I am right at the long end of the T1 or the short end of the T2 and the projector is not mounted, but could probably be scooched one way or the other if there's an advantage. Is there any advantage to going with with a T1 over a T2, T2 over a T1? Being at the long end of a short throw lens versus being at the short end of a medium throw lens?

The general consensus seems to be to go with the T2, when possible.

Having said that, I've seen and worked with both (no A/B) and frankly I can see no difference. Other opinions differ.

Jim

I use the T1 with absolutely no problems

So Rob does this mean you have given up on JVC and are going with the Sim? Wise choice if so

OB -- You know, my heart was stolen from the first time I saw the C3X1080 when you so graciously invited my wife and I to your house. I tried to find something else with which I could be happy at a lower price, but in the end, I kept coming back to the C3X1080 and it didn't hurt that Jason and AVS worked with me to help make the decision a no-brainer.

Congratulations on a great decision. I'm sure AVS will look after you well.

The T2 is theoretically better for 2 reasons.

1. It is apparently a better spec glass
2. At a longer throw your beam is narrower and would tend to pass through the lens more towards the center. This makes for a cleaner image with less CA etc.

Make sure the zoom is checked at the throw you will be using.

I echo Jims sentiment. In practice, the T1 units I've seen have been fine.

I'll be back home after the weekend and will put up the screen shots you wanted. Including 2 super close-up MC/CA shots, taken from around 2 inches from the screen.


OB........Got your message but Im on the frikkin ass phone ATM. Speak soon

Thanks -- I found this in the archives, see what you think....

Sim2 in their spec sheet states that the throw ratio for this projector, T2 lens, is 1.7 to 2.6 (times 16:9 screen width).

Mark Haflich (Soundworks in Maryland) has been helping me with some technical details in planning my video renovation for the new Sim2 C3X 1080 projector. [I've known Mark since 2000, when at the very first AVS CES Party at the Las Vegas Hilton buffet, informal, that I organized, giving out 12 grand in door prizes, with Mark being the grand prize winner, a $5K Stewart screen. HA!).

Mark has been doing some checking with Sim2 to ensure that his customers
get correct information, because it ain't no fun when you have picture problems and find that the given throw ratio doesn't seem to work right.
Mark talked to a technician at Sim2 very recently and got him to measure throw ratio with both the T1 and T2 lens. I'm concerned about the T2 lens. Turns out the throw ratio ain't 1.7 to 2.6, but 1.75 to 2.4 and also you are not to use the first six inches at each end of the throw ratio.

I've been advised that I am best to mount as close as possible to the end of the throw ratio - 110 (16:9 screen width) times 2.4 less 6 inches = 21.5 feet.

I am glad to get this cleared up for otherwise I would have gone a bit further back.

Based on this, it would seem like I should use the T1 and move the projector's lens 6" closer than max capability to the screen. That would mean 14' 8" from the screen, which would place the projector on the ceiling about two feet behind the main viewing row and between the main viewing row and the rear seating, which is closer to the ceiling.

Any problems with noise or any other reason this would be objectionable?

If you read my post above, it says to have the zoom checked at your specific throw. Tell him what your ratio is and he'll check for any issues.

I'm pretty sure you'll be taken care of.;)

Excellent advice -- thanks!

"I've been advised that I am best to mount as close as possible to the end of the throw ratio..."

Unless he is saying it best to to mount as close as possible to [EITHER] end of the throw ratio. In which case, if I take 108" x 1.75 and add six inches (T2 lens), that would mean 16' 4" from screen, which would probably be better.

Steve? Mark?

I mounted mine 6" in front of the rear throw distance

There's a thread here at the 20k forum, earlier this year, which discusses Scott Horton (GetGray on AVS, mfg of Cineslide) testing my C3X 1080 and ISCOIII and recommending a throw ratio T2 lens for me of 2.03 if I recall correctly, which I did. Scott found the T2 lens to have linear light loss using the zoom.

Another thought. I am assuming you are talking about a 16:9 screen. If you were to instead consider a CIH setup - perhaps a little shorter and wider - your throw ratio goes up. Might put you more comfortably in the T2 range if you are bumping up to the short end of the throw range.

