The "Wet Feet" of the Astrozap Equatorial Mount
Posted 26 May 2011 - 02:22 PM
By Dr. Fanis
Posted 27 May 2011 - 12:12 AM
Actually, one of the better reviews I've read. If anyone fails to realize what they're going to get when they buy the mount, it won't be because you didn't cover it.
Clear Skies to you as well!
Posted 27 May 2011 - 01:01 AM
Posted 27 May 2011 - 04:02 AM
The additional section contains rough language that is not suited for the CN forums but shows my feelings all the way. I tried to be funny initially and later I noticed a few details that took some of the fun away. I do not like it when people try to scam other people. Maybe I have old standards that not everybody understands. Who knows...
In general I would say that both reviews are very similar. I did not find any negative points beyond whatever I described in my original review. At some point I added control cables to the mount because in the dark they are more functional than knobs.
Posted 27 May 2011 - 02:48 PM
Though this mount handled the small scopes pictured, it would do horribly with a 20 lb load unless that included the weight of the counterweight.
You see, it's a function of shaft diameter, bearing size, casting robustness, etc.
I work in the industry, and what follows are my recommendations for price range of mount to accompany a particular load for visual use. Exceed this, and the periodic error will be too severe for decent imaging, and the shimmy period will exceed an acceptable period for visual use, though there are exceptions. The tripod makes a big difference. Mount most mounts on a pier and they will handle heavier loads. But I am assuming the tripods that come stock on the equatorial mounts. These weights are for OTA only.
$300-$500 up to 8 or 10 lbs.
$600-$1000 up to 15-17 lbs
$1300-$2500 up to 25-30 lbs
$3000-$4500 up to 40-45 lbs
$7000-$8500 up to 70-80 lbs
>$10000 heavier loads
I think a lot of people must either observe in no-wind environments, or simply put up with a lot more shimmy and shake than I would find acceptable. Certainly a lot of people have a fine time observing with overloaded mounts--I see them all the time. But my imaging friends would be a lot more stringent than I am about appropriate mount and OTA combinations (an 8" newtonian on an AP1200 mount, for instance), so I am being a lot more liberal. I think, too, that once you have experienced a rock-solid mount with a 1-2 second shimmy period, it would be hard to go back to one with an 8-10 second shimmy period.
The author found all the ins and outs of a lightweight mount with a lighter weight load, and the two examples of scopes he used with the mount were excellent examples of proper loading for the mount in question. I am presuming that the load requirement to which he was referring included the weight of the counterweights.
A nice write-up, with deeper exploration of the fine points of the mount than most users would give it.
Posted 01 June 2011 - 10:55 PM
As an example I will mention a variable projection eyepiece adapter. Adorama sells one with the Meade logo on it for $35 (S/H included), while telescopes.com sells the same item for $54 (S/H included). A Chinese no-logo version that looks exactly the same as the Meade one, cost me $15. No idea why such a difference in price is necessary.
Of course nobody sells good telescope mounts for a low price. But few seem to agree on what each mount can carry. The CG5 that I use is such an example. Your estimate for its $600 to $1000 price range is 17 lbs for decent results but telescopes.com suggests that you can put on it 65 lbs (I very much doubt it) and others suggest up to about 28 lbs for low PE. The weight of my C8 with a modified C70 on it, a motorized Creyford focuser, a mechanical digital counter for primary focus, a Telrad, a green laser pointer, a modified webcam and a very small balancing weight comes to about 19 lbs. To that I may add soon a Canon T2i and the total is going to be around 20 lbs. Will it work with low PE? Maybe. As you said there are exceptions. I hope to be one of those exceptions now that I replaced all that original sticky grease with better quality synthetic grease suggested by more experienced users.
Thanks for the positive comments on my review.
Posted 14 June 2011 - 12:25 PM
For those on a budget my advice would put your hard earned dollars into something you won't have to replace in a year or two.
That said I think this review for a new out of the box mount is in depth and well done.
Posted 28 July 2012 - 01:34 PM
Recently I performed a partial tune-up of the RA axis mechanical parts. One thing was obvious: the mount was made to function as cheaply as possible. There is no bearing inside, just a couple of very thin plastic washers to reduce the friction of the moving parts. The familiar Chinese sticky grease was everywhere but I removed it and lubricated the parts with a good synthetic US made grease. Before that I used fine sandpaper to clean up some edges and other manufacturing defects. The RA axis is smoother now.
Another issue is the polar finder. My original review stated that I had not seen one like this before. A bit of research on this and other astro-related web sites indicated that the Astrozap EQ mount is an almost exact clone of the Meade LXD75 mount, including its polar finder. Aligning the finder with the mount was not an easy task because the three hex screws that control the reticle movement were difficult to handle. There was too much sticky grease inside the polar finder reticle compartment. I removed most of it and I have replaced those screws with longer ones to help me align the finder faster. But it appears that I need to check and correct that alignment often. Due to the longer screws that I use the polar finder cap does not fit anymore.
To polar align the mount itself, I use the procedure found here: http://www.weasner.c..._alignment.html
I must say that I am extremely pleased by the simplicity and results of that procedure on both mounts that I own, the Astrozap and the CG5-GT. The latter features Celestron's polar finder. I have added a modified Galileo driving system on the RA axis of the Astrozap. The tracking results surprised me considering that it is an open loop system without feedback. A post with all the technical details and calculations will follow some time soon. I think that other users will find it very useful mainly because it combines information scattered on various web sites and posts.
None of the two scopes that I mentioned in my original review is used with the Astrozap mount anymore. They have been replaced by a Vixen R130Sf that I bought for a huge 50% discount on Amazon a few months ago. It was one of those flash sales they have often. The Vixen is a beautiful scope externally and works way better than other smaller scopes of its kind. Add to that the $113 price I paid for it and you have a winner. I need to replace its spider vanes though because bright objects look really bad with spikes around them. It's excellent on Saturn, a disaster on Venus, very good with the Moon, the Orion Nebula, etc.
That's all for now.
Posted 31 July 2012 - 10:08 AM