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Alt-Az tilt adjustment on Equatorial mount

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#1 Cyclop_si

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Posted 10 July 2009 - 06:07 PM

ASA is introducing new equatorial direct drive mount DDM60, small brother of their DDM85.

Some photos can be found here:
http://www.astrosyst...09_DDM60_03.jpg
http://www.astrosyst...09_DDM60_01.jpg

And also some drawings:
http://www.ims.tuwie...mann/DDM60.html
http://www.ims.tuwie...nn/DDM60_2.html
http://www.ims.tuwie...emann/ddm60.pdf

What surprises me is their new system for Alt-Az adjustment. I am not sure if I understand it correctly; but it looks to me that this is achieved by tilting top baseplate, which is centrally supported, with four knobs, separated by 90 degrees.

I am wondering if there is some other mount with similar Alt-Az adjustment and how does it work under full load (scope and counterweights)?

Due to its size, DDM60 is interesting as portable mount as well. However, Alt-Az range of DDM60 is supposed to be just +-2.5 degrees and this mount is without polar scope, intended to be drift aligned. I am wondering if this is sufficient for portable setup.

#2 Yedgy

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Posted 12 July 2009 - 02:43 AM

I think the four knobs on the baseplate are for azimuth. There are two knobs on each side of the head with curved grooves; this must be how they set elevation.

#3 Eddgie

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Posted 12 July 2009 - 11:10 AM

I agree. The curved grooves in the altitude Trunnions look to me to be used to set the elevation.

An interesting by-product of this is that it would allow the mount to be used in true Alt-az mode (I do not know if it has that capability electronically).

#4 Cyclop_si

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Posted 12 July 2009 - 12:20 PM

I think the four knobs on the baseplate are for azimuth. There are two knobs on each side of the head with curved grooves; this must be how they set elevation.


You might be right.

But for me, it looks like those "two knobs with curved grooves" are for rough Altitude adjustment and fine Altitude adjustment is achieved with two knobs on baseplate, which lies on the same direction as RA axis.

Actually, I think there is not problem for Altitude adjustment. The issue might be with Azimuth fine adjustment, since if this is achieved by tilting top baseplate, its range terribly depends on your geographic latitude, and it can be full range on north or south pole and zero on equator...






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