Why have they not got this function on a full frame SLR... Could save on lenses!

captures.in.time

captures.in.time

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Why dont full frame SLR's come with a switch where you can change it to a crop sensor SLR... would be fab because we could then have the best of both worlds with our lenses!

Ok Ok I know its simply not just a case of putting a button on the camera... but I bet the canon and nikon boffins could get to grips with this feature and offer it but imagine the lost revenue in long range lenses for wildlife and sports pros...

And would mean I could use my existing 70-300 instrad of thinking about an expensive upgrade to a 100-400 which is a beast weight wise also!

That was my random photography thought for the day!
 
Why not just crop the image post capture?

Would have exactly the same effect.
 
Well they kind of already do have that feature (well Nikon anyway) the D700 and I believe D3 will autosense a DX lens so you can use it. The only catch is that you're only using the centre of the sensor and therefore the image produced is a lower res. The type of result you want would involve a full frame body with a high resolution sensor like the D3x but even then I'm not sure what resolution the cropped image would be.

The catch of course, is that once you've spent £5-6k on such a body, then you wouldn't really worry about the expense of decent glass. :bonk:
 
I thought the Nikon D3 could do this. Auto with a crop sensor only lens and manually with a full frame lens.


Steve.
 
Nice idea but it wouldn't work unless the cropped sensor option had a greater pixel density than the uncropped option. What you're suggesting has no actual advantage over cropping the image in post processing.
 
Steve Smith said:
It can allow increased speed (number of shots per second).


Steve.
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And more shots per card, but I was referring to any gain in effective reach which was the suggestion from the OP.
 
kalibre said:
I ignored that bit in the OP as it'll turn into perceived focal length argument. lol.
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LOL There is no gain in focal length, which doesn't change regardless of sensor size. The two factors which make the difference are pixel density and the size of the file output at 1:1.
 
Yep you can "force" DX mode on the Nikon FX cameras.
As said it makes the D3 and D700 about 5MP and you can do the same thing in PP, not sure what the pixel count goes down to on the D3X, I'd guess at 10MP ish.
 
This thread is a bit like someone waking up one morning and deciding to invent the wheel - good idea, but its a bit late :)

My D700 and Sony A900 both have this function already :)
 
PMSL @ puddleduck :lol:

And I forgot to add, I don't know about the other manufacturers cameras.
 
Sorry I guess i've not made myself as clear as I should... basically if you had a 5d... it could suddenly become a crop sensor camera but would perform the same as the crop sensor camera for instance a 50d. Hence the pixel density would increase... and your 300mm lens would effectively become a 300 x 1.6 = 480mm lens... exactly as my 75-300 becomes on my fiancees 450d.

So yes I know I could just borrow her camera... right enough... but this really is a bit of daft chat and im thinking of people who cant just borrow another camera.
 
puddleduck said:
This thread is a bit like someone waking up one morning and deciding to invent the wheel - good idea, but its a bit late :)

My D700 and Sony A900 both have this function already :)
Click to expand...

Have Canon not latched onto this then... not something i am aware of on my 5d mk1
 
markelliot said:
Sorry I guess i've not made myself as clear as I should... basically if you had a 5d... it could suddenly become a crop sensor camera but would perform the same as the crop sensor camera for instance a 50d. Hence the pixel density would increase... and your 300mm lens would effectively become a 300 x 1.6 = 480mm lens... exactly as my 75-300 becomes on my fiancees 450d.

So yes I know I could just borrow her camera... right enough... but this really is a bit of daft chat and im thinking of people who cant just borrow another camera.
Click to expand...


I can imagine that it's possible in theory. But given the cost of a sensor in the first place and adding that sort of complexity to retain the low pixel density advantage in "FX", it'd probably be cheaper to just have 2 bodies.
 
All you could do is an in camera crop (ie just process and store the image seen by the centre of the sensor, which speeds up the processing because there is less meaning higher fps) - which is what the D700/D3/D3x do.

