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Photo Forum / Digital Photography / Digital Photo / September 2006

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How do you read the numbers on a lens?

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JimO - 24 Sep 2006 23:21 GMT
I have a Quantary 70-120 lens.  It works easy enough but I was curious how
to read the numbers on the lens.  In other words, how do I interpret and
apply them. There is one set of numbers on the lens side and on the mount
side there is a dial that has another set.  This ring is moveable but when I
move it to other settings, my lens doesn't work.  I've tried to search the
web but I'm probably not entering the right nomenclature to get a good
search phrase.  Can anyone direct me to site that I can use as a reference?

Thanks,
Jim
Cynicor - 24 Sep 2006 23:56 GMT
> I have a Quantary 70-120 lens.  It works easy enough but I was curious how
> to read the numbers on the lens.  In other words, how do I interpret and
[quoted text clipped - 3 lines]
> web but I'm probably not entering the right nomenclature to get a good
> search phrase.  Can anyone direct me to site that I can use as a reference?

You're probably looking at the aperture setting. It has to be set and
locked at the largest number so that the camera's autofocus will work.

Is this your first camera?
JimO - 25 Sep 2006 04:46 GMT
This is my first camera above the point and shoot. My last one was a
PowerShot G3.  It died and I got the "D50 Kit" with a Nikkor 18-55 and the
Quantary.  I work with computers but when I go into a camera shop, I feel
like a first-time computer buyer.  A subsequent post asked for the numbers.
Here they are...

First outer Ring
1:2   1:3  1:3.9
The next ring has two rows that are staggered.  I'll try to give the
approximate postions.

3.1                      3.5                    4                  4.5
4.9
0.95           1.0         1.1          1.2         1.3
1.5

There is another set of numbers along the same ring

    7               10       15     25     50
2                    3        4.5     7       15

Towards the mount there are some numbers that range from 300 - 70 but those
are pretty obvious.
The next ring has a lock and is moveable by position.  There are two sets of
numbers that are the exact same values and move together.  There is a set of
numbers on the larger part of the ring.  They range from

32  22  16  11  8  5.6  4
The smaller part of the ring has the exact same numbers only they are a
smaller size lettering (font).  The 32 is a different color and if the lens
is not on that setting, the camera will do nothing.  One other thing that I
just noticed in the orignal post is the information is wrong.  It's a 70-300
not a 70-120.  Sorry about that.  Anyway, that's what it looks like.

>> I have a Quantary 70-120 lens.  It works easy enough but I was curious
>> how to read the numbers on the lens.  In other words, how do I interpret
[quoted text clipped - 9 lines]
>
> Is this your first camera?
Randy Berbaum - 25 Sep 2006 06:09 GMT
: This is my first camera above the point and shoot. My last one was a
: PowerShot G3.  It died and I got the "D50 Kit" with a Nikkor 18-55 and
: the Quantary.  I work with computers but when I go into a camera shop,
: I feel like a first-time computer buyer.  A subsequent post asked for
: the numbers.
: Here they are...

: First outer Ring
: 1:2   1:3  1:3.9

This is the magnification for when you are using the macro setting. In
general what they mean is how much the image of the subject will be
magnified on the surface of the sensor. For non-macro use, these numbers
can be ignored.

: The next ring has two rows that are staggered.  I'll try to give the
: approximate postions.

: 3.1                      3.5                    4                  4.5
: 4.9
: 0.95           1.0         1.1          1.2         1.3
: 1.5

: There is another set of numbers along the same ring

:      7               10       15     25     50
: 2                    3        4.5     7       15

These are the focus distances. When you manually focus (and not just
looking through the lens to do so) these numbers will tell you where the
lens if focused. If you look next to the rows of numbers you should find
one is marked ft and one m (feet and meters).

Just guessing but the first set of numbers (3.1 to 4.9) is probably the
focus distance in feet when in macro. Just below that the numbers are
probably the same thing in meters. Then when you are not using macro mode
the nect two rings of numbers are correct. The range 7-50 is probably the
focus distance in feet while the 2 to 15 is the same thing in meters.

: Towards the mount there are some numbers that range from 300 - 70 but
: those are pretty obvious.
: The next ring has a lock and is moveable by position.  There are two
: sets of numbers that are the exact same values and move together.  
: There is a set of numbers on the larger part of the ring.  They range
: from

: 32  22  16  11  8  5.6  4

This is the aperture setting (measured in f-stop, sometimes just called
stop) the larger the number the smaller the amount of light passing
through the lens.

