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Thread: Sharpest settings for lenses

  1. #1
    dragonaxe's Avatar
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    Sharpest settings for lenses

    This may well turn out to be a really embarassing question I've only recently acquired a Canon 1000D with stock EF 18-55mm lens, and have noticed a couple of digital photography magazines mention settings (exposure/aperture etc) being chosen because they give the sharpest image for the lens being used at the time.

    Is this something particular to a specific lens? and if so...how can I work it out for mine?

    thanks

  2. #2
    Dansk's Avatar
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    Re: Sharpest settings for lenses

    Nothing to be embarassed about, I only discovered this feature of lenses a month ago!

    If you want to work it out yourself, you can spend a lot of time taking pictures of test charts and repeating patterns and doing math...

    Or you can just ask the guys who have already done that: http://www.dpreview.com/lensreviews/..._c16/page3.asp

    Looks like your lens is at its best around 28mm, with the aperture more or less wide open.
    Last edited by Dansk; 31st August 2010 at 09:11 AM.

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    Re: Sharpest settings for lenses

    Hi Dragonaxe (what's your first name by the way?),

    Usually a lens is at it's sharpest when stopped down 2 to 3 stops from it's maximum aperture (ie 2 to 3 F-stops up from the lowest F-Stop number), but it's not quite that simply as the more wide-open that you shoot, the less the depth-of-field (which may make part of the image blurry), and if you stop the lens down too far (ie BIG F-Stop numbers then you also get a thing called diffraction creeping in, which also blurs things). But just having said all that, the thing that makes the biggest difference of all is ...

    ... correct capture sharpening (you'll need to shoot RAW and then apply capture sharpening in some kind of post-processing package) ... more on this later if you need help with it.

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    Re: Sharpest settings for lenses

    Colin - Dragonaxe gives his real name as Have a guess
    When you think about it, this is no stranger than Morse (Endeavour) - or is the Oxford connotation a no-no on this Site?
    I think that Have a Guess (smiley face ) is a clue and suggest Havergal, the name of the composer, Havergal Brian.
    Some orchestral members thought, in error, that that was his nickname.

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    Re: Sharpest settings for lenses

    Quote Originally Posted by mikeshore View Post
    Colin - Dragonaxe gives his real name as Have a guess
    When you think about it, this is no stranger than Morse (Endeavour) - or is the Oxford connotation a no-no on this Site?
    I think that Have a Guess (smiley face ) is a clue and suggest Havergal, the name of the composer, Havergal Brian.
    Some orchestral members thought, in error, that that was his nickname.
    Hi Mike,

    I'm sorry, but you lost me after "Colin"

    I'm missing a few too many hours sleep!

  6. #6
    dragonaxe's Avatar
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    Re: Sharpest settings for lenses

    Yep, I lost it after "Colin" too, lol.
    My real name is Gareth, but you guys can call me "Sir" ...nah, only joking. I live in the south east of England. 43yo, married with 3kids, etc, etc, etc.

    Thanks for the replies. I've obviously got a LOT to learn!! but that's half the fun of a new hobby
    Everything's on the cheap at the moment (I won the camera...no way I'd be able to buy one!) so I'm using an old CS2 photoshop for PP.

    I've got a feeling you'll be answering quite a few basic questions in the future! (but I promise to look through previous posts, etc, before asking )

  7. #7

    Re: Sharpest settings for lenses

    Quote Originally Posted by dragonaxe View Post
    My real name is Gareth, but you guys can call me "Sir" ...nah, only joking. I live in the south east of England. 43yo, married with 3kids, etc, etc, etc.

    Thanks for the replies. I've obviously got a LOT to learn!! but that's half the fun of a new hobby
    Everything's on the cheap at the moment (I won the camera...no way I'd be able to buy one!) so I'm using an old CS2 photoshop for PP.

    I've got a feeling you'll be answering quite a few basic questions in the future! (but I promise to look through previous posts, etc, before asking )
    Sir... (insert doffing cap smilie here)

    It must be very confusing having three kids all with the same name.

    Lenses are variable creatures and depending on the aperture used they will deliver slightly different quality results. I think it's because a lens has an optimum 'best spot' at which it can operate. Usually this is around f/8, but it can vary. It's like your car - it probably has a certain gear ratio spot where it has the best torque.

