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Z4 Lens Shift

crackazz

Standard Member
I'm thinking of upgrading my AE300 to a Z4 and have some q's regarding the contrast levels and lens shift. I've got it ceiling mounted, but with not having any lens shift I have an image thats a little to high for my liking, I sit a little under 3m from a 77in screen. How much effect on the image focus does lens shift have? worked out I'd need about 35% below. Also, I've been reading about the improved CR ratings on the next gen LCD pj, really though, how much better will it be to a well setup AE300 in a room with cream walls, cream carpet and white ceiling?

thanks for any help! :) :) :)
 

gingercat

Established Member
Given that the Z4 has yet to be reviewed by any forum members (come on chaps, we know you've got them!), don't think anyone will be able to comment on its lens shift quality. A friend has his Z3 "shifted" and the image is still pretty damn good.

One review of new the Epson model was quite slating about its lens shift saying that it nastily blurred the image.
 

Mark_a

Prominent Member
I can confirm that I shift my Z3 about and it appears to have not the slightest effect on the picture quality, and can go a full screen's worth up and down, and half a screen's width from side to side. Damn good system. I can't imagine Sanyo has made it worse on the Z4, which comes with the addition of locking on the screen shift. Though, having said that, my Z3's never shown any inclination that it wants to shift the lens about itself.

Regards

Mark
 

wallzy

Established Member
Just flicked threw the instruction manual and it says it has a full screen up and down and a half left to right so the same as the Z3. although there is a note at the bottom of the page that says "The best image is obtained at the center of the Axis of the lens shift" but i carnt see no differnce in picture quality when its shifted

wallzy
 

maj74

Established Member
You will proabably find that as you near the limit of the lens shift, the edge corresponding to the direction in which you are shifting starts to bend.

I.e. If you scroll the lens shift all the way to the bottom, the lower edge of the picture may well not be straight any more. (The corners will be lower than the middle.) If you scroll all the way to the left, the left edge of the image may no longer be straight.

I think this has something to do with projecting the image through the extremities of the lens. (Remembering my A-Level physics, I guess the further towards the edge of the lens you move the projected image, the more glass it as travelling through (as the angle of incidence to the glass decreases) therefore the more the effect of diffraction from the lens has on the light path. The corners nereast the shifted edge will be closest to the edge of the lens and hence effected the most by the diffraction.)

There should be no ELECTRONIC deterioration from using lens shift. This is a purely geometrical deterioration. I guess the answer would be to have a huge lens on the front of the projector. (please note, bigger lens does not mean more magnifiaction, thats due purely to the curvature) The huge lens would allow the image being moved behind it by the lens shift to remain away from the extremities.

It is a slight (I mean slight) issue with the Sony HS-50. I couldn't say whether the issue exists on other lens shifting projectors. Perhaps other owners can confirm or deny?!!
 

Tempest

Distinguished Member
Perhaps someone can answer this.

You know with "NORMAL" non lens shift projectors, the centre of the projector lens was (roughly about) level with the BOTTOM of the projected image. Virtually all the image was ABOVE the projector.

On the Sanyo Projectors (I assume this applies the same to the Z4) is this the same, OR is it not the case and NOW with the lens shift system exactly centered the image is now central to the lens of the projector.

So, in other words, with everthing mid setting (which is supposed to be ideal apparently) the ideal height for a Sanyo projector would be exactly in the physical middle of the screen?

If any of that made sense!
 

crackazz

Standard Member
Thanks everyone for that.... I think you've pretty much answered the lens shift q :)

about the CR though? has anyone demo'd a Z3 next to an ae300? what was the difference? black vs very dark greys? and only have a 77" screen, how much benefit would I see in the higher resolution using just DVDs as a source? does it scale as well as mine?
 

Digger

Prominent Member
@Tempest... Yep you are correct, well at least with Z3 anyway. my previous Epson TW10h was projecting from the bottom of the image
 

inzaman

Moderator
Sorry to seem dense But. In general, does lens shift mean that no keystone will need to be compensated for?
Yes, assuming that the image fits the screen within the 'shift' limits of the pj.
 

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