: The smaller part of the ring has the exact same numbers only they are a
: smaller size lettering (font).  The 32 is a different color and if the
: lens is not on that setting, the camera will do nothing.  

I am not sure about your particular lens and camera so I can not be exact
on this but I suspect that the camera is set to control the aperture
internally and so the lens must be set to the setting that allows the
camera to do this (the 32). When you manually override things by
physically changing the stop the camera can not properly read the light
conditions and thus will lock you out of shooting the image. There may be
a setting in the camera that would allow manual aperture, but if you don't
know what you are doing you probably should just stick with the auto
settings. As you learn more about SLR photography you can begin exploring
such manual settings.

BTW if the second set of stop numbers are offset from the first set, this
may reflect the stop change as you zoom out. For example, when your lens
is set at 70mm and the stop is set at 3.5, and then you zoom in to the
300mm end the stop would likely change to 5.6 without any physical changes
in the aperture ring or the internal mechanisms. Not all lenses have the
dual numbers listed. For example one of my lenses is a 28-300 zoom that
when it is set to an f-stop of 3.5 and then I zoom to 300, the number on
the lens still says 3.5 but in the camera it is now 5.6. This can be
confusing to newcomers so for now just leave it in the automatic setting
(the marked 32) and let the camera handle the settings for you.

: One other thing that I just noticed in the orignal post is the
: information is wrong.  It's a 70-300 not a 70-120.  Sorry about that.  
: Anyway, that's what it looks like.

Hope this helps.

Randy

==========
Randy Berbaum
Champaign, IL
Jim - 25 Sep 2006 16:35 GMT
> : This is my first camera above the point and shoot. My last one was a
> : PowerShot G3.  It died and I got the "D50 Kit" with a Nikkor 18-55 and
[quoted text clipped - 62 lines]
> settings. As you learn more about SLR photography you can begin exploring
> such manual settings.
The OP previously said that he now owns a Nikon D50.   You must set the
aperature at the minimum size (f32 in this case) so that the automatic
exposure control will function.
The fine manual mentions this requirement, and it describes what the camera
reports if you don't.

> BTW if the second set of stop numbers are offset from the first set, this
> may reflect the stop change as you zoom out. For example, when your lens
[quoted text clipped - 18 lines]
> Randy Berbaum
> Champaign, IL

Jim
JimO - 26 Sep 2006 03:19 GMT
Thanks. That is a lot to digest mentally.  As with any technology, the
hardest hump to get over is getting the critical mass of knowledge to be
able start making the mental connections to put the theory into practice.

>> : This is my first camera above the point and shoot. My last one was a
>> : PowerShot G3.  It died and I got the "D50 Kit" with a Nikkor 18-55 and
[quoted text clipped - 94 lines]
>>
> Jim
Jim - 25 Sep 2006 00:06 GMT
>I have a Quantary 70-120 lens.  It works easy enough but I was curious how
>to read the numbers on the lens.  In other words, how do I interpret and
[quoted text clipped - 6 lines]
> Thanks,
> Jim

Why not through caution to the winds and post what these numbers are?
Maybe they are f stops, maybe they are focal lengths, maybe they are filter
size, maybe they are serial numbers, maybe .........
Jim
Bob Williams - 25 Sep 2006 00:28 GMT
> I have a Quantary 70-120 lens.  It works easy enough but I was curious how
> to read the numbers on the lens.  In other words, how do I interpret and
[quoted text clipped - 6 lines]
> Thanks,
> Jim

Jim,
Give us the numbers (or sequence of numbers)and we will get back to you.
Not many of us have a Quantaray 70-210 lens so we can't be sure which
numbers you are referring to.
Bob Williams
JimO - 25 Sep 2006 04:46 GMT
The numbers are on the first reply to my original post.

>> I have a Quantary 70-120 lens.  It works easy enough but I was curious
>> how to read the numbers on the lens.  In other words, how do I interpret
[quoted text clipped - 13 lines]
> numbers you are referring to.
> Bob Williams
MInister of Information - 30 Sep 2006 03:05 GMT
Is this because Quantaray is not considered a very good lens?

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> Jim,
> Give us the numbers (or sequence of numbers)and we will get back to you.
> Not many of us have a Quantaray 70-210 lens so we can't be sure which
> numbers you are referring to.
> Bob Williams
 
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