 1.5X portion of the photo.
 

Rick M

Senior Member
thanks RIck, for confirming the differences about bokeh. The degree of bokeh i find attractive probably necessitates that i move from my D7000 to a full frame. I have considered the 610, canon 6D and now the sony A7. have you been pleased with your D600? Maybe this is beyond this threads subject matter, but do the 39 focus points clustered so close to center of the frame work well for you using your D600?
Any advice?

The tight clustering can be annoying at times, but not a deal breaker for me.
 
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