my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Digital Cinema Forum   » focus best practice

Author Topic: focus best practice Gavin Lewarne Master Film Handler Posts: 278 From: Plymouth, UK Registered: Aug 2009 posted 12-18-2012 03:02 PM                     Simple question...... When setting the default focus for flat and scope, is it best to use a test pattern generated by the projector or some actual, real, dcp content? I'm currently focusing on the test patterns and in the auditorium its pinsharp, but features look a little bit 'soft' Thanks!  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 12-18-2012 03:11 PM                        The test pattern and DCP content should focus on the same plane (unlike RP40 and films printed on color print stock). If the test pattern is correctly focused, then the feature material should also be in focus. If you can see the individual pixels and the space between them when you walk up to the screen, then the focus should be correct. Lots of movies are just not shot in sharp focus, so the focus can drift from shot to shot from being razor-sharp to slightly soft; is it possible that this is what you are seeing?  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 12-18-2012 03:53 PM                     Always use the test pattern. Note too if boresight/Scheimfleug is not properly aligned during installation, you may find there is a place on the focus setting to get one or two corners in focus...going further on the focus brings them all in focus (sort of)...going further takes the previously blurry corners into focus and blurs the previously in focus. The proper solution to the boresight/Scheimfleug is to have your technician properly align the projector. You should be able to take the image out of focus, then bring it into focus and all 4 corners should just start to hit in focus simultaneously. Then you merely center the focus adjustment for best focus. Do note it is common to have one format properly aligned in respect to this, but not the others. This is due to optics and lens shift. I typically align for perfect focus on scope and then other formats will be just a tiny bit off. (Yes I am being super picky here, but we use binoculars and telescopes for calibration too.) This is important because if you have scope perfect, you can use the depth of field of the lens to find that middle ground for other formats so they are all in focus. If you put up a scope target pattern and walk up to the screen, you should be able to see the tiny black lines between pixels in all 4 corners of the target.  |  IP: Logged Gavin Lewarne Master Film Handler Posts: 278 From: Plymouth, UK Registered: Aug 2009 posted 12-18-2012 04:31 PM                     Thanks both, that reaffirms that's its the features themselves that are nit always razor sharp. Both scope and flat test patterns are razor sharp in all four corners and centre, and next to the screen I can see each indivual pixel with no "softening" of the edges. Our installer did a fine job at scheimflueg'ing, we were at it for over an hour and a half and I wouldent let him finish until I was happy. (Steve if your on this forum you did a grand job) Just wanted to check, thanks for the information :-)  |  IP: Logged Pete Naples Phenomenal Film Handler Posts: 1565 From: Dunfermline, Scotland Registered: Feb 2001 posted 12-19-2012 04:10 PM                     He's not Gavin, but I will pass on your sentiments.  |  IP: Logged Gavin Lewarne Master Film Handler Posts: 278 From: Plymouth, UK Registered: Aug 2009 posted 12-19-2012 05:45 PM                     thanks pete - tell him i haven't futzed with anything, was just checking it did a test screening of our DCP of the hobbit, was extremely sharp so yeah, digital films not always shot with the same focus either!  |  IP: Logged

All times are Central (GMT -6:00)

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.