Canon EF 50mm f/1.4 - Assessment

Discussion in 'Beyond the Basics' started by MarcusM, Apr 23, 2008.

  1. MarcusM

    MarcusM TPF Noob!

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    So I've had my 50mm f/1.4 for about 2 months or so now, and I just wanted to run down some of the main points I've noticed about it, as this is my first lens other than the 18-55mm kit lens, so I wasn't used to shooting really wide open like this lens allows. I was hoping I could get some verification or clarification of some of these points, or let me know if I'm completely wrong. I'm basically trying to understand this lens and the focus and DOF.
    • This lens seems to be inherently soft from f/1.4 down to about 2.5 or so, at which point objects that are focused on really start to look sharp.
    • The Depth of Field is extremely narrow at f/1.4 down to about f/4 or so...and even then, the closer you are to the subject, the more narrow the DOF.
    • As is typical of photography, there are trade-offs with this lens. Yes, it is fast as it can open up to f/1.4, but at f/1.4, what are the practical applications? I rarely use f/1.4 anymore when shooting portrait shots which is what I mainly bought the lens for, because often times I will have one eye that is sharp and the other eye is not in focus due to the razor-thin DOF. I usually try to limit my widest aperture to 2.0 and even that is still very thin.
    Thanks for any feedback.
     
  2. Big Mike

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

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    I don't think that you are wrong here. Shooting wide open isn't for everybody. Some people like to shoot with a razor thing DOF...some don't.

    Yes, the DOF gets thinner as you get closer to your subject.

    Keep in mind that when shooting with a thin DOF...it's more important that your focus is accurate and precise.

    As for softness wide open...many lenses (probably most) are softer when wide open. I would think that this lens is still pretty good when compared to your kit lens....but yes, it's usually better (for sharpness) to stop down a bit.

    That is one benefit of using really fast lenses. You can shoot at F2.8 and be in your lens's sweet spot. A slower lens might have to be at F5.6 or F8 before it's at its best.

    From most of what I've heard...this lens shouldn't be 'soft' when wide open. It's not at it's best...but it should still be fairly sharp. Can you show us some examples of what you are calling soft?
     
  3. Sarah23

    Sarah23 TPF Noob!

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    I have the f/1.8 and really dont use it at 1.8 very much, due do the shallow DOF...I would like to hear some practical applications for that also....but since I mainly do portraits when im shooting using that lens, I tend to stay around 4.0-8.0 range.

    I guess if it where something like a field of flowers or something like that really up close with a really small subject, you could use it wide open, but then even part of your subject will end up out of focus most of the time...so...yeah...
     
  4. Antithesis

    Antithesis No longer a newbie, moving up!

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    With a thin DoF, if you take a portrait straight on and just get the eyes both in focus it can look awesome. I was looking at some images taken with the 85 f1.2L II "Canonball", and the only thing that wasn't almost completely blurred where the eyes, which were exceptionally sharp. Obviously a different ball park, but if used correctly, it can look awesome.

    With my Nikon 50 f1.8, it tends to stay pretty sharp wide open. Are you sure you didn't get a poor copy? It seems the more I read about Canon, the less their quality control seems to impress, even with their nicest lenses.
     
  5. MarcusM

    MarcusM TPF Noob!

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    Thanks Mike, here's a good example.

    Shot on left:
    f/2.0
    1/100
    ISO 100

    Subject was still, yet image is soft. I know there was almost no camera shake, especially at 1/100

    Shot on right:
    f/2.5
    1/40 - (sharp at 1/40, so I know I can hold pretty steady at this speed.)
    ISO 400

    These are straight out of camera, absolutely no PP aside from resizing.

    [​IMG]
     
  6. Antithesis

    Antithesis No longer a newbie, moving up!

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    Yeah, the image on the right looks much sharper with better contrast.
     
  7. MarcusM

    MarcusM TPF Noob!

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    I guess I didn't notice the contrast other than the shadows if that's what you're referring to, there was harsh window light in a dark room on that one.

    But yea, the image on the right is much sharper. Just an FYI also, both of these shots I focused on the eyes (which almost all my shots of people are)

    And the difference in sharpness seems extreme IMO, for there only being a difference of 2/3 of an f-stop, and then especially when you consider the soft shot was at 1/100 SS. I just don't understand, and this is one of the issues that has been dogging me ever since I got the lens. I really need to download the focus chart and test it out, unfortunately my printer's broke.:grumpy:
     
  8. Antithesis

    Antithesis No longer a newbie, moving up!

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    I had a Sigma 70-200, and one whole stop (to f4) would change it from rediculously soft to tack sharp. Some lenses just don't work well wide-open.

    The image at f2.5 is about about one stop down from its widest. I'd just use it at f2.5 and above and only use f1.4 if you absolutely need a shot in low light. f2.5 is still a pretty large aperture.
     
  9. keith204

    keith204 No longer a newbie, moving up!

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    The conditions here are too different to tell anything.

    Take the exact picture, exact lighting, etc. The surroundings and window light would have caused the photo to be exposed differently. There's no way that stopped down from f/2.0 to f/2.5, the contrast would be that different.

    I'm pretty sure the left image is sharp. As BigMike said, the DOF gets smaller the closer you get to the subject. From this relatively small photo on here, it looks like the baby's collar is in focus (see front of collar to the left of chin).
     
  10. usayit

    usayit No longer a newbie, moving up!

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    When doing comparison shots you really should have a consistent setup AND a tripod. This is especially true when shooting wide open... even.. a body swaying forward or reverse can mess up the results and lead you to an incorrect conclusion.

    The two pics posted.. .obviously at two different subject distances, lighting, etc.. way too different to compare. This might just be my eyes playing tricks on me but the collar of the first pic seems razor sharp... so perhaps the "sweet" spot is there just not at the eyes.

    If you are concerned with the lens, setup chart and tripod... have at it. The first pic seems a bit softer than I recall seeing out of my copy if you indeed have the eyes focused in.
     
  11. MarcusM

    MarcusM TPF Noob!

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    usayit and keith204, I see what you mean about the collar on the left pic. It is way sharper than any part of her face.

    That really has me wondering if it is a mechanical issue now? From what I understand AF happens in both the body and lens, correct? I know for sure I was focusing nowhere near her collar. I am going to have to get the chart printed at Kinko's or something.
     
  12. keith204

    keith204 No longer a newbie, moving up!

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    If you were focusing near the collar, and it's in focus, then you were probably focusing on the collar, and the photo is sharp, and you have nothing to worry about.

    That being said, what mechanical issue do you think there is? Seems like the problem is solved...
     

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