still undecided about new lens, and have some AF questions...

Discussion in 'Photography Beginners' Forum' started by jerseygirl, Feb 16, 2007.

  1. jerseygirl

    jerseygirl TPF Noob!

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    so i borrowed a friends sigma 24-70 lens with the ability to test what an f-stop at 2.8 gives me (previously i'd been shooting with a canon 28-105). i have a canon EOS digital rebel (a few years old).

    now i got a few keepers, but am still baffled by my good photo to overall photos taken ratio. it seems like for every 50-80 shots, i get one "good one".

    my goal is to get crisp eyes, entire face in focus, and a shallow DOF.

    i have started to shoot exclusively in RAW.

    both of these photos needed exposure compensation and fill light help as they were both a tad dark. i didn't touch contrast yet. but as far as the eyes are concerned, i'm pleased with the outcome.

    so my questions are:

    1. what can i try to address my AF issue? is it me? is it the lens? i attempted to shoot consistently at f8 and f11, but really did not see an increase in the "crisp eyes" i wanted. how much of a role does light play in the ability for the lens to auto focus? what do i need to do to maximize my chances of getting a crisp shot both in low light and outdoor conditions? should i be standing farther away from my subjects (i don't want to do this as i like to frame the shot as is and only crop afterwards if needed)?

    2. i find my light meter to be "off". if i aim to set the exposure in the middle range i wind up having to adjust the photo sometimes because it's underexposed, sometimes overexposed. it's not consistently light or dark.

    3. flash. for my indoor shots i have started to use a speedlite 430 as a bounce flash. i can't figure out how to sync the light readings to the flash. it's like the camera ignores the existence of the thing. reading the manual i see that if i get the "correct exposure" the confirmation light will light up AFTER the photo is taken. a lot of good that does me setting up the shot :confused:. i am constantly guessing what shutter speed to use because the exposure always reads -2 even when i know the flash will do the trick. what am i doing wrong?

    4. what lens to buy? i was leaning towards the fixed focal but i do like the zoom feature if i can't get to where i need to be in a pinch. is the Canon Normal EF 50mm f/1.8 II Autofocus Lens worth a try or will i find the AF frustrating? is the Canon Normal EF 50mm f/1.4 USM Autofocus Lens worth the extra $200? why would i choose these over the Canon Telephoto EF 100mm f/2.8 USM Macro Autofocus Lens? or would something like the sigma with a zoom i have borrowed from my friend be a better investment?

    i don't mind spending a few hundred dollars if it will "do the trick" as far as my auto focus problems are concerned. what i don't want to do is drop a lot of $$$ only to find out i'm not solving my problems...

    [​IMG]

    Shooting Mode - Manual
    Shutter Speed - 1/200
    Aperture Value - 4.0
    Metering Mode - Center-weighted averaging
    ISO Speed - 200
    Lens - 24.0 - 70.0mm
    Focal Length - 36.0mm
    Flash - On
    Flash Type - External E-TTL

    [​IMG]

    Shooting Mode - Aperture-Priority AE
    Shutter Speed - 1/800
    Aperture Value - 8.0
    Metering Mode - Evaluative
    Exposure Compensation = -2/3
    ISO Speed - 400
    Lens - 24.0 - 70.0mm
    Focal Length - 64.0mm
    Flash - Off
     
  2. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    The eyes look pretty sharp to me in these shots. The first shot has a shallow DOF which may be affecting the sharpness of some of the face. One thing about RAW files...is that the camera does not sharpen the image...and most digital images can use a bit of sharpening. There is a great sharpening technique listed on this forum somewhere...also, Google will turn up a million sites for you to read.
    Shooting constantly at F8 or F11 is good...but only when you have enough light (or are using the flash)...otherwise that aperture may cause the shutter speed to be too slow.

    Light meters are not made to get the shot exactly right every time...and how could they be? The camera has no idea what the subject matter is...nor does it have any idea what you, the photographer, is trying to do. Camera meters take reflected light readings and give you settings to get 18% grey. It's up to you to know that and to make adjustments (exposure compensation) based on the reflectivity of the subject and the desired result. Do some reading on 'metering'.

