Lens required for c-mount camera

Hello,

I am looking for the proper specification of lens to put on a 1/2" CCD
camera. I would like to be able to focus and capture an object that is
18" to 24" away. The size of the image is 17" x 14".

The camera vendor said that a Computar c-mount lens (M0814-MP) with a
focal length of 8mm (f 1.4) would work. However when we attached it to
our camera, it couldn't properly focus on the object that was 2 feet
away. It only focuses on nearer objects (1 inch to about 10"). What
focal length lens do we need for this 1/2" camera sensor?


Thanks
Mike

eljainc

"eljainc" <> wrote in message news:6daab671-e7c2-48ed-9995-...

> I am looking for the proper specification of lens to put on a 1/2" CCD
> camera. I would like to be able to focus and capture an object that is
> 18" to 24" away. The size of the image is 17" x 14".
>
> The camera vendor said that a Computar c-mount lens (M0814-MP) with a
> focal length of 8mm (f 1.4) would work. However when we attached it to
> our camera, it couldn't properly focus on the object that was 2 feet
> away. It only focuses on nearer objects (1 inch to about 10"). What
> focal length lens do we need for this 1/2" camera sensor?

This may work...
Fuji TV-lens (for 2/3rds inch?), with what appears to be a "C" mount
(changeable, I think), 16-160mm at a constant f1.8, rather large and
heavy, nice condition, $80. There is a photo of it down the page at --
http://www.donferrario.com/ruether/f...ideo-audio.htm. With
zoom lenses, you can put an achromat (2-element close-up lens) on
the front, and then zoom to adjust magnification (use a medium-small
stop for best sharpness).
--DR ("d underscore ruether at hotmail dot com")

David Ruether

David Ruether wrote:
> "eljainc" <> wrote in message news:6daab671-e7c2-48ed-9995-...
>
>> I am looking for the proper specification of lens to put on a 1/2" CCD
>> camera. I would like to be able to focus and capture an object that is
>> 18" to 24" away. The size of the image is 17" x 14".
>>
>> The camera vendor said that a Computar c-mount lens (M0814-MP) with a
>> focal length of 8mm (f 1.4) would work. However when we attached it to
>> our camera, it couldn't properly focus on the object that was 2 feet
>> away. It only focuses on nearer objects (1 inch to about 10"). What
>> focal length lens do we need for this 1/2" camera sensor?
>
> This may work...
> Fuji TV-lens (for 2/3rds inch?), with what appears to be a "C" mount
> (changeable, I think), 16-160mm at a constant f1.8, rather large and
> heavy, nice condition, $80. There is a photo of it down the page at --
> http://www.donferrario.com/ruether/f...ideo-audio.htm. With
> zoom lenses, you can put an achromat (2-element close-up lens) on
> the front, and then zoom to adjust magnification (use a medium-small
> stop for best sharpness).
> --DR ("d underscore ruether at hotmail dot com")

What you may want to be careful of is whether your camera has a C-mount
or a CS-mount.
CS-mount cameras have a 5mm shoter distance from mount-to-sensor than
C-mount cameras, but the mounts are otherwise identical.
CS-mount lenses are used on all security cameras and on some of the
early home video cameras.

Eljainc may have been sold a CS-mount lens to put on his C-mount camera,
so found that it would only close/macro focus.

That "Fuji TV lens" may actually be a CS-mount lens, unfortunately
there's no way to tell without either looking at the engravings on the
lens (and checking for yourself) or mounting onto your camera.

I would suspect that unless a C-mount lens actually has "for 16mm film
camera", "cine lens" or something simliar engraved on the lens-barrel,
then there is a distinct possibilty that it's really a CS-mount lens.

dj_nme

eljainc wrote:
> Hello,
>
> I am looking for the proper specification of lens to put on a 1/2" CCD
> camera. I would like to be able to focus and capture an object that is
> 18" to 24" away. The size of the image is 17" x 14".
>
> The camera vendor said that a Computar c-mount lens (M0814-MP) with a
> focal length of 8mm (f 1.4) would work. However when we attached it to
> our camera, it couldn't properly focus on the object that was 2 feet
> away. It only focuses on nearer objects (1 inch to about 10"). What
> focal length lens do we need for this 1/2" camera sensor?

