Crop Factor for FZ-20/15

[cheese]

The lens on the fz-20 is a 6-72mm, but the 35mm equivlent is 36-432mm. Does this mean that the crop factor on the fz-20 is 6x !?! Is that how ultra zooms are possible, by having large crop factors?

[jaynads]

The lens on the fz-20 is a 6-72mm, but the 35mm equivalent is 36-432mm. Does this mean that the crop factor on the fz-20 is 6x !?! Is that how ultra zooms are possible, by having large crop factors?

That's exactly how they work. If you were to buy a real 35mm lens that zoomed to over 400mm yet stayed as wide as f2.8, you'd have a gargantuan lens (like the guys at football games with their 2 foot long white zooms).

It actually isn't a totally bad thing, however. The chip is smaller, which isn't the greatest thing in the world, but it gets the sweet spot in the lens which is good. Imaging this: Draw a circle on a scene. That is what the lens sees. With a 35mm camera, you'd essentially draw a rectangle whose corners nearly touch the outer edges of the circle. Because the CCD is smaller, (6X smaller), it sits neatly in the center of the circle, far from the edges. Since this smaller rectangle is blown up full size, it essentially "zooms" in or "crops" the view of the lens. This is good in that there's usually less distortion in the center of the lens as compared with the edges.

I realize you didn't actually ask "how" it works, so I'm sorry if I rambled . . .

[genece]

Now I am curious.
I am not sure I understood the question and I really do not understand the answer.

Is that not how digital zoom works not optical?

I am not arguing I just do not understand.


I also do not understand but have heard it mentioned so often it must be so that canon DSLRs have a 1.6 crop factor are these terms totally different.
I know my question makes no sense as I do not understand.

[cheese]

Now I am curious.
I am not sure I understood the question and I really do not understand the answer.

Is that not how digital zoom works not optical?

I am not arguing I just do not understand.


I also do not understand but have heard it mentioned so often it must be so that canon DSLRs have a 1.6 crop factor are these terms totally different.
I know my question makes no sense as I do not understand.

Crop factor has nothing to do with digital or optical zoom. DIgital zoom just zooms in on the picture itself, sort of like cropping the image in photosphop and keeping it full size, which loses quality.

Crop factor happens because the sensor (which is behind the lens and gets the picture) is smaller than a standard 35 mm. THis particular sensor is 6x smaller, which causes the image to be 6x larger. As a result, THis cammra can use a 6- 72mm lens, which on a standard camera would be very, very wide angle to slightly more zoomed in than normal. However, with the 6x crop factor, it multiply's the lenses actual focal length 6x, taking it from 6-72 to 36-432. This gives you a huge zoom for much less than what you would have to pay for a lens going up to 400mm, as well as a much smaller lense.

[genece]

Its getting a little clearer ..Thanks

I don't need to understand but I am grateful it does what it does.

[StanStan]

If I take a photo and crop it by 6x what do I end up with?

Is the area reduced to 1/6 of original?

I just do not 'get it'!

Thanks.

[Balrog]

Ok, try looking at it like this:

Picture your lens, which is taking light from the outside world, throwing it onto a circle onto the sensor inside your camera. Now imagine a block of 35mm film (actual dimensions 36*24mm) placed in the center of that circle, capturing the image for you. You take the image captured on the film and, let's say, project it on your wall. That would give you a certain "field of view", the amount of the world that was projected onto the film by the lens.

Now suppose you took away that film, and (without changing anything else) replaced it with a much smaller piece .. let's say, 6*4mm, right in the middle of the image circle created by the lens. If you take the image captured on the tiny bit of film, and again project it onto your wall, it would look like you "zoomed in" to the central part of the previous (35mm) image. The lens hasn't changed, but because you're cropping the central 1/6th (in horizontal and vertical dimensions .. the actual area captured is only 1/36th), it looks much bigger on your display medium (the wall).

The reason the crop factor is sometimes (incorrectly) referred to as a "focal length multiplier" is because if you wanted to produce the image that was on the 6*4 bit of film on the entire 36*24 piece, you'd need a lens with 6 times the focal length.

