Yes, I do... but,
the tuning standard is based on the ILDA test pattern; which comes in the form of an ILDA file.
Not trying to labor the issue. Just commenting in general about some of the connections you made in your previous post.
James.
Yes, I do... but,
the tuning standard is based on the ILDA test pattern; which comes in the form of an ILDA file.
Not trying to labor the issue. Just commenting in general about some of the connections you made in your previous post.
James.
Looks like he did an edit!
http://photonlexicon.com/forums/showthread.php?t=5740
If you still have questions about the ILDA format and its connection to the test pattern, please ask them here! That would be a good extension to the conversation!
Thanks!
James.
Last edited by James Lehman; 11-11-2008 at 09:47.
For *most* artwork, you can do this and get away with it. However, there are some ILDA files that will not display correctly when scanned at a faster scan rate. This is because the artist that created the files used the "pulled points" technique to make some of the elements, and scanning too fast will invalidate the technique.
Apart from those frames that contain pulled points, you should be fine. Furthermore, if you actually re-tune for 40K, the effect will be minimized, even on those frames with pulled points.Why would I not want to tune my galvos at 40K with the ILDA test pattern if they can handle that speed without overheating or erratic behavior?
The problem (as Steve already mentioned) lies in the case where you create your own original artwork. It might look good on your system when running at 40K, but when someone else tries to display it at 30K, it might look like junk because it will flicker more. So if you're going to draw your own frames, you really should test them to be sure they'll display properly at the 30K standard.
Apart from those two cases, there is one other advantage to running your scanners at 30K: You'll get a wider scan angle. Personally, I don't think the flicker is all that big of a deal, so I run my scanners at 30K and enjoy the wide scan angle... But you might choose to do the opposite.
Adam
Hi Adam,
Great message! My comments are below.
I wouldn't quite say "not between". 30K is a standard and 60K is what the Technical Committee would recommend people tune to as "the next standard" if you are not going to use 30K. But more on the role of standards below.
It is technically possible to run faster, this is not a problem. The question is -- are you doing yourself any favors or not? Well, the answer to this depends on several factors.
There are a few possibilities here. I will discuss each below:
* You have a 30K show, you have your sample-rate set to 30K, but you have 40K scanners.
* You have a 30K show, you have your sample-rate set to 40K, and you have 40K scanners.
In the first scenario, you simply have so-called "faster scanners". (I say so-called because there is so much BS equipment floating around, sometimes you never know...) In this scenario everything will work fine -- the images might look "hotter", like somehow have visibly brighter corner points. Most of the time this is not objctionable and some people even like this kind of look.
In the second scenario, you increase the sample rate coming from the software, so this can help to reduce flicker. So theoretically you will get the same show, only with less flicker.
The second scenario might sound tempting, but there are some potential problems -- mostly scanner related. Sometimes I hate Physics... especially when it says there is a fourth-power law (which is square-law multiplied by square-law) related to the amount of heat that the scanner must dissipate when compared to the scan-rate. So by scanning at 40K instead of 30K, you are asking your scanners to dissipate (40/30)^4 = 3.16 times as much heat! The scanners might be able to do this -- or maybe not. They might be able to do it for a short time (meaning minutes, or days, or weeks) but maybe not forever. The amount of time depends on several factors, including exactly who made your scanners. If Cambridge made them, AND if you have a good mounting of the scanner block to a good "cool" plate, then there will never be any problem. But if some other company made them, then it is a roll of the dice.
The "fourth power law" assumes that the scan angle would be the same. Many years ago Lightspeed operated shows above 40K with Cambridge 6800s. But they did active cooling of the scanner mount AND scanned shows at a smaller angle. Their theaters were configured for a long throw, so this was possible.
The 6800 (and derivative) scanners were made for 30K. Can they scan faster? Yes. But due to the cube-law mentioned above, for most people this is generally not a good idea. Also, sometimes when you re-tune your scanners "downward", it gives better performance. I have demonstrated this many times at various PL meetings, and also if you take a look at my Scanergy scanner report (in another thread) you will see that I was able to improve overall performance from tuning the scanners to 30K (from 40K).