C-mount lenses are usually manual focus. You should be able to adjust it
to suit the correct distance for your subject.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Bob Larter

> Hello,
>
> I am looking for the proper specification of lens to put on a 1/2" CCD
> camera. I would like to be able to focus and capture an object that is
> 18" to 24" away. The size of the image is 17" x 14".
>
> The camera vendor said that a Computar c-mount lens (M0814-MP) with a
> focal length of 8mm (f 1.4) would work. However when we attached it to
> our camera, it couldn't properly focus on the object that was 2 feet
> away. It only focuses on nearer objects (1 inch to about 10"). What
> focal length lens do we need for this 1/2" camera sensor?
>
>
> Thanks
> Mike

Doesn't the camera have a mechanical adjustment to bring the sensor nearer
to the lens?

David

David J Taylor

"dj_nme" <> wrote in message news:4af3691e$0$16741$ u...
> David Ruether wrote:
>> "eljainc" <> wrote in message news:6daab671-e7c2-48ed-9995-...

>>> I am looking for the proper specification of lens to put on a 1/2" CCD
>>> camera. I would like to be able to focus and capture an object that is
>>> 18" to 24" away. The size of the image is 17" x 14".
>>>
>>> The camera vendor said that a Computar c-mount lens (M0814-MP) with a
>>> focal length of 8mm (f 1.4) would work. However when we attached it to
>>> our camera, it couldn't properly focus on the object that was 2 feet
>>> away. It only focuses on nearer objects (1 inch to about 10"). What
>>> focal length lens do we need for this 1/2" camera sensor?

>> This may work...
>> Fuji TV-lens (for 2/3rds inch?), with what appears to be a "C" mount
>> (changeable, I think), 16-160mm at a constant f1.8, rather large and
>> heavy, nice condition, $80. There is a photo of it down the page at --
>> http://www.donferrario.com/ruether/f...ideo-audio.htm. With
>> zoom lenses, you can put an achromat (2-element close-up lens) on
>> the front, and then zoom to adjust magnification (use a medium-small
>> stop for best sharpness).
>> --DR ("d underscore ruether at hotmail dot com")

> What you may want to be careful of is whether your camera has a C-mount or a CS-mount.
> CS-mount cameras have a 5mm shoter distance from mount-to-sensor than C-mount cameras, but the mounts are otherwise identical.
> CS-mount lenses are used on all security cameras and on some of the early home video cameras.
>
> Eljainc may have been sold a CS-mount lens to put on his C-mount camera, so found that it would only close/macro focus.
>
> That "Fuji TV lens" may actually be a CS-mount lens, unfortunately there's no way to tell without either looking at the engravings
> on the lens (and checking for yourself) or mounting onto your camera.
>
> I would suspect that unless a C-mount lens actually has "for 16mm film camera", "cine lens" or something simliar engraved on the
> lens-barrel, then there is a distinct possibilty that it's really a CS-mount lens.

Thanks - good points. Since the lens is so fast and wide-range for
zooming (and large/heavy), it seems unlikely to have been intended
for either home video or security cameras - but it is marked "Fuji
TV Lens". At a longish FL, the extra 5mm would be less significant,
and at some zoom position, it may well cover the desired field area,
but likely not at the desired distance if it is a CS mount...
--DR

David Ruether

David J Taylor wrote:
>> Hello,
>>
>> I am looking for the proper specification of lens to put on a 1/2" CCD
>> camera. I would like to be able to focus and capture an object that is
>> 18" to 24" away. The size of the image is 17" x 14".
>>
>> The camera vendor said that a Computar c-mount lens (M0814-MP) with a
>> focal length of 8mm (f 1.4) would work. However when we attached it to
>> our camera, it couldn't properly focus on the object that was 2 feet
>> away. It only focuses on nearer objects (1 inch to about 10"). What
>> focal length lens do we need for this 1/2" camera sensor?
>>
>>
>> Thanks
>> Mike
>
> Doesn't the camera have a mechanical adjustment to bring the sensor
> nearer to the lens?

