Re: #iEXOS-100 What do I need to mount a DSLR directly to the iexos #iEXOS-100

Wes Mcdonald


As Ian stated the relative pointing of the camera is not important to the mount’s ability to provide you tracking along the path of stars. Alignment is however important for your mount to accurately point your camera at an object using the goto function.  

With the camera mounted and the mount in polar home position (weight bar vertical and dec pointing north, altitude set equal to your latitude) imagine the camera lens can be tilted up or down relative to the vixen bar.  This is called cone angle.   Now imagine the camera can also be twisted left (west) or right (East).  This is called dec home error.   These two errors will be reflected in your pointing.

If you are using a relatively short focal length lens ( about less than 300mm) you can probably not worry very much about these errors.   Your camera field of view will be larger than the errors if you use a little care when adjusting your camera mounting, and get it close by eye.

If you want to go longer focal length you might want to be closer than by eye.

The tilt of your camera can be measured with a digital level I think.  Remove the camera and measure the angle of the vixen bar.  Then install the camera and figure out how to measure the angle of the camera lens body. My guess is that if you have the camera mounted flat to the vixen and tightly screwed on with the  mounting bolt this should be close.

The twist is maybe a bit harder.   One way would be to get the mount aligned to polar home using a compass and your digital level.   Remove the camera and set the altitude of the vixen bar to your latitude.  Then use a digital compass to adjust your azimuth to true north.  You phone will have apps with both of these functions.   If you calibrate your compass it will work ok.  After that mount your camera.  At night adjust the camera mount left or right until Polaris is about in the center of the camera viewfinder.   That should do it.

Finally, before you do your alignment make sure the mount is level.  

With all this done you will find the system will point your camera very well and it will track objects so that you can take time exposures.


Wes, Southport NC
EXos2-GT PMC-8, iExos 100
ES ED 127, 10" LX200GPS+wedge, Astro-Tech 8" Newt, ETX-90, 60mm no-name guide scope ~ 260mm FL
Polemaster, Orion ST-80 and SAG, ZWO 290MM, D5300 astro modified
Nina, Bootcamped Mac Mini control computer, RDP to iMAC
110 amp hour lead acid deep discharge battery for field power
Electrical Engineer, Retired

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