25.06.2020 CF Digiscoping camera support bracket. Pt:4.

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I have cut a full length 50mm wide strip off the 340x150mm CF plate. A single strip still feels remarkably stiff in bending. I am now thinking about measurement of the effect of this cantilevered "leaf spring." The load on the free end is now about 2lbs. The intention is to compensate for much of the load on the pancake lens. An upward force is required on the free end of the cantilever to "lighten the load." 

If I set a block on each side of the leaf spring then I can place the digital scales on the blocks. Two further blocks will be placed on the scales to support the base of the camera. The load measured by the scales should reduce as I add packing between the camera base and the free end of the leaf spring. There is no need to use the camera itself. It just needs a similar weight to replace it. I used scrap timber blocks.

The bridging idea worked fine with the scales. The problem was that I had overestimated the stiffness of the CF. It took all three strips of 50mm x 2mm to achieve full upwards offset of the camera load. Otherwise the strips sagged too much. Three strips allowed an 18mm high block to completely neutralize the camera load.

Three strips, clamped firmly together only at one end, are not a true comparison with a single beam of full 6mm thickness. The combined stiffness could be increased if I epoxy the strips together, as laminations. I shall leave the CF strips untouched until I get the longer camera plate tomorrow. No point in drilling holes unnecessarily. A longer camera plate might offer a completely different insight.

The longer plate is just a bit longer. I decided to stop trying to be clever with leaf springs and make a rigid strip to support the camera. So now I have glued all three strips together to produce a single strip 340mm long x 50mm wide x 6mm thick.

Presently being pressed in the jaws of a B&D workbench. The new strip will be bolted at both ends. So will not suffer serious shearing forces between the laminations. The load being supported is also rather trivial. I just wanted to save weight over a solid strip of aluminium.

The images shows the results of laminating the three CF strips together. It is a long way from the telescope foot to the camera base. The short [standard] Manfrotto plate won't add very much support. The Manfrotto plate is clamping the CF strip between itself and the Kowa foot.

In fact the support was now adequate but I had discovered another problem. The short cable between the wireless receiver and the camera can get trapped behind the pancake lens. I kept clicking away thinking the camera was still not happy with its support. The shutter kept refusing to go off. Once I cleared the cable from the lens there were no more problems with releasing the shutter. Nor were there any more grinding noises.

Whoah! Sirui makes a range of adjustable, long lens, support plates/ brackets/ rails to suit different tripod heads. This is exactly what I need to support the G9 camera base. They even do one for Manfrotto heads: The VH-350. Their own heads need a TY-350.

Now I wonder whether the camera support system can go low enough. If not, I can add packing under the telescope foot. Except that these long, camera rails aren't a stock item at Danish camera shops.

But see the next exciting episode:

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25.06.2020. CF Digiscoping camera support bracket: Pt.3.

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An interesting possibility has occurred to me. The Panasonic BGG9 battery grip is almost the correct height to act as the necessary riser. Give or take an odd millimetre here or there. I already have a spare battery which I charge and recycle through the G9. That way both batteries are regularly exercised. Far better than leaving one untouched and constantly recharging only one.

The BGG9 has a tripod mounting hole underneath ready for the bracket retaining screw. If I need to make up height more over the BGG9 I can easily add Teflon spacers to support the camera base.

This will ensure the camera base can slide effortlessly on the CF plate. While allowing me to easily add more height if the lens needs more upwards bias to help unload the weight of the camera on the pancake lens mechanism.

I was already considering the battery grip to extend my digiscoping sessions with the reserve battery. Though changing batteries is hardly a chore, it does require access to the underside of the camera. Such fiddling, while standing in knee length grass is not ideal. Luckily I have found a dealer offering a heavily discounted example online. It should be here tomorrow.

Next day: The battery grip has arrived thanks to the dealer and the Danish postal service. I have arrowed the new image with the battery grip in place. On the left, the telescope foot is tipped up at the front. The camera is obviously too low, relative to the telescope and must be lifted slightly.

I  now realize that it might be possible to fix the camera firmly. Then have the lens trombone [or telescope] inside the DA-10 adapter. The linear lens movement [when focusing] is about 4mm. [Arrowed]

The DA-10 provides a wide, internal groove for this potential but only if the camera is properly supported. No doubt this is how the rigid, PS1 arm/bracket was supposed to function in combination with the DA-10 adapter.

The lens must obviously be placed a certain distance within the DA-10. This will avoid "hitting the buffers" during focusing. Only then can the camera be safely clamped to the supporting bracket.

For the rest of this [supporting bracket] project I shall proceed with the fixed camera arrangement unless it proves unworkable in practice. Now I just need to find the height of enough packing under the camera to unload the lens from most of the weight of the camera.

See new image [above right] with the telescope foot now level thanks to the 4mm packing under the battery grip. Until I can clamp the new [longer] camera plate to the CF and the telescope foot, I shan't know how much packing I really need. I have used a strip of 4mm, self-adhesive rubber for packing. Ideal for ensuring a slip free hold on the camera [grip] base.

It is fortunate that the CF [carbon fibre] plate is just the right length to reach from the telescope's foot to the camera base. Until I receive the longer camera plate [on order] I cannot determine where the holes need to be drilled in the carbon fibre. Nor have I yet decided how wide to cut a suitable strip from the CF plate. I can always epoxy laminate two layers of CF together if need be. Though the CF is amazingly stiff and very unlikely to need be any thicker.

Perhaps I ought to proceed with a trial bracket using the present camera plate. I'm trying to think how I can use my platform digital scales to measure the weight compensation. How can I measure the upward spring effect of the carbon fibre plate by changing the packing thickness under the camera base? I could try clamping the strip of CF to see.

Whoops! The camera shop has just this moment confirmed despatch of the longer camera plate. What a strange coincidence! 😊

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