3.06.2020 CF digiscoping camera support bracket. Pt.1.

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I have ordered a plate of carbon fibre from a model shop to make an extended camera support bracket. Like that available from Kowa. CF sheet is lighter and stiffer than the same dimensions in aluminium.

The plate has arrived and is incredibly stiff and light! It rings like a metal plate when struck. The sheet is 2mm thick and 340mm x 150mm. More than enough to make several camera support brackets.

I was going to order a 3mm sheet but even 1mm thickness might easily have done the job. A 1.5lb camera is hardly Olympic weight lifting! CF is very attractive as a material for this purpose. It is "camera" black and doesn't weather like bare aluminium. It will not add much weight of its own. The cost was about £30 equivalent including overnight P&P. The TSN-PS1 cost nearly £200 equivalent!

The difference in height of the telescope foot and the base of the camera must be allowed for. An upward spring bias will probably help to relieve more of the weight of the camera body on the pancake lens mechanism. This can be achieved with a suitable spacer. I already have an extended, camera base plate on order. So shall see if I can't add the CF extender to that. The new plate may be completely different from the very short one which was supplied with the Manfrotto 500 head.

The balance of the digiscoping system is already tail heavy. This is thanks to the considerable weight of the G9 camera on the far end of the Kowa DA10 adapter system and zoom eyepiece. So I shall have to keep the weight of my extending support bracket as low as possible. Or, slide the whole system forwards in the head. Which I obviously can't do with the standard camera plate.

From a quick measurement there is a difference of 55mm between the levels of the underside of the telescope foot and the camera base. I have some rectangular section aluminium tube which may be suitable as a lightweight 'riser' to match the difference in levels. 4mm of plate must be subtracted from the 50mm dimension to allow for two plate thicknesses.

I have no plans to make a copy of the PS1. There is really no need to try. A simple pair of CF strips, joined by the rectangular tube, as a riser, is all that is required. I am aiming for an upwards spring force to take most of the weight of the camera off the pancake lens. The telescope foot will rest on the CF where it fits over the tripod/camera plate. CF cannot be thermally bent to shape. At least not safely. It will want to return to its previous flatness if warmed. CF absorbs the sun's heat to become hot to the touch!

The bracket must not get in the way of normal digiscoping operations. So the spacer/riser tube cannot just go wherever it likes. Note from the image how the [deliberately placed] timber block would interfere with free access to the telescope's zoom ring and adapter thumbscrew. So this area must be avoided for the riser.

The aluminium riser [tube] is about 6mm short of enough height. The piece of ply under the camera is 10mm thick. So 10 - 4mm = 6mm. The 4mm represents two layers of  CF plate. Perhaps I can find a taller riser?  Or add some invisible packing somewhere to make up the difference.

A positive upward bias will best be achieved by altering the riser height. Or two risers can be used to produce a double stepped bracket. Placing a riser directly under the camera base would require a very long fixing screw for the camera's tripod bush.

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