Lens shift?

[ectoplasm]

I'm considering mounting positions for a Hitachi TX200.

I'd prefer to mount it slightly to the right of the screen and compensate with lens shift.

In the Hitachi spec sheet it states "Lens Shift - Horizontal 3:1~1:3". What does this mean exactly? That I can mount the thing up to a third of the screen width to either side? Or am I barking up the wrong tree?

[PJTX100]

Those figs are a bit confusing. The TX100 has a clear diagram showing that horizontally the picture can be shifted up to 25% of the screen width either side, ergo you can offset it by up to 25% from the middle. The less the better though.

I'd presume the TX200 was no less flexible.

[ectoplasm]

Originally Posted by PJTX100

horizontally the picture can be shifted up to 25% of the screen width either side, ergo you can offset it by up to 25% from the middle. The less the better though.

Cheers!

Is there noticeable PQ degradation if the maximum lens shift is used?

By my calculations a 10m HDMI cable will just about reach to the projector, but I'll have to wait and see until it's properly laid before I'll know whether I'll need to use the lens shift feature.

[PJTX100]

Originally Posted by ectoplasm

Cheers!

Is there noticeable PQ degradation if the maximum lens shift is used?

By my calculations a 10m HDMI cable will just about reach to the projector, but I'll have to wait and see until it's properly laid before I'll know whether I'll need to use the lens shift feature.

It can cause uneven focus, shift your menu around the screen when you get it all set up. This is a good test for focus.

For the sake of, say, 2m of HDMI cable I'd put the PJ as central as possible. Especially if you'd need to use a lot of lens shift to compensate.

[gingercat]

Due to a restricted room layout, I'm almost at the extremes of both vertical and horizontal lens shift with my TX200 (I can hear the collective "tutting"), and there is only a very small amount of focus difference across the screen. Unless you're displaying e.g. lots of hi-res text, you would never notice it. I'm sure at these extremes it's still (light touch paper) sharper than the AE900 (and stand well back)

[PJTX100]

Tut tut tut.

[ectoplasm]

Originally Posted by PJTX100

Those figs are a bit confusing. The TX100 has a clear diagram showing that horizontally the picture can be shifted up to 25% of the screen width either side, ergo you can offset it by up to 25% from the middle. The less the better though.

Just realised... what about vertically?

I'm going to mount the projector flush against a 190cm high ceiling, and am aiming for a 112cm high image in the centre of the wall. Just looked through the TX200 manual off the Hitachi site and the explanation of lens shift in there is very vague.

Does it mean I can shift the image vertically up to 75% of the screen height? If so, then mounting it flush to the ceiling means a big lens shift and possible poor focus. Would this then mean tilting the thing downwards and using keystone correction? Would that be worse than lens shifting?

AARRGH!! HELP!

[Timmie]

Originally Posted by PJTX100

Those figs are a bit confusing. The TX100 has a clear diagram showing that horizontally the picture can be shifted up to 25% of the screen width either side, ergo you can offset it by up to 25% from the middle. The less the better though.

I'd presume the TX200 was no less flexible.

I have just taken delivery of my TX200 and my temporary set up has the PJ 1/4 of the way in from a screen edge and this is at max horizontal offset. So it seems the same. Focus seems fine to me but I haven't fully tweaked everything up yet.

[PJTX100]

Originally Posted by ectoplasm

Just realised... what about vertically?

I'm going to mount the projector flush against a 190cm high ceiling, and am aiming for a 112cm high image in the centre of the wall. Just looked through the TX200 manual off the Hitachi site and the explanation of lens shift in there is very vague.

Does it mean I can shift the image vertically up to 75% of the screen height? If so, then mounting it flush to the ceiling means a big lens shift and possible poor focus. Would this then mean tilting the thing downwards and using keystone correction? Would that be worse than lens shifting?

AARRGH!! HELP!

OK, 112cm high image so you can offset the image 84cm (75%) or put another way you can have the PJ a max of 28cm above the screen. 28cm plus the screen depth 112cm is 140cm. Hence your screen can be a minimum of 50cm from the floor. Which is about 10cm above centre.

Don't tilt the PJ so introducing keystoning. Any optical lens shift degradation will be less than that produced by digital keystone correction.

[ectoplasm]

Thanks for the help mate

[StormHD]

If you're going to use it to project small text (say the size of what you're reading right now, yes this) then I'd avoid lens shift. It does blur it slightly, which I've not found to be a problem but can be a bit of a headache (literally) when reading lots of small text.

HTH.

[ectoplasm]

Originally Posted by StormHD

If you're going to use it to project small text (say the size of what you're reading right now, yes this) then I'd avoid lens shift. It does blur it slightly, which I've not found to be a problem but can be a bit of a headache (literally) when reading lots of small text.

To what degree does the lens shift have to be in effect for the blurriness to kick in?

Going by TX100's and my calculations, I'd have to shift the lens to near the maximum vertical setting.

[StormHD]

I've not tried different gradiations, but mine is right at the horizontal extreme, with a slight vertical adjustment.

It really isn't bad at all - I've not noticed any faults when watching movies. There's only a very slight issue when reading text - so slight it took me a while to figure out that something was actually wrong. In fact I didn't realise the cause until I read this thread.