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Thread: Images not Sharp Enough

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    Member DacrimL's Avatar
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    Images not Sharp Enough

    Ok have been reading some info from a reputable photo magazine as to why some images are not sharp. Their #1 point was to do with shutter speed and I quote -

    In the days of film photography there was a general rule that in order to get sharp images from a hand-held camera the shutter speed needed to be at least one second divided by the focal length of the lens.So if you were shooting with a 100mm optic the shutter speed needed to be at least 1/100sec, which because of the way shutter speed is set usually translates to a setting of 1/125sec or faster.
    This rule still holds today, but it is somewhat complicated by the focal length magnification factors of sub-full-frame sensors and image stabilisation systems.
    For example, if a 100mm lens is mounted on a Nikon APS-C format SLR like the D5200, which has a focal length magnification factor of 1.5x, the photographer would need to set a shutter speed of at least 1/150sec.
    Canon APS-C format DSLRs like the EOS 650D have a 1.6x focal length magnification factor, so the shutter speed would need to be at least 1/160sec.
    Will post link to article if that is allowed.

    Basically my question is how does one know what the focal length magnification should be for ones individual camera and how does the conversion equation work. So far I have sort of been guessing what shutter speed to use relative to which lens I am using or am I just making things too difficult for myself?
    Last edited by Kym; 06-04-2015 at 8:30pm. Reason: Fixed quote - readability

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    Account Closed tduell's Avatar
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    Hello DacrimL,
    An interesting story. Was the article referring to any specific subject type? That may be good advice for a passive subject (landscape etc) but I wouldn't think it is applicable for shooting kids, motorsport or other subjects that are moving rapidly, if you want a sharp image.
    Regarding your question on the focal length magnification (also known as 'crop factor'), this should be readily found by searching on that subject and including your camera make/model.
    The crop factor is simply a ratio of the size of a full frame sensor (35mm film) to the size of the sensor in your camera. Why it can change the effective focal length of your lens is probably explained in great detail with diagrams, on a number of web sites...and probably also on this site somewhere.

    Cheers,
    Terry

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    Moderately Underexposed I @ M's Avatar
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    Terry is on the money with his thoughts on moving subjects, a faster than focal length to shutter ratio may be needed in order to get a sharp shot but in cases where the photographer wishes to include plenty of motion in ( for example ) a racing car they will frequently photograph at shutter speeds well under that rule.

    In the case of hand holding the camera and photographing a stationary subject especially with a camera / lens that doesn't have some form of stabilisation built in, I am firmly in the camp of exceeding the focal length / shutter speed rule. This is especially relevant when using longer focal lengths and or high mega pickle bodies. I frequently aim for 2x shutter speed to focal length when using any lens on a D800 body, part of which is due to my hand holding not being as good these days as when I was younger.

    Yes, I agree with the "crop factor" being taken into account when calculating speed, it is the minute change in angle that shaking hands impart that causes the blur and a "crop factor" is magnifying the amount of movement that occurs in an image.
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    Arch-Σigmoid Ausphotography Regular ameerat42's Avatar
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    Usually the "crop factor" is mentioned SOMEwhere in the manual - or in specs found on-line - but for APS-C ~1.5 should help.
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    Certainly as we move to the higher pixelcount camera sensors it seems to be an issue raised more often. When Nikon released the D800/e there were numerous threads post and general discussion on the net about the clarity of the images produced. These dense sensors were more prone to show slight camera movement than those that had gone before. Many comments were about having to re-learn technique.

    shutter speed became much talked about. As was the relationship between focal length and shutter speed.

    I think it has made some current photographers stop and think, and go back to simple rules, defined many years ago.
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    Have just referred to the manual and the crop factor for my particular Canon is 1.6X. So it does seem that some of the images I shoot need this conversion particularly since I shoot mainly hand held, perhaps this may help with sharpness, among other factors.

    Rick I certainly remember the old rule and the simple logic to get the shutter speed in relation to the focal length of a lens.........it was just when I went digital the images taken with an old 35mm film camera somehow always seemed better and sharper than now.

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    Ausphotography irregular Mark L's Avatar
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    Quote Originally Posted by DacrimL View Post
    .........it was just when I went digital the images taken with an old 35mm film camera somehow always seemed better and sharper than now.
    Do you sharpen your photos in PP?
    And there's no reason you can't post links to anywhere now.

