8 by 50 binos

[Don]

I have a set of very good 8 by 50 binos that are perfect in their focal
length for a particular set of shots that I wish to take with my 10D. Does
anybody know how I convert the 8 by 50 size to camera focal length (in 35mm
terms)?

regards

--
Don From Down Under

[Paul]

Don wrote:
> I have a set of very good 8 by 50 binos that are perfect in their focal
> length for a particular set of shots that I wish to take with my 10D. Does
> anybody know how I convert the 8 by 50 size to camera focal length (in 35mm
> terms)?
>
> regards
>
> --
> Don From Down Under
>
>
Just multiply the focal length of the lens you are using by 8 (say, for
example, 50mm in a 28-90 zoom would be 400mm, further multiply by 1.6 if
you are using the digital 10D with said lens).
I would doubt that the image would amount to much as the exit pupil of
the binos would be much smaller than the lens front element. If all you
are after is the centre part of the image you could crop later.
The most difficult part is aligning the camera lens and bino squarely.
Both on separate tripods would be best.

[Scott Coutts]

Hi!

Paul wrote:
> Don wrote:
>
>> I have a set of very good 8 by 50 binos that are perfect in their focal
>> length for a particular set of shots that I wish to take with my 10D.
>> Does anybody know how I convert the 8 by 50 size to camera focal
>> length (in 35mm terms)?

Are you thinking of using the binoculars as a lens, or are you looking
to get a lens that will give you the same focal length effect as your
binoculars?

The first number in the binoculars measurements is magnification of the
image compared to how it looks without them. So 8x50 will by 8x. The
second number is the diameter of the front element.

>
> Just multiply the focal length of the lens you are using by 8 (say, for
> example, 50mm in a 28-90 zoom would be 400mm, further multiply by 1.6 if
> you are using the digital 10D with said lens).
>

You're talking about holding the binoculars up against a lens, right?

>
> I would doubt that the image would amount to much as the exit pupil of
> the binos would be much smaller than the lens front element. If all you
> are after is the centre part of the image you could crop later.
> The most difficult part is aligning the camera lens and bino squarely.
> Both on separate tripods would be best.
>

Yep, or otherwise you'd have to cut a hole in the body-cap and use the
binoculars as a lens of their own (i.e. focus the binoculars on the
film/sensor).

Also, it probably wont be that good a quality image, unless you have
expensive binoculars.

Bye!

Scott.

[Don]

Fellas

thanks. I was trying to establish what size lens I would need to purchase
to get the same multiplication and area of vision as I do with my binos.
The math may work but the practical doesn't. If the 8 by 50 is equal to a
400mm then when using my 300 with my 10D (which gets me 480mm) should do it.
However, it doesn't. the bino vision is more magnified. Any clues?

regards

Don
"Scott Coutts" <scott.coutts@med.monash.edu.au> wrote in message
news:FNlAb.41984$aT.9067@news-server.bigpond.net.au...
> Hi!
>
> Paul wrote:
> > Don wrote:
> >
> >> I have a set of very good 8 by 50 binos that are perfect in their focal
> >> length for a particular set of shots that I wish to take with my 10D.
> >> Does anybody know how I convert the 8 by 50 size to camera focal
> >> length (in 35mm terms)?
>
> Are you thinking of using the binoculars as a lens, or are you looking
> to get a lens that will give you the same focal length effect as your
> binoculars?
>
> The first number in the binoculars measurements is magnification of the
> image compared to how it looks without them. So 8x50 will by 8x. The
> second number is the diameter of the front element.
>
> >
> > Just multiply the focal length of the lens you are using by 8 (say, for
> > example, 50mm in a 28-90 zoom would be 400mm, further multiply by 1.6 if
> > you are using the digital 10D with said lens).
> >
>
> You're talking about holding the binoculars up against a lens, right?
>
> >
> > I would doubt that the image would amount to much as the exit pupil of
> > the binos would be much smaller than the lens front element. If all you
> > are after is the centre part of the image you could crop later.
> > The most difficult part is aligning the camera lens and bino squarely.
> > Both on separate tripods would be best.
> >
>
> Yep, or otherwise you'd have to cut a hole in the body-cap and use the
> binoculars as a lens of their own (i.e. focus the binoculars on the
> film/sensor).
>
> Also, it probably wont be that good a quality image, unless you have
> expensive binoculars.
>
> Bye!
>
> Scott.
>

[Scott Coutts]

Don wrote:
> Fellas
>
> thanks. I was trying to establish what size lens I would need to purchase
> to get the same multiplication and area of vision as I do with my binos.
> The math may work but the practical doesn't. If the 8 by 50 is equal to a
> 400mm then when using my 300 with my 10D (which gets me 480mm) should do it.
> However, it doesn't. the bino vision is more magnified. Any clues?
>

Yeah, that's what I thought you wanted. (:

Ok, this is how I see it:

Well, in theory, a 50mm lens is supposed to be '1x', i.e., what
you see through a 50mm lens should be the same as what you see
with your eye. So a 100mm lens is '2x' etc. But I dont think
it's quite right with the 10D. Someone else will probably
clarify it.

Your '8x50' means 'lens diamater x magnification'... so they have a
magnification of 50 (actually, magnification isn't really the right
word, but I'm sure you know what I mean).

So therefore your binoculars would be the equivalent of a 2500mm lens
(50x50).

The 10D has a multiplication factor of 1.6 so that would mean you'd need
a 1563mm lens to get the same effect.

