Quick lens ?

Discussion in 'Digital Photography' started by SWC, Aug 26, 2007.

  1. SWC macrumors 6502

    Joined:
    Jan 6, 2004
    #1
    Just a quick question about the difference between ef and ef-s lenses. I have been reading up bit still am a bit confused. I know on the non full frame cameras the multiplier is 1.6 for canon.

    I am looking at two lenses the ef-s 17-85 and the ef 28-135 now the ef-s after conversion is roughly the same as the 28-135 before. I want to stay open to a full frame camera down the line so the ef is my best bet to not have to rebuy.

    My main question is does the 1.6 conversion also apply to the ef lenses effectively making the 28-135 a 45-216mm?
     
  2. sjl macrumors 6502

    sjl

    Joined:
    Sep 15, 2004
    Location:
    Melbourne, Australia
    #2
    Focal length is focal length, regardless of the sensor size. The easiest way to visualise it is to think of a pinhole camera: you have film (or a plate, or a digital sensor) on one side of a light-proof box; on the opposite side, you have a tiny pinhole to let light in. This pinhole casts a certain image on the sensor. The focal length of a given lens is the distance that pinhole would have to be from the sensor in order to cast the same image (ignoring distortions and the like.)

    So just because the sensor is smaller doesn't change the focal length. It changes the field of view (again, visualise the image cast by the pinhole and consider what would happen if the sensor were bigger or smaller), but not the focal length. A 400mm lens is still 400mm regardless of whether it's mounted on a 1.6 crop body or a full frame body. The 1.6 crop will give you a field of view equivalent to a 640mm lens mounted on the full frame body, but that doesn't make the 400mm lens a 640mm lens.

    In the same way, a 28-135mm lens mounted on a 1.6 crop body is still a 28-135mm lens. Field of view is equivalent to a 45-216mm lens mounted on a full frame body, but it's still a 28-135mm lens.

    If you look carefully at digital compacts, you'll realise that that's what's happening - the actual lens may be 7mm-21mm with the film equivalent of "35-105mm" being trumpeted (for example).
     
  3. Abstract macrumors Penryn

    Abstract

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    Dec 27, 2002
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    #3
    You need to multiply both lenses by 1.6x, but ONLY if you want to compare your field of view to the view you get using a 35 mm film SLR, or full frame Canon. Otherwise, for personal use, who cares? Don't multiply. The smaller sensors found in most DSLRs aren't going away. It's just a new format. It's not like 35 mm was the pinnacle of perfection, and everything has to be compared to it. Take it for what it is.

    Anyway, multiply both field lengths by 1.6. You need to multiply both lenses, including the EF lens meant for full frame, because the EF and EF-S designations only tell you which lenses will fit on both a full frame and APS-C sized sensor (ie: the EF lenses), and which lenses will only made for smaller sensors used in the large majority of DSLRs (EF-S). Basically, it indicates compatibility. You still need to multiply focal lengths. :)


    The EF-S lenses are also "designed for digital", which means they're coated with something and will provide you with better contrast in your photos. Also, the small, digital only lenses may (supposedly) result in less chromatic abberation.
     
  4. SWC thread starter macrumors 6502

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    Jan 6, 2004
    #4
    Awesome, thanks for the info guys. That answers my question. The way some websites explain it it seemed as though the crop multiplier only applied to the ef-s lenses. Again, thanks for the info.
     
  5. Poeben macrumors 6502

    Joined:
    Jul 29, 2004
    #5
    Just don't overlook the fact the ef-s lenses are physically incompatible with a full-frame body. The lens extends farther into the body and would hit the mirror on a full frame camera, or so I hear.
     
  6. M@lew macrumors 68000

    M@lew

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    Nov 18, 2006
    Location:
    Melbourne, Australia
    #6
    If you don't plan to go FF in the near future and are looking at the two lenses you suggested, I would go for the 17-85 unless you really didn't care about wide angle. Then when you do upgrade to FF, match the body with an L lens, such as the 24-105. That way, you'll make your upgrade much more worthwhile.

    If you're going to upgrade to FF soon, why not keep saving up and shoot FF earlier?
     
