C-Mount Zoom Lens for EJ230

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Starlight
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C-Mount Zoom Lens for EJ230

Post by Starlight » 06 Feb 2014, 00:16

Greetings,

I am new to this forum. I have been reading for a few days now and can not seem to locate the answer to an issue I am running up against in my desire to build a Scopeless out of an EJ230. I would like to put a zoom lense on this camera without having to mill it back. I believe--and correct me if I am wrong--that a C-Mount lens will make this possible. 5-7 X zoom is preferable, and fixed is fine. I am having a very hard time trying to locate such a lens. Any advise from you gentleman would be greatly appreciated. Thank you.

P.S. I have an adapter recommended by Roland of "Rolaids Bench" Youtube Channel that I believe will accommodate a C-Mount Lens. I am looking for recommendations on which lens to buy. I plan to mount this on an AR-15 for pest control.

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some bloke
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Re: C-Mount Zoom Lens for EJ230

Post by some bloke » 06 Feb 2014, 00:26

Hi Starlight. If you get a zoom lens you need to decide what mag/FOV you want them lock up the zoom because it will almost certainly shift zero every time you adjust the zoom.

You may have seen have one on my scopeless tube rig - but it is primarily a means of deciding what FOV I want before fitting a fixed focal length lens.

C mount lenses and CS mount lenses merely have different distances between the flange of the lens and the face of the image sensor. http://www.chinasecuritysystem.com/Surv ... s/416.html

A CS mount lens rig can be about 5mm shorter than a C mount rig.
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Starlight
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Re: C-Mount Zoom Lens for EJ230

Post by Starlight » 06 Feb 2014, 01:10

Thank you for the reply and the link. I will set about reading it.

andybig
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Re: C-Mount Zoom Lens for EJ230

Post by andybig » 06 Feb 2014, 16:15

Also take into account that many sellers will advertise a lens as a CS when sometimes its a C lens because they dont know what they have.
Im sure many forum members have seen lenses marked CS only to find they were a C lens.

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some bloke
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Re: C-Mount Zoom Lens for EJ230

Post by some bloke » 06 Feb 2014, 18:25

andybig wrote:Also take into account that many sellers will advertise a lens as a CS when sometimes its a C lens because they dont know what they have.
Im sure many forum members have seen lenses marked CS only to find they were a C lens.
Yup - and some arrive with no indication of which they are - so it gets forgotten once it's been in the components drawer for a while.
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seewolf
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Re: C-Mount Zoom Lens for EJ230

Post by seewolf » 07 Feb 2014, 15:36

Question! When I mount a C-mount lens with a adapter to a EJ230 Bulletcam, then I dont must cut it 5mm back? Is this right?
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andybig
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Re: C-Mount Zoom Lens for EJ230

Post by andybig » 07 Feb 2014, 15:59

A couple of things to take into account when fitting the m12-C/CS adapter.

1, the adapter will add 1mm to the focal length.
2, before you start cutting your bullet camera try to fit the C/CS lens.
3, different bullet cameras require slightly different amounts to be removed.

Finally.... you will notice people saying to remove about 5mm.
So start with 4mm and try the lens, you can always take a bit more off but you cant stick it back on.

Iv not do this with an ej230 yet but i have done it with a couple of other bullet cameras with great results.

m_pragnell
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Re: C-Mount Zoom Lens for EJ230

Post by m_pragnell » 07 Feb 2014, 18:21

What Andy said I've seen formulas and people measuring to the sensor and if that works for your great but it was trial and error for me, took a while but you can only do it once

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Hilbily
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Re: C-Mount Zoom Lens for EJ230

Post by Hilbily » 07 Feb 2014, 20:41

Look on ebay or amazon for a S(m12x.5) to C(1"x32) adapter, here is a cheap place where I got mine: http://www.ebay.com/itm/C-mount-thread- ... 41744b5a8b
If you use a true c mount lens you will have to cut the camera but only a little off 1-2mm or so.
A little to long it will never focus, a little too short and you only lose the very close focus ability.
When cutting the camera and checking your focus in daylight, you need to go past where you achieve infinity focus, just a little, as the IR focuses differently.
Japanese C and CS lenses are better quality(tamron, computer/fujinion/pentax/ECT) and I think C are better than CS.
Cheap lenses and zoom lenses will cause POA/POI issues
I cut my ej off to use CS and with the 5mm adapter it will use C mount, I also hot glued the 50mm lens focus adjustment, only the iris is free to adjust.

Starlight
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Re: C-Mount Zoom Lens for EJ230

Post by Starlight » 08 Feb 2014, 19:26

Hilbily wrote:Look on ebay or amazon for a S(m12x.5) to C(1"x32) adapter, here is a cheap place where I got mine: http://www.ebay.com/itm/C-mount-thread- ... 41744b5a8b
If you use a true c mount lens you will have to cut the camera but only a little off 1-2mm or so.
A little to long it will never focus, a little too short and you only lose the very close focus ability.
When cutting the camera and checking your focus in daylight, you need to go past where you achieve infinity focus, just a little, as the IR focuses differently.
Japanese C and CS lenses are better quality(tamron, computer/fujinion/pentax/ECT) and I think C are better than CS.
Cheap lenses and zoom lenses will cause POA/POI issues
I cut my ej off to use CS and with the 5mm adapter it will use C mount, I also hot glued the 50mm lens focus adjustment, only the iris is free to adjust.

Thank you very much for this post. I have the adapter and am waiting on delivery of a 75mm C-mount lens presently.

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