8mm Forum: HTI, Xenon, and Color Temperature

This is topic HTI, Xenon, and Color Temperature in forum 8mm Forum at 8mm Forum.

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Posted by Alan Rik (Member # 73) on April 11, 2016, 12:29 AM:

I wanted to start a new thread about this since a forum member had talked about not wanting an HTI or Xenon due to the color temperature.
When I use to work at a film lab in the early 90's they made all the 16mm prints for Disney. They made standard/regular prints and they also made Xenon prints which were timed differently. I was told the Xenon prints were sent to the Armed Forces to be shown on their ships. I saw Xenon prints of "Pocahontas", "Beauty and the Beast" and a few more. As far as I know this was never done with Super 8mm.
So I was watching "Beauty and the Beast" first on the Beaulieu HTI. Wonderful image with more than enough light. 8 foot image with a 20ft throw.
Then for R2 I put on the Bauer T610. The colors were a little warmer, thats true, but the image lost some of its sizzle and the sound wasn't as good as the Beaulieu! That was a surprise.
I only watched 1/2 the reel than I put it on the GS1200 Xenon. Once again Beautiful Image and the sound was the best of the 3. That could be because it was re-recorded from another GS1200 or it could be the external speakers are Elmos so they are optimized for Elmo projectors.
Even though the color temp may not be right, the extra light, even on an 8ft image is truly stunning. I only use my Bauer to check prints but when I want to watch a film..the HTI or the Xenon is the way to go. And funny enough..as I was rewinding R2 I noticed that I have been watching the films on the "low" lamp setting! I forgot the GS Xenon had the 2 settings because the Beaulieu only has one.
Anyone else here using a Xenon machine? What are your thoughts? I use these 2 machines almost exclusively.

Posted by Miguel Gimenez (Member # 1952) on April 11, 2016, 01:47 AM:

Hey Alan, I am afraid I can't give you the projection feedback, but I can comment a little on this.

As a context information only: we have to take into account that the human eye luminosity perception is higher for green-blues (peak at greens) being the red ones the smallest one. This means that we always perceive cool lights/colors brighter than they are, or if you prefer, brighter than a warmer version of the same image with same actual luminosity (measured) than the cool sample.

Of course this is not against the actual lumens thrown by each lamp/projector. Which normally is higher for HTI than for halogens, talking in general.

This is the reason why screen/TVs/beamers manufacturers always adjusted their equipment by default for cool temperatures (normally even 9300 K !): they appeared cooler (in both senses [Wink]

), and brighter to the potential purchaser.

Try to measure with a calibration probe a TFT screen adjusting temperature levels and, although the difference is there, the perceived brightness is much more. There is a nice article of Charles Poynton in his page, explaining the concepts behind this.

At side of that, I have concluded (please note that these are only my conclusions) that the Xeon/HTI was produced due to two facts mainly: the "need" to project for larger audiences AND to the people change of taste: progressively people were pushed to cooler looking screens, as explained above, and the 'world color tone' around us in our quotidian life has shifted from warmer tones to cooler ones (remember classic car colors, advertisements, illustration, clothes, lighting, etc), so a cooler light was considered more modern and more sales-safe...and warmer is perceived as worn-out, old-fashioned, and a grand-parent thing, at least for most people.

But for me the important point of all this, the key question, is with which light in mind were the prints made.

I have found some information through the years, about the process behind the Derann Disney prints, and -although I have not found final evidence of it yet, as there are several factors involved- it seems that they were done considering a color temperature between 3000 and 4000 k (closer to 3000). If so, then the 'best' way -related to color temperature- to project these copies is in a neutral controlled reflection screen, with a 3300K lamp, and if possible with a relatively neutral decorated room (or slightly shifted toward warm tones).

Alan, you say you worked in a lab (that's very interesting!), and you comment that the Xenon copies were timed differently, but you don't comment anything about the color tint. This seems to confirm me that these copies (not Xenon) were done all with the same tint, and that this tint "seems" the one for standard/halogen projection light. Did you ever had information about the color temperature balancing / timing or which were the origin of the films/masters?

I would love, though if someone could give more details about the film origin, ideally for the Derann Disney editions, to check or correct my information.

[ April 14, 2016, 05:21 AM: Message edited by: Miguel Gimenez ]

Posted by Andrew Woodcock (Member # 3260) on April 11, 2016, 05:25 AM:

Going off Ugo Grassi's video on you tube showing his home cinema and his Xenon GS 1200, I'd have to agree Alan with your description of the sheer brilliance of the image projected with these, even on relatively small screen sizes.

