optoma HD70 image shift ?

[golfman]

Does using the image shift on the projector effect the picture quality like keystone does?

[Blaser]

Hello Golfman,

I am not specifically familiar with your projector, but I think the answer is no. Lens shifting is an optical action that is different from Keystoning. The only issue (if ever) would be increase of chromatic aberration. Nevertheless, chromatic aberration is much more dependant on lens optics than lens shift, so you might not notice any difference anyway.
Hope this helps.

[golfman]

thank you for responding. I cant notice a difference in the picture when I use it. I have found reviews on this projector and it says it doesn't have lens shift, but the menu has an image shift horizontal and vertical. It also has keystone adjustments in the menu so I am trying to figure out what it does and if it effects the picture.

[Blaser]

OK...as I told I am not familiar with this projector, but to be honest I was misunderstood your post. Let's correct things: your projector does not have lens shift which is a mechanical process (lens is moving) and my comments 2 posts above are not valid in your case. Image shift in your projector is similar to keystone and therefore will negatively affect image quality. Try to minimize it by better placement if applicable.
By the way, that is one of the advantages of LCD technology (generally higher placement flexibility). Nevertheless, your projector is great and has also its benefits....

[Rajesh]

You will not be able to make out any image distortion unless you run test pattern.

I must have installed at least 10 HD70's . I have found keystone affects the picture quality. Since Dlp projectors suffer from lens shift flexibility they have incorporated digital image shift in HD-70.

I have avoided both in all my installations to get the best of the projector. After talking to optoma so much They have just released a Projector HD-82 with center lens and lens shift.

Wow ! i am ready for it.

[tcarcio]

At what point does keystone effect the image? I use keystone in my set up and I didn't notice any change. I don't use much but I do use it. So does it have an immediate effect or just if you have to use too much?

[Rajesh]

Keystone is an option when the installation is not perfect. Optoma's come with fixed image offset. The HD-70 has 135% image offset. Keep in mind the lens has to be at the center of the screen.

Keystone is a feature which will electronically alter the image. So you will have image compression/distortion . So it means your DMD will not be utilized full. That is why the height/width of your picture frame varies . It is always better to have it 0 . Worst case +/- 2 . Beyond this you can notice significant corner de-focus.

Example for a 110" diognal screen HxW is 94"x54" . When you install the projector perpendicular to the screen . Then 54"x 35 (135-100) = 1890 divided by 100 = 18.90" from the center of the lens is where your image starts. Throw angle is 6.2 degree.

So you either need more ceiling height or you need to flush mount the projector .Else keystone is the way to go.

Regards
Rajesh

[tcarcio]

Thanks Kris, I have mine at -4 and I really don't see any difference at all. The picture is beautifull. I should see if I can set it up so I don't have to use keystone but it might not be possible in my room.