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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Collimation on RED ONE

khmuse said:
I couldn't agree more.

Really, unless we are talking about PL mount glass, I don't think this applies. Individuals that try to use still camera mount versions can't expect repeatability (lens to lens) that justifies this level of concern. Even with just one of these types of lenses I doubt you could mount and then remount it twice and achieve the same results. Again, its all speculation until we see what provisions RED has made for this.
Click to expand...

Hi,

I have used Nikon lenses on motion control (with bellows focusing) & the lenses can be remounted & focus remains perfect. However the mount must be made very 'tight'.

Stephen
 
khmuse said:
Really, unless we are talking about PL mount glass, I don't think this applies. Individuals that try to use still camera mount versions can't expect repeatability (lens to lens) that justifies this level of concern. Even with just one of these types of lenses I doubt you could mount and then remount it twice and achieve the same results.
Click to expand...

True !

I did a quick test on my Nikon DSLR with my autocollimator and it's much harder to get a good image on a sensor than it is on a piece of film. The low pass filter gives a stronger return than the sensor, and the sensor is not as reflective as a piece of film. You can see a faint grid like pattern on the sensor but the collimator target does not resolve very well.

Obviously anything involving a depth gauge is a bad idea and wouldn't work anyway.

I think the best use of it is more like the way the zeiss sharpmax is used. That is as a target that gives a reliable infinity that you verify from a hi-res monitor.

Matt Uhry
www.mattuhry.com
 
Stephen Williams said:
I have used Nikon lenses on motion control (with bellows focusing) & the lenses can be remounted & focus remains perfect. However the mount must be made very 'tight'.
Click to expand...

"perfect"? Unlikely.

Good enough not to be noticeable? That seems much more possible.

I am curious, how did you achieve the "tight" mount?
 
khmuse said:
"perfect"? Unlikely.

Good enough not to be noticeable? That seems much more possible.

I am curious, how did you achieve the "tight" mount?
Click to expand...

Hi,

Good enough to be repeatable, tape the lenses at infinity measure the focus distance, put distance in computer & shoot. Works wide open! However as Nikon lenses are not accurately collimated infinity has to be set on the bellows focus the first time the lens is used. Focus is determined from just the infinity focus & lens focal length.

I made the base of the Nikon mount thicker than normal, so it's tight!

Stephen
 
Matt Uhry said:
I think the best use of it is more like the way the zeiss sharpmax is used. That is as a target that gives a reliable infinity that you verify from a hi-res monitor.

Matt Uhry
www.mattuhry.com
Click to expand...

I think this is the best approach, Matt do you know how the Sharpmax achieves infinity, could this be duplicated on the cheap?

This is basically the same product, no?
http://www.schneideroptics.com/ecommerce/CatalogItemDetail.aspx?CID=1098&IID=1069
Schneider/Century HD Collimator
0HD-C150-00.jpg
 
Hi Evin,

Cheap Collimator's have been built, there was a camera engineering selling them on Ebay for $180 but he retired.

http://www.trioptics.com/test_equipment/collimators/description.php

Explains how it works.

Stephen

Evin Grant said:
I think this is the best approach, Matt do you know how the Sharpmax achieves infinity, could this be duplicated on the cheap?

This is basically the same product, no?
http://www.schneideroptics.com/ecommerce/CatalogItemDetail.aspx?CID=1098&IID=1069
Schneider/Century HD Collimator
0HD-C150-00.jpg
Click to expand...
 
Can we just use the digital image?

Can we just use the digital image?

With film cameras, the mirror at the film plane is needed for collimation because film doesn't generate an image in real time. But the digital sensor delivers an image in real time. So could we simply project the image of the reticle at infinity onto the sensor, and use a high quality monitor to show the image off the sensor to make back focus adjustments. Alternately, for those of us without a collimator, could we simply point the camera at an object at infinity, and using a high quality monitor, make the back focus adjustments? A suitable object at infinity might be a distant stand of bare trees -- objects with complex detail and good contrast.
 
Doubt it, the laser would reflect off the Low Pass filter instead of the sensor.

I see why some of you are confused...
With any HD or D-cinema camera you have the option of viewing the image from the sensor, with Red you could use the (1080P HD-SDI out and probably be OK). The trick is geting the lens to focus on a point that is at infinity and high enough contrast and sharpness to reliably judge the plane of focus, and determine if the mount is poperly aligned. The Sharpmax/HD Collimator uses optics and a test target to achieve this.
 
Ouch! I'd hate to have to also buy a $3500 Collimator, but a few hundred I could swallow easily.

Evin, I like where you're going with using the 1080p HD-SDI out for collimation assistance. What sort of low-cost tool could be used in conjunction with that?
 
Yes, between $3,500.00 and EUR 6,250.00...

http://www.filmfoto.info/forums/viewtopic.php?p=45

I doubt that there will be so many Red One customers changing mounts to PL lenses from their own B4 or SLR glass. If there will not be a reasonable solution for this, there will be less people trading new glass.
 
Shawn Nelson said:
Ouch! I'd hate to have to also buy a $3500 Collimator, but a few hundred I could swallow easily.

Evin, I like where you're going with using the 1080p HD-SDI out for collimation assistance. What sort of low-cost tool could be used in conjunction with that?
Click to expand...

Not sure there is one yet. Sound like a job for Red or Curt. What kind of optics are needed to create infinity focus on a small target?
 
Don't shoot lasers at your sensor !

Nothing inherently expensive about a collimator. It's a light source, a reticle, and a long focal length lens permanently focused at infinity. you probably could score all the parts for a few hundred bucks. a useful reticle is probably the hardest thing to find on the cheap.


Matt Uhry
www.mattuhry.com
 
Matt Uhry said:
Nothing inherently expensive about a collimator. It's a light source, a reticle, and a long focal length lens permanently focused at infinity. you probably could score all the parts for a few hundred bucks. a useful reticle is probably the hardest thing to find on the cheap.
Click to expand...
Okay but how much would it be? Who could it provide? People like you for example? Or Mr. Grant?
 
Hey Evin,
I'm talking about a sharpmax like device - no eyepiece or beamsplitter.

Hey Don,
I'm having a lot of fun being a D.P. Hacking optics is a hobby, sometimes there are useful results. I'm probably not going to get into making and selling equipment. If I come up with a good design, I'll probably share it with you.

Matt Uhry
www.mattuhry
 
I want to be able to switch mounts from the Birger EF to the Red PL quite freely. Not necessarily on the same project, but from day to day I'd like to make a decision without worrying about screwing everything up.
 
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