I cannot say that the image lacks anything though on even on my halagon variants so long as it is completely dark when projected.

The Disney prints in particular really stand out on the big screen though due to the vibrant colours and the sheer colour palette used on these. Plus of course, the vast amount of contrast.

I'm guessing my Panasonic projector at 2200 lumens is something similar to what you're experiencing with a xenon, and the picture from this on Blu Ray is stunningly bright and beautiful.

One thing I did notice though, when a collector posted screenshots of another Disney favourite on film using a xenon, was that to my eyes, the screenshots posted appeared a little washed out or bleached almost compared to the screenshots of the same print from my halogen lamp. This could of course just be a difference in print, but for this particular title I'm referring to here, they were all renowned for their consistency and quality for both sharpness, contrast and indeed colour.

Posted by Miguel Gimenez (Member # 1952) on April 11, 2016, 05:51 AM:

Andrew, aside of a lot other possible factors, it could be that the Xenon user had taken his pictures with a camera using AdobeRGB color space, and published directly in the internet. If he did so, then the images will be rendered in the PC screen hopelessly unsaturated, except if you were seeing them in a color profiled and calibrated monitor and color managed browser (as Firefox, if activated), which is not usual.

Posted by Andrew Woodcock (Member # 3260) on April 11, 2016, 06:05 AM:

Wouldn't have thought so in this particular case as there are plenty of other screenshots posted by the same guy that look superb. I'm not saying the ones for this print didn't look superb either, because they did!
Just a little unsaturated in colour and contrast to my eyes that's all.

I've found myself in this same predicament when posting screenshots of a image from the halogen Beaulieu, but with far too close of a throw distance.
The image I've then captured loses detail in the faces etc and appears just too stark altogether in my attempts.

It's only then when I revert back to my usual 24ft throw distance do the images captured, resemble those witnessed by the naked eye when offered up as screenshots.

Posted by Miguel Gimenez (Member # 1952) on April 11, 2016, 06:07 AM:

Then likely it could be another cause, projector related maybe (except if the guy used that day a different camera... Who knows [Big Grin]

, but not likely, I agree)

About the distance for taken the image, the first think could be that the camera was in manual mode (although I strongly doubt this is your case [Smile]

)

Maybe the flickering is somewhat smoothed when the image is camera is farer from the screen.

Posted by Andrew Woodcock (Member # 3260) on April 11, 2016, 06:12 AM:

What I'm saying here Miguel, is there is a point where an image can simply be too bright altogether depending on lamp and throw distance used.

You simply can begin to lose detail on an image with film if it's projected from too near with too bright a lamp.

Posted by Miguel Gimenez (Member # 1952) on April 11, 2016, 06:20 AM:

Ops. Crossed mails.

Yes, it could be. I understood that you talked about the distance from the camera (to take the photo) to the projection screen, not the distance of projection. Now I understand what you meant.

[ April 11, 2016, 09:30 AM: Message edited by: Miguel Gimenez ]

Posted by Maurizio Di Cintio (Member # 144) on April 11, 2016, 04:08 PM:

In my opinion the image on an Elmo Xenon is not just brighter than the halogen version: it's also sharper. I do not know to explain this even to myself: in fact if I had to believe my own eyes, I should logically draw the conclusion that image quality on screen also depends on the type of illumination th film gets. Or perhaps there is something inherent in the Xenon reflector that creates an effect not dissimilar from a light condenser which increases image sharpness with the downside of also increasing grain and blemishs (scratches, lines...): which is not the case with xenon lights. I am baffled but after upgrading to the elmo Xenon, I would never go back to halogen which I now use only to check films.

Posted by Miguel Gimenez (Member # 1952) on April 11, 2016, 04:28 PM:

It could be another reason, but definitely a cooler light provide an increased perceived contrast, which is usually interpreted by the postprocess (ie, brain) as an increased (fake) sharpening effect in the limit zones (so no grain sharpening).

This is a known effect, but it has the downside that it is linked to cooler lights, so if you want it, you have to stand a cool light. These are reasons why all manufacturers pushed cool tints in their devices (and this includes tablets and mobiles, which abuse this effect, btw).

Posted by Brian Fretwell (Member # 4302) on April 12, 2016, 04:32 AM:

I'm not sure of in which order the layers in film emulsions are placed, but I have always thought the red shows less definition - possibly because it is nearer the base and the light to expose it is diffused by higher emulsions that it has to pass through. If so the xenon lamp would give a brighter image from the higher definition pigment layers making the image visually sharper.
I know that when scenes lit only in red light are seen the picture looks less detailed (the prom fire scenes in Carrie for example).

