Digital lens vs Regular lens

Discussion in 'Photography Equipment & Products' started by kamilla, Jul 14, 2007.

  1. kamilla

    kamilla TPF Noob!

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    I want to buy fisheye lens for Nikon D70. I picked sigma 15mm/2.8 lens. However, there are two types of this lens on the market one is digital and the other one is not. If I buy the regular lens will I have to multiply the local lenght of the lens by 1.5 and istead of having 15mm lens I will end it up with 24mm lens. I'm very confused,I apreciated any feedback.Thank you
     
  2. Don Simon

    Don Simon TPF Noob!

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    No, you won't have to multiply anything. 15mm is a 15mm is 15mm.

    If you use a 15mm lens on your D70 and use a 15mm lens on a Nikon film SLR, you will get a different angle of view. But two different 15mm lenses on your D70 would both give you the same angle of view.

    "Digital" lenses simply means that they are only designed to cover your digital sensor. In other words they will not work on a film camera. This is obviously not a problem if you're only using a D70. "Regular" lenses are designed to cover a larger area of film/sensor, but will still fit and work on the digital camera... there are no real disadvantages to using a "regular" lens except for higher weight and cost.

    The 1.5x multiplication is only a way of comparing lenses used on 35mm film with lenses used on sensors which are approx 1.5x smaller. No 15mm lens will ever turn into a 24mm lens on your digital SLR... a 15mm lens ("digital" or not) on the D70 just happens to have a similar angle of view to a 24mm on a 35mm film SLR. If you are not used to using 35mm film cameras, this really means nothing.
     
  3. panocho

    panocho TPF Noob!

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    It does mean something: it means that a 15mm lens when mounted on a digital is not anymore a fisheye, but a wide-angle, aprox. what a 22.5mm lens would be on a 35mm camera
     
  4. Don Simon

    Don Simon TPF Noob!

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    OK it means something... if the 15mm in question is a fisheye... in this case it is. Sorry I hadn't spotted that. IMO my point stands if talking about any rectilinear lens (it is possible to have a 15mm rectilinear)... but here the OP was specifically talking about a fisheye which I missed - sorry and thanks for pointing that out.
     
  5. Sw1tchFX

    Sw1tchFX TPF Noob!

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    if you want 180 degrees worth of view, get the 10.2mm Nikkor fisheye. The sigma 15mm fisheye will just act like a 22mm prime with a heck of alot of barrel distortion, unless you use it on a film camera, THAN you'll be able to take advantage of it.
     
  6. WingedPower

    WingedPower TPF Noob!

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    [​IMG]

    Something not covered yet is the glass composition/contstruction/coatings. Digital lenses have the added benefit of being designed so that the three different colors of light converge to a single point in a more parallel fashion, onto the sensor. This way, you get less chromatic aberations(purple/green/red fringing at wide angle and in light/dark borders). This is more important with wides and super/ultra-wides like the 15mm and the 10.5mm lenses.

    Another aspect of digital lenses are the coatings that resist reflecting light that bounces off of the sensor. Since the sensor behaves alot like a mirror, light bounces back to the lens, which might bounce back onto the sensor, causing visual defects. Digital lenses will sometimes employ an anti-reflective coating on the glass facing the sensor, thus reducing this effect.

    As another poster pointed out, digital lenses MAY be designed to project a smaller image, so will not fully expose a full sized sensor or one larger than the sensor that lens was designed for. There are APS-C(1.5-1.6x) and APS-H(1.3x). A digital lens designed for these sensors will result in severe vignetting(corner/edge darken/shadowing) when used on a full sized sensor camera like the Canon 5D.

    Edit:

    FYI, a friend of mine shoots with the Nikon D80 and the 10.5mm fisheye and the shots from it are amazing. You can get awesome landscapes, and trippy closeups. The 15mm will not "feel wide", when put onto a D70/D80, because of the cropping factor. If you had a choice, go with the 10.5mm. It will give you the wide you are looking for. If you're getting the 15mm, you might as well get one of the 16/17mm-50/75mm f/2.8 wide zooms, in conjunction with the 10.5mm. That's the way I went and am saving up for an ultra-wide like the 10.5mm.
     
  7. Alpha

    Alpha Troll Extraordinaire

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    I'm calling bull on this one. There's no way that all, or even most "digital lenses" are apochromatic.
     
  8. Alpha

    Alpha Troll Extraordinaire

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    I should also add that digital lenses are better than non-digital lenses. It's because they're digital. Trust me.
     
  9. WingedPower

    WingedPower TPF Noob!

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    *grins* Perhaps I should qualify my statement by stating that digital lenses "marked" as apochromatic will properly align the various color spectrums. Ever since I became aware of the issue, I've only bought lenses that would work better with digital. My bad for the omission.
     
  10. Sw1tchFX

    Sw1tchFX TPF Noob!

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    [​IMG]
     
  11. Don Simon

    Don Simon TPF Noob!

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    You do know they had apochromatic lenses before "digital" lenses came along, right? ;)

    No offence intended, but if you've been buying only "lenses that would work better with digital"... how do you know that they would work better with digital? :) IMO the idea of lenses designed for digital sensors being inherently better for digital sensors than lenses designed for film is a theoretical one rather than one that will be seen in practice... I very rarely find flare or chromatic aberrations be a problem - because I try to use good lenses which have good coatings, "digital" or not.
     
  12. RVsForFun

    RVsForFun TPF Noob!

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    ...most lenses made in modern times are apo's, IMHO. How much they achieve this given the ever-widening zoom ranges is another thing. Every lens I own for my Canon 20D has aspherical elements in it, something unheard of 15 years ago. If you had ONE lens with ONE aspherical element other photographers would crowd around you and ask to touch it. In the case of my 17-85mm USM, it has THREE!

     

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