You couldnt take the same amount of "megapixels" and get a "crop" image because the sensors are physically different sizes. You couldnt even (somehow) move the sensor backwards (or would it be forwards?) to achieve the same thing as that wouldnt work...

Nope, no way you could do this!
 
markelliot said:
Sorry I guess i've not made myself as clear as I should... basically if you had a 5d... it could suddenly become a crop sensor camera but would perform the same as the crop sensor camera for instance a 50d. Hence the pixel density would increase... and your 300mm lens would effectively become a 300 x 1.6 = 480mm lens... exactly as my 75-300 becomes on my fiancees 450d.

So yes I know I could just borrow her camera... right enough... but this really is a bit of daft chat and im thinking of people who cant just borrow another camera.
Click to expand...

I think you would have to move either the lens or sensor, would be tricky:thinking:
 
I wander if they could not embed one sensor within another... so the center crop sensor part has more pixels per inch... then when you switch the magic switch it morphs into a full frame sensor and the extra pixals per inch in the centre crop sensor area somehow lessen to the density of the full frame!
 
The reason they don't do it is that EFS lenses would break the mirror on EF only cameras when the shutter opened. You could of course use macro tubes, but lose light and the ability to focus to infinity...
 
markelliot said:
Am I wrong with that??? Now I'm lost as I thought that was the story with focal lengths of crop cameras

M
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Focal length doesn't change - its simply cropped.

A 70mm lens is always a 70mm lens.

Think of it this way - if you squint your eyes, you see less of the view - but you don't see a BIGGER view. Its just a crop... :D

This is an example - as you can see, its simply cropped, you don't get magnification of the subject.



DSC_3731-web.jpg


full frame

DSC_3731%20copy.jpg


crop camera: the colour area is what you are losing - subject size stays the same, your lens really doesn't become any longer!

​
 
I believe they call this (ahem, feature) 'digital zoom' in the world of camcorders. Please let's not get dragged down that pointless rathole. I've seen camcorders with '600x Digital Hyper Zoom' advertised. Great, if you like a picture consisting of 16 pixels. It's all just marketing bullcrap.
 
markelliot said:
Sorry I guess i've not made myself as clear as I should... basically if you had a 5d... it could suddenly become a crop sensor camera but would perform the same as the crop sensor camera for instance a 50d. Hence the pixel density would increase... and your 300mm lens would effectively become a 300 x 1.6 = 480mm lens... exactly as my 75-300 becomes on my fiancees 450d.

So yes I know I could just borrow her camera... right enough... but this really is a bit of daft chat and im thinking of people who cant just borrow another camera.
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Some mothers do have `em. :bonk:
 
OK ok... so technically you are all correct but am I not also in practice???

As the crop sensor tends to have a denser spread... then if you where enlarging the image it would be better to use the one from the cropped sensor rather than a croped image from a full frame... so what looks like a 300mm image on full frame does indeed look like a 480mm image on a crop sensor body... yes I know what you are saying there is no actual diference in focal length... but there is if the crop sensor bodys have denser pixel density on the sensor which I thought they did??? Maybe I am wrong... Oh I don't know... Im a bit of a technophobe with tecki stuff... im a know how to use it rather than how it actually works kinda guy!

I know what I mean and it makes sense to me... :thumbs:
 
SLRist said:
I believe they call this (ahem, feature) 'digital zoom' in the world of camcorders. Please let's not get dragged down that pointless rathole. I've seen camcorders with '600x Digital Hyper Zoom' advertised. Great, if you like a picture consisting of 16 pixels. It's all just marketing bullcrap.
Click to expand...

Is that how digital zoom works? I'd often wondered what was going on. That's why digital zoom is lower resolution then, it is just a crop of the original image?
 
markelliot said:
Am I wrong with that??? Now I'm lost as I thought that was the story with focal lengths of crop cameras

M
Click to expand...

Mark,

A crop sensor simply has the same effect as holding the tube from the centre of a toilet roll up to your eye....everything is the same size, just less of it.

