Any Tricks for alt/az with no slow motion?
Posted 08 March 2010 - 11:55 AM
Posted 08 March 2010 - 03:25 PM
But in general, those of us that want slo-mo adjustments just buy a mount with slo-mo adjustments. They're not hard to find, and not terribly expensive. A versa-mount or porta-mount goes for less than the price of a premium eyepiece.
Posted 08 March 2010 - 03:58 PM
Posted 08 March 2010 - 07:09 PM
I found the key to smooth operation is to try for perfect balance fore and aft with a long dovetail plate. Once balanced the OTA seems weightless. Stays at the exact location I point the scope. Works for me up to 300X( with 2X barlow). I keep no tension at all on the altitude knob.
Of course this arrangement works with a single payload only. I would have to rebalance if I change from a 6 mm plossl to a ethos. ;-))
No handle is needed because the scope is in perfect balance. Only finger tip pressure is needed to track. I have my Giro 2 DX on a extra heavy duty tripod with geared center column. I can raise and lower the center column and the scope stays fairly close to the object I am pointing. But I also have a 9X50 RACI finder on the main scope so it's pretty easy to make small corrections if needed.
I much prefer using the Giro type mount than dealing with the stiff slow motion cables on the Oriona AZ 3 mount.
Posted 08 March 2010 - 07:26 PM
thanks; Don T.
Posted 08 March 2010 - 07:29 PM
Posted 08 March 2010 - 08:04 PM
Adding wt on the opposite side will help Az slewing but will have no effect on altitude operation.
I had a long discussion with someone who was using the Orion dual arm mount lasr year. He said his balanced OTA became unbalanced when he changed elevations. Sometimes take a dive if he tried to change EPs. Turned out he had a 50 mm finder (IIRC) mounted on the center clamp ring. As he tilt the OTA up the load will become unbalanced because the center of gravity shifts towards the rear. If you have similar mounting arrangement it will not work. Slo mo control will be needed.
I purchased two 12 lb counter wts for my Giro 2 for use with my 29.5 lb load. But found one 12 lb counter wt was sufficient for smooth panning so I usually don't take out the 2nd counter wt.
Posted 08 March 2010 - 09:11 PM
The C6 weighs around 10 lbs. The 4.5" will weigh abought 4 lbs with EP. the tube on the 4.5 is steel so I can add magnets to help counter ballance top heavy on the other scope if nessisary. Thanks for the information. Don T.
Posted 10 March 2010 - 07:26 PM
I have that very mount and that very problem. I recently posted on it, and had some respondents who had installed a sort of handle to the scope rings. I think it might even be possible to attach a handle to an unoccupied part of a long dovetail, but this needs study.
My configuration is a C80ED on one side and a 127 Mak on the other. Each/both could have a digital or video camera attached. At least, that was my plan, more for digiscoping than for astronomy. That was one reason I did NOT look at mounts with slow motion controls--I wanted to be able to pan quickly to follow a bird in flight. I haven't been able to reach the magical balance that another poster mentions, where it glides along at pressure from your fingertips. Maybe with more practice?
I'll see if I can find a link to that earlier discussion and post it.
Posted 10 March 2010 - 09:08 PM
Posted 10 March 2010 - 11:17 PM
--I wanted to be able to pan quickly to follow a bird in flight. I haven't been able to reach the magical balance that another poster mentions, where it glides along at pressure from your fingertips. Maybe with more practice?
I should clarify about my set up with the Giro 2 DX. My 6 inch F8 AP scope is about 5 ft long with dew shield attached and the focuser extended for normal viewing. I estimate I have at least 24 inch of lever arm to make small adjustments by holding and shifting the 2 inch diagonal end. That's why I do not need a handle. If you are mounting a SCT with shorter OTA on a different mount it may not be as smooth.
I have gone as high as 300X with the Giro DX for lunar viewing. My usual magnification for the planets with my 6 inch refractor is ~150 to 220X. Seeing limited, not the mount.
You can see photos of the Giro 2 DX mount in David N's review of Alt Az mounts in the CN review section.
For smooth tracking of flying objects I use Manfrotto 501 or 516 fluid heads with dual pan handles. But that's usually at lower power of 20 to 54X.
My viewing sessions are usually less than 1 hr so I prefer the ease of set up with Alt Az mounts. One mount I found unsatisfactory is the Orion AZ-3 mount. Just not refined enough for my taste. But I guess that's to be expected for low cost mount with slo mo controls AND tripod for ~$150.
Posted 11 March 2010 - 03:22 AM
Posted 11 March 2010 - 08:11 AM
Posted 16 March 2010 - 08:26 AM
Posted 16 March 2010 - 02:39 PM