back focus check - Page 3 - DVXuser.com -- The online community for filmmaking

Cees Mutsaers · 10-26-2009, 08:13 AM

Ok I will try shorter distance, just maybe followed the Fujinon manaual to strict. A traditional CRT has however lower resolution than a SD monitor right? So is a CRT also enough?

If also connect the two audio outputs of the cam to the two audio inputs of the CRT I should some sound?

Quote:

Originally Posted by balster

Cees,

The distance should be about 2,5 meters then the star won't be that small. Zoom in, focus, zoom out use back focus and zoom back in, focus and out back focus... An SD monitor should work fine.

About composite: It's two signals: black and white image + color. No sound, this is only possible thru an SDI connection.

Cees Mutsaers · 10-26-2009, 09:15 AM

I decreased the distance from 3 meter to about 1.5 meters. I focussed the Siemens starr in tele (also using expand) and you can see all the individual lines till the center of the star. If you go now to wide the lines from the center till about 1/4 to the outside are blurred and you can not get it better by changing the back-focus. To me this means that the resolution of the CRT is not good enough and I need a SD or even a HD monitor right?

Ok connecting the 2 audio outputs (2* tulip) to the CRT helps :-)
However I get the same problem as I already encountered when listening to the sound via the earphone, the sound is not very loud (not in manual and not in auto even without limiter) and what bothers me most is that there is a lot of noise. If I put the cam from -40 to -50 to -60 dB the sound becomes louder but also the noise. Untill now I am not able (and not even close) to get the same sound quality out of the sennheiser MKH416 as samples I heared on the internet. Very dissapointing for a mic of more than 1000 euro !!! By the way is it possible to change the treshold of the limiter, did not find a way in the menu to do this.

edit : the cable (about 15 cm long) between the two XLR connectors is a thin one, can this be the reason for the noise.

Quote:

Originally Posted by Cees Mutsaers

Ok I will try shorter distance, just maybe followed the Fujinon manaual to strict. A traditional CRT has however lower resolution than a SD monitor right? So is a CRT also enough?

If also connect the two audio outputs of the cam to the two audio inputs of the CRT I should some sound?

balster · 10-26-2009, 11:55 AM

Cees,

CRT has nothing to do with SD or HD, both formats are supported by this type of display.

About the backfocus, try doing it the other way around. Zoom out, focus, zoom in, use backfocus and zoom out. You have to do this a couple of times to get proper back focus. Renting an hd monitor won't solve your problem.

Cees Mutsaers · 10-26-2009, 01:00 PM

Yes I know a CRT has nothing to do with SD or HD (I worked in the R&D of displays like CRT, ZEUS, PALC, LCD, Plasma, OLED, polyLED). An old CRT TV (yes i am still old fashion) of more than 15 years old has a lower resolution than the worst SD monitor of today. I tried of coarse the other way around but there is no way that you will be able to see the lines separated at the center of the Siemens star at the wide position (in tele yes very easily). Whatever correction I made in the wide position the centerpart keeps blurry (till about 25% from the center) so the only thing I could do is to make the diameter of the blurry part around the center of the star as small as possible but that can not be done very accurate. A rotation of 1/3 of a milimeter of the back-focus has already a very big impact !! I will hire a Marshall HD monitor for 30 euro (half a day), else I don't know how to solve this.

What about my mic problem, any ideas?

Quote:

Originally Posted by balster

Cees,

CRT has nothing to do with SD or HD, both formats are supported by this type of display.

About the backfocus, try doing it the other way around. Zoom out, focus, zoom in, use backfocus and zoom out. You have to do this a couple of times to get proper back focus. Renting an hd monitor won't solve your problem.

marstaton4 · 10-26-2009, 02:11 PM

Your macro is turned off as well correct? I typically do it while opening my iris as much as possible as it will make the focus that much more critical. And have my chart set up to where i have to zoom in all the way to fill the frame. Thats just me.

Cees Mutsaers · 10-27-2009, 09:16 AM

Yes macro is off and iris completely open. If I am at tele the star is at a distance of the lens that only the the center and half the star fills the complete lcd screen (hmm hope you understand what I mean). I can focus well that you can see the induvidual lines at the center of the star. If I than go to wide the Siemens starr becomes blurred going from the center to about 1/4 to the outside. Changing the back focus makes it only worse to a point where the complete star is blurred. Will see what the tomorrow will bring when I hire the Marshall HD monitor. If this does not help i don't know what to do anymore.

