Nikon DX ' FX query

stickytape

stickytape

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Good evening all

While very much enjoying my recently purchased fz1000 bridge, I am already hankering after a DSLR. While researching various makes, models and technologies, I have come across the following that still confuses me with regards to Nikon DX and FX.

So, I understand Nikon DX are crop sensor DSLRs (c sized sensor)

FX are the full sensor models
There are also AFS DX lens and FX lens - the FX can be used on both FX body and DX body

The DX lens can be used on DX bodie - BUT this is where I'm getting confused. You could put the DX lens on the D700 as it will physically fit. The D700 will then either auto mask the sensor to make it a crop size sensor. Other option is to leave it on FX mode but you will get (I assume) corner shading due to lens/sensor difference.

Now, the results from the auto crop should be the same as the FX ones cropped to the same size - but will the quality be the same or will it be worse? As I don't imagine (and having seen some examples) that the shading would be "that bad" when used in FX mode, that you'd have to do a massive 1.5x crop therefore you would have a better quality image in FX mode with perhaps a slight crop?

I'm getting a bit list myself now with this, I hope it makes a little sense to someone with greater know how than myself!

Many thanks
 
Basically you've got it right although many DX lenses will result in major cut off from the corners of the FF sensor and those that don't are typically soft in the corners.

The thing to remember about cropping is that in doing so you are magnifying the image which effectively loses you any advantage you had of shooting FF in the first place.
 
Ok, DX lens can't cover the full frame sensor, so therefore you have that auto crop from the FX camera. Like you said you can use it in FX mode but because the lens can't fill the sensor you will see the black corner/shading/frame. On auto crop in FX camera, I believe on the D700 you get 5mp instead of the 12mp.

For DX camera, if you mount the DX lens, it will fill the sensor and you get a full mp image from your sensor. If you mount FX lens on DX, your DX sensor can only see around the middle of the FX glass, but you also get the full mp from your sensor.
 
Using a camera in DX mode or cropping it in post will in theory give the same results. However, it may meter differently as in DX mode it only meters to the DX frame. That being said with a DX lens on FX body they're be severe vignetting and not a lot to meter outside the DX frame anyway.
 
A lot depends on the lens. I have used a Tamron 10-24 (a DX lens) on FX and between 15 and 24 there was no noticeable vignetting in FX.
 
Further to @badboy1984 - mounting an FX lens on a DX body will (ostensibly) render a sharper image as you'll not be using the edge of the lens which is generally poorer: just the centre of it. That is, of course, an oversimplification but is a reasonably good assumption.

DX lens on FX is an auto crop function - I've had 3x FX bodies and I don't recall ever being able to over-ride the cropping/masking in the viewfinder or frame.
 
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chuckles said:
Further to @badboy1984 - mounting an FX lens on a DX body will (ostensibly) render a sharper image as you'll not be using the edge of the lens which is generally poorer: just the centre of it. That is, of course, an oversimplification but is a reasonably good assumption.

DX lens on FX is an auto crop function - I've had 3x FX bodies and I don't recall ever being able to over-ride the cropping/masking in the viewfinder or frame.
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Screen Shot 2017-01-13 at 10.49.03.png


:p
 
chuckles said:
Further to @badboy1984 - mounting an FX lens on a DX body will (ostensibly) render a sharper image as you'll not be using the edge of the lens which is generally poorer: just the centre of it. That is, of course, an oversimplification but is a reasonably good assumption.

DX lens on FX is an auto crop function - I've had 3x FX bodies and I don't recall ever being able to over-ride the cropping/masking in the viewfinder or frame.
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This. In theory with a good quality FX lens on a crop body would give great sharp results in the field.
 
For those who want a bit of extra reach on an FX body, is there a disadvantage to using a DX tele to obtain the same effective focal length as if they had a DX body? The general assumption is that present sensors out-resolve the lenses we use.
 
ancient_mariner said:
For those who want a bit of extra reach on an FX body, is there a disadvantage to using a DX tele to obtain the same effective focal length as if they had a DX body? The general assumption is that present sensors out-resolve the lenses we use.
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Probably the only disadvantage is that there aren't any really good DX telephoto lenses.
 
StewartR said:
Probably the only disadvantage is that there aren't any really good DX telephoto lenses.
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you are right about that, but isn't it cheaper to just buy a DX body and mount your FX lens on? instead of mounting DX lens to FX body? lol.
 
ancient_mariner said:
For those who want a bit of extra reach on an FX body, is there a disadvantage to using a DX tele to obtain the same effective focal length as if they had a DX body? The general assumption is that present sensors out-resolve the lenses we use.
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Only if you want to crop heavily afterwards as you have less MP to work with.
 
badboy1984 said:
you are right about that, but isn't it cheaper to just buy a DX body and mount your FX lens on? instead of mounting DX lens to FX body? lol.
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It is, I'm just curious about the principles and also Say, having a DX body and FX body and lens not being interchangeable etc.