  7. OreoCookie macrumors 68030

    Joined:
    Apr 14, 2001
    Location:
    Sendai, Japan
    #7
    Get the 17-85. Even if you eventually go full-frame, you wouldn't want to use anything but top-notch (read: expensive) glass. Also, the focal length range of the 28-135 lens isn't too appealing if you shoot with a crop sensor, the 17-85 is the way to go.

    I would advise to stop thinking about FF, unless you have a clear time-frame in mind when you want to switch. Canon has excellent cameras with crop sensors (e. g. the new 40D) which offer 95 % of what FF cameras do and sometimes even more.
     
  8. Mantat macrumors 6502a

    Joined:
    Sep 19, 2003
    Location:
    Montréal (Canada)
    #8
    I have a FF and love it and it is a totaly different beast than my old 1.6crop camera. FF gives you massive FoV ( I use a 17-40mm) and much narrower DoF (if the subject is the same size in the view finder for both FF and cropped camera). Also, FF are much better (in general) in low light shooting but maybe the new 40D is an exception. On the down side, the /$%/$% sensor gets dirty much faster too :-S
     
  9. OreoCookie macrumors 68030

    Joined:
    Apr 14, 2001
    Location:
    Sendai, Japan
    #9
    There are plenty of ultra-wide angle lenses out there, e. g. Sigma's or Canon's 10-22 or the various 12-24 mm lenses. You are right about the depth of field as that is determined by the focal length. You can get equivalent focal lengths for cropped sensors these days. (The only exception I can think of is a 14 mm FF non-fisheye lens, but you could replace your 17-40 with a 10-22/12-24 lens easily.)
    Full-frame cameras are prohibitively expensive and require premium glass, i. e. nobody except for a select few can afford FF equipment. Buying glass on a big, big if that in the foreseeable future, full-frame sensors will be offered in the price range of the 40D is pointless, unless you are a pro and have decided that you will migrate towards a FF body.

    Also, full-frame sensors don't have noise levels that are leagues apart from crop sensors, they are marginally better at best. Crop sensors are so good that neither noise nor image quality is an issue anymore for 90+ % of the applications. In particular, the small difference does not IMHO justify the factor of 2 or 2.5 in the price between a 5D and a 40D, for instance. I've taken this snippet from dpreview's review of the Canon 5D:
    My guesstimate is that Canon has improved the noise levels of the 30D and 40D compared to the 20D, so that noise levels might actually be better than that of the 5D.


    I have nothing in principle against FF cameras other than that they aren't affordable and the huge price difference doesn't pay off for most of us.
     
  10. SWC thread starter macrumors 6502

    Joined:
    Jan 6, 2004
    #10
    Thanks for all the great information. I have no real timeframe for going FF I just like to keep my options open. As were all aware the glass isn't cheap and my logic here is that I would rather buy the better quality lens now plus have it be compatible with a FF camera if I upgrade bodys later. The way I see it is it will cost me more now but I get the overall better quality product plus I'm compatible down the line.

    There is a place in my area (rentglass.com) that rents lenses and I have been playing with a bunch of different ones to see what I like and what will fit my shooting style. I have absolutely fallen in love with the push/pull zoom of the canon L telephoto lenses just don't know how to fully utilize everything yet.
     
  11. sjl macrumors 6502

    sjl

    Joined:
    Sep 15, 2004
    Location:
    Melbourne, Australia
    #11
    This is true, but as I've said elsewhere, the EF-S 10-22mm holds its value very well. So too does the EF-S 17-55mm f/2.8 (not to be confused with the EF-S 18-55mm kit lenses Canon puts out, which are cheap glass and don't hold their value well.) If you don't mind swapping lenses, you only "need" one EF-S lens (the 10-22mm); the rest of your glass can easily be EF L series glass (24mm up) if you want to spend the money.

    The only two push-pull zooms I know of in the Canon lineup are the 100-400mm and the 28-300mm. The latter is a compromise, and not a particularly good one, at that; if you want just one lens, it's okay, but I wouldn't really consider it for my lens collection (personal opinion.) The 100-400mm is a decent telephoto zoom, but a word of caution: you may not need a telephoto as much as you think you do. Mine hasn't had as much use as the other glass in my collection; if I had the choice over, I'd probably skip it in favour of the 24-70mm f/2.8 (or 70-200mm f/2.8 IS.)

    Your money, and your choice, just be careful about plonking down your hard earned on an expensive lens until you've had a long, hard think about whether you'd actually use it.
     

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