Calibrating BFD

[Rory_Moles]

Hi Im new to the BFD, does anyone have any tips to make the calibration procedure as accurate and repeatable as possible, so that the white marking strips can be permanently marked up and reused ?

 

tia

 

Rory Moles

[Benjamin Treplin]

Depends on the lenses you use.

With video lenses this is maybe an option but with lenses for 16/35mm or cine HD it is not. Every lens has it's own markings. Zeiss use 7 different scales for every focal length on there standard lenses, Cooke makes a unique one for every single lens.

Hope this helps.

Best

[Rory_Moles]

Sorry I didnt make myself clear, I meant marking the strips up semi-permanently, for a set of lenses for the duration of a job. So interchanging between the same set of lenses. I am trying to figure out the best procedure for calibration, do you always set the lens to the same position when initially engaging the motor, do you calibrate only up to the infinity mark and the close focus mark, or do you go right to the end stops, and so on. I want to be confident enough in the procedure to swing a lens, calibrate with a pre-marked strip in place, quick check, and go, rather than re-mark a blank strip.

 

sorry for the confusion

 

Rory

[Benjamin Treplin]

I always calibrate from the infinity to the close focus marks. IMHO it is not possible to reproduce the exact tension like a autocal remote focus. It is not necessary to hit the exact same mark on the lens while inserting the gear. It should be close to the middle of the lens range of travel, to spread the resolution equally. This way I had very reliable results.

Sorry, for misreading your question.

 

Best

[Tom Schnaidt]

Hey Rory-

 

We have used the BFD for a number of years now and have had excellent luck with repeatable calibrations. We mark the strips for the lens we are allocating to it - on that strip make a note of what you are setting the lens to as its middle. Say for example 3'6". That way you always know exactly where to set that lens when you begin your calibration. Once youve "zeroed" your motor and taken the calibration wheels to their begging setting, you should always have the same scale to marks alignment. In the end, if you really want to be able to mark your strips for repeatable use, be as consistent in every step of your set up as possible. Happy BFDing

 

tom schnaidt

[Tom Schnaidt]

Hey Rory,

 

I meant to say in the last post that Yes, we do take the calibration to the ends of the lens barrel travel not just to the infinity or closest focus marks. Now, I do think that there may have been an improvement the Jim made in some capacitor or other electronic widgmet that fixed the problem of backlash, which of course would have prevented reliability on marking your strips.

 

If you have an older one that for some reason hasn't had the upgrade, I think Jim would set you up, if not you should be cruisin with consistency.

 

Tom

[Rory_Moles]

Tom and Benjamin, thanks for your answers. I emailed Jim earlier and he basically reiterated your answers. My "problem" is having the M-One mounted on 15mm bars... it is so torquey that however gently you ease the wheel towards the end stops, the motor ends up twisting the bars (in an unrepeatable and inconsistent way) hence I have to go via the infinity/CF marks. But the general opinion is that as long as you're consistent in your method (and this includes where on the lens you first engage the motor) then the strips and markings will match.

 

regards

 

Rory

[Brett Manyluk]

You can always use a very slight tweek on one of the pots to make it match again when it goes on. Use the same marks (Don't use the end of the travel of the lense, it's better to work with the markings if possible), and retouch the pot slightly if it is out at all. The most change I ever see is about a witness mark width on the hand set, and you can tweek that out.

 

Brett Manyluk