Red problem !

Swen Goebbels · March 20th, 2008, 03:24 AM

Quote:

Originally Posted by Matt Daviss

there was a sage engineer at the BBC who patiently demonstrated why the BBC didn't think the PD150 was Broadcast Quality - he used the remote (an Infra Red remote) and pointed it through the lens.
You could see the IR LED in the viewfinder.

I tested this with the Ex1 and the IR remote controll of my TV. With my eyes I can't see the light. On the Ex1 LCD I see a RED light (not very bright).

Now I tried the same with my PD170. And there the light was GREEN (and much brighter. You could really "dazzle" the camcorder which was not nice for the picture-EX1 doesn't have this "Problem").

So my question: Why is the same light shown RED on Ex1 and GREEN on PD-170. Does the PD170 has an inside filter or similar and the Ex1 not?

Sure the PD170 is CCD and not a CMOS. So I also tested to make a picture of the light with my Eos5d: The light was RED (same as Ex1).
However, my Eos don't have that color problem and allways shows balck as black.

Michael Maier · March 20th, 2008, 04:30 AM

Quote:

Originally Posted by Greg Voevodsky

Also, NOTE - tiffen's hot glass reflects and thus has to be the out filter, whereas the 486 obsorbs IR and UV and can be screwed on and be the inner filter - ie - replace your lense protection filter.

This is nice because that way you can have the filter on the camera lens when using 35mm adapters and not on the front lens, which would mean having to screw it on and off every time you changed lens. But is absorption as effective as reflection? Seems to me a filter could reflect more IR than it could absorb. Then again I have no idea. When are you getting yours?

Sean Donnelly · March 20th, 2008, 05:46 AM

I'm going to try and find one to test with today. I believe the reflective filters are more effective, however I hope the 486 filter is enough to counteract this problem, since I really don't like the idea of having to put it on the outside of a 35 adapter. Also I'm not sure about the hot mirrors, but the 486 has no required stop compensation.

-Sean

Steven Thomas · March 20th, 2008, 06:24 AM

Quote:

Originally Posted by Greg Voevodsky

I'll let you know, I just ordered the 'thin' version that is in stock.

http://www.bhphotovideo.com/c/produc...tal_UV_IR.html

Greg, let us know if this filter fits well and does not obstuct the hood.
Also, let us know if you see an improvement.

Michael Maier · March 20th, 2008, 08:43 AM

Just checked the B+W 486 description again on BH and it actually reflects the IR instead of absorb it. It seems to be the same as the Tiffen Hot Mirror. With a little more research I found their 489 filter which seems to be the one that absorbs rather than reflect the IR. So the B+W 489 seems to be the ticket. I'm just wondering if using NDs and Polarizers in front of it will bring the problem back.

Zenes Petrusin · March 20th, 2008, 09:56 AM

Yes Michael, but 489 has Filter Factor 1.2 and 486 factor 1 . 489 maybe change color more, becouse has some colour smell, so not be realy transparent. If you want use polarizer you can attache 486 on polarizer. But i dont know if for this realy help IR cut-off/hot mirror filter, this is for me only theory. Maybe sony do some conclusion about this, is for me this IR contamination if really is, problem.

Michael Maier · March 20th, 2008, 10:06 AM

Well, the 486 would need to be used in front of the other filters because it needs to reflect the IR. The 489 can be used under other filters because it absorbs the IR. This seems more useful if you are using a 35mm adapter for example. So the 489 can go on the camera lens instead of on the Nikon or PL lens in front. Also, if you use a matte box the 486 screw in is no good.

Greg Voevodsky · March 20th, 2008, 12:53 PM

Well, "interference" between layers on the 486 'sounds' like its not reflecting it like a mirror either. Here's what is says:

"This B&W 77mm 486 Digital UV/IR Blocking Slim Glass Filter has a completely colorless glass carrier coated with a number of extremely thin, partially reflecting layers with precisely computed thicknesses, similar to MC coating (multi-coating).

The B&W Filter 486 does not block by means of absorption, but by interference of the unwanted UV and IR radiation that is repeatedly reflected between these layers affecting the wavelengths on both sides of the visible spectrum with a steep cut-off.

B&W slim filters are for wide-angle lenses and are 3mm thick. They do not have a front thread.

Key Features

• Used mainly on digital and video cameras with CCD sensors without an integrated IR protection filter, because the IR sensitivity of the CCD sensor would otherwise cause color changes and unsharpness.
• That unsharpness results from the chromatic aberration of the lenses that are only corrected for visible light.
• In the visible range, the transmission curve is very high and straight."

---
If it does not work, I will have to get tiffen Hot Glass 4x4 and place it in front of my mattebox - since I use polas and grads all the time shooting high contrast sunsets.

QUESTION?!

If RED light like a sunset gives off more IR, and creates more distortion...
Then, wouldn't a BLUER setting, or cooling filter reduce IR - and then in post one could warm it up with less IR???