Avoid the ends of the throw by all means. Have seen 6 different C3X's. Also thought T2 was the only way to go until I saw OB's setup on T1 and have to say it had amazing depth and looked terrific even though it tapped the entire glass of the ISCO lens. Would not hesitate to go with the T1 if that's the only thing that works for you and you can't do a T2.

OB's set-up is certainly a compelling argument for the T1.

Based on the 6" rule;

My options are to use the T1 at 14' 8" from the screen at the long end of its throw or to use the T2 at 16' 4" to 17' from the screen at the short end of its throw. Can't go further back than that.

The projector will be inverted and ceiling mounted.

17' from the screen is probably best from a room aesthetic point of view, but I want to locate the projector and use the lens that is going to give me the best picture.

The C3x 1080 is obviously not an on/off CR champ. Using the long end of the lens would maximize the contrast you will get. You will lose some brightness at the long end. Its a brightness vs contrast trade off.

In my application, I believe it would be wise to trade a little brightness for more contrast.

With 1.1 gain, 700 Lumens gives me 17 FtLumens from the screen.

You obviously would maximize contrast by using the long end of the T1. That said there really is no definitive way to rank optics of the T1 vs T2 vs brightness and contrast with the two lens at various throws. I would probably conclude that you will not be able tp tell much difference with out side by side at various throw tests. Put it up at 17 ft with the T2 and you will be fine. Put it up at the long end of the T1, you will be fine. Contrast will be a little better, brightness a little less. optical difference,you will never notice.

you obviously would maximize contrast by using the long end of the T1. That said there really is no definitive way to rank optics of the T1 vs T2 vs brightness and contrast with the two lens at various throws. I would probably conclude that you willnot be able tp tellmuch difference with out side by side at various throw tests. Put it up at 17 ft with the T2 and you will be fine. Put it up at the long end of the T1, you willbe fine. Contrast willbe a little better, brightness a little less. optical difference,you will never notice.


I agree and that is why I went with the T1

Excellent info -- Thanks!

One more wrinkle:

I am using a Firehawk screen. Wouldn't it be better to use the longest possible throw with this screen?

In continuing to research this projector, I am trying to understand exactly how the different lenses work.

I made more measurements in my room last night. I COULD probably use the long throw of the T2 lens, but it certainly would not be an optimal setup. Alternatively, a better setup would be towards the short throw of the T3 lens.

As I don't have a particularly large screen (115" wide 2.35:1), and as this projector obviously is not an on/off contrast ratio champ, I would probably be inclined to sacrifice some brightness for improved on/off contrast.

I'm sure the consensus is going to be to use the far throw of the T2. I would PREFER to use the short throw of the T3, though. I'm curious, if anybody knows, how the brightness and on/off contrast towards the short throw of the T3 would compare to the shortest and longest throws of the T2.

(I suppose this would be similar to how the longest throw of the T1 would compare to the shortest and longest throws of the T2, if anybody has that information)

Kevin

The light output varies with the throw on a particular lens. If you search for one of Bruzonsky's threads about his C3X, I posted an extensive spreadsheet there that shows how the various PJ settings affected CR and light output with a C3X1080. It's in the 20k forum IIRC.

Without looking back at it myself, I think the best place to be is at the longest throw possible, but the widest zoom setting. Widest zoom let out the most light. With the most light, you could still crank down both the power and iris for better CR but still saving light and noise. So you want to choose the lens that fits those conditions if possible. IIRC. In other words, the T3 set wide would likely be better than a T2 set narrow at the same throw distance. Depending on your light needs of course.

Based on the 6" rule;

My options are to use the T1 at 14' 8" from the screen at the long end of its throw or to use the T2 at 16' 4" to 17' from the screen at the short end of its throw. Can't go further back than that.

The projector will be inverted and ceiling mounted.

17' from the screen is probably best from a room aesthetic point of view, but I want to locate the projector and use the lens that is going to give me the best picture.

You are welcome to come and take a look at mine if you would like. It's very close to being 16'4" from the 129" screen.