Pixel density is the key to potential magnification, pure and simple.

Bob
 
Canon Bob said:
Mark,

A crop sensor simply has the same effect as holding the tube from the centre of a toilet roll up to your eye....everything is the same size, just less of it.

Pixel density is the key to potential magnification, pure and simple.

Bob
Click to expand...

Ok I know im being thick now... do crop sensor cameras of the same magapixel rating as a full frame then have a higher pixel density... and if they do then surely the effective focal length of the lens does in proctice change?
 
markelliot said:
Ok I know im being thick now... do crop sensor cameras of the same magapixel rating as a full frame then have a higher pixel density... and if they do then surely the effective focal length of the lens does in proctice change?
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Logic suggests that they must do, but I don't see how that is supposed to lead on to saying that the focal length alters.

Focal length is a physical state of the lens, whilst it might be adjustable, as in a zoom, that then becomes the new focal length. Pixel counts/density won't alter that.
 
markelliot said:
....do crop sensor cameras of the same magapixel rating as a full frame then have a higher pixel density...
Click to expand...
If you have the same number of pixels in a smaller area then the density is higher....typically by 2.56x (for Canon's APS-C sensors)

markelliot said:
....and if they do then surely the effective focal length of the lens does in practice change?
Click to expand...

Yes it does and so would having another crop sensored body with more pixels.
My 30D and 5DMkII have pretty much equal pixel density...one is a crop, the other is full frame.

Bob
 
iirc the APS-C sizeed crop area on a 24Mp A900 is ~13Mp.

FF sensors lag crop sensors in terms of pixel density because it costs more to make the sensor due to larger area but also that larger area means more potential for faults so lower yield >higher cost.

& of course, not everybody is going to argue that higher pixel density=better ....
 
Higher pixel density means more electrical interference between pixels when you crank the gain up... which is what we call "noise". Hence the D700 has far less noise at high ISO vs the D300. Same number of pixels, but mounted on a wider area.

D700 rocks!
 
Canon Bob said:
Mark,

A crop sensor simply has the same effect as holding the tube from the centre of a toilet roll up to your eye....everything is the same size, just less of it.

Pixel density is the key to potential magnification, pure and simple.

Bob
Click to expand...

Yes, that's true. Without the ability to capture the detail, then all is lost. However, you also need a lens capable of delivering the necessary resolution, and an inescapable fact of lens life is that when resolution goes up, contrast goes down. IMO contrast is at least as important as resolution, and that is what gives the finest lenses the 'pop' that people talk about, those bright, clean colours and general sparkle that makes a really brilliant image. You can only do so much in post processing.

So, even if you manage to cram as many pixels on to a smaller format sensor, you will not get exactly the same effect as fitting a longer lens on to full frame camera with the same number of pixels. You are asking the lens do do a heck of a lot more. This is one of the benefits of full frame and while crop DSLRs and compacts do a very good job with very sharp lenses and clever image processing, a good big 'un will always beat even the best little 'un. It's not just a question of noise with smaller formats and if it wasn't so, I guess we'd all be using tiny sensors.
 
puddleduck said:
Focal length doesn't change - its simply cropped.
A 70mm lens is always a 70mm lens.
Think of it this way - if you squint your eyes, you see less of the view - but you don't see a BIGGER view. Its just a crop... :D
This is an example - as you can see, its simply cropped, you don't get magnification of the subject.



DSC_3731-web.jpg

​
Click to expand...
Arrrr SIMPLES!!!!

sorry, but someone had to say it.....:cuckoo:
 
My 1Dslll has a Small RAW function. Effectively it gives you the equivalent of a 5Mp camera when you don't want the full 21Mp option.

The downside is that the files are nearly 13Mb in size. Only half of the full size version. I suspect the reason for this is the amount of processing time needed to reduce the RAW file doesn't give them sufficiant time to do a good lossless compression on the final RAW file.

If I need to crop the center of the image, I'd sooner use the crop tool anyway

So when I need smaller files I dig out the 5D or 20D
 
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