Help with Focal lengths please

[Feathered one]

I would appreciate some answers to the questions below please.

1 What would be the focal length of my ED82 scope with a 30x eyepiece

2 What would be the focal length with a 50x eyepiece

3 What would be the focal length, digiscoping with the 30x eyepiece, and the nikon P5100 set at say 10mm zoom.

4 Same as 3 but using the 50x eyepiece.

I have seen a calculator somewhere on the internet, but the calculator needed lots of information that I don't understand :C

Malc

[Sandpiper]

http://www.jayandwanda.com/digiscope/digiscope_calc.html

Hi Malc,

You may find the above link useful.

[Feathered one]

Thanks Sandpiper for the link.

That is the calculator that I found, unfortunatley it doesn't list the Nikon ED82 scope, so would need the Scope Objective Focal Length, and Scope Magnification to be input into the calculator.
This is where my problem starts, not knowing these figures.

Malc

[Sout Fork]

I would appreciate some answers to the questions below please.

1 What would be the focal length of my ED82 scope with a 30x eyepiece

2 What would be the focal length with a 50x eyepiece

3 What would be the focal length, digiscoping with the 30x eyepiece, and the nikon P5100 set at say 10mm zoom.

4 Same as 3 but using the 50x eyepiece.

I have seen a calculator somewhere on the internet, but the calculator needed lots of information that I don't understand :C

Malc

You are misunderstanding something:
The focal length of the scope does NOT change no matter what you connect to the scope. The focal length is intrinsic to the objective lens of the scope. In this case about 500mm.

What does change is the focal length of the eyepieces you use in the scope. In this case a 30x ep in your scope would require an ep with a focal length of about 16mm and a 50x would require about a 10mm focal length ep.

I don't have a clue as to how this would effect the magnification of your scope (which, I think is what you are really asking) through any particular camera.

SF

[Feathered one]

Thanks Sout Fork for putting me right.

What I was trying to find wasn't the scope focal length, it should have been the digiscoping 35mm equivalent focal length, with the different eyepieces and camera zoom.

I found this on nikons website, which gives me the answer.
http://www.ave.nikon.co.jp//bi_e/how_to/digisco/step1/index.htm

Regards

Malc

[revs45]

Thanks Sout Fork for putting me right.

What I was trying to find wasn't the scope focal length, it should have been the digiscoping 35mm equivalent focal length, with the different eyepieces and camera zoom.

I found this on nikons website, which gives me the answer.
http://www.ave.nikon.co.jp//bi_e/how_to/digisco/step1/index.htm

Regards

Malc

thanks for that Malc, i'm always asked what the focal length of my ED82 is and i always give a dumb answer, now i can say with authority "lots"
:t:

[Neil]

Malc,
You've probably got this sorted now , but a 30x eyepiece gives 1500 mm equivalent magnification (30 x 50 ) and a 50x eyepiece will give 2500 mm magnification (50 x 50 ). If the figures are for an 80 mm scope and then you put them on a 65mm scope you will get proportionally less magnification due to the shorter focal length.
Multiply by the optical zoom from the camera to get the total magnification. 10 mm on the P5100 is about 43 mm so multiply the eyepiece magnification by 43 instead of 50.
Neil.

[iporali]

thanks for that Malc, i'm always asked what the focal length of my ED82 is and i always give a dumb answer, now i can say with authority "lots"
:t:

Well... to be specific... it is actually just the opposite ;)! When you put an eyepiece on a scope, it becomes "afocal" ie. it does not have a focal length, only magnification. Your camera lens has a focal length that can be multiplied with this magnification.

Ilkka