is the canon 135mm L worth it for full body shots?

Discussion in 'Digital Photography' started by doodledum, Jul 25, 2010.

  1. doodledum macrumors newbie

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    #1
    HI
    I'm looking into buying a canon 135mm L lens for my t2i. I am mainly wanting to use it for taking portraits in outdoor settings so i should have lots of room. Not that all of my pictures will be full body shots (in fact most of them won't be, but for each shoot I'm sure there will be a few) but I'm just wondering if the bokeh will still be good at a distance. I am also wondering weather this is too much distance for portraits in general or if it will just take getting used to. Thanks so much for all your help!
     
  2. Gitgat macrumors newbie

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    #2
    With the T2i a crop body the 135 is gonna be pretty long. your not going to be able to get close enough to get that really appealing background blur that the 135 is known for at distances needed to frame a full body shot, especially standing.
    the 24-70 is probably a better option if you dont mind the zooms. Its a teriffic lens. A bit tight (about 39mm) when used on a t2i, but I still find myself using it outdoors a lot on my 7d. It really really shines on my 5d.

    Also when your looking at a purchase that expensive consider trying it out for a few days by renting it (i use lensrentals.com when i rent super-teles.)

    If you have any questions feel free to send me a message via these forums and i can point you in the direction of a few resources to help you decide.
     
  3. dipm06 macrumors member

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    #3
    on your camera it will be a 200 f2, which will be amazing for full body shots.... if you have the space to move far back enough. if you will be using it outdoors and have the space, i say go for it. i think its too long for indoors most of the time.
     
  4. raymond lin macrumors regular

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    #4
    85/1.8 would be a much better choice i think and i have both. I think the 135 is too long for full body portrait even on my 5Dii so on a crop is way too long.
     
  5. luminosity macrumors 65816

    luminosity

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    #5
    Remember, the DOF must be changed with the crop factor. It is not f/2 on a 1.6x camera. More like about 2.8 or so. Not many people understand that, though.

    The 135/2 is one of the finest lenses anywhere, and is always a good buy, provided you use it.
     
  6. Edge100 macrumors 68000

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    Sorta.

    If you stand in the same place with the same lens on a FF camera and a 1.6x camera, the DoF is the same. The angle of view changes, but the DoF is identical. f/2 = f/2

    If you frame your shots equivalently on a FF and 1.6x camera (i.e. you stand further back with the 1.6x camera), then DoF is larger with the 1.6x, by virtue of standing further from the subject. In this case, f/2 does not give the same DoF on each sensor; the 1.6x is probably closer to f/2.8 or f/3.2, effective.

    Note that this ONLY applies to the DoF of an image; when using f/stops to calculate exposure, the size of the sensor is irrelevant. If the exposure is f/4, 1/60, ISO100 on FF, then it is the same on 1.3x, or 1.6x, or medium-format, or whatever.
     
  7. pdxflint macrumors 68020

    pdxflint

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    #7
    I'm a bit confused on this... isn't the depth of field actually a lens factor... put the same lens on two different bodies, it still has the same depth of field at a given distance/f-stop combination. So, my 300f/4 wide open has the same depth of field as it would on an FX camera at a given distance, only I would be looking at the middle (cropped) section of the FX equivalent frame. How does the depth of field decrease on my DX body?

    Maybe you're referring to "apparent" depth of field, where my 300f/4 lens gives an simulated reach to 450mm (35mm equivalent) on DX, when it's still just a 300mm lens. So, if you compare it to a real 450mm lens focused at the same distance, then the depth of field would be less at the same aperture... at least that makes sense to me. But, it's still f/4 at 300mm, regardless of whether it's cropped sensor or full frame.
     
  8. Edge100 macrumors 68000

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    DoF is related to distance from the subject.

    Let's say that on a FF camera and a 100mm lens, you are standing 20 feet from the subject.

    With a 1.5x sensor, you'd have to stand 50% further back to get the same framing (i.e. 30 feet). So your DoF will increase strictly because you had to move further from the subject. Emphasis added because I want to stress that sensor size, per se, does not change DoF.

    However, if you shoot with the 100mm lens on a FF camera and a 1.5x camera from the same position, resulting in a smaller angle of view on the 1.5x camera, then DoF is equivalent.

    No matter what the system, however, f/2 is f/2, when it comes time to calculate exposure.
     
  9. toxic macrumors 68000

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    #9
    this thread is full of misinformation...

    to answer the topic, no, 135mm is not good for full body unless you like standing 30+ ft away. Go with 30 to 50mm or thereabouts. 85 is already a little too long, for me.

    just to clarify, bokeh is the quality of blur, not the amount, and not depth of field. it is property of the lens, like contrast or resolution.

