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Thread: DigLloyd on the Focusshift compensation on Hasselblad H MF

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    Senior Member Stefan Steib's Avatar
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    DigLloyd on the Focusshift compensation on Hasselblad H MF

    diglloyd.com blog - Why Don´t Nikon and Canon Compensate for Focus Shift? (Hasselblad Does!)

    Lloyds title was connecting the question to Nikon/Canon bodies:
    why Don´t Nikon and Canon compensate for Focus Shift (Hasselblad does!)


    I post this here in the MF section as I would like to ask people who use H camera bodies if they feel this works well and they may give some experiences with it and maybe their thought on a transformation to other formats.

    TIA and greetings from Kiev

    Stefan
    because photography is more than technology - and " as we have done this all the time "
    facebook:hcam.de - www.hcam.de - www.hartblei.de

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    Re: DigLloyd on the Focusshift compensation on Hasselblad H MF

    I use True Focus almost all time when shooting models. It works very well. This gives about 100% score of sharp images.

    I don't need to press a button to select a focus point in view finder and have much less chances to loss focus after re-frame.

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    Senior Member KeithL's Avatar
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    Re: DigLloyd on the Focusshift compensation on Hasselblad H MF

    I believe the corrections are made by the DAC calculations and are not limited to the H4D models.

    Surely True Focus (H4D) and the corrections made when using it are addressing a different issue?

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    Member Miller's Avatar
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    Re: DigLloyd on the Focusshift compensation on Hasselblad H MF

    Stefan, Evgeny,
    I think this is was ment over at Diglloyd (from the factsheet of my cam):
    "Ultra-Focus and Digital Auto Correction for image perfection
    The H3DII-39 camera allows information from the lens and exact
    capture
    conditions to be fed to the camera processor for ultra-fine
    tuning of the auto-focus mechanism, taking into account the design
    specifications of the lens and the optical specifications of the sensor.
    In this way the full HC/HCD lens program is even further enhanced,
    bringing a new level of sharpness and resolution. Digital correction
    for color aberration and distortion is also added. “Digital Auto
    Correction”
    (DAC), is an APO-chromatic correction of the images based
    on a combination
    of the various parameters concerning each specific
    lens for each specific shot, ensuring that each image represents the
    best that your equipment can produce. Based upon these techniques,
    Hasselblad
    has been able to expand our lens program with a 28mm
    lens that has been especially developed for the H3DII product family.
    The design of this lens has been optimized for the actual 36x48mm
    area of the sensor to make it more compact and to work in conjunction
    with DA C. This is a critical part of the technology behind capturing
    perfect images with this extraordinary lens. The result is clear:
    DAC increases image resolution and delivers perfect pixels, thereby
    providing
    an ideal basis for optimal image rendering."

    Does it work or is it just marketing talk? Don't know, couldn't care less, I'm just a happy shooter.
    I frankly don't think this has anything to do with MF, and I can't imagine why a world class D800E would need such a stupid feature...

    Frans Rutten

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    Senior Member Stefan Steib's Avatar
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    Re: DigLloyd on the Focusshift compensation on Hasselblad H MF

    Yevgeni + Keith

    It´s not about the Truefocus feature. it´s about the fact that some- especially highly opened lenses - do shift focus quite significantly when you change aperture. Of course it is impossible to switch this off, so my question is to some of the long term Hasselblad users here : did you mention a difference on this from the H1/2(3?) to the H4 ?
    Any real - visible - improvement ?

    TIA
    Stefan
    because photography is more than technology - and " as we have done this all the time "
    facebook:hcam.de - www.hcam.de - www.hartblei.de

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    Senior Member EH21's Avatar
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    Re: DigLloyd on the Focusshift compensation on Hasselblad H MF

    I'm curious about how much error one would see with this phenomenon. Presumably the camera is focused with the lens wide open - then when the shot is taken the lens is stopped down by the camera but the DOF will be larger then. How much focus error is introduced by stopping down? Does it happen with all lenses or just some optical designs?

    Probably adjustment for this error was included in the true sense software so the comments about that are not so far off base.

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    Re: DigLloyd on the Focusshift compensation on Hasselblad H MF

    I'd buy a Canon 50L in a second if they did correct for it, Hasselblads focus technology, especially coming from a small company, is something Canon and Nikon would do well to get their heads out of the as-ses about.
    I am not a painter, nor an artist. Therefore I can see straight, and that may be my undoing. - Alfred Stieglitz

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    Re: DigLloyd on the Focusshift compensation on Hasselblad H MF

    Ultrafocus was introduced with the H3D, one of the things it handles is focus shift with aperture change. True focus was introduced with the H4D and that of course controls the focus by following the camera pitch and yaw. Here is something that explains it in more detail from the factory dated Nov 1st 2007.

    Today the ultra focus function is actually made up from a two different parts:

    - Any lens has a aperture dependant focus shift. With the introduction of IR-filter and cover glass in the optical path, this behaviour is slightly changed. One part of ultra focus compensates for this. Technically we refer to this as SA-correction.

    - The other part of ultra focus is where we in production will match the exact sensor position of the sensor unit to the AF target position of the actual camera. In theory eliminating mechanical tolerances. We of course still calibrate the AF- and sensor position to the sae standards as before to ensure the interchangeability of sensor units between different cameras. However, focus is more exactly matched to the actual camera body that the sensor unit was sold together with. This ultra focus function also goes for up to two extra spare bodies that the customer can have (requires FC4.8.2). For spare bodies, the complete camera needs to go back to the factory for calibration together with the new cameras.

