what's the difference between these 2 lenses?

Discussion in 'Digital Photography' started by bearbo, Oct 16, 2006.

  1. bearbo macrumors 68000

    bearbo

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    #1
    i found 2 lenses, 1 and 2... altho 1 is more expensive, intuition tells me 2 is better, altho i have no basis... can someone who understand this a bit more help me explain what's the difference between these two?
     
  2. miloblithe macrumors 68020

    miloblithe

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    #2
    The first one looks mislabeled. If you look at the picture it's a 28-200 or something.
     
  3. beavo451 macrumors 6502

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    #3
    According to the titles, the first lens has Internal Focus while the second does not. IF implies that the lens length will not change when focusing.
     
  4. Jay42 macrumors 65816

    Jay42

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    #4
    If you are looking for a macro lens, I know that a lot of people strongly advise against zoom macros in favor of primes, especially the inexpensive models.
     
  5. bearbo thread starter macrumors 68000

    bearbo

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    #5
    good point, how do i make sure which one is it?

    hehe, here i'll show my idiocy again, could you please explain to me what's a macro lens... and by the compairson, i assume prime lens are lenses that don't zoom? sorry again :p
     
  6. Grimace macrumors 68040

    Grimace

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    #6
    Prime lens: fixed focal length; ex. 100mm
    Zoom lens: adjustable focal length; ex. 70-200mm
    Macro lens: lens that can focus up close, up to 1:1 ratio and sometimes better.
     
  7. bearbo thread starter macrumors 68000

    bearbo

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    #7
    thanks!

    do you know where can i get this?... or is there one for nikon?

    for this, is the f/2.8 only at 17mm?

    are those two good lens in other aspects?
     
  8. bearbo thread starter macrumors 68000

    bearbo

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    #8
    http://www.dpreview.com/news/0609/06093012sigma18-50dc.asp
    for the sigma 18-50...

    what does DC and APS(sized sensor) mean? it doesn't mean it's not for cameras like nikon d80, right?

    also i guess it's new and everything not many people have it, how long does it usually take for something like this to become available? and how much do you estimate this baby to be?
     
  9. miloblithe macrumors 68020

    miloblithe

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    #9
    Most digital camera have sensors that are smaller than a 35mm negative, so the light from the lens gets cropped by the sensor's small size. In effect, what is a 50mm lens on a film camera becomes a 65mm lens, or a 75mm lens, and 80mm lens, or even a 100mm lens depending on the small size of the sensor. Some digital cameras are full-frame, meaning a 50mm lens is a 50mm lens.

    If you're going Nikon, you're dealing with a 1.5 crop factor. 50mm = 75mm.

    Now, what DC and APS or whatever means is that these lenses are designed to work with the smaller sensors of digital cameras, so they will ONLY work with digital cameras with small sensors (on a full-frame digital or film they will be cropped at the corners.

    The advantage of lenses made for digital cameras is they are cheaper to make, so you get more lens for your buck. The disadvantage is that if you buy a full-frame digital camera in the future, these lenses will not work.
     
  10. GoCubsGo macrumors Nehalem

    GoCubsGo

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    #10
    APS is perfect for the d80. APS is the sensor size of the N70 digital camera and afaik the n80 has the same size sensor.
    The new 17-70mm from sigma (new now with better focus and macro) is a GREAT lens. I decided to get the 10-20mm though because I didn't need a walk-around lens, I wanted a real wide lens. The 17-70 is a GREAT substitute for the kit lens, better than the kit lens in many people's opinions.
     
  11. Abstract macrumors Penryn

    Abstract

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    #11
    Yes, but since this is a very very new lens and they only make one type of this lens, I'm guessing Amazon is actually referring to the same lens, although it may not seem like it.

    The "DC" means that this lens can only be used on the smaller sized APS sensors. The lens was designed for smaller sensors so that they could make the lens physically smaller, which is fantastic. :)

    Of course there's a negative side to this. Firstly, if Nikon were to ever come out with a full frame (ie: 35 mm film sized) sensor, and you bought that camera, the Sigma 17-70 mm lens you're looking at would be useless, because it wouldn't work. Actually, it WOULD work, but you'd only get a photo in a part of the frame, and a pitch-black corners because the lens is too small to spread the light over the entire sensor. Call it "vignetting" if you want. ;) I will only buy lenses designed for 35 mm film AND digital sensors so that when Nikon goes with a full-frame sensor, my lenses can still be used. I made an exception when I bought my Tokina 12-24 mm f/4, but that will be very easy to sell. ;)

    Secondly, corner sharpness is incredible on digital DSLRs with the smaller APS/APS-C sized sensors when coupled with a larger lens designed to be used on digital and 35 mm film cameras. Why? Because the centre of the lens is the sharpest. Since the lens is, in a way, too big for the sensor, you're using mostly the centre of the lens, and getting sharp sharp photos as a result, and with less vignetting. ;)
     
  12. bigbossbmb macrumors 68000

    bigbossbmb

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  13. Spectrum macrumors 6502a

    Spectrum

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    #13
    That's what i thought. Ont the sigma website there is only ONE 17-70mm lens.

    The 18-50 _has_ just been updated to MACRO capability though.

    In any case. I'd still buy the Nikon 18-70 over the Sigma 17-70. That apparent f/2.8 advantage over the f/3.5 of the Nikon will drop off very quickly as you zoom in. The Nikon also has a silent-wave motor. This allows instant manual focussing override, and extremely fast silent focusing. bhphoto sell the 18-70 for around $300 so the price is better too.
     
  14. bearbo thread starter macrumors 68000

    bearbo

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    #14
    doesn't APS stand for Active Pixel Sensors, most of which are CMOS, aka CCD is not APS? or does APS mean something completely different in this case...

    my concern is, since D80 only has CCD, is it gonna work well with the 18-50mm one?

    i think now i'm between the 18-50 and the 24-70, with some preference on the 18-50, however if it's not close to be available in a month or two, i might get the 24-70... and if somehow both of those 2 are out of reach, i'll consider the Nikon 18-70

    i figure i want the f/2.8 lens with some zoom compatibility, 50,60,70 doesn't matter... and PREFERBLY macro compatibility... and later if i decided to get a zoom lens, i'll get it later or something, what do you think?
     
  15. beavo451 macrumors 6502

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    #15
    In this case, APS means something else.

    A few years before the boom of digital, Kodak released a film format called the Advanced Photo System (APS). Each frame was smaller than a regular 35mm frame. Since most digital SLR cropped sensors are roughly the same size as the APS film frame, they are called APS sized sensors. The "-C" stands for "classic" and refers to the traditional aspect ratio of 35mm film (3:2), hence APS-C.
     
  16. bearbo thread starter macrumors 68000

    bearbo

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