EQ mounts not usable outside their latitude range?
Posted 18 February 2014 - 10:42 AM
I believe equatorial mounts cannot be used outside of their latitude range because the counterweights start hitting the tripod legs when setting them to lower than specified latitudes...anyone that can add any light to this please comment.
For example the orion 130 ST comes with an EQ-2 equatorial mount specified for latitudes 16-72. This is good for most of the world including North America, Europe, etc but does not cover observation sites closer to the equator (like almost half the north part of South America)
Posted 18 February 2014 - 10:50 AM
This CGEM needed a 15-degree wedge to reach 1 degree latitude, but the weight still clears the tripod (with a bit of care) because the wedge raises the mount an inch or two.
Some EQ mounts are designed for zero latitude and don't need a pier at all (e.g. Mach1).
Posted 18 February 2014 - 10:57 AM
Posted 18 February 2014 - 11:02 AM
1) Use counterweights that have smaller diameters. Helpful if an internal stop for RA does not already limit you from setting the RA axis for a lower latitude.
2) If there is an internal stop for RA and it looks like you can tweak it a bit to gain a few more degrees of movement (by grinding it), and you are real close to your goal, I would consider doing a bit of surgery on the stop.
3) Adjust the north facing leg (or legs) lower. Note that if you do this you will create a balance issue for the mount and telescope. Not really in respect to getting the scope balanced, but more of one for everything toppling over. If one leg faces north and it is shortened, you should consider using tent stakes and bungies or cord on the rear legs to keep them anchored. Counterweights on the south facing leg or legs (if north of the equator) or counterweights on the north facing legs (if south of the equator) is an option.
4) If setting up on a slope, use the slope to your advantage. You do not want to be looking north up a slope if north of the equator, or looking south up a slope if south of the equator. Do the opposite and let the slope help you. Note that the steps in #3 above is still very important. Take steps necessary to keep the mount stable.
Posted 18 February 2014 - 11:28 AM
I'm looking for validation that outside the latitude range an EQ scope will run into mechanical issues. Trying to recommend my brother not to buy the mentioned Orion setup because he will run into issues because of his latitude is too low for it ( it already shipped but can always exchange for something else) ....
I'm wondering whether doing modifications to the mount/tripod ( other than adding the wedge which means more $$s if available) or lowering the legs, etc will leave the mount not leveled thus impair the ability of the mount to track objects correctly ( intended use of mount is with the optional tracking motor).
Posted 18 February 2014 - 12:27 PM
Edit: Oh, I see Orly already suggested this, only he called it a pier.
Posted 18 February 2014 - 01:58 PM
Will help him look for something that works out of the box.
Posted 18 February 2014 - 06:53 PM
Posted 19 February 2014 - 09:11 AM
Most small EQ mounts are shown in the pictures configured so that when the couterweight shaft is positioned straight down, it will be aligned to be direclty over a leg.
This means that the angle of the leg will cause it to intefere with the counterweight.
But what is shown in the picture is not always the only way to configure the mount.
If the mount head can be turned with respect to the hub at the top of the tripod, try turning is to that when the shaft is straight down, it will be exactly between two of the legs.
If the mount has an azimut lug on the hub, usually they are designed so the lug can be removed and installed exactly opposite of the "North" leg.
For a light scope this will work OK, but if there is a lot of counterweight, the scope can become easy to knock over because the legs will not have the angle out from the hub to keep the CG back.
But this may by several degrees, You did not say how much you need, but this is the "Low Lattitude" configuration required for most GEMs. Still, not all will have enough clearance, but this can often get you 10 to 15 degrees of latitude.
Posted 19 February 2014 - 09:14 AM
Note there there is considerably more clearance for the counterweight shaft.
Low Latitude configuration of a GEM
But notice how the counterweights on this one stand so proud of the leg circle. This mount will tip over if the tube is removed before the weights. Correct assembly/disassembly would be to mount the tube, lock it into place, then mount the weights, opposite for tear down.
You can see though that it appears to have some kind of shaft extension??? And this made it necessary to go to the low latitude configuration. It considerable improves the angle and the arc clearance.
Posted 20 February 2014 - 05:06 AM
Posted 20 February 2014 - 10:52 AM
Right you are. A stock Paramount ME can adjust from 10 to 58 degrees. A stock Paramount ME II or MX can adjust from 10 to 65 degrees. Latitude adjustment wedge accessories are in stock and available in the Software Bisque online store to allow each of these mounts to adjust from 0 to 90 degrees.
I believe Software Bisque and AP provide a wedge adapter that will help reach lats that are outside the standard adjustments. Sorry, didn't see the rephrase part.