Anyway, I would say that the best argument for tuning your scanners to 30K and then running shows (that are designed to run at 30K) at 30K is because that's what the standard is. You are guaranteed to get "standard performance" if you do this. You can do things outside the standard, but... there are risks involved. The success of this will depend on your own projection scenario (throw distance, brand of equipment, cooling techniques, etc.)
As a testament to running at the standard, at Pangolin we tune our scanners to only 30K or 60K and we REALLY know what the heck we are doing with scanners (two award-winning servos, blah blah blah...).
Bill
Last edited by Pangolin; 11-13-2008 at 05:51.
Hey Adam!
That makes sense. If your dealing with pulled points and they are part of the show, that would create a large difference in the shows output. Thanks for pointing that out to me.
Yes, I agree, sticking to 30k for my scanners and my software speed since I plan on sharing many more shows. That reason alone is good enough for me.
As for the filcker, I see it, and personally think that running 40K makes a great difference. That's my eyes though. When I can afford it, I'm going for 60K capable scanners.
I absolutely agree that scan angle is twice as important as speed however.
Thanks a lot for your input!
Hey Bill!
WOW Great info!
I agree with the analysis on the scanners. My question was more of a "what if" than "I am going to". I'm currently running LaserWorld LW-50K's. While they do seem like "very good" scanners in my personal, limited experiance, They are NOT capable of running 50K in my opinion. While the galvos stay cool, the amps get pretty hot, 140 deg.F+ at that speed. I do hovever feel they would run okay at 35-40K @ 8-10deg. However, this may limit lifespan.
No question that these scanners are 6800 knock-offs and are most likely designed to run no more than 30K.
"Sometimes I hate Physics..."
Yeah, me too. Especially when it comes to the math part.
Yes, the load put on the scanners does rase exponentally in the 30-40K speed jump and is a serious factor for my particular scanners so I completely agree with the info you provided.
I guess the core of my question, which I did not explain correctly, is....
If you have shows programmed in 30K and you have 60K capable scanners, could you then run the 30K shows at 60K at the same angle and they'd turn out graphically identical (take this term lightly, I know nothing is perfect.) and the flicker would basically be gone?
I may be stating something wrong in my question, I just want to get the basics about how their is a 30K and a 60K standard and if it works in the senario I described.
Either way, I'm learning a lot and really appreciate everyone's input.
Thanks for your time!
Adam
While we're sort of on the topic, and for future reference, what model 60k scanners are recommended? Flicker is a little peeve of mine and I definitely plan on upgrading to more capable scanners someday.
I remember before I got my DT40Pros, I checked with Cambridge about a pair of 60k-capable scanners/amps and they quoted me $1995 for a 6215HB scan set, but I don't think those are really great for wide angle if I remember correctly.
Someone also mentioned EyeMagic 4000s as being good scanners recently.
-Jonathan
There are only one set of scanners on earth, currently capable of scanning at 60K (and giving you good images), and that is the Cambridge 6215 when coupled with the "High Power" Amps. These are capable of scanning imagery at roughly the same angle, and at 60K. So yes, when using those scanners, you can truly get double the scan speed from the same imagery, and the imagery really looks the same.
As far as I know this is an expensive combination. I don't know for sure (since we buy a lot of Cambridge scanners, and don't pay the quantity-1 price) but I think this combination is around $2400.
But if you are a top laser show producer, like Doug McCullough or Hugo Bunk, the price is a secondary concern to the quality of the shows you can produce.
Doug and Hugo have been using these scanners for four or more years. They are pioneers when it comes to these scanners. There have not been all that many other laser show producers using them -- mostly because they are comfortable with Cambridge 6800s.
Also, the 6215 with high power amps will consume up to 120 watts of electricity, which is four times the electricity of a 6800 system.
Bill