    When focusing manually, we don’t compensate the focus position at all. Manual focus is completely manual. In theory you could change focus position as a function of aperture as in AF mode, but this would add an extra shutter lag. You are correct that there is a substantial focus shift for some lenses. We could perhaps consider a mode where the camera compensated for this focus shift also in manual focus mode. You will have to live with a longer shutter lag though. Could perhaps add 100-200 ms.

    If you are using the focus assist system, we do take the aperture dependant focus shift into account.

    If the photographer is using AF drive to set focus, it is exactly the same as if the camera was in AF mode and all ultra focus functionality is used. When pressing the USER button, the camera will actually momentarily switch to AF mode.

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    Re: DigLloyd on the Focusshift compensation on Hasselblad H MF

    I don't think that their (Canon & Nikon) manufacturing processes are precise enough to do such things - their spread in the production is too big (wide/far ?).

    I bought my first Hassi just three months ago and never did so exciting shots in terms of sharpness and spot-on for the AF in 15 years of Canon-ownership (1Ds III and L-Glass)

    btw: That's also the reason I bought the X-Pro1: Even that AF is more exact than the big iron from Canon ... but that's another story :-)

    S.

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    Re: DigLloyd on the Focusshift compensation on Hasselblad H MF

    I have to admit that this information just raised my opinion of Hasselblad H system nearly 100 % upwards ! Amazing info and as well astonishing that a comparably small company did devellop this. On the other hand it is disappointing that they do not make features like this clearer in their advertising. For me this was completely new information !

    Greetings from still Kiev (will fly home tomorrow)

    Stefan
    because photography is more than technology - and " as we have done this all the time "
    facebook:hcam.de - www.hcam.de - www.hartblei.de

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    Re: DigLloyd on the Focusshift compensation on Hasselblad H MF

    Quote Originally Posted by Stefan Steib View Post
    I have to admit that this information just raised my opinion of Hasselblad H system nearly 100 % upwards ! Amazing info and as well astonishing that a comparably small company did devellop this. On the other hand it is disappointing that they do not make features like this clearer in their advertising. For me this was completely new information !

    Greetings from still Kiev (will fly home tomorrow)

    Stefan
    Most good authorized Hasselblad dealer/resellers both know about this True Focus/Micro Adjust AF feature and demonstrate it.

    Mine did so in a quite studio, where we altered the aperture and could hear the micro-focus adjust feature in action. Just a brief little ... zizzt! ... as it corrected the focus.

    Also, when working tethered you can manually micro-focus adjust in Phocus while using the audio feed back/audio graph with live view.

    We used the audio adjust feature when I had a Schneider 120 view lens on my Rollie Xact-2 that wasn't exactly stellar sharp. My dealer added shims to the lens using the audio feed/graph as a guide.

    However, all that aside, I'd also still like a flip magnifier for the H viewfinder for manual focus.

    -Marc

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    Re: DigLloyd on the Focusshift compensation on Hasselblad H MF

    How much of a lag is there for the true focus to compensate Marc?
    I am not a painter, nor an artist. Therefore I can see straight, and that may be my undoing. - Alfred Stieglitz

    Website: http://www.timelessjewishart.com

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    Re: DigLloyd on the Focusshift compensation on Hasselblad H MF

    Quote Originally Posted by Ben Rubinstein View Post
    How much of a lag is there for the true focus to compensate Marc?
    Literally none ... as you can imagine, the amount needed is minuscule ... and if I recall correctly, it happens as you adjust the aperture wheel.

    Hasselblad also employs a "True Exposure" technology that many do not know about ...

    http://www.hasselbladusa.com/media/2...osure_mode.pdf

    -Marc

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    Re: DigLloyd on the Focusshift compensation on Hasselblad H MF

    Quote Originally Posted by Stefan Steib View Post
    I have to admit that this information just raised my opinion of Hasselblad H system nearly 100 % upwards ! Amazing info and as well astonishing that a comparably small company did devellop this. On the other hand it is disappointing that they do not make features like this clearer in their advertising. For me this was completely new information !

    Greetings from still Kiev (will fly home tomorrow)

    Stefan
    Two things Stefan. First, Hasselblad haters are too busy trashing the company to do a little research to find out the good things Hasselblad does. Second, Hasselblad's marketing does not match their products and service in quality. I have complained time and again to the company about their poor marketing efforts (mostly in the public relations area).

    Greg

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    Re: DigLloyd on the Focusshift compensation on Hasselblad H MF

    As a Hasselblad user myself I do like the system despite everyone smashing on it and praising phase. Despite having a H2 and Phase back I love the lenses and their precise focusing, I have demoed a H4x and the true focus works rather well with wide open lenses like the 100 f2.2, which is a stellar lens. The speed is not noticeable but the correction is seemingly instantaneous.

    Also they have a 50-110 zoom lens with a leaf shutter so you can sync your strobe at any aperture, and they've had it since 2002.. I believe that only recently phase even announced one.. I use this for most of my work with strobes indoors and outdoors where syncing at any speed is a great help..

    Don't forget their cameras and LS lenses can do up to an 18 hour 12 minute exposure, just incase you ever need anything that extreme

    now for marketing… thats where they fail.. at least it's not the cameras!
    Rick Rose
    www.RickrPhoto.com
    HasselPhase
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