Megapixel reduction in DSLR

Discussion in 'Photography' started by viper357, 13 Sep 2009.

  1. viper357

    viper357 Admin MASA Contributor

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    I've been reading the manual on my camera and it says that when you zoom in to max, which is 18x on mine, that the megapixels drop from 10mp down to 3mp. Is this the same with DSLR camera's and zoom lenses or does it only apply to the compact camera's?
     
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  3. Drew

    Drew

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    Viper, generally, there are two types of zoom in a compact. There is "Optical Zoom" and "Digital Zoom" To describe optical vs digital zoom very briefly, is to say that with optical zoom, the object is brought closer to your eye and has full MP size. Digital zoom can be done on a PC and what it effectively does, is zoom in on an area of the object, but does not recapture it in full size, as you are viewing a small piece of the whole image.... hope this helps.
     
  4. viper357

    viper357 Thread Starter Admin MASA Contributor

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    Thanks Drew, the camera I have has 18x optical zoom, but it says in the manual that when you take photo's at the full 18x zoom then the image is reduced from 10mp down to 3mp. Unless I'm reading the manual wrong, let me have another good read of it and clarify.
     
  5. seank

    seank

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    bump
     
  6. mariusmeyer

    mariusmeyer

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    Its a panasonic right? I have the FZ50 and it has the same thing. (I think it is only panasonic that does this). Its called their extra optical and it is not digital zoom at all. The camera does have digital zoom but this is not it. On the Fz50 that I have you can take 10MP images with zoom up to 12X and by reducing the megapixels to 3MP I can go up to 21.4X optical. The camera will not automatically reduce your megapixels as you extend the zoom. It will go to the max as what your camera is allowed to with the selected megapixels.

    If your camera works the same as mine it means that if you leave the camera on 10MP then you will get 18X zoom and by dropping down your megapixels manually to 3MP then you should get more zoom.

    All that it does is make the resolution of the image smaller. I have experimented with this on a few occasions and have found is that does not make any usable difference. Its quite difficult to explain so say if you are not following.

    Take a picture on 10MP at full zoom (18X). Now manually reduce the megapixels to 2MP and zoom in as far as you can on the same subject. You will notice that the object will be bigger in the second picture if you look at the image on the cameras' LCD screen. This is the only difference that it makes and this is the reason I say so...

    Take both the images you took and download them to the PC. Now open both pics in MS paint and have a look a the object that you took the pic of. You will notice that the size of the object appears to be very similar in size in both pic even though the one image is larger than the other one. This means that it does not make any usable difference. So rather take the pic at 10MP and manually crop the photo on the PC if you want to.


    Hope this helps.
     
  7. Reef Maniac

    Reef Maniac MASA Contributor

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    What camera is this, Viper?

    I would have thought that optical zoom would retain the pixel size, as the image is still projected onto the whole sensor, and it would thus have the same pixel count. I suppose that it's possible that the zoomed-in image projected onto the sensor could be smaller (like the burning point of a magnifying glass...), and thus cover only a portion of the sensor, with resulting lack of pixels - although that would be akin to digital zooming...

    Hennie
     
  8. seank

    seank

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    I have seen the same on my N96. If I zoom in and take a pic, the pixels are much less than without the zoom
     
  9. Rory

    Rory Admin MASA Contributor

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    Basically the "extra" zoom is just cropping.
    Basically if you take a 10mp image and you crop it to a quarter of the size its "zoomed" another 4 times, but is only 2.5MP. It's basically a better way of doing "digital zoom" because what's normally called digital zoom is the equivalent of cropping the image to 1/4 of the size, then resizing it back to the original size (usually with some sort of sampling that makes it "smoother"). It's zoomed in, has the same number of megapixels, but not the same quality.

    Both "old school" digital zoom and the "extra" zoom that reduces megapixels are only really useful if you want to show the pics to your friends on the phone/cam etc. If you transfer all pics to your pc anyway then I'd just turn off anything that's not actual optical zoom.

    So to answer your question, no, I'm not aware of any DSLR that offers that sort of feature. I think very few people will ever even swith a DSLR to a less than full res (except maybe Hennie when he starts running out of hard drive space with his 25MP camera ;)).
     
  10. viper357

    viper357 Thread Starter Admin MASA Contributor

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    It's the Panasonic FZ28 Hennie - LUMIX Digital Cameras - Super Zoom - DMC-FZ28 - Overview - UK & Ireland
    You hit the nail on the head there Marius, thank you :thumbup: I was misreading the manual, as you said it is called Extra Optical zoom and by reducing the MP down to 3MP I can zoom up to 32.1x, it says the CCD area is cropped to the centre 3MP area. Spot on, thanks.:)
     
  11. jacquesb

    jacquesb Retired Moderator

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    LOL! No - does not happen on DSLR's Viper - what are the cost of DSLRs these days in your valley? ;)
     
  12. viper357

    viper357 Thread Starter Admin MASA Contributor

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    Not too bad, certainly a bit more affordable over here and many more people seem to have them, still a bit of a luxury item though.
     
  13. Reef Maniac

    Reef Maniac MASA Contributor

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    Hey, I can now use digital zoom :slayer:

    Hennie
     
  14. jacquesb

    jacquesb Retired Moderator

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    Digital Zoom, Hennie? What the heck is THAT?!?!?! ;)

    JPG saving is bad enough..... I should perhaps start saving in RAW as well - just have to get me that 16GB SSD card for my Nikon D40! ;)
     
  15. Lowflyer

    Lowflyer

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    I got a 8 gig SD card for my D60 for R295
     
  16. jacquesb

    jacquesb Retired Moderator

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    WOW Luke! That's not shabby, hey mate! ;)

    BTW: What do you think of the latest pics of my tank?
     
  17. Lowflyer

    Lowflyer

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    Pretty good price, gonna check out your latest pics now
     
  18. Lowflyer

    Lowflyer

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    I dig the ones of the little lion fish, he's a real beauty. I must admit that taking pics of marines stumps me too hey, wow its difficult!!! Well done their mate.:thumbup:
     
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