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Thread: Help with manual focus

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    Member IK-Labs's Avatar
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    Help with manual focus

    Problem: focussing in low-light candid situations, either where I don't want the AF light coming on and spoiling the moment, or where the AF light will do sweet bugger-all.

    Eg.


    That's a crop - the dude and the light would've been about ten paces away, way too far for the AF light to do any good. This is the closest to an in-focus shot I got, and it took about, erm, *eleven* goes and much groping around the focus ring to get even that.

    The weedy little in-focus indicator which appears way over on the left side of the status bar in the viewfinder in manual focus mode is too small and too fleeting (it flashes on and off with so much as an eyeblink from the subject) to be of much use, so, short of shelling out $150 for a Katz Eye split prism screen, what else is there to do?

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    Administrator ricktas's Avatar
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    Is that a studio shot? Turn lights on, focus, lock focus, turn lights off and shoot? Depending on how good your eyes are, just use manual focus completely, look through viewfinder, when photo looks sharp, use that? What Camera and Lens were you using. A good combo with an F2.8 lens ( or better) will allow you to autofocus in very low light. AF works with the lens wide-open, no matter what aperture is selected, so an F2.8 lens will give you a lot more options compared to a kit lens etc.
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    Studio shot? Hell, no. It's the dancefloor in a nightclub. No control over what happens whatsoever...

    Kit: D700, 24-70/2.8G AF-S lens set to wide open.

    In that particular instance, because the subject was in his own little world and wouldn't have noticed one extra tiny flashing light, I tried AF and it just waved the white flag - too much dark overlaid with flashing lights, too confusing for it. As the result shows, I got close enough by hand, but it took literally a good couple of minutes and there would've been no cigar for anyone if the dude had decided to twirl out from under the light. Plus, standing there and doing a manual focus bracket isn't even remotely an option if I'm going for a candid snap of someone just doing something random...

    Like, say, this,


    A complete and utter fluke, helped along by the fact that he's stretching out away from the camera, so there were plenty of candidate DoF "slices" to make the shot work. A second or two later, the contortions would've been unwound because he'd've been done yelling something to his mate standing outside of frame and I would've had no shot.

    ...and when I've sat down and deliberately tried to get manual focus right first go, it just wouldn't happen; "yup, looks clear, *click* Gah! Again!"

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    Focusing in low light is never easy but it's helpfull if you are using the right gear for the job. The gear you are using sounds OK but having never used the D700 I'm only guessing. My idea of the right gear for the job is possibly a range finder camera, not much good to you, or possibly some of the faster Nikon lenses but only if they are actually sharp wide open. An F1.4 lens is 2 stops brighter than your zoom and although it may not be razor sharp wide open, which can also make it hard to focus, the brighter image should be a big help.

    Are you sure you are using a fast enough shutter speed to freeze motion? It could be that some of the lack of sharpness is not due to your focusing but your shutter speed and camera shake.

    JJ

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    A royal pain in the bum! arthurking83's Avatar
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    Focus bracket.

    Depending on the distances to subject and all that.. ie. DOF, it;s very unlikely that you'll get the exact spot you want in focus with a shallow DOF.. so I focus bracket.
    One of my favoured lenses is the 50mm f/1.2, but trying to get a set point in focus(at 100% view) is damned near impossible, and if I do, it's simply dumb luck!

    Then one day I discovered via liveview that the manual focus mirror may have been misaligned a little and throwing off the the focus indicator.
    Live view confirmed focus, and yet the focus indicator didn't agree, and vice versa.
    So with a 1.5mm allen key I guessed at which point the manual focus mirror needed tweaking, and all seems to be much better now with using the focus indicator.

    50mm f/1.2 is an AIS manual only lens, so manual focusing is not a new or strange concept to me, as I like using this lens a lot.
    It's a near impossible concept to me.. bright/dark/purple or orange lighting conditions... I hate it and a KatzEye is something I need
    Set to f/2 and beyond though.. I have no problems.

    If getting critical focus is a priority and you need to manually focus, try focus bracketing.. shoot at something like 3-6fps(I choose about 3, as any more is too fast for the rate at which I adjust focus), and simply shoot continuously whilst slowly adjusting the focus ring.. a mil this way and that.
    This way I'll end up with at least 1, hopefully two, sharp images out of six or so, even at f/1.2

    Katzeye screen seemed a bargain a few months back(when the dollar was worth more!) they are approx US$105 (~AU$160) and it serves me right for procrastinating for so long.

    ps. I can't see a listing for the D3/700
    Nikon D800E, D300, D70s
    {Nikon} -> 50/1.2 : 500/8(CPU'd) : 105/2.8VR Micro : 180/2.8ais : 105mm f/1.8ais : 24mm/2ais
    {Sigma}; ->10-20/4-5.6 : 50/1.4 : 12-24/4.5-5.6II : 150-600mm|S
    {Tamron}; -> 17-50/2.8 : 28-75/2.8 : 70-200/2.8 : 300/2.8 SP MF : 24-70/2.8VC


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    Quote Originally Posted by jjphoto View Post
    An F1.4 lens is 2 stops brighter than your zoom and although it may not be razor sharp wide open, which can also make it hard to focus, the brighter image should be a big help.
    I do have a Nikkor 50/1.4 AF-D. Haven't tried it in a club because the 24-70/2.8 can catch enough light for usable images at the high ISO the D700 is capable of and I find I'm making a lot of use of the zoom. Honestly, my only complaint with the setup is this manual focus thing. Maybe my memories of using a film SLR with a split-prism reticle for focus are too rosy, but my problem really appears to be that it's hard to gauge focus from the image alone.