PS - I get my filter tomorrow. I will try to shoot some tests this weekend and post ASAP.

Steven Thomas · March 20th, 2008, 10:18 PM

Thanks Greg. I'm looking forward to hearing and possibly viewing your findings.

David Hadden · March 20th, 2008, 10:26 PM

Quote:

Originally Posted by Greg Voevodsky

QUESTION?!

If RED light like a sunset gives off more IR, and creates more distortion...
Then, wouldn't a BLUER setting, or cooling filter reduce IR - and then in post one could warm it up with less IR???

PS - I get my filter tomorrow. I will try to shoot some tests this weekend and post ASAP.

That might "fix" it but I'm pretty sure that would make you have other problems such as areas that aren't suffering from this shift because there is adequate light reflecting off of some of the subject matter in your shot. So even though those few spots that are giving you problems, are corrected, I think you'd see other problems creep in to areas that are being represented accurately.

Dave

Graeme Fullick · March 21st, 2008, 02:44 PM

Guys,

I am a Chemist by trade and work with spectroscopic equipment all the time. We use interference filters quite often. Essentially it works by setting up the filter so the light that you do not want transmitted is used to cancel itself out. Without going into the physics of it the fancy optics generate interference patterns in the IR (and in this case UV) light waves that are 180 degrees out of phase with the incoming radiation effectively blocking its transmittance into the lens. The fact that it is a sharp cut filter means that it will not interfere with the visible wavelengths - therefore you should see not interference at all in the visible range if the filter is well built - and with a B&W that is likely. The absorptive filters use chemical compounds embedded in the glass that absorb specific wavelengths of IR radiation. Of course this means that they may get a bit warm if there is excessive IR (the energy has to go somewhere) - but this is not a likely scenario with a camera filter where we are talking about small amounts.

Bottom line is that it is likely that the filter will work well - but we will see shortly. The proof is in the testing!

Paul Kendal · March 21st, 2008, 04:14 PM

Just got my filter today from B&H. So far, it appears to work great at getting rid of the RED cast when filming certain black fabrics in lower light situations.

I will post some before and after shots when I get a chance.

Paul

Sean Donnelly · March 21st, 2008, 04:24 PM

That's great news Paul. Just for fun I put a piece of Rosco heat shield in front of the lens today, and it did make a small difference. Certainly not optically clear, but it did help to prove that it is an IR problem.

-Sean

Swen Goebbels · March 21st, 2008, 05:41 PM

Paul that are really great news! For me this was the main problem of my Ex1.

What do you guys think? Have we all to buy this filter for 200$ or will Sony offer us an "upgrade"? Why did Sony not just build such a filter directly into the camcorder... for them this will maybe make the cam 40$ more expensive, but that's much better than angry customers and wrong colors.

Here in Germany some TV stations bought also the Ex1. I would bet they will get an "upgrade" from Sony!

Graeme Fullick · March 22nd, 2008, 04:45 AM

Great news Paul, I expected that it would work well.

On another note - do you ever intercut your HV20 footage with the EX1? Just wondering as I also have both of these, and haven't done it just yet. If you have I was wondering how the HV20 held up. I have been to busy to try it, but have been thinking they might look OK together in good light

March 21st, 2008, 02:44 PM	#56
Graeme Fullick Major Player Join Date: Mar 2005 Location: Newcastle, Australia Posts: 337	Guys, I am a Chemist by trade and work with spectroscopic equipment all the time. We use interference filters quite often. Essentially it works by setting up the filter so the light that you do not want transmitted is used to cancel itself out. Without going into the physics of it the fancy optics generate interference patterns in the IR (and in this case UV) light waves that are 180 degrees out of phase with the incoming radiation effectively blocking its transmittance into the lens. The fact that it is a sharp cut filter means that it will not interfere with the visible wavelengths - therefore you should see not interference at all in the visible range if the filter is well built - and with a B&W that is likely. The absorptive filters use chemical compounds embedded in the glass that absorb specific wavelengths of IR radiation. Of course this means that they may get a bit warm if there is excessive IR (the energy has to go somewhere) - but this is not a likely scenario with a camera filter where we are talking about small amounts. Bottom line is that it is likely that the filter will work well - but we will see shortly. The proof is in the testing! __________________ Graeme

March 21st, 2008, 04:14 PM	#57
Paul Kendal Regular Crew Join Date: Nov 2006 Location: Asheville, North Carolina Posts: 89	IR 486 Filter Works! Just got my filter today from B&H. So far, it appears to work great at getting rid of the RED cast when filming certain black fabrics in lower light situations. I will post some before and after shots when I get a chance. Paul __________________ Canon HV20 \| Sony FX1 \| Canon XH-A1 \| Sony XDCam EX1 \| 8 Core Mac with FCP and lots of Hard Drives

