Digital zoom is useless?


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Mar 20, 2008
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#1
I read somewhere that it is better to use the camera's optical zoom and switched off the digital zoom. This is due to the poor quality of images by using the digital zoom. Is this true all the time? Please advise. Thanks!

In dslr, is there digital and/or optical zoom features? Or, dslr is suppsed to rely solely on the lens' ability?
 

Prismatic

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#2
Digital zoom is just like the magnifying glass tool in your computer. What it does is simply magnifying the picture and cropping it to keep it within the same picture size. So what you are actually doing is just magnifying the individual pixels in your picture.

The zoom of DSLR is dependent on the zoom lenses that they are equipped with. As far as I know, most DSLR don't have a digital zoom function.
 

#3
the DSLR (digital single lens reflex) or rather.. any digital camera.. has no optical zoom.. it's juz a black box with a shutter that opens to allow light onto the sensor..

when you refer to optical zoom you are referring to the lens..

and i think it's technically not possible to have digital zoom function for a dslr.. (correct me if i am wrong!)

and btw.. you dun need digital zoom coz you have a CROP function in any basic photo editing software..
 

Octarine

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#4
In dslr, is there digital and/or optical zoom features? Or, dslr is suppsed to rely solely on the lens' ability?
In any SLR (be it an analog one using film or the newest digital SLR) "optical zoom features" = "the lens' ability" ;)
 

Legoz

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#5
On PnS, the digital zoom is essentially a crop function.
 

Mar 20, 2008
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#6
What I mean by digital zoom or optical zoom is found in prosumers and PnS cameras. Should the digital zoom feature be switched off in them when taking photos?
 

night86mare

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#7
What I mean by digital zoom or optical zoom is found in prosumers and PnS cameras. Should the digital zoom feature be switched off in them when taking photos?
depends on you.

also depends on the camera.

i thought my sony h2's digital zoom feature was pretty nifty, and the output wasn't too bad either. but i've seen really, really bad digital zooms as well. i'm not sure what's the difference between a good digital zoom and a bad one, maybe someone who knows the more technical parts can enlighten so we can learn something. clockunder or littlewolf know?

but as what others say, it is like the crop feature.. so unelss you really must see the details when you look at the picture when travelling.. just edit when you go home loh
 

splim

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#8
..
also depends on the camera.
...
like you said, it depends on the camera.

If the camera internal processor render better than the computer on the cropped (digitally zoomed) image, then the better result from the camera. The camera can used the original cropped data from sensor while the computer is using the already compressed jpeg data.

Which result is better ? the camera owner have to find out themselves.
 

viewwing

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#9
What I mean by digital zoom or optical zoom is found in prosumers and PnS cameras. Should the digital zoom feature be switched off in them when taking photos?
If the digital zoom is more than 4x... turn it off... cause it will not produce any good product....

What most of the fellow CSer are telliing can be simplified into this.

1. Optical zoom = Real zoom. kinda like u putting a binocular to see further.

2. Digital Zoom = Fake zoom. Imagine this. U have a A3 size photo of say... the Singapore Flag. Now... say u wanna "digital zoom" to one of the stars. So just cut out the star from that A3 size photo... voila.. digital zoom....

So u see... in terms of quality of image... up to the point where the optical zoom stops... nothing will be "zoomed" anymore... hope this help. :bsmilie:
 

sytan81

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#10
and i think it's technically not possible to have digital zoom function for a dslr.. (correct me if i am wrong!)
actually, with live-view DSLRs, it is possible.. I have such a function in my A350.. just a press of a button and I get a 1.4 or 2 times magnification effect.. Sony called it the "Smart Teleconverter" function..

Sony claimed that it does not interpolate like what PnS cameras usually does, thereby contributing image loss and noise.. a pity that I've yet to try this function out.. will prob do so tonight when I get home.. ;)
 

#12
Digital zoom is the cropping and then interpolation of a photo by the camera's processors.

Basically what the camera does is that it's just cutting out the edges of your photo [cropping], and then rendering out pixels to make the cropped photo as large [in resolutions] as the camera's set resolution. It's good ONLY if you're the kind of person who don't care about 'pristine' picture quality, and are too lazy to crop your photos. It's bad if you plan to print your photos for publication, competition, or showcasing purposes. Basically: if you care about your photos, forget about digital zoom. If you're just a typical PnS user who's not tech-savvy, you wouldn't be reading this, and still continue to use Digital zoom. So don't use it.

As far as I know, DSLRs don't have digital zoom [only zoomed preview]. If you want to have the same function as digital zoom, one way is to use your computer. Softwares like Photoshop Starters Edition, Photoshop, Aperture, etc. can crop your photos. If you want to interpolate them [still not encouraged, because it's like uncompressing a compressed file. redundant.], some softwares can do that too.

Oh, normally we don't think of zoom in a DSLR as a feature of the CAMERA BODY. we think of zoom as a characteristic of the lens. Why characteristic? Because there's lenses like my 50mm f/1.4, which is called a "Prime lens", which doesn't have any zoom. What's the use, you ask? Well, in the case of the 50mm, it has a really large aperture [f/1.4], which makes this lens very suitable for photos with lots of bokeh [another issue, not elaborating here].

So please don't think of zoom as the all-in-all de-facto standard of defining a good camera from a worse one.

Cheers!
 

sytan81

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#13
Ok, I've tried out the function on my Sony A350. The picture quality is as good as without digital zoom! Seems like no interpolation was done.

However, there are some differences. The A350 offers 1.4x and 2x teleconverter modes:

1. At 1.4x, only photos of "Standard" image quality and "Medium" size (i.e. 7.7MP) can be taken. Cannot use "Fine" or 14.2MP.

2. At 2x, only photos of "Standard" image quality and "Small" size (i.e. 3.5MP) can be taken.

So in a way, it works in the same way as you would using Photoshop to crop a 14.2MP image down to a smaller size.

Conclusion: Don't think I'll be using much of this function. Unless it's for macro or if I just need the 2x magnification to confirm certain details before I decide to take the shot.
 

karnage

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#14
Personally, I would not turn on the digital zoom feature on my camera if it has one. Like everyone has said, it's just cropping. I suppose a digitally zoomed picture can turn out well if it's set at the highest resolution, which should be high. It's the same as why some people prefer higher megapixel count cameras so that they can crop their pictures to get the view they want.
 

night86mare

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#15
Personally, I would not turn on the digital zoom feature on my camera if it has one. Like everyone has said, it's just cropping. I suppose a digitally zoomed picture can turn out well if it's set at the highest resolution, which should be high. It's the same as why some people prefer higher megapixel count cameras so that they can crop their pictures to get the view they want.
well, but i won't call it *useless*

this was taken on my sony h2 a while back using max digital zoom, cropped into near-square format

certainly the IQ isn't as great as without digital zoom, but i think i did take a few without, they turned out with focus off so i gave up and used digital zoom



maybe it's to be avoided, but certainly not useless. :)
 

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