    Are you sure you are using a fast enough shutter speed to freeze motion? It could be that some of the lack of sharpness is not due to your focusing but your shutter speed and camera shake.
    Quite sure; I'm between 1/80 and 1/20, the AF shots taken in the same conditions are sharp, and my hand position on the camera doesn't change between then and shooting MF.
    Last edited by IK-Labs; 15-01-2009 at 2:02pm.

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    Quote Originally Posted by arthurking83 View Post
    If getting critical focus is a priority and you need to manually focus, try focus bracketing.. shoot at something like 3-6fps(I choose about 3, as any more is too fast for the rate at which I adjust focus), and simply shoot continuously whilst slowly adjusting the focus ring.. a mil this way and that.
    This way I'll end up with at least 1, hopefully two, sharp images out of six or so, even at f/1.2
    Nod. The way I had been doing it, such as, for example, in the first shot in the thread, has been to bracket visually, then move through the nearly-in-focus range in *steps*, rather than continually; tweak focus ring, squint, shoot if image looks clearer, tweak focus ring, squint, shoot if image looks clerer, repeat.

    I have an irrational aversion to superfluous shutter activations.

    Katzeye screen seemed a bargain a few months back(when the dollar was worth more!) they are approx US$105 (~AU$160) and it serves me right for procrastinating for so long.

    ps. I can't see a listing for the D3/700
    They say they're working on it... mind you, has there ever been a satisfactory explanation for why manufacturers have just started leaving out focus reticles?

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    A royal pain in the bum! arthurking83's Avatar
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    Quote Originally Posted by IK-Labs View Post
    ......Maybe my memories of using a film SLR with a split-prism reticle for focus are too rosy, but my problem really appears to be that it's hard to gauge focus from the image alone.



    ....
    I've read elsewhere and then yesterday on the Katzeye website that DSPR screens have been optimised for AF systems by producing lower contrast matte screens. So the image doesn't appear to snap into focus.
    I remember way back just after I got my D70s(terrible viewfinder coming from a film camera.. and a cheapie at that Nikon EM!) that was my biggest gripe, and having two manual focus lenses.. it was even more horrible as I couldn't use them effectively

    One day I was out shooting some landscapes with my 500mirror and not only was it hard to gauge focus, but the dual problem of mirror slap on a not so stable tripod/head. I got my two shots out of twelve, but decided then that I needed a D200 at the least, and read everything I could about it from professional experiences, and that was it. In the end I splashed out on a D300(slightly better Vf again) but what I really truly wanted was a D3(and subsequently D700)
    I've asked on other forums if there is any visible difference between the D700 and D3 for manually focusing a 50/1.2, and the reply was that there is.. but it's very small(obviously in favour of the D3)
    I like manually focusing, but it has to be a good experience.

    Before I got my D300, I tried a cheapie $30 focusing screen from ebay for my D70s and it definitely helps(manually focusing) but as the mirror is an f/8, the black spot always made it annoying trying to gauge exact focus at the center.

    With a small $30 punt, I now made the decision to get a Katzeye, but with the OptiBright treatment too(I still enjoy using the 500mirror, and I don't it to bite me on the.... retina )

    That's USD$155 or so(AUD$200)!!! just for a piddly lil plastic matte screen

    Problem is that I still want the D700(sometime this year if prices drop below $3K) so getting the $200 matte screen for the D300 is eventually going to be wasted.

    Kind of a dilemma for me, but with most manual focusing, I make full use of LiveView for now.. hence no rush.
    The D700 is going to be a priority.
    If you're happy with the D700.. and don't plan to rush into the next upgrade cycle, get the focus screen(from KatzEye) as soon as it's available!
    I'm assuming Katzeye's will be much more effective than the 'Cheapie from China' that I got for my D70s.
    It was an effective purchase for using with the 300/2.8 and 50mm, but not so with the 500/8!!(the blackout).
    Didn't affect AF nor metering(as I feared) but even if it does on my D300(or possibly a D700), now that I understand the mechanics of adjusting the focus system(mirror/hot-mirror).. I have no reservations about doing so if the need arises(anyone that's used an allen key can do it )


    Hope my experiences helps a little.
    ie. split prism focus screens are good(if not expensive!)

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