    DoF depends on subject distance, f-stop, focal length, and circle of confusion. CoC depends on visual acuity, viewing distance, and enlargement factor. enlargement factor depends on sensor size and final image size.

    at the same distance at the same f-stop with the same FL, and at the same final image size, DoF with the larger format is larger because the image was enlarged less. but no one actually does this since the framing is not the same, so this is fairly useless information.

    when you frame the two images the same way at the same f-stop, you need to use a longer FL on the larger format. this decreases DoF to a much larger degree than the larger format increases DoF. the net result is the larger format has less DoF for the same framing. in the case of 35mm vs APS, it happens to be about a 1 1/3 stop difference.
     
  10. Phrasikleia macrumors 601

    Phrasikleia

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    #10
    Actually, no. The DoF would be slightly different, at least according to the online DoF calculator. If you choose the same focal length, same aperture, and same subject distance, you'll get different values for DoF by changing the camera from a crop to a FF sensor. This completely brackets out the issue of framing (angle of view), which would also change, of course.
     
  11. Edge100 macrumors 68000

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    #11
    Good thing you're here to sort us all out, then. ;)

    Agreed. The 135L is a great lens, but too long to be practical for full-body shots, even on FF.

    I'd like to see some evidence for this. At the same f/stop, distance, and FL, using a cropped sensor is exactly the same as taking a FF image and cropping it by 60%. DoF is not affected. But I agree with you, this is not how most people use their camera.

    No. The smaller DoF seen with FF cameras is primarily due to the fact that you have to be closer to the subject than you do with a 1.6x camera, given equivalent FL. Focal length has a very, very minimal effect on DoF, especially compared with the effect of subject-to-camera distance. The apparent effect of FL on DoF is due to the fact that you have to change camera-to-subject distance to yield the same framing.
     
  12. pdxflint macrumors 68020

    pdxflint

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    #12
    That's basically what I understood to be the case... the lens doesn't know or care where the image circle falls. So if I frame my subject in DX to the same size as with FX at the same focal length, I'd obviously have to stand further back, so the distance would be different. I do get that. "Cropped" sensors do just exactly that... they crop/record the middle part of what a FX sensor would record... from the same image projected by the image circle.
     
  13. OreoCookie macrumors 68030

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    #13
    Even though the lens is excellent, IMHO it is the wrong focal length for full body shots or even upper body shots.

    I don't own a 135 mm prime, but an 80-200 mm f/2.8 zoom. Even outside, full body shots at 135 mm is practically out of the question. Even 80 mm is quite long on crop sensor cameras already, I think that'd work for upper body shots (torso + head) at the most. (You should keep in mind that you have to keep in touch with your model somehow, yelling from across the field doesn't work so well ;))

    I think what you want is something between 30 and 50 mm (focal lengths for crop sensors). Sigma makes a wonderful f/1.4 prime and the 50 mm f/1.8 costs next to nothing, so you should have one anyway. I own both (well, I'm a Nikon head, so I own Nikon's 50 mm) and the 30 mm is capable of very nice portraits. At f/1.4 it gives you lots of leeway to separate your subject from a noisy background.

    50 mm is plenty for upper body shots, you'll have a comfortable working distance that way. With 80 mm, you'd have to back off further (doable, but probably not as comfortable). To me, anything beyond 135 mm is for sniping unsuspecting targets and headshots.

    Another thing to keep in mind is the shallowness of the depth of field: I don't think you'll be able to shoot portraits (head shots) at 135 mm and f/2, the depth of field is so small that only parts of the face (if anything) are in focus. I reckon, you need to work with f/4 the least.
     
  14. toxic macrumors 68000

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    #14
    if you want visual evidence, I can't give it to you since I only have a 5D. what I can tell you to do is plug in the same numbers in a DoF calculator. the 5D will have more DoF than a 50D.

    moving closer to the subject changes perspective. the image is no longer the same if the perspective is not the same.

    what everyone forgets is that digital images still have a physical size. enlarging from the initial size decreases resolution, therefore making the image blurrier. what is in-focus in a 4x6 may not be in an 8x12.
     
  15. Edge100 macrumors 68000

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    #15
    1.6x crop, f/4, 100mm, 10 feet to subject: Total DoF = 0.45ft
    FF, f/4, 100mm, 10 feet to subject: Total DoF = 0.71ft

    I stand corrected; clearly sensor size, does, per se, affect DoF, though I can't figure out precisely why that should be. All the literature I can find on this subject suggests that the only effect sensor size has on DoF is due to the change in camera-to-subject distance.

    FF, f/4, 160mm, 10 feet to subject: Total DoF = 0.27ft

    This implies that with equivalent framing, the FF camera has a smaller DoF than the 1.6x camera.

