Viewing Distance

[alxltd]

My first post, so excuse my ignorance. I am building a dedicated theater room and I have seen the 2X or 1.5x ,etc. calculation. My question is when any calcualtion states 2x or 1.5x or whatever x screen width, are they referring to diagonal or actual horizontal width?

Also, I am placing 2 rows of seating, so is there a range of distance to work within, say 1.5x for first row and 2x for second row? (the second row will be on a 7 inch riser)

Thanks in advance for any help.

 

[Audioholics]

I use screen width, but others use screen height - so you have to pay attention to the review/article.

The desired distance has everything to do with the display (projector in this case) capabilities. You simply want to make sure you are far enough back for the resolution so you don't see any pixels. Too far back and you miss out on the big screen effect. I look for projectors that let me do 2x the screen width at minimum.

 

[Dapper Dan]

I agree with Clint, beware of reviews that state the viewing distance, they either use screen height or screen width. Essentially the answers work out very close, but still some fudge factor is involved. This link has a very good description of viewing distance and also provides a calculator, so you can plug in some numbers and get an idea.

Cheers...

Dapper Dan...

 

[BMXTRIX]

If you haven't viewed www.projectorcentral.com yet, then do so and spend several hours/days/weeks reviewing their deep list of reviews. Of course, that is after you have gone through the list of Audioholics reviews as well.

The viewing distance calculator above seems to almost be the gold standard. Go to Google - search for THX Viewing Distance - That is the first link you will get. I send people there all the time.

THX and SMPTE standards are a good basis for your design to begin with. But, it is important to keep this in mind:

Those standards are based upon viewing of HD material. Film based movies actually. They really are designed for the professional movie theater in your local mall. Not for viewing regular 'tv' in your home.

This is an important distinction as you will find that your best results will come from viewing of HD material and using an HD projector. If you are not viewing HD material, but are viewing a regular DVD, then your image will suffer. Fortunately, the drop in quality to DVD is not tremendous. It is a real drop, but nothing like the drop you will see when going to VHS or regular analog cable.

Does regular cable look bad? Well, sure it does. It already probably looks bad on your 27" TV, so at 10' it's going to look that much worse! But, it is still plenty viewable if you are so inclined. Mostly though, I would expect that you will watch DVDs and HDTV and for that, if you have a 1280x720 projector, you will be very happy between 1.5x and 2x screen width.

I don't believe I've ever seen Projector Central refer to seating distance in reference to screen diagonal. ALWAYS screen width is the norm for them.

 

[Dapper Dan]

BMXTRIX makes some very relevant points, take note… I would also like to add that, the idea with screen distance is and always has been based on the height of the image. Let me explain;

The horizontal width of a screen (in a Cinema) is the factor that always changes with aspect ratio, not the height of the image, so the optimum viewing distance is a function of that height, hence the angle is used rather then actual height because as that remains constant as you go from a 1:1.85 to a 1:2.35, you would need to move back to encompass the viewing angle…

(Next time you go to the movies, note that it’s the side of the screen (curtains) that changes the aspect ratio and the height of the image remains constant)

Now this is where it becomes interesting, the standard TV, Plasma, LCD or projector, all crop the height to fit within the screen width… You can not change the physical properties of the screen but you can change the image, so that’s why, you see those “black bars” top and bottom; to fit the screen. Now whist the image is squeezed into the available width, the height is smaller in the larger format, thus, smaller image overall, therefore you could move closer to regain that “big screen” effect; as Clint has already mentioned.

That’s why now for all intensive purposes, the screen width is the factor most commonly used to determine viewing distance when using the above devices.

For a rule of thumb; 2x screen width is adequate, i.e. if you have 6' (2 metre) screen width, you would ideally be 12’ (4 metres) back.

The quality of the image also has a major factor on the viewing position… (to a point)

After all is said and done, just like at the movies, some people like to sit at the back row and others move to the front. If you use the above as a guide, you should be within the ball park for some great viewing.

Cheers…

Dapper Dan…