Thread: MAXIMUM LENS MOUNTING DEPTH - Red Ranger Monstro & DSMC2 - PL

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  1. #11  
    Senior Member Patrick Tresch's Avatar
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    The sensor is behind the OLPF. So you changing the back focus won't give more space. you would hit firts the fixed OLPF.
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  2. #12  
    Senior Member Jacek Zakowicz's Avatar
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    Quote Originally Posted by Neil Abeynayake View Post
    Hi Jacek, Hope you guys are doing well. We need to go back to the days of pre-COVID-19, soon. I certainly miss those days when we met people in person and had a meal together, shoot the breeze etc.

    I was referring to this specific instance. If the operator knows what they are doing, you can change the back focus anytime. We used to do this during our Television studio production days.

    Sometimes a DoP might insist that he/she wants to use a specific lens (perhaps for the looks or likes the freggin' lens, getting a boner etc.) If and when this occurs, you could resort to adjusting the back focus or by inserting flanges or shims to a cinema lens.
    Unfortunately the distance from the rear element surface to the imaging plane (sensor surface) is fixed so no matter what you do the clearance remains the same . If you move the glass away from the sensor the lens can only be sharp in macro (close up) mode.
    Correction:
    yes the OLPF clearance will change so you may be actually able to clear some lenses.
    Jacek Zakowicz, Optitek-dot-org, jacek2@optitek.org
    Professional Broadcast and Digital Cinema Equipment
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  3. #13  
    Senior Member Patrick Tresch's Avatar
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    Quote Originally Posted by Jacek Zakowicz View Post
    U
    yes the OLPF clearance will change so you may be actually able to clear some lenses.
    But the OLPF doesn't change postion. Only the sensor.
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  4. #14  
    Senior Member Jacek Zakowicz's Avatar
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    Quote Originally Posted by Patrick Tresch View Post
    But the OLPF doesn't change postion. Only the sensor.
    Yes but if the lens to sensor position is fixed and they both move forward, the rear part of the lens that hit the OLPF before may clear it now as it has moved forward with the sensor. Up to the point when the sensor is prevented from moving forward any more by the rear surface of the OLPF..
    Jacek Zakowicz, Optitek-dot-org, jacek2@optitek.org
    Professional Broadcast and Digital Cinema Equipment
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  5. #15  
    Senior Member Patrick Tresch's Avatar
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    Quote Originally Posted by Jacek Zakowicz View Post
    Yes but if the lens to sensor position is fixed and they both move forward, the rear part of the lens that hit the OLPF before may clear it now as it has moved forward with the sensor. Up to the point when the sensor is prevented from moving forward any more by the rear surface of the OLPF..
    Ok so shimming the mount?
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  6. #16  
    Senior Member Jacek Zakowicz's Avatar
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    Quote Originally Posted by Patrick Tresch View Post
    Ok so shimming the mount?
    Sorry no shimming is needed as you maintain the back focal distance
    Jacek Zakowicz, Optitek-dot-org, jacek2@optitek.org
    Professional Broadcast and Digital Cinema Equipment
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