Massive zoom ranges

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I thought I knew everything there was to know about cameras but the Nikon Coolpix P900 (and many others) have me a little bemused. The P900 has a 83x optical zoom range with effective focal length from 24mm to 2000mm and I am failing to see how this works so a quick explanation would be much appreciated. I am assuming that the camera uses smaller and smaller sections of the sensor to avoid the lens having to reach ridiculous proportions but does this not reduce the pixels per inch as one zooms in and hence lose resolution?
 
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It just a crop factor ie smaller sensor which reduces the field of view,so giving the effect of a long lens,i do most of my birding now on a p610 as i find lugging 3 kilos of gear around too much for me,IQ suffers but i enjoy my walks more and am still taking pictures.
Just bought a D750 and use it for when ime not walking far,looking to try the P900 though as it has a longer lens than the P610.
 
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I use a Panasonic FZ200 for Birds and Video. It goes up to 600mm or doubles to 1200mm. But wow if this image came out of a camera with 2000mm it looks worth investing in.
 
ShinySideUp said:
I thought I knew everything there was to know about cameras but the Nikon Coolpix P900 (and many others) have me a little bemused. The P900 has a 83x optical zoom range with effective focal length from 24mm to 2000mm and I am failing to see how this works so a quick explanation would be much appreciated. I am assuming that the camera uses smaller and smaller sections of the sensor to avoid the lens having to reach ridiculous proportions but does this not reduce the pixels per inch as one zooms in and hence lose resolution?
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To answer your question, it's an optical zoom, and it manages the massive length only with a 'crop factor'. The lens focal length is actually 4.3-357mm, which whilst a massive zoom range isn't as ridiculous as trying to squeeze in a 2000mm lens.
 
Tom Curtis said:
I use a Panasonic FZ200 for Birds and Video. It goes up to 600mm or doubles to 1200mm. But wow if this image came out of a camera with 2000mm it looks worth investing in.
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Dont know if your talking about the goldfinch but just in case this was at about 1400mm max zoom on the P610 i dont use digital zoom,waiting to try the P900 when my dealer gets one he can spare for demo purposes
 
ShinySideUp said:
I am assuming that the camera uses smaller and smaller sections of the sensor to avoid the lens having to reach ridiculous proportions but does this not reduce the pixels per inch as one zooms in and hence lose resolution?
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No. What you've just described there is called 'digital zoom', and it's how phone cameras create a zoom effect despite having a fixed focal length lens.

But you've already said how the P900 works:
ShinySideUp said:
The P900 has a 83x optical zoom range with effective focal length from 24mm to 2000mm
Click to expand...
It's as simple as that. The camera has a zoom lens which actually goes from 4.3mm to 357mm, so build in a crop factor of 5.6 and you get 24-2000mm equivalent.

The camera *also* has a 4x digital zoom which crops the image to give you the field of view equivalent to 8000mm. At that size it's only giving you 1 megapixel of resolution instead of 16 megapixels, but that's fine for web use.
 
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