Posted by Gary Crawford (Member # 67) on April 12, 2016, 06:47 AM:

There are so many variables to picture quality. Here's another. At a recent film gathering someone with a GS xenon was showing super 8 prints ....prints which I owned also. The picture was hazy...somewhat bleached...no contrast. Evidently the owner of the machine didn't notice how bad it looked. I mentioned it and he took the lens out...and the rear element was filthy. It was diffusing the light badly. Once he cleaned it, picture was good and sharp with good contrast.
Then think of ALL the variables from the negative of the print, to how the print is timed, the stock for the print, the projection bulb, lens, AND screen, then the camera used to snap the stills..and its settings, lens, lens cleanliness, light in the room and bouncing off the ceiling. Then the program used to make the digital still and send it out....and the monitor we use to view the screenshot. It's a wonder anyone can pinpoint the cause of ANY color balance or sharpness issue.

Posted by Andrew Woodcock (Member # 3260) on April 12, 2016, 08:22 AM:

True Gary, but you can definitely tell a good print from a bad one by using digital screenshots as a guage, when projected properly.

A good print will always stand out in the crowd.

Posted by Alexander Vandeputte (Member # 1803) on April 12, 2016, 02:55 PM:

My experience with xenon both in Super 8 and 16mm: Xenon lamps for projection have a color temperature of approx. 6200 K. This is quite close to daylight and accounts for the perceived 'brillance' of the colors. The image will always seems livelier with xenon as opposed to halogen...
The other thing is sharpness. The increased sharpness is not just 'perception'. The xenon light is a very bright and very tiny dot, much smaller than the filament of any conventional lamp. Hence there is less diffusion of the light beams and this results in a sharper image.

Posted by Andrew Woodcock (Member # 3260) on April 12, 2016, 02:57 PM:

And an unbelievable amount of racket to accompany that brilliance!!

Posted by Paul Browning (Member # 2715) on April 12, 2016, 04:27 PM:

I've called mine the "VULCAN" because of the bloody racket, but like the Vulcan the likes of this machine will never come by us again, the light output is very special and it makes the viewing of any film on it very special. I think alexanders explanation of it is damn near spot on, but its not everyone's cup of tea.

Posted by Miguel Gimenez (Member # 1952) on April 12, 2016, 04:29 PM:

Well, a lot of concepts mixed up here. We are mixing luminosity, with saturation, with illuminant color spectrum, and all of that between perceived and measured.

'Livelier' is a relative term. We can have bluish looking image with tungsten light and warm image with xenon. It all depends on the light (illuminant) considered when balancing colors in the print.

Personally I never saw 'livelier' colors than at dawn or sunset, although luminosity is weaker than at noon, for example.

The same applies to photography, painting, and any other pictorial art.

That's the reason why I said that the 'key question' is 'with which light in mind were the prints made.'

...because, after all, you can compensate an image color to obtain what you want with any type of light spectrum illumination.

IMHO, regarding sharpness, I disagree about the influence of filament size. The light touches the film before the rays could be 'addressed' by the lens (aligned in divergence): halogen or Xenon lamps both throw a mess of light rays regardless of filament size: try to light something with them outside the projector (except if Xenon has some kind of lens inserted in the glass protection).

And even if they were aligned, it -theoretically- should be better for thicker filaments (more paralelism), but in practice there is a 'pollution' of rays that disguises the theoretical advantage of filament thickness, at the scale we are talking. Theoretically we could think a thinner filament has less crossed rays, but even without considering the rebound rays, it has higher dispersion...

I have been working with fresnel spots for years (and yet I do) in a portrait studio. Although a PJ does not use them, the basic principle behind is common. When you have the best defined contrast between shadows and lights is when you adjust the light to lens distance as flood (which is counterintuitive), i.e. when you have less dispersion and less crossed-rays (smaller angle).

Maybe some Xenon/HTI projectors have the bulb farer from the lens (not only the frame) than some halogen ones, depending on the characteristics of the lamp it could -theoretically- be a very slight increase of focus. But the small distances and smaller filament size, together with the scale we are talking about makes this irrelevant in practice, in my opinion.

In that regard it *could* be that if the Xenon lamps had some kind of pre-lens included in the same bulb and the distance to lens is increased considerably versus the halogen one, then that may lead, depending on the 'pre-lens', to a very slight increased sharpness. Although I would judge it very faint, which would mix with the perceived sharpness, which is also there, for sure.

I insist: the human eye contrast perception varies greatly depending of light wavelength and luminosity: as we know we have a non-linear brightness perception, when we project with higher lumens, the black is not shifted (or not too much) and highlights are pushed quite a lot vs an halogen one. This expand the efective dynamic range of the image and necessarily produces higher perceived contrast (eye's dynamic range is still wider), and, btw, perceived sharpness.