    Don't worry about asking any questions, that's what this site is for.

  8. #8
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    Re: Sharpest settings for lenses

    Check out dpreview.com and photozone. The 28mm ef f2.8 is sharpest wide open. So all the knowledgeable stuff is a bit of prejudice. It don't work like that anymore even if it did.

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    Moderator Donald's Avatar
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    Re: Sharpest settings for lenses

    Gareth

    Another way of thinking about it is in terms of sporting analogies.

    Golfers, cricketers etc talk about the 'sweet spot', that place on the club/bat where, if you can get the ball, the world just seems a perfect place; everything zings and the birds start singing in the trees. Now of course a cricketer can get a 4 or a 6 without getting it on the sweet spot, but it makes life much more satisfying and more pleasing when you do get it and the task feels so much easier.

    It's the same with the lens. There's an f number at which it gives you its best, and that varies from lens to lens. Now, that is quite different from what you do creatively with the lens in terms of, for example, using f numbers to increase or decrease depth-of-field. Just keep reminding yourself that the learning is as much fun as the picture-making.

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    Re: Sharpest settings for lenses

    Quote Originally Posted by Donald View Post
    Golfers, cricketers etc talk about the 'sweet spot', that place on the club/bat where, if you can get the ball, the world just seems a perfect place; everything zings and the birds start singing in the trees.
    Unless of course you manage to hit the same said birds with a ball delivered from the sweet spot of the said club/bat!

    (sorry, just couldn't resist!)

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    Re: Sharpest settings for lenses

    I like Rob's (car engine) torque analogy - just because there's a figure for revs that gives the highest torque doesn't mean one should always drive everywhere at that number of revs.

    It's the same with the lens' sweet spot, it'll be a long time before you're consistent enough with focusing, focal length, exposure, composition and, most importantly, sharpening, to even notice a difference. Personally, I'd suggest you forget it and just enjoy photography

    Dave exits CiC, to sound of court-marshal, charged with treason

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    Re: Sharpest settings for lenses

    Quote Originally Posted by Dave Humphries View Post
    I like Rob's (car engine) torque analogy - just because there's a figure for revs that gives the highest torque doesn't mean one should always drive everywhere at that number of revs.
    Hmmm - that might be a concept that young hoons shoud take note of!

  13. #13
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    Re: Sharpest settings for lenses

    I think we amateurs get caught up in the tech of photography sometimes instead of why we started shooting pictures in the first place. I like to take allot of shots and figure out what is the best for the equipment I have.
    I can say just reading this forum I have learned more than reading allot of books and I thank everyone for their time and knowledge.

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    Re: Sharpest settings for lenses

    Quote Originally Posted by Sam Smith View Post
    I think we amateurs get caught up in the tech of photography sometimes instead of why we started shooting pictures in the first place.
    I agree. Another "variation on the theme" is that many folks put a lot of effort into "saving pixels" but ultimately "ruin the picture" in doing so, eg

    - using low ISO's to avoid noise, but getting camera shake or motion blur because the shutterspeed was too low

    - shooting at the lenses sharpest aperture, but having large out of focus areas because the fepth of field was insufficient

    - avoiding small apertures because of the percived diffraction issue

    - using fancy plugins that do everything apart from make a cup of tea - and then post an image that's flat or incorrectly sharpened.

    Like it or not, photography these days is a PROCESS; it has many areas that require attention (often to the same standard), and if any one of those areas isn't properly addressed (from shooting through to post-processing) then the entire image can be severely degraded. It's NOT enough to be competant in some areas, but avoid others anymore.

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    Re: Sharpest settings for lenses

    yeah, the post processing is a new thing to me! and I have to admit I used to think it was basically cheating (I'm next on the Court Marshall list, Dave)

    However I'm getting into the habit of looking at my "just taken" images as the first step. Cropping is not a problem, and I understand the rule of thirds etc, but I'm still unsure about sharpening. I'm only using CS2 (cos it was free to put on my work laptop, LOL) and find myself very reluctant to sharpen any more than the smallest amounts, as it just seems to add "grain" to the image. Are there any Rules of Thumb? or is it just down to personal taste?

    cheers
    Gareth

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    Re: Sharpest settings for lenses

    Quote Originally Posted by dragonaxe View Post
    ~ but I'm still unsure about sharpening. I'm only using CS2 (cos it was free to put on my work laptop, LOL) and find myself very reluctant to sharpen any more than the smallest amounts, as it just seems to add "grain" to the image. Are there any Rules of Thumb? or is it just down to personal taste?
    Hi Gareth,

    There a lot of threads on sharpening, as well as the tutorial linked below, but to specifically deal with your experience ...

