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Nikon Optex 50-300 zoom


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#1 Dan Goulder

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Posted 18 August 2007 - 12:06 PM

Have any of you had any experience or feedback with the Nikon 50-300mm zoom (converted to Arri bayonet by Optex) for use with 35mm cinematography?
Thanks.
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#2 Paul Bruening

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Posted 19 August 2007 - 11:16 PM

I've thought about using Nikon zooms for cinema. In earlier threads people warned me they breath on focus. As well, they shift focus through the zoom range. I don't know how accurate those posters were. But, it may be something to look out for.
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#3 Leo Anthony Vale

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Posted 20 August 2007 - 02:48 PM

I've thought about using Nikon zooms for cinema. In earlier threads people warned me they breath on focus. As well, they shift focus through the zoom range. I don't know how accurate those posters were. But, it may be something to look out for.


Panavision converted the 50-300mm Nikkor to a 60-600mm for 65mm ages ago.
They don't seem to have rehoused the body of the lens & since this one been adopted by others for cine use
it's probably a better choice than some 35-135mm with the Nikon mount intact.

I learned long ago to not use zooms for focus shifts.
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#4 jan von krogh

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Posted 21 August 2007 - 07:46 PM

I've thought about using Nikon zooms for cinema. In earlier threads people warned me they breath on focus. As well, they shift focus through the zoom range.

There are emerging solutions to these problems.

http://www.reduser.n...read.php?t=3101
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#5 Leo Anthony Vale

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Posted 22 August 2007 - 01:34 PM

There are emerging solutions to these problems.


& how will these mounts eliminate breathing ang focus shifts in a zoom lens?

& be usable on a different camera?
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#6 jan von krogh

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Posted 22 August 2007 - 05:05 PM

& how will these mounts eliminate breathing ang focus shifts in a zoom lens?

probably by adjusting FL to compensate.

& be usable on a different camera?

Should be - as long as you give them power.

But i think its wiser to ask Birger himself (once hes returned from holidays) - as we have to speculate and hes the one who knows.
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#7 Max Jacoby

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Posted 23 August 2007 - 04:11 AM

probably by adjusting FL to compensate.

I don't see how that is possible or at the least practically feasable. As far as I'm aware the movement inside a lens, be it for focus or a zoom shift, is not linear, so making adjustments to either one of these will prove to be a nightmare.
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#8 jan von krogh

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Posted 23 August 2007 - 02:21 PM

I don't see how that is possible or at the least practically feasable.

That might be the reason why you don´t develop it :)
It is already done (in a way more expensive) way with motion controls.
Indeed i did my first own fl-corrected gliding focus in ~94 on a cheap fujinon lens which breathed terribly.
However, this was stopmotion-work, frame by frame, and it took us like 2 days for ~15 seconds.

But i am still sceptic as well - there are massive obstacles to overcome,
And its pretty much more challenging with moving images in realtime.

As far as I'm aware the movement inside a lens, be it for focus or a zoom shift, is not linear, so making adjustments to either one of these will prove to be a nightmare.

Yes. As we both don´t know for sure -how- Birger is intending to implement this, we have to speculate.

disclaimer: i am no expert in canon/nikon lenses, especially not in the newer ones for digital cameras, so i might overlook important features/possibilities inherent to these lenses.

The simplest, primitive, method one could think of would require building a lookup-list for the individual lens.
Basicly measuring every focal lenght in small steps in any focus position.
This measured data then is used to control fl to compensate breathing focus.
Indeed, thats the way we have done it on motion controls - but for a small range, frame by frame, in a controlled environment and in non-real-time.
I suppose/speculate that performing this in realtime would be pretty vulnerable to jitter, especially if one does a fast, tough focus change.