All the C-mount lenses I've seen have one, yes. You need to adjust it
when you attach it to the camera.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Bob Larter

David Ruether wrote:
> "dj_nme" <> wrote in message news:4af3691e$0$16741$ u...
>> David Ruether wrote:
>>> "eljainc" <> wrote in message news:6daab671-e7c2-48ed-9995-...
>
>>>> I am looking for the proper specification of lens to put on a 1/2" CCD
>>>> camera. I would like to be able to focus and capture an object that is
>>>> 18" to 24" away. The size of the image is 17" x 14".
>>>>
>>>> The camera vendor said that a Computar c-mount lens (M0814-MP) with a
>>>> focal length of 8mm (f 1.4) would work. However when we attached it to
>>>> our camera, it couldn't properly focus on the object that was 2 feet
>>>> away. It only focuses on nearer objects (1 inch to about 10"). What
>>>> focal length lens do we need for this 1/2" camera sensor?
>
>>> This may work...
>>> Fuji TV-lens (for 2/3rds inch?), with what appears to be a "C" mount
>>> (changeable, I think), 16-160mm at a constant f1.8, rather large and
>>> heavy, nice condition, $80. There is a photo of it down the page at --
>>> http://www.donferrario.com/ruether/f...ideo-audio.htm. With
>>> zoom lenses, you can put an achromat (2-element close-up lens) on
>>> the front, and then zoom to adjust magnification (use a medium-small
>>> stop for best sharpness).
>>> --DR ("d underscore ruether at hotmail dot com")
>
>> What you may want to be careful of is whether your camera has a C-mount or a CS-mount.
>> CS-mount cameras have a 5mm shoter distance from mount-to-sensor than C-mount cameras, but the mounts are otherwise identical.
>> CS-mount lenses are used on all security cameras and on some of the early home video cameras.
>>
>> Eljainc may have been sold a CS-mount lens to put on his C-mount camera, so found that it would only close/macro focus.
>>
>> That "Fuji TV lens" may actually be a CS-mount lens, unfortunately there's no way to tell without either looking at the engravings
>> on the lens (and checking for yourself) or mounting onto your camera.
>>
>> I would suspect that unless a C-mount lens actually has "for 16mm film camera", "cine lens" or something simliar engraved on the
>> lens-barrel, then there is a distinct possibilty that it's really a CS-mount lens.
>
> Thanks - good points. Since the lens is so fast and wide-range for
> zooming (and large/heavy), it seems unlikely to have been intended
> for either home video or security cameras - but it is marked "Fuji
> TV Lens". At a longish FL, the extra 5mm would be less significant,
> and at some zoom position, it may well cover the desired field area,
> but likely not at the desired distance if it is a CS mount...
> --DR

The odds are that the camera that this "TV lens" was designed for may
not have had a full 16mm cine sized sensor, more likely it has a much
smaller one.
So that when it's mounted on the correct camera (which likely has a
CS-mount), it covers the sensor.

dj_nme

"dj_nme" <> wrote in message
news:4af804ed$0$5421$ ...

> The odds are that the camera that this "TV lens" was designed for may not have had a full 16mm cine sized sensor, more likely it
> has a much smaller one.
> So that when it's mounted on the correct camera (which likely has a CS-mount [which does not have the same back focus distance as
> a C-mount lens]), it covers the sensor.

The intended sensor size may be 1/3rd", and the likely use for
the lens was for surveillance - so I will be changing my listing at --
http://www.donferrario.com/ruether/f...ideo-audio.htm to,
"Fuji TV-Z lens, with what appears to be a "C" mount (or "CS"
mount - not sure), 16-160mm at a constant f1.8 widest stop,
rather large and heavy, nice condition, $80." Thanks.
--DR

David Ruether

David Ruether wrote:
> "dj_nme" <> wrote in message
> news:4af804ed$0$5421$ ...
>
>> The odds are that the camera that this "TV lens" was designed for may not have had a full 16mm cine sized sensor, more likely it
>> has a much smaller one.
>> So that when it's mounted on the correct camera (which likely has a CS-mount [which does not have the same back focus distance as
>> a C-mount lens]), it covers the sensor.
>
> The intended sensor size may be 1/3rd", and the likely use for
> the lens was for surveillance - so I will be changing my listing at --
> http://www.donferrario.com/ruether/f...ideo-audio.htm to,
> "Fuji TV-Z lens, with what appears to be a "C" mount (or "CS"
> mount - not sure), 16-160mm at a constant f1.8 widest stop,
> rather large and heavy, nice condition, $80." Thanks.
> --DR

No problem
I ran into the odd world of c-mount lenses about ten years ago when I
tried to stick a c-mount onto a p&s camera.
Half the lenses didn't say whether they are c or cs mount and working
out if a nice looking fast "c mount" lens on eBay was usable on my
kludge camera ended up being more trouble than it's worth.

dj_nme