March 22nd, 2008, 04:45 AM	#60
Graeme Fullick Major Player Join Date: Mar 2005 Location: Newcastle, Australia Posts: 337	Great news Paul, I expected that it would work well. On another note - do you ever intercut your HV20 footage with the EX1? Just wondering as I also have both of these, and haven't done it just yet. If you have I was wondering how the HV20 held up. I have been to busy to try it, but have been thinking they might look OK together in good light __________________ Graeme

March 20th, 2008, 05:46 AM	#48
Sean Donnelly Regular Crew Join Date: Jan 2008 Location: New York, NY Posts: 188	I'm going to try and find one to test with today. I believe the reflective filters are more effective, however I hope the 486 filter is enough to counteract this problem, since I really don't like the idea of having to put it on the outside of a 35 adapter. Also I'm not sure about the hot mirrors, but the 486 has no required stop compensation. -Sean

March 20th, 2008, 08:43 AM	#50
Michael Maier Trustee Join Date: Apr 2005 Posts: 1,269	Just checked the B+W 486 description again on BH and it actually reflects the IR instead of absorb it. It seems to be the same as the Tiffen Hot Mirror. With a little more research I found their 489 filter which seems to be the one that absorbs rather than reflect the IR. So the B+W 489 seems to be the ticket. I'm just wondering if using NDs and Polarizers in front of it will bring the problem back.

March 20th, 2008, 09:56 AM	#51
Zenes Petrusin Regular Crew Join Date: Sep 2007 Location: Czech Republic Posts: 52	Yes Michael, but 489 has Filter Factor 1.2 and 486 factor 1 . 489 maybe change color more, becouse has some colour smell, so not be realy transparent. If you want use polarizer you can attache 486 on polarizer. But i dont know if for this realy help IR cut-off/hot mirror filter, this is for me only theory. Maybe sony do some conclusion about this, is for me this IR contamination if really is, problem.

March 20th, 2008, 10:06 AM	#52
Michael Maier Trustee Join Date: Apr 2005 Posts: 1,269	Well, the 486 would need to be used in front of the other filters because it needs to reflect the IR. The 489 can be used under other filters because it absorbs the IR. This seems more useful if you are using a 35mm adapter for example. So the 489 can go on the camera lens instead of on the Nikon or PL lens in front. Also, if you use a matte box the 486 screw in is no good.

March 20th, 2008, 12:53 PM	#53
Greg Voevodsky Regular Crew Join Date: Sep 2006 Location: Portola Valley Posts: 105	Well, "interference" between layers on the 486 'sounds' like its not reflecting it like a mirror either. Here's what is says: "This B&W 77mm 486 Digital UV/IR Blocking Slim Glass Filter has a completely colorless glass carrier coated with a number of extremely thin, partially reflecting layers with precisely computed thicknesses, similar to MC coating (multi-coating). The B&W Filter 486 does not block by means of absorption, but by interference of the unwanted UV and IR radiation that is repeatedly reflected between these layers affecting the wavelengths on both sides of the visible spectrum with a steep cut-off. B&W slim filters are for wide-angle lenses and are 3mm thick. They do not have a front thread. Key Features • Used mainly on digital and video cameras with CCD sensors without an integrated IR protection filter, because the IR sensitivity of the CCD sensor would otherwise cause color changes and unsharpness. • That unsharpness results from the chromatic aberration of the lenses that are only corrected for visible light. • In the visible range, the transmission curve is very high and straight." --- If it does not work, I will have to get tiffen Hot Glass 4x4 and place it in front of my mattebox - since I use polas and grads all the time shooting high contrast sunsets. QUESTION?! If RED light like a sunset gives off more IR, and creates more distortion... Then, wouldn't a BLUER setting, or cooling filter reduce IR - and then in post one could warm it up with less IR??? PS - I get my filter tomorrow. I will try to shoot some tests this weekend and post ASAP.

March 20th, 2008, 10:18 PM	#54
Steven Thomas Trustee Join Date: Sep 2005 Location: Gilbert, AZ Posts: 1,896	Thanks Greg. I'm looking forward to hearing and possibly viewing your findings.

March 21st, 2008, 04:24 PM	#58
Sean Donnelly Regular Crew Join Date: Jan 2008 Location: New York, NY Posts: 188	That's great news Paul. Just for fun I put a piece of Rosco heat shield in front of the lens today, and it did make a small difference. Certainly not optically clear, but it did help to prove that it is an IR problem. -Sean

March 21st, 2008, 05:41 PM	#59
Swen Goebbels Regular Crew Join Date: Dec 2007 Location: Aachen, Germany and Las Vegas NV Posts: 107	Paul that are really great news! For me this was the main problem of my Ex1. What do you guys think? Have we all to buy this filter for 200$ or will Sony offer us an "upgrade"? Why did Sony not just build such a filter directly into the camcorder... for them this will maybe make the cam 40$ more expensive, but that's much better than angry customers and wrong colors. Here in Germany some TV stations bought also the Ex1. I would bet they will get an "upgrade" from Sony!