Simply made DSLR laser pointer

[Guest peepshow]

Just knocked up this device for sighting a DSLR with any type of lens.

  Made from a brass disc, a green laser pen and a plastic housing for it.

 

The laser must be mounted  square to the disc's surface.

In use just place the flat side of the disc on the front surface of any lens barrel.

Flick on laser and sight to sky object.  Remove laser and take exposures.

Disc position on lens is unimportant.

 

To get laser square with disc place disc in corner of a door frame or window.

Rotate disc with laser on and watch dot on other side of room.  If it rotates disc is not

sq. Adjust until rotation stops or is small. 

(4 inch rotation across a 12 ft wide room = 1 degree error for example)

 

 

 

 

Lens barrel on disc

Edited December 7, 2013 by peepshow

[Perkil8r]

That's a neat idea.

[Guest peepshow]

Mike, I forgot to mention that it can also be used on the end of a telescope tube, providing the disc is large enough diameter to fit across the end of the scope tube and also that the end of the tube surface is square with the optical axis of the scope. 

 

 One can always make some type of clip to hold it in place temporarily and also a sliding ring to put the laser switch on.

 

If one doesn't have the means to drill a hole big enough to house the laser it could be wired to a block of wood mounted on the disc.  This too could be wood.  In fact a slab of wood could be used instead of a disc.

 

 So just 2 lumps of wood and a 5 quid laser and Bob's yer uncle.

Edited December 7, 2013 by peepshow

[Brantuk]

"it can also be used on the end of a telescope tube, providing the disc is large enough diameter to fit across the end of the scope tube and also that the end of the tube surface is square with the optical axis of the scope."

 

Can it be attached to a tube lid - or dew cap cover?

[Guest peepshow]

 

 

Can it be attached to a tube lid - or dew cap cover?

I don't have a scope myself  but see no reason why that shouldn't work,  providing that any surface used is at 90 degrees to the axis of the scope.

Accuracy required will depend on your FOV of course..............

 

On my DSLR I have a 200mm lens giving a FOV of about 8 degrees wide.  So even with a 1 degree error in the width direction I will still

have a selected object well within the picture frame.   Fortunately, the end of camera lens' barrels are very accurate.

 

Longer focal length lenses and scopes with narrower FOVs will be more critical in any angular error there is.   

 

Going to extremes, If the error is greater that half the FOV, that  will put the selected object

at the very edge of the picture frame.