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DIY Canon Micro focuser

Guest peepshow

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Guest peepshow

I have started doing all my AP outside without any PC at  present. ( bringing camera indoors to download.) 


Having just spent an arm and a leg (well two legs actually !) on a Canon 200mm f2.8 lens I thought it time to enable accurate focusing with it.


I used two 6-1 gear ration epicyclic gears used in old wireless sets to give me 36-1 step down driving the 12-1 toothed belt around the Canon lens barrel.

This gives me 1/4 inch movement around the black knob which  moves the lens focusing ring .001 inch radial movement.


It is all mounted on the lens using a tripod mounting, so when the lens is removed from the camera all the focusing gear comes off with it.

Note the lump of wood. :lol:


There is also a red dot finder and a laser finder as you can see mounted on the camera flash shoe(!),  all in addition to my skywatcher GOTO.


Do you think that I will be  able to find M31 with that lot. :lol:  ;)








Edited by peepshow
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  • 4 weeks later...
Guest peepshow

Interesting set up Richard.

I am dying to see this in action.


I've had very few clear night to get this lens into sharp focus with my thingy.    Had to take series of images at slightly different settings to hit the right spot.

 But here is a 7 second image at f2.8 full aperture and at ISO 1600. taken last night.  Un cropped.

Taken at short exposure to ensure that there is no tracking error on my unguided barn door, so that star shapes are due to lens performance and not star trails.

.....noise also removed. :)

UV filter at front of lens but no other filters.  Modified Canon 600d.


Stars seem very good shape to me right up to the edges, although it doesn't seem to like Vega very much. :)


So I shall be using this fast f2.8 at full aperture in future for all my imaging......It might even pierce through all the clouds I have every night. :D





Edited by peepshow
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