The closest you're going to get is the 1200mm f/5.6L, maybe with a 1.4
or 2x extender. You'd better be quick and give Canon a call now, if you
need it in a hurry, because they custom make it for you when you ask
them for one. Oh, and it'll set you back somewhere around $280K. (:

But seriously, if you're going to photograph things that need a really
long lens, you'd be better off looking into 'digiscoping' - that is,
using a high-quality spotting scope with a camera attachment. A lot of
bird watching people do it.

Otherwise, most professional photographers use 400mm to 600mm lenses for
this type of work.

You can also buy (if you can find one) 600mm and 1000mm reflecting
(mirror, catadioptric, schmidt-cassegrain) lenses but the image quality
is usually not as good.

Bye!

Scott.

[Vin]

Scott Coutts <scott.coutts@med.monash.edu.au> wrote:


> Your '8x50' means 'lens diamater x magnification'... so they have a
> magnification of 50 (actually, magnification isn't really the right
> word, but I'm sure you know what I mean).

I think it should be 'magnification x diameter', so your magnification
is 8x. It depends on how wide your eyepiece lens is as well (Some
10x will have the same fov as a 8 or 7x depending on the eyepiece).
The best thing to do is look at the specs of your binoculars and get
the actual field of view and then find the equivalent in your
camera.




--
Vin
Melbourne, Australia
Remove no and spam from both sides of the @ sign email address to reply

[Scott Coutts]

Scott Coutts <scott.coutts@med.monash.edu.au> wrote in message news:<qwvAb.42377$aT.26352@news-server.bigpond.net.au>...
> Don wrote:
> > Fellas
> >
> > thanks. I was trying to establish what size lens I would need to purchase
> > to get the same multiplication and area of vision as I do with my binos.
> > The math may work but the practical doesn't. If the 8 by 50 is equal to a
> > 400mm then when using my 300 with my 10D (which gets me 480mm) should do it.
> > However, it doesn't. the bino vision is more magnified. Any clues?
> >
>
> Yeah, that's what I thought you wanted. (:
>
> Ok, this is how I see it:
>
> Well, in theory, a 50mm lens is supposed to be '1x', i.e., what

> you see through a 50mm lens should be the same as what you see
> with your eye. So a 100mm lens is '2x' etc. But I dont think
> it's quite right with the 10D. Someone else will probably
> clarify it.
>
> Your '8x50' means 'lens diamater x magnification'... so they have a
> magnification of 50 (actually, magnification isn't really the right
> word, but I'm sure you know what I mean).
>
> So therefore your binoculars would be the equivalent of a 2500mm lens
> (50x50).
>
> The 10D has a multiplication factor of 1.6 so that would mean you'd need
> a 1563mm lens to get the same effect.
>
> The closest you're going to get is the 1200mm f/5.6L, maybe with a 1.4
> or 2x extender. You'd better be quick and give Canon a call now, if you
> need it in a hurry, because they custom make it for you when you ask
> them for one. Oh, and it'll set you back somewhere around $280K. (:
>
> But seriously, if you're going to photograph things that need a really
> long lens, you'd be better off looking into 'digiscoping' - that is,
> using a high-quality spotting scope with a camera attachment. A lot of
> bird watching people do it.
>
> Otherwise, most professional photographers use 400mm to 600mm lenses for
> this type of work.
>
> You can also buy (if you can find one) 600mm and 1000mm reflecting
> (mirror, catadioptric, schmidt-cassegrain) lenses but the image quality
> is usually not as good.
>
> Bye!
>
> Scott.

Duh... of course it's 8x50 not 50x50. I wasnt thinking too straight
when I wrote that stuff!

Anyhow, the theory should still work...

[Scott Coutts]

Vin wrote:

> Scott Coutts <scott.coutts@med.monash.edu.au> wrote:
>
>
>
>>Your '8x50' means 'lens diamater x magnification'... so they have a
>>magnification of 50 (actually, magnification isn't really the right
>>word, but I'm sure you know what I mean).
>
>
> I think it should be 'magnification x diameter', so your magnification
> is 8x.

Yeah, I know, I realised that after I'd sent it... duh!


> It depends on how wide your eyepiece lens is as well (Some
> 10x will have the same fov as a 8 or 7x depending on the eyepiece).
> The best thing to do is look at the specs of your binoculars and get
> the actual field of view and then find the equivalent in your
> camera.

True, but often the info isnt available. Also, when it comes down to it,
there arent really that many options for long lenses!

[Vin]

Scott Coutts <scott.coutts@med.monash.edu.au> wrote:

> Vin wrote:

>> It depends on how wide your eyepiece lens is as well (Some
>> 10x will have the same fov as a 8 or 7x depending on the eyepiece).
>> The best thing to do is look at the specs of your binoculars and get
>> the actual field of view and then find the equivalent in your
>> camera.

> True, but often the info isnt available. Also, when it comes down to it,
> there arent really that many options for long lenses!

Well, if you really want to see the same as your binoculars
through your camera, then the Normal x Magnification should
work fine. I was thinking the field of view. If you want
to calculate the Normal x Magnification, you dont use
50mm as the normal. Look in the specs for your camera and
get the Eyepiece Magnification. In my D100 its 0.8x I think
for a 50mm. So, it will be 8*50*0.8 to get the eqivelant.
So its a 320 on my D100. (I think ive got that right?)


--
Vin
Melbourne, Australia
Remove no and spam from both sides of the @ sign email address to reply