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Direct Drive Mounts small to mid range

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#1 Dodde

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Posted 25 May 2022 - 11:53 AM

Are there any commerically available at all for photographic instruments below 100kg, like in the 25-40kg range?


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#2 archer1960

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Posted 25 May 2022 - 01:40 PM

Are there any commerically available at all for photographic instruments below 100kg, like in the 25-40kg range?

Planewave L-350 is rated for 100lb (45kg or so). It's an alt-az, not eq mount, though.



#3 nebulasaurus

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Posted 25 May 2022 - 02:27 PM

Planewave L-350 is rated for 100lb (45kg or so). It's an alt-az, not eq mount, though.

Planewave supply an EQ wedge for the L-350.  Several folks here at CN are using it in the EQ configuration.


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#4 archer1960

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Posted 25 May 2022 - 02:28 PM

Planewave supply an EQ wedge for the L-350.  Several folks here at CN are using it in the EQ configuration.

And I use it in alt-az, which is why I forgot to mention that!



#5 nebulasaurus

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Posted 25 May 2022 - 04:43 PM

And I use it in alt-az, which is why I forgot to mention that!

That gave me a chuckle!



#6 archer1960

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Posted 25 May 2022 - 06:07 PM

That gave me a chuckle!

I like that it can be used either way. In my setup, using it in alt-az mode saves a lot of space on my deck compared to eq mode, and a Pegasus Astro Falcon rotator takes care of the frame rotation. The only negative about that setup is that I lose my lovely diffraction spikes. (BTW, I'm not being facetious about that; I like the spikes around my bright stars in pictures that I hope to hang on my wall).



#7 pmuller

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Posted 25 May 2022 - 06:13 PM

I like that it can be used either way. In my setup, using it in alt-az mode saves a lot of space on my deck compared to eq mode, and a Pegasus Astro Falcon rotator takes care of the frame rotation. The only negative about that setup is that I lose my lovely diffraction spikes. (BTW, I'm not being facetious about that; I like the spikes around my bright stars in pictures that I hope to hang on my wall).

How do you take care of flats?



#8 nebulasaurus

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Posted 25 May 2022 - 06:31 PM

If the camera is on the optical center then the vignetting will be constant as the camera is rotated. The vignette should have infinite rotation symmetry. 

 

And of course all the dust donuts will go round and round with the camera and will stay in the same relative positions and calibrate out.  

 

I don't bother with rotation angle when taking flats with my ES 100 or my iDK.  I do rotate the camera for framing and I usually shoot 2 targets a night over several sessions, often with very different rotation angles.

 

If the vignetting changes as the camera is rotated, something is optically wrong.


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#9 pmuller

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Posted 25 May 2022 - 06:59 PM

Thanks! I will send a message as I don’t want to keep off topic.


Edited by pmuller, 26 May 2022 - 12:08 AM.


#10 archer1960

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Posted 26 May 2022 - 08:26 AM

If the camera is on the optical center then the vignetting will be constant as the camera is rotated. The vignette should have infinite rotation symmetry. 

 

And of course all the dust donuts will go round and round with the camera and will stay in the same relative positions and calibrate out.  

 

I don't bother with rotation angle when taking flats with my ES 100 or my iDK.  I do rotate the camera for framing and I usually shoot 2 targets a night over several sessions, often with very different rotation angles.

 

If the vignetting changes as the camera is rotated, something is optically wrong.

Where you might have issues is when you have something upstream of the rotator, such as on your primary or secondary mirrors. Which reminds me: I need to check if my filter wheel is before or after the rotator; I just stick it together without thinking about this aspect of it, and don't remember which way I set it up.




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