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    The thing to keep in mind is that the 'one-over-focal-length' (1/FL) shutter-speed (s/s) 'rule' is a 'rule-of-thumb' - i.e. an approximation. Strictly speaking the 'crop-factor' should be considered, however the actual minimum s/s that should be used will vary between individuals and shooting situations. For example other factors that might affect minimum s/s are:-
    - the photographer's own level of firmness / 'shakeyness'
    - the photographer's hand-holding technique
    - equipment characteristics and ergonomics (for example a camera without a viewfinder held out in front of the face can be less stable than holding a DSLR 'tucked in' against the face)
    - whether the photographer is able to brace themselves (against a fence, wall etc)

    What's important is to work out what works for YOU - i.e whether you can still get sharp images shooting a bit slower than 1/FL or whether your shooting 'style' requires a s/s a bit faster than 1/FL.



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    No one has mentioned the effect of image stabilization built into lenses where manufacturers state that it can allow you to handhold at up to 4 stops slower.

    What does IS or VR in a lens really do to the 1/FL rule when you're hand holding the 100mm lens on a stationary scene

    Under normal conditions, we should now be able to shoot at 1/10 sec instead of 1/160 using a Canon APS-C sensor

    IS doesn't work this miracle very well for me, especially since I moved from a 6MP DSLR camera back in 2003 to 21MP now
    Canon EOS 7D Mk II, Canon 70D, Canon G12, Canon EF-S 15-85mm, EF 70-200 L f4 IS, 580EX II


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    I like my computer more than my camera farmmax's Avatar
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    I guess I'll never be a serious photographer. By the time I tried to think and calculate all the things I'm supposed to, the moment to take the photo probably would have passed

    Luckily I didn't own a tripod for many years, so just had to hand shot. I think that has been a good thing and now don't hesitate to shoot stationary objects down to around 1/15 expecting them to be OK. Moving objects definitely need higher shutter speeds ... at least I've worked that much out

    It is all right to have theory, but life is full of examples where theory and practice don't meet, so I don't get too hung up on photographing "correctly". I know other people like to try and do it by the book, and that works for them. So long as new photographers don't feel they "have" to do it the technical way, and give up because it is too hard.

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    Who let the rabble in? Lance B's Avatar
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    The 1/FL rule is only a guide and has only ever been a guide as it depends on a number of factors and these other factors that are to be taken into consideration are:

    1) How large you are going to print/view the image. A small image from just about any camera viewed on your phone screen can look sharp, but when you enlarge it to the size of your computer screen it may look quite unsharp and blurry depending on the image. This is where the "myth" about the new very high Mp cameras needing higher shutter speeds needs to be put to rest. The fact is, a high Mp camera will not look any worse then a low Mp camera when viewed at the same size and all other things being equal, ie physical camera sensor size (FF compared to FF for example), aperture, shutter speed, lens used , ISO etc. Where you may need to employ better camera technique and possibly employ higher shuuter speeds is when you decide to usitlise those extra Mp's and are going to display the image larger than that from a lower Mp camera or where you are going to crop significantly. It is only then that you may detect camera shake more so than from a lower Mp camera. However, you may have been able to hold the camera well enough for that not to be an issue.

    2) Whether you are going to crop your image significantly when compared to a lower Mp camera. However, if you need to crop the high Mp cameras image, then you'd also need to crop the lower Mp camera's image the same amount to have the same resultant subject size thus making them both look just as blurred as each other.

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    Arch-Σigmoid Ausphotography Regular ameerat42's Avatar
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    Quote Originally Posted by flashc View Post
    No one has mentioned the effect of image stabilization built into lenses where manufacturers state that it can allow you to handhold at up to 4 stops slower.

    What does IS or VR in a lens really do to the 1/FL rule when you're hand holding the 100mm lens on a stationary scene

    Under normal conditions, we should now be able to shoot at 1/10 sec instead of 1/160 using a Canon APS-C sensor

    IS doesn't work this miracle very well for me, especially since I moved from a 6MP DSLR camera back in 2003 to 21MP now

    Good point, Flashc. I guess it hasn't been mentioned because the discussion has been about basic techniques so far, but now that you've raised it...

    You'd probably know about it, but IS is stated in terms of "stops". For instance, "4 stops" at a certain focal length. (As I understand it) that means that
    the image is stabilised to 4 exposure stops (not f-stops, but in this case) of exposure time, ie, shutter speed. So, if your camera is set to 1/15sec, the
    image will be stabilised to the equivalent of 1/250sec. (Sequence: 1/ 15, 30, 60, 120, 240.)