Quote:

Originally Posted by marstaton4

Your macro is turned off as well correct? I typically do it while opening my iris as much as possible as it will make the focus that much more critical. And have my chart set up to where i have to zoom in all the way to fill the frame. Thats just me.

Cees Mutsaers · 10-28-2009, 10:41 AM

Ok today I used a HD monitor with waveform/vectorscope option. Yes Balster you were right it does not make a lot of improvement (although a bit) to make the Siemens star better visible at wide but I put it as best as I could. Real time shooting will have to prove if I did a good job or not.

jmarkham · 10-29-2009, 05:20 PM

I think you can do the BF procedure without an HD monitor if you use
the focus assist button.

jeff

Cees Mutsaers · 10-31-2009, 02:04 PM

Not in wide position, the star is just to small even in "expand" mode and even if you decrease the distance to 1.5 - 2 meters (3 meters is mentioned in the manual of the lens !). Moreover the adjustment goes to rough, a turn of 1/3 of a millimeter gives already a dramatic change of the appearance of the star. So I think put it as good as possible, shoot some stuff and look at the recorded footage in an editing system. If not good do the "try and error" loop of changing the back focus and checking in editing suite.

Quote:

Originally Posted by jmarkham

I think you can do the BF procedure without an HD monitor if you use
the focus assist button.

jeff

jameswmulryan · 11-07-2009, 11:26 AM

Cees:

You should check your back focus on a regular basis. Bring the Fujinon star chart with you on location. I use them every time I shoot with a Sony 900R, do it through the viewfinder, Just ordered a 300 will get it next week, will let you know if I think the viewfinder is sharp enough to check back focus. Not sure if this is the case with the 300 but if the camera is in a hot location, the metal in the mount changes slightly, potentially changing your back focus. This used to happen all the time with the original Sony 900.

10-26-2009, 11:55 AM	#23
balster Member Join Date: Feb 2008 Location: Amsterdam, The Netherlands Posts: 92	Cees, CRT has nothing to do with SD or HD, both formats are supported by this type of display. About the backfocus, try doing it the other way around. Zoom out, focus, zoom in, use backfocus and zoom out. You have to do this a couple of times to get proper back focus. Renting an hd monitor won't solve your problem. __________________ Happy shooting with the Panasonic HPX300 and P+S Technik Mini35c. Check my blog for my insights on this great combo. http://blog.s106.com/

10-26-2009, 02:11 PM	#25
marstaton4 Senior Member Join Date: Nov 2005 Posts: 155	Your macro is turned off as well correct? I typically do it while opening my iris as much as possible as it will make the focus that much more critical. And have my chart set up to where i have to zoom in all the way to fill the frame. Thats just me. __________________ www.masivmultimedia.com

10-28-2009, 10:41 AM	#27
Cees Mutsaers Senior Member Join Date: Aug 2005 Location: The Netherlands Posts: 1,107	Ok today I used a HD monitor with waveform/vectorscope option. Yes Balster you were right it does not make a lot of improvement (although a bit) to make the Siemens star better visible at wide but I put it as best as I could. Real time shooting will have to prove if I did a good job or not. __________________ Artivideo www.artivideo.nl

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10-29-2009, 05:20 PM	#28
jmarkham Senior Member Join Date: Aug 2008 Posts: 158	I think you can do the BF procedure without an HD monitor if you use the focus assist button. jeff

11-07-2009, 11:26 AM	#30
jameswmulryan Member Join Date: Jun 2005 Location: Los Angeles Posts: 93	Cees: You should check your back focus on a regular basis. Bring the Fujinon star chart with you on location. I use them every time I shoot with a Sony 900R, do it through the viewfinder, Just ordered a 300 will get it next week, will let you know if I think the viewfinder is sharp enough to check back focus. Not sure if this is the case with the 300 but if the camera is in a hot location, the metal in the mount changes slightly, potentially changing your back focus. This used to happen all the time with the original Sony 900.