Oh a cobbling we will go.

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PESCA

Oh a cobbling we will go.

Post by PESCA » 24 Jul 2013, 09:22

As mentioned yesterday, I've been cobbling again.

Been playing with prisms for a long time now, with the intention of using one in conjunction with a near eye display, but, due to the the poor picture quality of the cheaper ones and not wanting to shell out several hundred pounds on a high res one, I've utilised a 5" screen.

Anyhow, main components are a Watec board cam (courtesy of Bruce), 16mm lens, 5" high res monitor, 3 amp/hr 12 volt cell, Amici prism, Pulsar dsa and generous amounts of acetal sheet.

Because a prism is used, there is no farting about with focal lengths. Camera can be hard up to the prism and the prism can be hard up to the rear of the eyebell, hence the fact that the unit only adds 80mm to the back of the scope.

The Watec board cam is mounted in a little project box and is fitted with a cheapie 16mm ir lens. The 3amp/hr pack slides into a cradle, hence there's no need for a big pack, I simply have a spare and change them over. All of the brackets are made from Acetal sheet as it's very easy to work with and once formed is very stable.

In use, it's much more than average and pleasantly surprising. Once you mount the ubiquitous illumination onto your scope, you're away. I think it's also possible to have your illuminator mounted on this unit, so it's truly self-contained. It's not the prettiest unit out there, but improvements will be made with the wiring, which should help. I'm guessing that a loupe could be mounted to the screen for those of you who would prefer this.

Anyhow, a few pics for you. Screen shots are both 16:9 and 4:3 (excuse the shakey shots, I need more hands).

The trees are at 80 yards. Bright sunlight. Low sensitivity on Watec. Bushnell 6500 on 2.5x.

George

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some bloke
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Re: Oh a cobbling we will go.

Post by some bloke » 24 Jul 2013, 12:14

There's no wood... but looks good my 'ansom. :clap:
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paulham
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Re: Oh a cobbling we will go.

Post by paulham » 24 Jul 2013, 17:57

George that looks awesome. What are the prisms,

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sunndog
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Re: Oh a cobbling we will go.

Post by sunndog » 24 Jul 2013, 18:18

nice and neat that george. can you get a proper cheek weld and still see the screen?
oslon black drivers
http://nightvisionforumuk.com/viewtopic.php?f=35&t=2333

when asking for advice, please include what n.v device and/or illumination you already have (if any) and what rifles you intend to use them on...cheers

PESCA

Re: Oh a cobbling we will go.

Post by PESCA » 24 Jul 2013, 23:15

Paul, there's only one prism. It's an Amici prism. It gives you a correct left/right image, unlike a mirror (without a camera which has mirror image facility).

Adam, you can't get full 'normal' cheekweld, but I've got the monitor pretty much as low as it will go, so it's not a total 'head up' shooting position.

George

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BT65
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Re: Oh a cobbling we will go.

Post by BT65 » 25 Jul 2013, 00:00

That's quite a thickness of glass inbetween the scope and the camera.

Is there any perceptible reduction in image intensity at night, as compared to mounting the camera directly behind the scope?
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PESCA

Re: Oh a cobbling we will go.

Post by PESCA » 25 Jul 2013, 07:28

BT, I've tried it both ways, and while there is some loss, it's barely perceivable (I'd guess at 5-10%). Prisms are good at light transmittance.

Guess I'll have to try and do some footage to show that it works well. Tried to take some screen shots last night, without any success. Without any illumination, I was viewing the same trees at midnight. No moon because of the heavy cloud cover, but obviously not that dark either.

George

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snoopy
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Re: Oh a cobbling we will go.

Post by snoopy » 25 Jul 2013, 08:59

for two prisms you could have an inch infront the eyebel.
'who is that masked man? its the kemosabby der..the bloody injun tells you every week!'

PESCA

Re: Oh a cobbling we will go.

Post by PESCA » 25 Jul 2013, 09:11

snoopy wrote:for two prisms you could have an inch infront the eyebel.
How would that work then, snoops?

You need a decent size prism, of maybe 25mm or so, and then you have to get the light through a 90 degree path. An Amici prism is essentially two prisms bonded together.

A beamsplitter reduces the overall length but you would need to use a camera with the mirror image facility (I know 'cos I've tried a beamsplitter).

George

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Re: Oh a cobbling we will go.

Post by snoopy » 26 Jul 2013, 01:01

the camera sits looking backwards on top of the scope at prism one which looks down into 2 which is looking up the scope..
'who is that masked man? its the kemosabby der..the bloody injun tells you every week!'

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