    The camera's meter does not read the flash...it only reads the light before the flash. (ambient reading). E-TTL flash metering is how it determines the flash exposure. The flash fires a pre-flash, just before the exposure...and uses that to determine the required strength of flash required. The flash will act differently, depending on the shooting mode you are in. In P it will act like the main light...in Av or Tv, it will act as fill. Read this for lots and lots of info.
    The trick with flash, is balancing the ambient and flash exposures. Use the camera's meter to determine how much ambient exposure you will get and adjust the settings (exposure compensation or manual mode)...then use FEC (flash exposure compensation) to determine how much flash exposure.
    Shutter speed won't affect flash exposure...but will affect ambient exposure. Also, the shutter has to remain under 1/200 (on your camera) while using flash.

    The prime (non zoom) lenses are good because the are optically very good and the big max aperture is good for low light shooting and/or shallow DOF. The 50mm F1.8 is good because it's cheap. The 50mm F1.4 is a little faster (bigger aperture) but it's also built much better and has USM focus. I don't think you would be terribly disappointed by the cheaper one...but the more expensive one certainly is better. As for other focal lengths...that's up to you. A longer lens will allow you to full the frame from farther away. Longer lenses also allow you to get an even shallower DOF.

    I suggest getting a prime lens...be it a 50mm F1.8 or F1.4...or the 85 F1.8 or the 100mm F2.8 macro...etc. At least that gives you the option to shoot with large apertures. Then maybe work on your metering and then work on your post processing (photoshop). It may take some time...but you will see results. You certainly have a cute subject...so that part is taken care of :D
     
  3. JIP

    JIP No longer a newbie, moving up!

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    I think this is a fact that more people would do well to understand.
     
  4. jerseygirl

    jerseygirl TPF Noob!

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    right, i do like these shots, but out of say 150 takes, these were the only 2 i could/would want to use. all the others lack the sharpness i am trying to achieve, they are flat out out of focus. learning how to sharpen these good ones even more will be great, but the other photos are useless to me...

    now that i know i have the ability to take these types of images (which was what i originally was doubting), how on earth do i increase my good shots/overall shots taken ratio? what i don't know is if my poor lighting (and/or corresponding manual settings) is affecting the lack of focus, is it camera shake, is it my subject squirming around too much, all of the above, none of the above...and will the prime lens help my ultimate goals and make my life a little easier?
    thanks for this info, i definitely have to read up...
    i'm leaning towards the F1.4 to start. reading lens reviews is making my head spin. for each good review there is a bad so i'm :confused:...

    and although cute, my little one is not the most cooperative subject on the planet :lol:

    thanks for your help :D
     
  5. MACollum

    MACollum TPF Noob!

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    For sharp eyes, I make sure the "active" AF point is on the eyes, press the shutter half way and recompose if necessary. Otherwise the camera may pick the wrong area of the face to focus on.
     
  6. EOS_JD

    EOS_JD TPF Noob!

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    Good point! How many active AF points do you have? When shooting at f2.8 with your subject very close, slight camera movements can throuw out focus because the dof is very short (just a few mm). Use the correct AF point and do not recompose. By recomposing you will change the focus point and this can be enough to give the out of focus shot.

    It takes some practice to shoot at f2.8 never mind f1.4!
     
  7. fmw

    fmw No longer a newbie, moving up!

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    No, when you use focus lock, it locks the focus. Recomposing does not change the plane of focus. That is the reason for focus lock. Shooting at f1.4 is identical to shooting at f2.8. Only the dof is different.

    Personally, I think the multiple focus points are silly. Focus lock works just fine.
     
  8. EOS_JD

    EOS_JD TPF Noob!

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    Yes it locks the focus at the position your camera is in compared to the subject you shoot. But if you move the camera to recompose you throw out the focus point at which the camera locked! Not so important when the dof is pretty large but at large aperures and very small dof it can be the difference in sharp and out of focus.

    My point regards the difference of f2.8 v f1.4 is exactly as you say. Shooting with a very small dof is difficult to master.

    Check this - Why focus/recompose sucks.....

    http://visual-vacations.com/Photography/focus-recompose_sucks.htm
     
  9. MACollum

    MACollum TPF Noob!

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    I tend to agree to a point but I think it's also a matter of personal preference. To me, it takes too much time to change the AF point so I usually just use the middle point and recompose. It's faster than changing the point to suit each subject. Actually, unless I have a specific reason, I don't let the camera pick the AF point at all. It seems to always want to pick the wrong part to focus on.
     
  10. EOS_JD

    EOS_JD TPF Noob!

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    I have a 20D and can rotate the wheel very quickly to select the appropriate focus point for the shot. I only use one but choose the right one so I do not require to recompose.
     

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