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Astromania Field Flattener For FF Digital

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#1 skyler

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Posted 14 July 2019 - 09:00 AM

Been searching for info on the Astromania Field Flattener that I would be using with a Sony A7S and a Stellarvue SV80ST. I do know there might be some vignetting in this combo but not a real concern. Not interested in using a reducer/flatterner at this time and I also have an Astrotech flattener that I will test as well when the scope arrives. Heard good things with the Hotech flattener and even the SFF 3-80. BUT, I am wanting to compare it to the Astromania since the company detail notes that it generates pinpoint stars out to the edge of the frame.  A pretty bold statement but if it applies to my application, I would add it to my buy list. It is on Amazon so I can test it and send it back if it is not up to snuff. I am looking for feedback from anyone who has actually used the Astromania flattener.

 

Thanks !

Skyler


Edited by skyler, 14 July 2019 - 09:02 AM.


#2 skyler

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Posted 25 July 2019 - 10:37 AM

I think most people are probably using something other than the Astromania as it seems to come down to  reducing f ratios as well.  The usual favorable Televue TRF and AP .67X are what I find mostly in the write ups. I will toss this out there again but maybe not expecting a lot of feedback from the given response to date.  My plan was to use only a flattener but I have an older AP reducer flattener that I will give it is try and report on. Plus I may choose to purchase a specific SV product if it is matched well with the scope as I understand there have been some new upgrades in their flattener line.  The scope it will be used on will be (update) an SVX80T f6 refractor and I know I have a lot of options. And yes, I will still try the inexpensive Astrotech flattener to see how that will compare. 

 

Skyler



#3 balu01

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Posted 01 August 2019 - 12:21 AM

The AT flattener is very good.
The pixel scale with your A7 will not show you better stars IMO as the imaging resolution will destroy the difference if there was to be any. So as long as you get proper star shapes and a flat field I would not chase flatteners just for pinpoint stars. As it will very possibly be the same no matter better quality flattener.

If anything look for a flattener that has a threaded connection to scope, with M48 for camera connection that would reduce some of the vignetting and give you some extra field. Compared to say the AT version that uses a smaller camera connection.

Edited by balu01, 01 August 2019 - 12:23 AM.


#4 skyler

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Posted 02 August 2019 - 04:54 PM

I will agree that these initial tests are not conclusive and that I prefer a threaded connection vs just a compression fit.  I was perusing some other sites since I could not remember the rule of thumb for how the distortion would appear in the image depending on distance of image sensor from the reducer/flattener shoulder.  I am borrowing this as  guide from Ian on SGL.

 

The 1st image pattern is when the R/F is too far away from the sensor so you have to reduce the distance.

 

The 2nd image pattern is when the R/F is too close to the sensor so you need to increase the distance with spacers.

 

If you have suggestions or corrections, please feel free.

Attached Thumbnails

  • Too far away star pattern.jpg
  • Too Close Star Pattern.jpg

Edited by skyler, 02 August 2019 - 05:01 PM.



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