On the other hand I think that the point Brian has commented may have some influence too. To check, in any case.

So I think that, as Gary points out, there are a lot of factors that can influence it, perception, distance to film/lens, quality of lamp (more than size), etc.

Of course it could be that I may be completely wrong too [Big Grin]

Posted by Andrew Woodcock (Member # 3260) on April 12, 2016, 04:38 PM:

It certainly would never ever, not for one moment ever be for me Paul, I spend all my life making machines run as they should without excess noise!
There is no way I'm coming home to a Jumbo Jet!!

Not for one millisecond in my lifetime!!

I'm happy with my LCD solution of 22dba @ 2200 Ansi Lumens, and equally happy how I've engineered the noise levels to negligible on the Beaulieu for the brightest halagon lamp that ever got installed!!

Unnoticeable in the screen room without a dividing wall!!

A xenon would never be my choice outside of a separate screening room to lock that baby well and truly into!!!

Even then I'd need padded walls to entertain one!

Not for me, and I seriously doubt it ever would be!!!

Posted by Paul Browning (Member # 2715) on April 12, 2016, 05:07 PM:

I'll give you lift home in my Vulcan Andrew, I can assure you the noise won't bother you. I think your over thinking this post Miguel, I didn't expect such scientific explanation of a projected film, I like your passion to explain it though, but I'm not sure I understand everything you say, its certainly an education though.

Posted by Andrew Woodcock (Member # 3260) on April 12, 2016, 05:09 PM:

Paul you're a top guy in this hobby ... but seriously....
Vulcan??... not for my filmshows mate!
As for Miguel and his nervous treads.... indeed!

No man would ever have walked on the moon with this amount of doubt, speculation and suspicion! [Big Grin]

It comes to a point at sometime where you simply have speculate to accumulate!

Posted by Miguel Gimenez (Member # 1952) on April 12, 2016, 05:22 PM:

Ah, sure Andrew. That's true. It is simply a subject that passionates me.

Sure I go too in-depth [Smile]

I enjoy throwing ideas and theories on the table, but I really don't mind if I am more or less wrong: I just like to exchange about some subjects. Sorry if posts seem nervous, I am not.

But you have reason that to decide which projector to purchase I doubt quite a lot ! [Roll Eyes]

I have some pressure here and not a second chance in quite some time, though...

Posted by Andrew Woodcock (Member # 3260) on April 12, 2016, 05:28 PM:

Wait your time Miguel. Every good book deserves a good cover!
Never forget that Miguel l!!

Posted by Paul Browning (Member # 2715) on April 12, 2016, 05:55 PM:

Actually thinking about it Andrew, the Vulcans is quieter at close quarters.........

Posted by Andrew Woodcock (Member # 3260) on April 12, 2016, 06:00 PM:

Really , really really ??? !!!

Posted by Alan Rik (Member # 73) on April 12, 2016, 09:17 PM:

These are great replies! Yes I just finished watching R3 of "Beauty and the Beast" and I can say that the picture quality to my eyes with Xenon or HTI is truly spectacular. I sit as far away from the Jet sound (GS1200 Xenon) and as close to the screen as possible and after a while the Jet sound goes away. Well in my mind it does! I can say that I love, love, love that projector!

Posted by Andrew Woodcock (Member # 3260) on April 13, 2016, 06:38 AM:

It is a lovely machine which produces a stunning image Alan, no doubting that, but it would have to live in a 2ft padded cell with a 2 inch hole cut out of it for me to ever desire one personally speaking.

Posted by Alan Rik (Member # 73) on April 13, 2016, 08:15 AM:

My hearing is probably going so that's why I can tolerate it now!! [Smile]

Posted by Andrew Woodcock (Member # 3260) on April 13, 2016, 08:40 AM:

No bloody wonder Alan, going off Paul's likening of it, to the Vulcan! [Big Grin]

Posted by Paul Browning (Member # 2715) on April 13, 2016, 11:42 AM:

I think you could get the noise down a lot by changing the blade shape to that of a slight vortex like a jet turbine.If you compare the noise level of a dyson vacuum cleaner and the henry vacuum cleaner, the henry is very quiet compared to the dyson, but both are probably about the same suction power. I know which one I would use every time. So how do they get it so quiet, although they do different jobs, it can be done. The laptop uses a small fan in the base to keep it cool, I knows its there but I've never really heard it start up, these are designed to cut through the air without to much noise, curved blades maybe the way to go.

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