And the reason SLRs have so much better dynamic range, etc than P&S cameras is because (as you saw above) the area of their sensors is so much bigger... a sensor with a 1.5X crop factor would have 16 times the area of one with a 6X crop factor (6 squared divided by 1.5 squared).

Hope that clears things up a little ... :)

[StanStan]

Thanks .....Balrog..... I 'get' more of this. Never thought of this as I did not see it the forums. A little knowledge doesn't hurt.

What you are telling me is that the FZ20 with a larger sensor would be a digital SRL. How big could the sensor be in the FZ20? If the sensor gets larger then the
35-432 would be less.[?]

OK: Panasonic Give me a large sensor! With a larger digital zoom [crop] to drop back to 5MP.

My Minolta has a mirror that bounces back and forth and takes great shots but I could not afford the cost film for the thousands of pictures I take with a digital. I'm in the 106xxxx folder. 6000+
Even with digital I print very few pictures due to the high cost of paper and ink.
I do refill cartridges but I believe quality suffers

OK again. Does the FZ20 interpolate pixels in digital zoom? How does that work?

Thanks.

[John_Reed]

OK again. Does the FZ20 interpolate pixels in digital zoom? How does that work?If you do a DZ shot with the FZ20, you've got the camera set to full optical zoom, let's say 432mm equivalent. If you zoom out to 24X, that means you're asking for a 2X digital zoom, and so the camera responds by cropping the full 12X image by a factor of 2 in each direction. So your 5MP, 2560 X 1920 full image would thus get internally cropped down to 1280 X 960 pixels, and you'd see an image of that size in the viewfinder. But before the camera stores the image on your SD card, it first interpolates pixels back to the original array size before doing its JPEG compression, so that what you download is still a full 5MP image, albeit an image based on only 1/4 of the detail that would emerge from an "optical-only" image.

[jaynads]

Even with digital I print very few pictures due to the high cost of paper and ink.
I do refill cartridges but I believe quality suffers


Just as an aside - you might want to try MPIX or Adorama Photo instead of ink jet. They're pretty inexpensive (about $.19-.21/4X6, sometimes free shipping). They don't mess with your pictures, what you send them is what they print, no color correction, etc., as at that price, I believe it's actually less than printing yourself (especially if you get the occasional need to re-print). Plus, it's an actual photograph (digital projection onto photo paper and chemical developing). I think the quality is superior to ink-jet, especially in shadows, where ink-jets often reflect black differently than the other colors making it look flat.


As for your other comment about wanting a bigger chip - that has it's limitations. Once the chip gets larger, and the crop factor decreases (less zoom) and the lens needs to get bigger to allow for more light (variable f-stops through the zoom range instead of a fixed 2.8). Not to mention the cost. That's why you don't see any fixed-lens mega-zoom cameras with large CCD's. The lens would have to be so huge it would outweigh the cost of the camera body. Believe me - I would love a large, high quality CCD in my camera, but it's a trade-off - small chip, big zoom and wide f-stops vs. large chip with low noise at high ISO but $500+ for quality large zoom lenses.

[cheese]

Thanks .....Balrog..... I 'get' more of this. Never thought of this as I did not see it the forums. A little knowledge doesn't hurt.

What you are telling me is that the FZ20 with a larger sensor would be a digital SRL. How big could the sensor be in the FZ20? If the sensor gets larger then the
35-432 would be less.[?]

OK: Panasonic Give me a large sensor! With a larger digital zoom [crop] to drop back to 5MP.

My Minolta has a mirror that bounces back and forth and takes great shots but I could not afford the cost film for the thousands of pictures I take with a digital. I'm in the 106xxxx folder. 6000+
Even with digital I print very few pictures due to the high cost of paper and ink.
I do refill cartridges but I believe quality suffers

OK again. Does the FZ20 interpolate pixels in digital zoom? How does that work?

Thanks.

Belive me, you don't want a large sensor on the fz-20, because it would have to hgave a lens with much more focal lengh, which would a. cost much more and b. be very, very big.