    1.6x crop, f/2.5, 63mm, 10 feet to subject: Total DoF = 0.72ft

    This means that at the same camera-to-subject distance, 100mm, f/4 on FF is equivalent to 63mm, f/2.5 on 1.6x. Of course, when calculating exposure, f/4 is f/4 on all systems.
     
  16. Edge100 macrumors 68000

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    #16
    Yes, and what I'm not sure of is precisely why that is. At the same subject distance, focal length, and f/stop, the crop sensor is just that: a "crop" of the FF image. The lens projects a certain image, based on the FL and f/stop, which has a certain DoF that should be sensor-independent; it's a property of the lens, not what you stick in the path of the projected light. Yes, you enlarge the image afterward to reach the same output size, but why does that affect DoF; the image is the same.

    Yes, it does; absolutely, which is why "zooming with your feet" is not the same as having a zoom lens.

    Not sure how this is relevant. A lens projects an image that has a certain DoF. If you use a longer FL or a narrower f/stop, or get closer to the subject, that image will change. But why should it matter if you have a different sized piece of silicon in the path of the light? I'm just not able to conceptualize why sensor size, ceteris paribus, affects DoF.
     
  17. toxic macrumors 68000

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    #17
    the physical sensor size has to do with everything. I mentioned all the DoF variables above: f-stop and focal length (i.e. aperture), camera-subject distance, and CoC. CoC depends on the sensor size. smaller sensor = more enlargement = more apparent blur and other aberrations.

    the lens does not "have a certain DoF". DoF is not a physical property.

    as for the Cambridge in Colour article, the purpose of his "focal length" section is to point out that using a longer FL and framing the same way as a shorter FL does not change the DoF. this is to dispel the conception that using a longer FL (and framing the same way) decreases DoF, since the background is blurrier when you use a longer FL, even at the same f-stop.

    the author mentions aperture and distance as DoF variables, rather than f-stop, FL, and distance as I did. I did it that way because most people think f-stop and aperture are the same, though they are not. aperture is the FL divided by the f-number. in other words, what he and I said are the same.
     
  18. Edge100 macrumors 68000

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    #18
    Now I'm starting to get what you were saying. I apologize if I've misconstrued your argument.

    What I meant to say was that a lens projects a certain image which has properties based on f/stop, FL, and camera-subject distance. That image is not at all affected by sensor size.

    DoF, on the other hand, is not a property of the image (I wasn't trying to imply that it was), but rather a subjective measurement based on CoC (ie. what is "acceptably 'in focus' or 'out of focus').

    Given equivalent framing and equivalent FL, you have to be closer to the subject with a FF camera, thus DoF is smaller. However, when you have to 'enlarge' an image from a cropped sensor, the CoC is smaller; you have less tolerance for out of focus regions. I completely agree with this.

    However, this, to me, is not the same thing as saying "sensor size changes DoF". The actual image is not altered when switching sensor size alone; what changes is our perception of what is in focus.
     
  19. Designer Dale macrumors 68040

    Designer Dale

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    #19
    Great info here. Will someone tell me how to find the Program setting on my XSi?

    FS: DSLR+lenses. Will trade for Point & Shoot...;) Will consider sketch pad and pencils.

    Dale
     
  20. toxic macrumors 68000

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    #20
    yeah, ok.

    again, you have to use a longer FL, not move closer, though the DoF effect is the same. 160mm on FF from 10' yields the exact same image as 100mm on Canon APS-C from 10'. 100mm on FF from 6.25' does not.

    CoC is influenced by the enlargement factor, which is intimately tied to the sensor size. sensor size does not change DoF by itself - I don't recall anyone even claiming that - but the smaller enlargement is the reason why a 35mm camera at 10' at 100mm and f/4 has more DoF, not the same DoF, than an APS-C camera at 10' at 100mm at f/4, for the same final image size, viewing distance, and viewer visual acuity.

    how 'bout an Etch A Sketch?
     
  21. funkboy macrumors regular

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    #21
    Here's what works for me on my 40D for facial portraits and "portrait Americain" (head + shoulders):

    - Zeiss 35 f/1.4 Distagon (c/y mount adapted) for tight indoor situations

    - Zeiss 50 f/1.4 Planar (ZE) for most indoor situations

    - 85 f/1.8 USM in larger rooms or most outdoors scenarios.

    - 135 f/2L "because I can". Outdoor facial portraits only unless I'm doing something outdoors where I need the extra range.

    An interesting new lens for much crop-camera portrait work could be the new Voigtländer 58mm f/1.4 Nokton. It's built like the Zeiss but less expensive & a little longer (it'll feel like a 93mm on a 1.6x body). The electronically-coupled EF version (works just like ZE mount) should be available pretty soon. If it was available when I got the ZE early last year I might have gotten the Voigtländer instead.
     

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