Analog to clearly see 30"x30" area 90" away

[cashgardner 0]

The camera has to be an analog type.

At our new complex, need to clearly see what is written on the concierge desk which is 90" from the ceiling. The desk is 30"x30".

Due to above requirements, I do understand that we need a longer mm lens that what a smoke-detector camera can offer, any idea?

Thanks for your aid

[EarlT 0]

Either that or a closer camera. I have a 60mm lens on an analog box cam that could read that easily. That may be a tall order fitting that much lens in a smoke detector.

 

But I defer to the experts.

[NotoriousBRK 0]

The camera has to be an analog type.

At our new complex, need to clearly see what is written on the concierge desk which is 90" from the ceiling. The desk is 30"x30".

Due to above requirements, I do understand that we need a longer mm lens that what a smoke-detector camera can offer, any idea?

Thanks for your aid

 

What is the size of the text you are trying to see?

 

An analog camera is going be in the range of 704x480 pixels. If you're trying to cover a 30"x30" area, then you're going to be limited to having about 480x480 pixels on that area.

 

480 pixels / 2.5 feet (30 inches) would be 192 pixels per foot, so you should get good clarity down to at least about a credit-card font.

 

So, it's just a matter of lens math... On a 1/3" sensor 4:3 camera you're going to want a 10mm lens. Most lenses are varifocal, so look for something that goes from at least 7-13mm (give or take a bit), so that you have a little bit of wiggle room in the lens setting based on how things end up after the install.

[rory 0]

The camera has to be an analog type.

At our new complex, need to clearly see what is written on the concierge desk which is 90" from the ceiling. The desk is 30"x30".

Due to above requirements, I do understand that we need a longer mm lens that what a smoke-detector camera can offer, any idea?

Thanks for your aid

 

7.5 feet from the ceiling, 2.5 x 2.5 feet?

 

you could get either a varifocal lens like a 5-50mm to be sure (more $$), or get some fixed lenses like 8mm, 12mm, and 16mm.

[Nimrod 0]

My calculation show a 14mm lens on a 1/3 inch camera at 90 inches will cover an 30x30 area.

 

This is the best free lens calculator i have ever found, very flexible but it takes a little while to get

used to it.

 

http://www.theiatech.com/calculator.html

[Soundy 1]

My calculation show a 14mm lens on a 1/3 inch camera at 90 inches will cover an 30x30 area.

 

This is the best free lens calculator i have ever found, very flexible but it takes a little while to get

used to it.

 

http://www.theiatech.com/calculator.html

THAT is really freakin' cool. Bookmarked!

[NotoriousBRK 0]

My calculation show a 14mm lens on a 1/3 inch camera at 90 inches will cover an 30x30 area.

 

This is the best free lens calculator i have ever found, very flexible but it takes a little while to get

used to it.

 

http://www.theiatech.com/calculator.html

 

A 14mm lens will have a 2.5ft *horizontal* FOV, but only a 1.75ft *vertical* FOV, so you wouldn't cover the entire 30"x30" area.

 

In this case, since he's looking for a square (1:1 ratio) area on a rectangular (4:3) camera, and the vertical resolution is smaller than the horizontal, you have to solve for the vertical.

 

At a 7.5' working distance, an 11mm lens will give you a vertical FOV of ~2.5ft and a horizontal FOV of ~3.3ft.

 

Note, the actual numbers may be *slightly* different, I'm working off an old skool lens calc wheel, not that fancy online thing

[Nimrod 0]

“A 14mm lens will have a 2.5ft *horizontal* FOV, but only a 1.75ft *vertical* FOV, so you wouldn't cover the entire 30"x30" area.”

 

Good work, thanks for the correction.

[cashgardner 0]

" title="Applause" /> As usual, you guys are amazing. " title="Applause" />