Throw Calculator Accuracy?

[Daniel.Armenio]

I picked up the Benq TH671ST for the DIY garage setup i will be kicking off in a few weeks. I had originally planned to go 16:9 but it was a bit too tight in the garage so i am now going with a 4:3 at 144" x 108".

Before picking up the projector, i used the projector central calculator to calculate my throw distance. (screenshot attached) Given the manual adjustable zoom, it gave me a range of 132" to 156". I then checked out the benq calculator and it gave me a fixed distance of 132".5 . It doesnt seem to have a range like the projector central calculator for some reason.

I dont have my enclosure/screen yet but i received the projector yesterday and decided to project against the wall to see how close i could get and keep 108" high 4:3 image. The closest i could get to the wall while maximizing the image size using the manual zoom and getting a 108" tall image was 141" wall to lense.

I know i can play with it to get it close once i get everything setup but i am hoping to get an idea of where my mount needs to go ahead of time because i will need to either put it on a support beam that hangs down at about 134" - 139" with 9.5' of clearance or from the ceiling that has a little over 11' clearance.

Any ideas why i am seeing some discrepancies? Why doesnt the Benq calculator have a range for the zoom?

[jasonreg]

If it is a digital zoom vs a mechanical zoom then it will be a feature you select from the remote. That said - Page 8 of the user manual shows a focus and a zoom ring. I assume you took a look at the user's manual on the BenQ site? TH671ST User Manual | BenQ Canada

[Daniel.Armenio]

Yes it’s a mechanical zoom. I had that maximized when I tested against the wall to get a 108” high image.

[GungHoGolf]

Make sure that no vertical keystone correction is dialed in - that will shrink the image.

Also, don't set a 4:3 ratio in the projector. Leave it set to 16:9 or auto-detect, and do the image aspect ratio correction in the PC (using Nvidia Control Panel and/or Windows Display Settings).

[Daniel.Armenio]

Thanks Ron, I should have mentioned that I’m using an iPad screen mirrored to an appleTV. Not sure if that makes a difference.

I’ll retest, make sure the key stone is zeroed out and see what I get.

[Daniel.Armenio]

My numbers were much closer after accounting for the vertical keystone. Thanks again for the tip. My next complication will be figuring out the vertical position to account for the lense offset while avoiding shadows from the top of the enclosure. Ill probably wait until i get the enclosure setup to start messing with those #s. Any tips or things to look out for there would be greatly appreciated.

[GungHoGolf]

Ah, using an iPad is an important factor. The iPad output is fixed at a 4:3 aspect ratio, and many have reported that the resulting image it sends out to the projector is shrunken from the full size of the projector's capability - so that probably explains your issue.