So, the Nikon 55-300 DX and the 70-300 DX..

Crop and full frame one. Considerable difference in cost - the glass covers a small area on the DX one? Apart from the cheaper model and lighter I think - what's the whole point of the 55-300? Surely the 70-300 does everything else but seems to have very favorable reviews on DX and FX as well?
 
stickytape said:
It is, I'm just curious about the principles and also Say, having a DX body and FX body and lens not being interchangeable etc.

So, the Nikon 55-300 DX and the 70-300 DX..

Crop and full frame one. Considerable difference in cost - the glass covers a small area on the DX one? Apart from the cheaper model and lighter I think - what's the whole point of the 55-300? Surely the 70-300 does everything else but seems to have very favorable reviews on DX and FX as well?
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The 70-300 isn't a DX lens, it is FX and that's the point, it focusses faster than the cheaper DX lens too.
 
stickytape said:
That's it then, its just faster focusing therefore more expensive!?
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FX is normally more expensive because the elements need to be larger, and may be more expensive to manufacture. Also modern FX lenses may be considered a little more 'serious' for the enthusiast market, so command higher prices compared to consumer products.
 
Don't forget that you take a huge hit in MP count if you use a dx lens on an fx body in crop mode - divided the FX pixel count by 2.29. E.g. Your 24MP becomes 10MP.
 
ancient_mariner said:
For those who want a bit of extra reach on an FX body, is there a disadvantage to using a DX tele to obtain the same effective focal length as if they had a DX body? The general assumption is that present sensors out-resolve the lenses we use.
Click to expand...
StewartR said:
Probably the only disadvantage is that there aren't any really good DX telephoto lenses.
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I think @ancient_mariner was making a point that many people overlooked. Let's try to put it another way. If you already have an FX body, and you're struggling for reach so you don't mind cropping the images anyway.... what's the point in having a FX telephoto lens? You're just going to use the centre of the image anyway, so - other things being equal - why not use a DX telephoto lens which would be smaller and lighter and cheaper?

One reason I suggested was that all the really good telephoto lenses are FX. (Though it would be interesting to compare the new Nikon DX 70-300 against other FX 70-300s. With zoom lenses, new designs tend to be much better than old designs.(Other things being equal.))

Another reason, of course, is that if you use a FX lens and crop, you're using just the central part of the image, so the lens performance should be good. Whereas if you use a DX lens you're using the whole image so there's a higher risk of a drop in quality towards the edges and corners. (Other things being equal.)
 
Thanks Stewart, that was indeed my point. The thing is that my D610 should give roughly 12mp crop-size images with lower noise and better dynamic range than many older crop-sensor cameras of similar pixel density, so images produced using that body should be at least as good as images with the same lens on an older body. But your point that DX lenses are (or were) of lower image quality is a good one - I may be wrong, but my perception is that while other makers, particularly Sony, have been making some lenses for crop with excellent image quality, that hasn't been true of Nikon.
 
ancient_mariner said:
Thanks Stewart, that was indeed my point. The thing is that my D610 should give roughly 12mp crop-size images with lower noise and better dynamic range than many older crop-sensor cameras of similar pixel density, so images produced using that body should be at least as good as images with the same lens on an older body. But your point that DX lenses are (or were) of lower image quality is a good one - I may be wrong, but my perception is that while other makers, particularly Sony, have been making some lenses for crop with excellent image quality, that hasn't been true of Nikon.
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D610 will give you 10MP in DX mode (y)
 
StewartR said:
I think @ancient_mariner was making a point that many people overlooked. Let's try to put it another way. If you already have an FX body, and you're struggling for reach so you don't mind cropping the images anyway.... what's the point in having a FX telephoto lens? You're just going to use the centre of the image anyway, so - other things being equal - why not use a DX telephoto lens which would be smaller and lighter and cheaper?

One reason I suggested was that all the really good telephoto lenses are FX. (Though it would be interesting to compare the new Nikon DX 70-300 against other FX 70-300s. With zoom lenses, new designs tend to be much better than old designs.(Other things being equal.))

Another reason, of course, is that if you use a FX lens and crop, you're using just the central part of the image, so the lens performance should be good. Whereas if you use a DX lens you're using the whole image so there's a higher risk of a drop in quality towards the edges and corners. (Other things being equal.)
Click to expand...

Thanks Stewart, I think I'm understanding it now.. it's still a bit of a confusing thing though!
 
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