Nikon Optex 50-300 zoom

[Dan Goulder]

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.

[Paul Bruening]

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.

[Leo Anthony Vale]

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.

[jan von krogh]

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.net/forum/showthread.php?t=3101

[Leo Anthony Vale]

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?

[jan von krogh]

& 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.

[Max Jacoby]

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.

[jan von krogh]

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.

[jan von krogh]

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.net/forum/showthread.ph...3101&page=5

[jan von krogh]

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.net/forum/showthread.php?t=3082

[Stephen Williams]

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

[jan von krogh]

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.

[jan von krogh]

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.

[Paul Bruening]

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?

[chuck colburn]

Not everyone can afford a $45,000 Angenieux or Cooke zoom lens.

[Max Jacoby]

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.

[jan von krogh]

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?

[jan von krogh]

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.

[Max Jacoby]

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. ;)

[Stephen Williams]

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

[Max Jacoby]

I can see with a zoom within limits it would work but I am sure there would be strange distortion going on.

Vertigo all over again.

[Stephen Williams]

Vertigo all over again.

 

Hi Max,

 

Which would in effect defeat the object of the exercise!

 

Stephen

[Max Jacoby]

You often see that effect at its worst during the Tour de France when a motorcycle drives away from the cyclists and the cameraman zooms in at the same time.

 

Yes I do know they're all doped...

[jan von krogh]

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

 

I can confirm the distortion with zooms. It looks like a, hard to describe, like a "mini-vertigo with a slight pincushion distortion". If you know its there, you always see it.

However i have to say that i can´t explain why - the vertigo is clear, but the pincushion... my knowledge about zoom lens design is to mediocre to understand why, as of yet, at least.

 

Also, sadly, i have no longer a motion control in house and can´t test it anymore.

 

Basicly the allocated budget for a cheap moco now is in certain cameras we ordered.

Edited August 23, 2007 by jan von krogh

[jan von krogh]

Yes I do know they're all doped...

The cameraman as well?