[mechman]

My projector (Mitsubishi HC3000) is a 1000 lumen projector which I've seen reputable reports that when 'video optimized' it's more in the 400 lumen range. I have 2000 hours on the current bulb with a new one on the way.

Would this be considered a 'lower lumen' projector? In the past I've seen less knowledgeable folks discard Black Widow as an option for a screen because their projector was 'lower lumen'. And I know that in the past less knowledgeable folks said that "you really need a 'light cannon' for Black Widow".

What's the threshold for 'lower lumen'? What's the threshold for 'light cannon'?

mech

 

[mechman]

Found the lumen rating:

Our measurements on the Mitsubishi in it's best mode, which also means low power, and Iris stopped down for best contrast and black levels, measured 465 lumens.

http://www.projectorreviews.com/mitsubishi/hc3000u/performance.php

So what do you think it would be at with 2000 hours on the bulb?

mech

 

[mechman]

Can't you use your spot meter to find how many lumens your PJ is really shooting? Just shoot a 100% white field and take a reading.

Yep I could and I think I will get a before and after when the new bulb arrives. And maybe a before and after calibration on the new bulb.

I don't think I've ever seen a definition of what makes a "light cannon" or a "low lumen" PJ.:scratchhead:

I know in testing I had a very watchable image with my BW screens at a measured 12 foot lamberts brightness. I don't think most would call that screen as being hit by a "light cannon".

And I seriously doubt that I'm at 12 fL. I'd guess 9. And my image is very watchable, even with the high hours on the bulb. I just had 5 people over on Monday night and they all sat with their mouths agape. One kept insisting that I had to set him up with a pj and screen.

If memory serves me, light canon was anything over 2500 lumens. But then again it depends on whose definition. Low lumen was any projector that needed total light control while viewing.

And then it depends on who's doing the lumen measurement too I suppose. I know there's a couple folks from LumenLab using Black Widow. And I'd call those 'lower lumen' I guess.

mech

 

[mechman]

And lumens would be equal to foot candle times square feet, right?

If that's correct I'm currently at 136 lumens...

That seems awfully low!

100% white field measured 4.6 foot candles. I measured as low as 3.9 and as high as 5.0. I took the average as that was the measurement at the center of the rectangle.

100" screen = 29.6 square feet

Someone tell me I'm measuring/converting this wrong!

mech

 

[mechman]

4.6 fL. is a very dim screen!

Was this a reflective measurement of the screen or a incident measurement of the PJ beam with the meter at the screen (I know your meter can do both)?

Lumen/sq ft, foot candle and foot lambert are all the same. Lux multiplied by 0.0929 = foot candles. Conversely, foot candles multiplied by 10.7643 = Lux. Lux = lumen/square meter.

That would be a dim bulb I guess! No reflective measurement, just an incident reading. I didn't have a ton of time before I left for work so I'm not 100% sure if I had the meter setup correctly. I'm going to double check it tonight. It can take incident readings a number of different ways and I was in a hurry.

Then again, my bulb does have 2000 hours on it. :dontknow:

So my calculation was correct in 4.6 X 29.6 = 136 lumens?

mech

 

[mechman]

Thanks Don! I'll putz with the meter some more tonight before bed time and report back tomorrow.

What's really intriguing to me is that if those numbers were true, everything said elsewhere in the past (and more than likely currently as well) is wrong.

mech

 

[mechman]

Ok I quickly redid it using the projectors white test pattern. 11 foot candles.

11 X 29.6 = 325.6 lumens

That's a bit more realistic. So.... am I a 'lower lumen' pj guy?

mech

 

[mechman]

Ahhh, there's that 'quickly' again. :nono: Haste makes waste, I keep proving this over and over again myself. :laugh:

All I need is 2 or 3 extra hours in a day! :bigsmile:

Did you redo the test with both a 100% white field image and the PJ's test pattern, or just the PJ pattern alone? I would be very interested to know if they differ.

The advantage of using a 100% white field image from a known source, such as the 'Digital Video Essentials' DVD, is that it is an industry standard; I'm not sure the patterns built into PJ's are.

I revisited it again today. With the 100 IRE I was getting 12 at the brightest and 9 as the lowest. It gave the same reading as the pj lamp pattern at what I consider the brightest location from my pj - top center. I would guess if I were to check it tonight it would be a tad bit lower. I've got a tad bit of daylight coming in right now.

At 325 lumens I would say that is fairly 'low lumen'. This of course, is with a bulb that has almost reached end-of-life. I would suspect you will easily double that figure with the new bulb (or I guess I should say 'lamp'), and perhaps get even more brightness.

Now the big question: does your screen image look dim?

Most definitely not. It doesn't appear to be dim at all. However, I probably have gotten used to it if it has. :dontknow: I'm still amazed at the image. :T The only reason I ordered a new bulb is because I figured it was time to put the current one on the shelf as the backup and get a new one. After thinking more about the time on the bulb, I remembered that this is not the original bulb. The original was replaced by Mitsubishi two years ago. And I'm uncertain as to whether or not the bulb timer rests itself or not. :dontknow: :scratch: The new one arrives Wednesday. We'll know more then.

mech

 

[mechman]

In another 5 days or so I should be able to start doing more work. Since I already started this I'm going to finish it before moving on. Thinking about it though, the new bulb shouldn't change much. I mean it will initially I'd think. But after calibrating it should fall pretty much in line with what I have now. :dunno:

mech

 

[mechman]

I installed the new bulb last night and top center of my screen reads at 15 foot candles. There was 1992 hours on the old bulb.

And keep in mind that 15 is not video optimized yet. Time to calibrate... again. :gah:

I wonder how many people fail to re-calibrate after a bulb change or after X number of hours?

mech