The elegant approach would be to have the parameters of the optical system in the lens.
In that case, a -nearly- perfect compensation would be feasible, as one then would use algorithms instead of datasheets.
however, i highly doubt that canon or nikon would share these confidential data with birger, and reverse engineering this, due to the non-linear characteristics, would be really challenging,

Anyhow, Birger really seems to plan this, and i really whish him all the best for this stunt.
If i am not missing something important, i don´t think he´ll be able to compensate -all- lenses, but a few ones.
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#9 jan von krogh

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Posted 23 August 2007 - 02:27 PM

ok, i looked up the post on reduser.net.
he seems to intend to go the way with calibration datasheets.


Does anyone know if the Birger mount+ follow focus is going to compensate for some breathing still lenses do?
Or is that not possible?

It is one of many features on a list for later. Once we either release our own zoom motor, or have integrated with the RED motor, we will look at implementing this. The real issue is the production of the calibration data.

We have ways to do this automagically... but that will require our auto-interactive focus module that we will not be announcing for some time...

The other request that comes quite often is aperture comensation on variable aperture zooms. Because of the quarter stop steps of the Canon iris mechanism, this feature may not be that interesting without some intervention in post. This also requires a zoom motor.
Erik Widding
www.birger.com

source:
http://www.reduser.n...h...3101&page=5
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#10 jan von krogh

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Posted 23 August 2007 - 02:35 PM

As it seems, the second company is starting to work on it.
Viewfactor.

We are also working on a lens breathing compensation mode that will basically eliminate breathing on your lenses. The setup for that is a little trickier and I'd expect that the data would have to come from us by setting up a calibration bench of some sort. Basically you would need two motors-one for focus and one for zoom. As you rack focus, the zoom motor will back off or advance to adjust the zoom and keep the framing same through out the shot. We tried it out manually and its looking very promising on the POS fujinon lens we have here. Once we get to that point of testing we may enlist the help of redusers to donate lenses and hardware to get a decent database for everyone to download to their remotes.
__________________
Curt von Badinski
View Factor
source:
http://www.reduser.n...read.php?t=3082
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#11 Stephen Williams

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Posted 23 August 2007 - 02:39 PM

That might be the reason why you don´t develop it :)
It is already done (in a way more expensive) way with motion controls.
Indeed i did my first own fl-corrected gliding focus in ~94 on a cheap fujinon lens which breathed terribly.
However, this was stopmotion-work, frame by frame, and it took us like 2 days for ~15 seconds.


Hi Jan,

Are you sure breathing was fixed? Normally a motion control follow focus base does nothing for breathing. It focuses by moving the camera relative to the lens (it can be lens relative to camera). Simple lenses focus by moving forward away from infinity and naturally breathe.

Stephen
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#12 jan von krogh

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Posted 23 August 2007 - 02:58 PM

Hi Jan,

Are you sure breathing was fixed?

Yes. I have done that shot myself and i took me a whole day to compensate.
To be precise - it was a DOS basing text interface, no undo, one wrong entered information and the whole program had to be redone.

Normally a motion control follow focus base does nothing for breathing. It focuses by moving the camera relative to the lens (it can be lens relative to camera). Simple lenses focus by moving forward away from infinity and naturally breathe.
Stephen

Correct.
If you remember i told you once - that was the mutant motion control we build ourself (ah, the early days).
In fact, we had the idea as we had to do the shot and the z-axis wasn´t working at that time, so we decided to do it with the lens motors, which were already working.

One day, i will track that motion control down. It was sold, i think, in ~1997/8 and i lost it out of my eyes in ~2000.
However, i hear its still in use, somewhere near Stuttgart. The guy who designed it was really a cool engineer.
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#13 jan von krogh

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Posted 23 August 2007 - 03:03 PM

Ok, Curt von Badinsky also has it on his feature list. Viewfactors spec sheet:

* Wireless (Zigbee) and Wired control options - wireless range: 1Mile in open, 300 ft indoors
* Encrypted transmission - avoids radio interference and no addressing is necessary (no dips to set)
* Mono Graphical LCD - full user interface with numerous features that are easily upgraded
* Modular design - all control axis are assignable to any of the three input devices (Force sensor, Knob, or Capacitive slider), right or left handed operation
* Solid construction - water resistant magnesium case, o-ring seals, minimal mechanical components
* 3 channel simultaneous control
* Motion control functionality - **record and repeat moves, goto preset positions automatically, settings for speed and easing
* Removable battery pack, rechargeable via usb connection
* Lens database - choose a preset lens to auto calibrate the motors to a given lens. Fully upgradeable via usb or SD card.
* Receiver unit accepts 12V-24V power source and connects to three motors, includes usb connection for use with certain digital cinema cameras
* Receiver unit dimensions are approx. 3.0"x2.0"x0.75"
* **Lens Breathing Compensation (LBC) - during a rack focus, zoom motor compensations for breathing to keep framing consistent
* **Works with Mirus motion control system - Record FIZ tracks separately or during a moco shot

** This functionality may not be in place at time of shipping but will be enabled through future software releases.
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#14 Paul Bruening

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Posted 23 August 2007 - 04:03 PM

Do I recall correctly that some cine and video zooms are made to not change focus on zoom? I used an Angenieux in college that could hold focus through the whole zoom range. If this is so, then why go through all of those compensations on a cheaper still lens when you could just use a better lens?
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#15 chuck colburn

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Posted 23 August 2007 - 04:06 PM

Not everyone can afford a $45,000 Angenieux or Cooke zoom lens.
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#16 Max Jacoby

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Posted 23 August 2007 - 04:19 PM

The simplest, primitive, method one could think of would require building a lookup-list for the individual lens.
Basicly measuring every focal lenght in small steps in any focus position.

That's similar to nodal point tracking that CGI people do to be able to recreate the move in post. But my issue would be with calibrating the zoom lenses for every single focal lenght (to compensate for breathing) or for acurate focus (while zooming). The existing remote foci on cine lenses do these calibrations automatically and it is very reliable, especially with LDS lenses, but stills lenses have a much smaller tolerance because their focus scale is much smaller.

And let's not forget that compensating for breathing can only be done on zooms, not primes.
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#17 jan von krogh

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Posted 23 August 2007 - 04:50 PM

That's similar to nodal point tracking that CGI people do to be able to recreate the move in post. But my issue would be with calibrating the zoom lenses for every single focal lenght (to compensate for breathing) or for acurate focus (while zooming). The existing remote foci on cine lenses do these calibrations automatically and it is very reliable, especially with LDS lenses, but stills lenses have a much smaller tolerance because their focus scale is much smaller.

correct.
We also use compensation on our angenieuxs.
however, this thread isn´t about cinelenses but about converted nikon (or photo in general) lenses.

And just to be sure: You said:

I don't see how that is possible or at the least practically feasable.

Now you understand, i suppose?
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#18 jan von krogh

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Posted 23 August 2007 - 04:52 PM

I forgot...

And let's not forget that compensating for breathing can only be done on zooms, not primes.

Can be done for primes as well - but then you will not use a FL control, but a moco on the z-axis.
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#19 Max Jacoby

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Posted 23 August 2007 - 05:23 PM

I forgot...

Can be done for primes as well - but then you will not use a FL control, but a moco on the z-axis.

Guess that producer will be happy when I tell him that I will need to do my whole shoot moco to compensate for the breathing of my stills lenses. ;)
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#20 Stephen Williams

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Posted 23 August 2007 - 05:25 PM

I forgot...

Can be done for primes as well - but then you will not use a FL control, but a moco on the z-axis.


Hi Jan,

Not convinced that will work, I often use a Fries AF35R, the lens focuses by moving forward so the image breathes. Might work with a lens with internal focus such as a Cooke S4, however that does not breathe in the first place, so no point! I can see with a zoom within limits it would work but I am sure there would be strange distortion going on.

Stephen
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