View single post by Robert

Posted: Tue Mar 19th, 2019 06:44

Joined:	Mon Apr 2nd, 2012
Location:	South Lakeland, UK
Posts:	4066
Status:	Offline

The biggest issue at the moment is the 'wedge' the adjustment of elevation to equal the latitude, for long time exposures >30 seconds, it needs to be within a couple of arc seconds 5 at most and alignment with true celestial North within a similar margin. Magnetic North is simply misleading.

I am working on the design of the adjustment assembly, currently trying to find a short length (100mm?) of 8mm fine thread (1mm pitch) stainless rod. Those adjusters you pointed me to were amazing but way too accurate! For now anyway! I can find high tensile steel fine pitched rod and I may go with that but unless I keep it greased, it will corrode because of the condensation and damp air, due to being used outside at night.

At the moment I am using a Manfrotto 701 HDV head but the clamp locking is not positive enough and the adjustment is a nightmare. It has to be fine screw adjustment to stand a chance. If I can get to the point where the rigidity of the tripod is my limiting factor I will be satisfied. Currently fine adjustment of elevation and heading is the limiting factor, there isn't any!!!

I have considered the Manfrotto geared head but the SKU 400 which is about the only one rigid enough is £834.95.

https://www.manfrotto.co.uk/studio-geared-head

The other gears heads are gangly and wouldn't afford the rigidity needed, if indeed the SKU 400 would due to it's height, the head needs to be simple, very solid and squat.

____________________
Robert.