    If CS2 has it, use the UnSharp Mask method of sharpening (known as USM), not any other named varieties for now (I'm just keeping things simple before anyone jumps in).
    It is currently under the "Enhance" menu item in Elements, CS2 may be similar.
    When you have a dialog open, it should have 3 variables called Amount (in %), Radius (in pixels) and Threshold (no unit given, but is effectively a bit level)

    If you attempt to sharpen a slightly noisy picture, it will, as you've found, grab the noise and sharpen that too, highlighting it horribly.
    If you use these figures in the USM dialog; 100%, 0.3 pixels and 10 for the threshold, it should avoid the problem.

    In reality, 10 for a threshold is a bit high unless it's a really noisy picture, usually somewhere between 2 and 6 will do, higher if jpg not RAW.
    (You eally should be shooting RAW)

    It is the threshold setting which stops USM sharpening the noise - it is basically saying; ignore transitions smaller that 10 levels, which is the 'size' noise is. Many other sharpening methods may not have a threshold setting hence the sharpen the noise

    Give that a go, assuming you can in CS2, and let us know how you get on.

    Bedtime reading:
    Guide to Image Sharpening

    HTH,
    Last edited by Dave Humphries; 1st September 2010 at 01:18 PM.

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    Re: Sharpest settings for lenses

    Quote Originally Posted by Colin Southern View Post
    - shooting at the lenses sharpest aperture, but having large out of focus areas because the fepth of field was insufficient
    Curse that fepth of field!! I can NEVER get it right!!

  18. #18
    dragonaxe's Avatar
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    Re: Sharpest settings for lenses

    cheers Dave.
    I was at a wedding last weekend, and shot most of it in RAW (giving a .CR2 file ext), but CS2 won't open them.
    I get a "could not complete your request because it's not the right kind of document" error

    any ideas why that might be?

  19. #19
    Moderator Dave Humphries's Avatar
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    Re: Sharpest settings for lenses

    Quote Originally Posted by dragonaxe View Post
    cheers Dave.
    I was at a wedding last weekend, and shot most of it in RAW (giving a .CR2 file ext), but CS2 won't open them.
    I get a "could not complete your request because it's not the right kind of document" error

    any ideas why that might be?
    Yes, unfortunately, it means the version of ACR you have with CS2 is too old for the camera model.

    Since the Canon 1000D is a fairly recent model, I doubt Adobe will have an up-to-date enough ACR version for CS2.

    That'll mean one of two things;

    1) Download the free Adobe converter to DNG, and convert the .cr2 files to .dng, they should then open with CS2, but no promises.

    2) A more foolproof way is to buy Elements 8 for about 57 from somewhere lke Amazon.co.uk.
    That will open the files OK, but even a modern Elements probably isn't as fully featured as CS2.
    if you order the software from Amazon, save some time and also buy Scott Kelby's The Photoshop Elements 8 book for Digital Photographers at the same time (I did a few weeks ago, total price, with free delivery, was less than 72).

    What I think you'll be able to do then is from ACR/Elements, save the cr2 files as 16 bit Tifs. They should open in CS2 if Elements proves too limiting for you.

    Further, you'll be sent an e-mail from Adobe after registering Elements, offering you CS5 at half price, which is still a little over 320, but better than about 606, if you really want CS5. This is a UK only offer I believe. I may well go that way, as after 2 years with Elements, there are some things I covet in CS5

    Cheers,

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    Re: Sharpest settings for lenses

    I started in this game back in the late '40s. I remember spending many hours in the darkroom, "cheating" my photographs, trying to turn them into pictures.

    Ansel Adams has indicated the finding and photographing was about 1/3 of the process of creating a picture. You might say he spent 2/3 of his effort in "cheating." This is a favorite rant of mine, as your previous thinking is so common in the world today.

    Pops

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