Sorry I know it has a Max of 20,000 mcd.

I did try it out and yes I need this Brightness.

I will be putting it upside down on a little mirror to make it Brighter.

The Battery Holder I have take 4. Dabble A Batteries.

This will be 6. Volts so I will use a Resistor but the LED will be taking 80 mA just to Run.

This is why I asked how many Hours I would get if I Ran this with 3.2 Volts at 80 mA till the Batteries go?

 

Sorry I know it has a Max of 20,000 mcd.

I did try it out and yes I need this Brightness.

I will be putting it upside down on a little mirror to make it Brighter.

The Battery Holder I have take 4. Dabble A Batteries.

This will be 6. Volts so I will use a Resistor but the LED will be taking 80 mA just to Run.

This is why I asked how many Hours I would get if I Ran this with 3.2 Volts at 80 mA till the Batteries go?

AA alkaline cells are about 2000 mAh. So, drawing 80 mA, it should theoretically last about 25 hours. But, you would need a constant current driver to keep the current at 80 mA. And when the batteries are depleted, I believe they are about 0.8V, so I would guess you would get more like 10 to 15 hours at 80 mA.

 

The Battery Holder I have take 4. Dabble A Batteries.

Just a little thing, the word is "double". Maybe you are using speech to text? You might try saying "A A".

 

Do you understand the meaning of the viewing angle? If you have a 10° viewing angle and you are 10 ft away, positioned so it looks maximally bright. Then you move 1 foot to the left or right, you are outside the viewing angle, and the brightness will be greatly reduced.

Reminds me of a set of LED Christmas lights I used to string on the house. Each LED cast a beam focusing to a small area. If you were in that target zone the LED was very bright. My neighbor commented on "That one very bright yellow LED". It was pointed directly at her window. The same LED's also cast a ring of light. At a distance of (estimating) 15 feet the ring it cast on the ground was roughly 6 feet in diameter.

Viewing angle IS a huge factor in how LED's are rated.

 

Ok so now I know my LED is 20,000 mcd and I need 3.2 Volts at 80 mA.

I now my Battery holder will give 6. Volts and this is to High.

So I now know the Math to find the Resistor I need to get the Right Voltage.

I know when I turn this on the LED will take what it needs to Run.

The LED needs 80 mA so am I not Right it will just keep taking 80 mA for as long as it can?

 

Correct as long as the battery remains at 6 volts.
Also expect with a 35 ohm series resistor the voltage across the LED may vary a few hundred millivolts which also effects the current.
A volt meter will confirm.

 

If you want it to stay constant brightness for the longest time possible, you need a constant current driver, as I said previously.

Half way through the life of an alkaline cell its voltage is 1.2V. Now your current calculation becomes:

(4.8 - 3.2) / 35 = 45 mA

actually Vf will drop as well at the current is lower. Let’s say it drops to 3.0V

(4.8 - 3.0) / 35 = 51 mA

But you said you needed 80.

A constant current driver will reduce the resistance to keep the current at 80 mA.

 

the beam angle is very narrow.

it depends on how much current you draw. You don't have to run the LED at 80mA, you can run it more in the suggested range of 65 to 75mA.

In the datasheet there is a suggested current of 65 to 75 mA.

I found this LED I have it is 10,000 mcd and is Rated 3.4 Volts at 20 mA.
It has a 10 Viewing Angle.

You say I can Run the LED at a Lower Current.

All important things to keep in mind.
Something I didn't stop to consider, also well worth information:

Half way through the life of an alkaline cell its voltage is 1.2V. Now your current calculation becomes:
(4.8 - 3.2) / 35 = 45 mA
actually Vf will drop as well at the current is lower. Let’s say it drops to 3.0V
(4.8 - 3.0) / 35 = 51 mA