Meter Placement Questions - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
 1Likes
  • 1 Post By Dominic Chan
 
Thread Tools
post #1 of 5 Old 11-09-2019, 11:32 AM - Thread Starter
Advanced Member
 
gravi's Avatar
 
Join Date: Feb 2007
Posts: 593
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 404 Post(s)
Liked: 205
Meter Placement Questions

I want to confirm some basic placement questions for measuring projector with white screen and consumer meters (i1D3, Spyder X, i1pro2):

- Does distance from screen matter? Some people recommend 2-3' at a slight angle to avoid shadow, but I have seen some people place 6' away at an upward angle. I have seen luminance vary with distance, so not sure if distance is immaterial.

- How do I find FOV for a given meter? This is to place it to avoid shadow on screen.

- For projectors, full screen patterns are always recommended?

- For grayscale measurements, is it best to havethe brightest setting possible (iris fully open) to better enable dark readings, and later set the desired iris level? Or does it not matter?

Thanks!
gravi is offline  
Sponsored Links
Advertisement
 
post #2 of 5 Old 11-09-2019, 02:52 PM
Advanced Member
 
SirMaster's Avatar
 
Join Date: Aug 2009
Location: Wisconsin
Posts: 943
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 806 Post(s)
Liked: 499
Luminance should not change much with distance, unless the meter is starting to read past the screen edges or you are not aiming it at the same point on the screen, like directly at the middle where most projectors are brighter. Or if the view angle changes with distance and you are not using a utility gain screen.

It may drop a slight bit with distance because you are reading at a farther radius from the screen center of the screen which is usually brighter than the edges, so the overall reading will be slightly dimmer, but it shouldn't be more than a couple percent at most.

There should only really be 3 things that matter for ideal meter placement. Keeping the reading out of the shadow, maximizing luminance, and reading the screen from a similar angle as the viewer (mainly if you screen is not not a perfect 1.0 utility gain screen). So that you are calibrating it for how the viewers see it.

There is no reason not to use full screen patterns and would be necessary if you are placing some meters far away anyways.

For gamma it doesn't matter the iris position, so open it to maximize brightness. For color and grayscale iris can affect it, so use the iris position that you will be using.


My screen is 65" tall and I mount my i1D3 about 7ft back which lets me mount it eye level and pointed at the center of the screen with barely any upward angle on the meter. At 7ft it also casts no shadow on the screen whatsoever.

Moving it closer does not give me any brighter reading.

For my i1 Pro 2, I mount it in the same place, mainly because I am usually using it to create a correction matrix for my i1D3, and it's best to have both meters in the same position when doing so.

Otherwise I have put my i1 Pro 2 at about 12ft before basically right in my main seat and the luminance readings weren't any dimmer. The i1 Pro 2 has a pretty narrow field of view.

Last edited by SirMaster; 11-09-2019 at 05:00 PM.
SirMaster is online now  
post #3 of 5 Old 11-09-2019, 03:56 PM
AVS Forum Special Member
 
Join Date: Dec 2014
Location: Mississauga, ON, Canada
Posts: 7,143
Mentioned: 133 Post(s)
Tagged: 0 Thread(s)
Quoted: 5022 Post(s)
Liked: 1934
Quote:
Originally Posted by SirMaster View Post
There is no reason not to use full screen patterns and would be necessary if you are placing some meters far away anyways.
One potential drawback of using full screen patterns is that you’ll get more reflections from the surroundings.

Quote:
For gamma it doesn't matter the iris position, so open it to maximize brightness.
Gamma does vary slightly with iris (the iris reduces black more than it reduces white). However, for JVC projectors the same calibration data is applied regardless of the iris position.
SirMaster likes this.

Last edited by Dominic Chan; 11-09-2019 at 04:32 PM.
Dominic Chan is online now  
Sponsored Links
Advertisement
 
post #4 of 5 Old 11-09-2019, 04:52 PM
AVS Forum Special Member
 
Join Date: Dec 2014
Location: Mississauga, ON, Canada
Posts: 7,143
Mentioned: 133 Post(s)
Tagged: 0 Thread(s)
Quoted: 5022 Post(s)
Liked: 1934
Quote:
Originally Posted by gravi View Post
- How do I find FOV for a given meter? This is to place it to avoid shadow on screen.
You can find some data in this paper:

https://app.spectracal.com/Documents...%20Article.pdf
Dominic Chan is online now  
post #5 of 5 Old 11-11-2019, 05:34 AM
AVS Forum Special Member
 
ConnecTEDDD's Avatar
 
Join Date: Sep 2010
Location: Athens, Greece
Posts: 8,672
Mentioned: 212 Post(s)
Tagged: 1 Thread(s)
Quoted: 3416 Post(s)
Liked: 4241
The ideal meter placement for projectors is when the meter will match the same angle you have your eyes height from the sitting position towards to the center of the screen.

You can use a mobile phone or a digital angle meter to find the angle.

Imagine a virtual line (you can use a laser pointer) from your eye's @ sitting position aiming the center of the screen, the meter ideally has to placed the that line height and angle.

When you are using Window patterns, you need to find out the meter FOV (field of view), because we don't need the meter to see larger area from the pattern area. (not see the meter shadow also if you place it very close to the screen).

For the pattern size, 10% Windows will be fine, with max of 18% Windows patterns.

When someone will use a very narrow FOV meter, he can place the meter to actual sitting position: https://www.avsforum.com/forum/139-d...l#post57368096

Ted's LightSpace CMS Calibration Disk Free Version for Free Calibration Software: LightSpace DPS / CalMAN ColorChecker / HCFR
S/W: LightSpace CMS, SpaceMan ICC, SpaceMatch DCM, CalMAN 5, CalMAN RGB, ChromaPure, ControlCAL
V/P: eeColor 3D LUT Box - P/G: DVDO AVLab TPG
Meters: JETI Specbos 1211, Klein K-10A, i1PRO2, i1PRO, SpectraCAL C6, i1D3, C5
ConnecTEDDD is online now  
Sponsored Links
Advertisement
 
Reply Display Calibration

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off