X
Xpose
Guest
ARRGGGHHH!! I know I saw a thread on here about the best binoculars to take to Alaska, but I can't find it at the moment. Anyone have recommendations? 10/50 7/35??? Help!!
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C
Cruizer
Guest
Is this what you are looking for? ...
http://www.cruise-addicts.com/forums/read.php?3,927264,929214#msg-929214
http://www.cruise-addicts.com/forums/read.php?3,927264,929214#msg-929214
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halfdome86
Guest
I suggest not going over 10 power. That will mean you'd probably need a tripod to hold them steady.
10 x 50 is the largest I'd go. I used 7 x 35 on our cruises and was plenty happy. They were bright enough and powerful enough for me from the ship. Don't break the bank either. Bushnell's or Tasco, etc at Target or Walmart for under $50 will meet your needs.
The second number (aperature) is the more important number. This will determine how much light enters the binoc's. The more light...the sharper the image. Power is secondary.
And there is a physics law regarding optics, and I can't recall exactly what it's called, but twice the aperature isn't twice the light gathering ability. Twice the aperature is 4 times the light gathering ability.
10 x 50 is the largest I'd go. I used 7 x 35 on our cruises and was plenty happy. They were bright enough and powerful enough for me from the ship. Don't break the bank either. Bushnell's or Tasco, etc at Target or Walmart for under $50 will meet your needs.
The second number (aperature) is the more important number. This will determine how much light enters the binoc's. The more light...the sharper the image. Power is secondary.
And there is a physics law regarding optics, and I can't recall exactly what it's called, but twice the aperature isn't twice the light gathering ability. Twice the aperature is 4 times the light gathering ability.
C
Cruizer
Guest
I agree with Half Dome. I have a 7x and 8x, used to have a 10x and have used a zoom going to 15x. I could see in the store that the 15x was impossible to hold still. So, why pay for the extra power? I gave away the 10x because in the field it was also too powerful to hold still. The 7x and 8x work just fine. Now of course, if money is no object you can find stablized binoculars. For about $300 they hold the image very steady.
As to light gathering ability, it is not physics. It is simple math. The amount of light that can be gathered is based on the area of the aperature. The formula is pie R squared, where R is the radius. Double a number then square it and it is four times bigger ( 4 squared = 16, 8 squared = 64, 5 squared = 25, 10 squared = 100).
So, 7x25 binocular has an opening that is 3.14 x 12.5 squared or 490.625 square mm.
A 7x50 binocular has an opening that is 3.14 x 25 squared or 1,962.5 square mm.
(mm = millimeters = 1/1000th of a meter - 25.4mm = 1 inch - 39.4 inches = 1 meter)
So, as you can see, the reason doubling the aperature increases the light gathering ability by a factor of four is because doubling the diameter (or radius which is 1/2 of the diameter) of a circle makes the circle four time bigger. If it is four time bigger, it can gather four times the light.
This also worked for photographs. A 4x5 photograph is 20 square inches. An 8x10 photograph is 80 square inches. A 16x20 photograph is 320 square inches.
As to light gathering ability, it is not physics. It is simple math. The amount of light that can be gathered is based on the area of the aperature. The formula is pie R squared, where R is the radius. Double a number then square it and it is four times bigger ( 4 squared = 16, 8 squared = 64, 5 squared = 25, 10 squared = 100).
So, 7x25 binocular has an opening that is 3.14 x 12.5 squared or 490.625 square mm.
A 7x50 binocular has an opening that is 3.14 x 25 squared or 1,962.5 square mm.
(mm = millimeters = 1/1000th of a meter - 25.4mm = 1 inch - 39.4 inches = 1 meter)
So, as you can see, the reason doubling the aperature increases the light gathering ability by a factor of four is because doubling the diameter (or radius which is 1/2 of the diameter) of a circle makes the circle four time bigger. If it is four time bigger, it can gather four times the light.
This also worked for photographs. A 4x5 photograph is 20 square inches. An 8x10 photograph is 80 square inches. A 16x20 photograph is 320 square inches.
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Xpose
Guest
Thank you so much for your expertise--you all have helped immensely!
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halfdome86
Guest
I was taught that inverse square law type stuff in an astronomy class....didn't understand it then either!
: ^ )
What's the old Bugs Bunny joke......."It's the law of physics, but I never studied law"
: ^ )
What's the old Bugs Bunny joke......."It's the law of physics, but I never studied law"
P
Polar Bear
Guest
Re: Binoculars/cameras
Hello;
Just a note - I have found the same applies to cameras as binoculars in that optical zoom is good up to about a 5x, but after that you can't really hold the camera still enough to get a really quality picture. And if you are looking at digital cameras, don't be confused by digital zoom versus optical zoom. Digital zoom is really not zooming, use only the optical zoom numbers.
For what it's worth, Polar Bear
Hello;
Just a note - I have found the same applies to cameras as binoculars in that optical zoom is good up to about a 5x, but after that you can't really hold the camera still enough to get a really quality picture. And if you are looking at digital cameras, don't be confused by digital zoom versus optical zoom. Digital zoom is really not zooming, use only the optical zoom numbers.
For what it's worth, Polar Bear
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halfdome86
Guest
I've noticed that the digital cameras that are now coming out with 10-12 optical zoom ability do have a built in steadycam as do camcorders. Without that they would be pretty worthless without a tripod.
The best zooming trick is to, if at all possible, move closer to the subject (not a good idea when taking photos of bears). ; ^ )
The best zooming trick is to, if at all possible, move closer to the subject (not a good idea when taking photos of bears). ; ^ )