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    Ausphotography Regular Hamster's Avatar
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    Quote Originally Posted by Lance B View Post
    The 1/FL rule is only a guide and has only ever been a guide as it depends on a number of factors and these other factors that are to be taken into consideration are:

    1) How large you are going to print/view the image. A small image from just about any camera viewed on your phone screen can look sharp, but when you enlarge it to the size of your computer screen it may look quite unsharp and blurry depending on the image. This is where the "myth" about the new very high Mp cameras needing higher shutter speeds needs to be put to rest. The fact is, a high Mp camera will not look any worse then a low Mp camera when viewed at the same size and all other things being equal, ie physical camera sensor size (FF compared to FF for example), aperture, shutter speed, lens used , ISO etc. Where you may need to employ better camera technique and possibly employ higher shuuter speeds is when you decide to usitlise those extra Mp's and are going to display the image larger than that from a lower Mp camera or where you are going to crop significantly. It is only then that you may detect camera shake more so than from a lower Mp camera. However, you may have been able to hold the camera well enough for that not to be an issue.

    2) Whether you are going to crop your image significantly when compared to a lower Mp camera. However, if you need to crop the high Mp cameras image, then you'd also need to crop the lower Mp camera's image the same amount to have the same resultant subject size thus making them both look just as blurred as each other.
    Yes, I couldn't understand this "higher Mp needing better technique" view that appeared in discussions. I'm with you regarding the need to compare images at the same size. People seem to have this view that at an un cropped image on a high Mp sensor will magically show hitherto unseen levels of camera movement. You explained it well.
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    Member Tony Jay's Avatar
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    The debate about shutter speed to focal length rears its head every now and again. It is rather a horses-for-courses sort of thing. (Obviously this is an issue of handholding.) If one is only posting images to flickr then motion blur (camera/photographer as opposed to subject) is much less of an issue compared to printing that image at size several feet by several feet.

    This kind of blur is absolutely a function of sensor resolution and also sensel pitch (the two are related). In the (old!) days of slide photography a shutter speed of 1/focal length was generally regarded as adequate, provided one's handholding technique was good. Now, in the days of rapidly increasing resolution (or sensel pitch) of modern camera sensors, the reciprocal of focal length is usually not good enough. The rule that I use now (using a 36 MP sensor camera) when shooting handheld is at least the reciprocal of twice the focal length of the lens and preferably thrice.

    Clearly, the way to go, if possible, is to use a tripod (or whatever one uses as a substitute). Then, shutter speed can probably used as a much creative tool, unencumbered, as it were, by the above constraints.

    In summary, it will be obvious to anyone reading this post that I am a newbie to this forum. Nonetheless, IMHO anyway, the info is sound.

    Tony Jay
    Last edited by Tony Jay; 06-04-2015 at 12:07pm.

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    Quote Originally Posted by Mark L View Post
    Do you sharpen your photos in PP?
    And there's no reason you can't post links to anywhere now.
    Yes I do, mainly using LR 5.7 as I cannot get my head around PS.
    Basically I attempt to get most images to a point where not to much PP is required, so now using the above information am going to start from scratch again and try to improve the images even further.

    Just one other quick question regarding faster shutter speeds.......Will they impact any on the amount of noise per image or does that remain generally from higher ISO's?

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    Arch-Σigmoid Ausphotography Regular ameerat42's Avatar
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    Well, "impact". Try an earth-hitting asteroid, but for this...

    Shutter speed DOES affect exposure, as part of the idea in the Exposure Triangle (see AP Library). Too little exposure and you get
    underexposed images which will need boosting by s/w, usually with attendant noise, which is often treatable, but at cost of IQ.

    However, ISO increase can add signal noise to images.

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    It's a good rule. So if your camera's crop factor is 1.6 then for a 100 mm lens the equivalent is 160 mm, so you'd shoot at 1/160 - OR FASTER. It does depend on subject. Also remember modern cameras/lenses have image stabilisation - that wasn't available to us back in the 'old days'. The manufacturers say you can claw back 2 stops!
    When shooting surfing with a 400-500 mm lens I used to shoot in shutter priority and start at 1/1000 shutter sopped and dial up accordingly, always on at least a monopod.
    Experiment with your own camera and lens combinations, you'll be able to read off the EXIF data what speed you used when you look at the images onscreen.
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    Ausphotography irregular Mark L's Avatar
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    The amount you crop a photo can impact the noise.

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    Member Cris's Avatar
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    Ok. i am now confused, surely you don't have to factor in crop factor when using this rule, The lens is still the same focal length lens regardless of what sensor it sits in front of, the only thing that changes is the field of view- from the sensor. So why would you need to factor in any adjustment because you are using a smaller sensor. The rules of physics surely don't change just because you are using a smaller sensor. Does someone who uses a D810, which I think has an option to shoot in dx mode all of a sudden have to increase their minimum shutter speed whilst still using the same lens. Seems odd, still the same sensor, just using less of it.

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