Astrophotography: My EQ 5 Mount for Astronomical Observations
Last Update: 23 March 2001
What is the EQ 5 Mount
The EQ 5 Mount is a German equatorial mount made probably in China. It is almost a clone of the well-known Japanese VIXEN GP Mount.
Jeff deTray (www.astronomyboy.com) has written a good description of this mount and I do not have to repeat it here. The Celestron CG-5 Mount he describes seems to be the EQ-5 mount. According to his text, I own the latest version with two ball bearings. He alse writes on disassembling, cleaning and adjustment of the mechanics.
My experience ...
I had been in search for a larger mount than my VIXEN NP mount which indeed does a good job and I will keep as backup und highly portable mount. I read Newsgroup articles on GP, GP-DX and EQs. I also read on difficulties with the EQ-5 mount especially with the thick grease inside. But I decided for it, as the price was unbeatable low.
I bought the mount in November 2000, when it was sold for a good price as DM 590.-. I additionally purchased the polar finder scope - which is NOT worth its money (DM 90.-). The mount arrived three days after I had ordered it per standard mail.
I unpacked everything and I had to build up the tripod, which was packed in single pieces. After I put everything to its place I had a quite heavy mount with a very lightweight tripod. Just to say it right now: That tripod is good enough as stand for your flowers AND this is all that it is good for. I own a backup tripod for my NP mount and I put the legs to the EQ mount, what gives a good improvement in stability.
I unpacked the EQ-5 mount and fixed it to the tripod. At once I saw the problem I read only before: The grease inside came out of some holes. Once you have it on your fingers you will have difficulties to get rid of it again.
But when I first tried to turn it in Rightascension I found you`ll need a lot of force to move it with the worm gear. I loosened the clamp to make a fast move, but I needed heavy force to turn it. Frustration (!) The Declination axis is a lot easier to turn and almost that what I expected.
With the MT-1 RA drive attached I had my 150mm f5 Newton mounted and I made my first observations in November 2000. But the problems mentioned above made no the observation no fun. The moter drive worked hard and quickly moving the scope by loosing the RA and DEC clamp to another object was a torture. So I decided on improving the mount
According to Jeffs article I opened the mount and took all things I could find apart. This was almost easy and made no further problems - Yes on our kitchen table, when the wife was in bed already ...
I found a brass/aluminium combination in the worm drive of the mount and two ball-bearings. Unbelievable that this should not move easily.
Everything that is intended to be able to move somehow was hidden in thick grease. I cleaned all parts with washing-benzine and an old toothbrush. This made the parts turning very smooth. Exept the worm and clamp ring. It stuck very tight and moved only with heavy forces. And even after cleaning it did not do any better. I removed some sharp edges with smooth sand paper and then I took the ring to my 87 year old neighbour who owns a milling machine and we milled 50 micrometer (=0.05 mm) out. This made the ring rotate easy and with new graphite molicote grease it works almost perfectly. I put this new grease very thin to all turning and moving parts. So every work I made on the RA gear I repeated with the Declination axis too. Milling the ring of the DEC axis was nat necessary. And I have half a good working mount now turning everywhere very smooth. It is easy to balance out.
Adding the Motors
I bought the original VIXEN motors (MT1) and fixed them to the mount. As the holes for the screws to fix the RA drive motor is somewhat hidden I had to loosen the polar height screws. But normally do this once and it does not matter any further. The two motors drive the mount now very precisely. The only thing I had to do was to adjust the worm drive carefully. You should really spend some time on this work it pays off in almost no dead play in the worm drives. I control the motors with the original VIXEN SD-1 controller from my NP-mount in Rightascension and a modified MD-6 controller I got from a friend for Declination.
What to do
I'll have to make an adapter to attach the mount to my fixed aluminium pod in the garden. The one from the NP mount does not fit. Then observation sessions hopefully will make a lot of fun as they do already with the NP mount on that pod.
The EQ-5 mount as it came from the dealer did not meet my expectations. But I could improve it in a good way and I can use it for observations and photography now. With attached MT-1 motors it works smooth. I did not check its periodic error, but all I can see is that it behaves a bit better than my NP mount and that one is not bad.I highly recommend reading the article of Jeff deTray (www.astronomyboy.com) on the EQ-5 / CG-5 mount.
Text and All Images are Copyright by Christoph Petermann DF9CY
GO (back) and visit my homepage