Friday

March 27, 2015

March 27, 2015

Posted by **Sandra** on Sunday, July 19, 2009 at 3:15pm.

Telephoto lens. find

the image distance i for an object that is 2,000,000 mm from

a 250-mm telephoto lens.

tel formula is 1/f=1/o + 1/i

1/250=1/2,000,000 + 1/i

5i(1/250)=(1/2,000,000 + 1/i)5i

1/50i = 5i/400,000i + 5i/5i

1/10i = 5i/80,000i + 5i/5i

I=8,000

Is this right?

- algebra -
**Damon**, Sunday, July 19, 2009 at 3:53pm1/250=1/2,000,000 + 1/i agree

I like powers of ten

10^-2 / 2.5 = 10^-6 / 2 +1/i

(2/2.5)10-2 = 10^-6 + 2/i

(2/2.5) 10^4 = 1 + 2*10^6 / i

8*10^3 = 1 + 2*10^6/i

8000 i = i + 2*10^6

7999 i = 2*10^6

i = 2,000,000/7999

i = 250 mm

In other words the object is effectively at infinity and its image is effectively at the focal point.

**Answer this Question**

**Related Questions**

Algebra - check to see if correct - Telephoto lens. Use the formula from ...

Algebra - Telephoto lens. Use the formula from Exercise 67 to find the image ...

are these correct - b. Calculate the profit or loss on 12,000 bags and on 25,000...

healthcare fiancare - HINT: 6% X $1,000,000 – {20% X ($1,000,000 – (6% X $1,000,...

please help - . If Healthy Foods has an annual interest expense of $10,000, ...

Algebra - Last question I hope...here is the problem This equation illustrates ...

i needhelp with e and i want to know if i am right - 13. Healthy Foods, Inc. ...

fin. am I correct? - 13. Healthy Foods, Inc. sells 50-pound bags of grapes to ...

fin. am I correct? - 13. Healthy Foods, Inc. sells 50-pound bags of grapes to ...

math - A certain sweepstakes ticket has four categories of prizes with the ...