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Gemini Integra85 focuser rotator review

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#1 thomastro


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Posted 18 September 2019 - 03:31 PM


First, sorry if I made mistakes but English is not my first language, I’m a French astronomer.


I will explain here my experience with the focuser/ rotator Gemini Integra 85 from GTD. I hope it could help somebody to make his choice of a focuser / rotator for an observatory setup.

I have no parts in the GTD workshop, it’s just an experience and I will list the pros and the cons of this equipment.


I’m using this equipment for more than one year now. It’s used with my 14” Ritchey Chretien telescope from Altair astro (2845 mm focal length – F/8).
The imaging system is a QSI 583WS camera (bin 2*2 to achieve 0.78”/pixel), the autoguider is a StarlightXpress Ultrastar (bin 3*3, 1.45”/pixel to match my seeing) and I use an off axis guider Skytrack 2.5 from Skymeca.
This setup is put on a Mesu200 mount and driven by Prism Astro software.


Why this Integra85 ?
When I started to look at focuser and rotator for my setup I clearly take a particular attention to the well known suppliers onto the market : Optec and FLI.
But there are 3 things which are not really good for me :
- I need to buy 2 equipment : a focuser + a rotator
- The back focus will be too high to put it onto a Newtonian scope (I will buy one in the future)
- The price for these 2 items is high despite the really excellent products quality.
And I find the Intergra85. It could manage up to 8Kg, down to F/5 (or lesser) F/D ratio, the travel is 10 mm, you could put a focal reducer/corrector inside the with his 85 mm inner diameter and the backfocus is only 69 mm. And the price is lesser than the Optec or FLI solutions. He his just less known as his big brothers.


The pros :
I don't remember I have this system in my observatory. It means that I have 0 failures during more than 1 year with cold (-10 °C) and hot (25°C) temperatures.
Never had any problem to achieve the best focus with my system, never had any problem to make a rotation (within 0.3° precision due to astrometry precision( astrometry.net), not to rotator).
No problem to drive it with Prism Astro software and the ASCOM driver. There is also an INDI driver.
No problem to use it at F/8 system and with more than 1.5 Kg at 10 cm behind the focuser, no tilt due to the Integra85 is visible onto my pictures.
No problem to use the system with Windows 10 pro
Really easy to discuss with Andras (in English) and  you should have every time a quick answer.


The cons :

Need a baffle to avoid light reflection onto the 3 curved metal plates inside the Integra85. For my particular case, I had no problem at this time. Now an inside baffle is available from GTD on request.
Need another baffle outside the system (in front of it) to avoid light to enter inside (between the adapter plate and the Gemini Integra85). I have put a 3 turns of electrical tape and it works perfectly.
With windows 10, we can't see the ASCOM program running (IE. for calibrating), just need to Ctrl+ALt+Sup // task manager // left click ASCOM GTD.Integra.FocusingRotator server (32 bits) and right click onto  GTD.Integra.FocusingRotator server (the second in the list) and choose put in the first plane. But we just need to do this when we need to make a calibration of the focuser and /or the rotator.
Need to put outside the temperature sensor to place it where we need. Ask Andras how to do and you could make yourself with a DS18B20 sensor.
Need an extra length cable to put electrical driver away of the scope if needed. Just ask Andras if you need a specific length other than the 80 cm original cable.
For my system there is a black plate (side of the scope)  which touch the carbon fiber box when I'm near the 0 mm position. But without loss of precision of the focus.
It's difficult to disassemble the focuser and the scope/camera if all are screwing (the Integra85 rotate at the same time, and we put high torque onto the stepper motors). A blocking system should be a perfect idea in this case.


In conclusion :
I highly recommend this system if we need short backfocus (69 mm) and precise rotation and focusing system. All the cons should be pass away without any problems. It's a really good product and proudly made in Europe !


Have clear sky.


  • lambermo and psandelle like this

#2 psandelle



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Posted 18 September 2019 - 05:18 PM

Nice review. Good to know about the baffles, as that would have driven me crazy if I had run into that without knowing. There's a chance I might need one in the future, so this has been very helpful.



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