Topics

Can EXOS2-GT PMC-EIGHT handle 200mm diameter f/5 newt? #EXOS2


zernikepolynomial
 

Many have a better understanding of the mount now, and I am seeing astrophotography payloads up to 28 pounds. Do you think this mount can handle a 200mm f/5 newt? With both the usual weight (maybe 20 pounds with a camera) and length? Do other users have too much trouble keeping PHD under 1"?


Bill Black
 

Hi Zernike Polynomial (nice!)
I have no problems using this mount with my 8" SCT. It sort of looks like a 200mm newt with the dew shield on it.
On top of the SCT, I have my 80mm APO riding piggy back plus cameras on both scopes.
My total equipment weight is 27 lbs and I have 27 lbs of counterweight as well.
If the seeing is good, I can guide to about 0.5" RMS in PHD.
--

Bill
Location: Dallas, GA
Scopes:
 Celestron C8, AstroTech 80mm APO

Mounts: EXOS II PMC-Eight, LXD75

Cameras: ZWO ASI294MCPro, ASI385


Dan Kahraman
 

Bill:

The answer is yet but the other challenge will be good cable management...shifting cables are a no-no so they should be held in place yet allowed "slack" within those constraints.

Dan Kahraman

On Thu, 25 Jun 2020 at 16:08, Bill Black <wcblack1020@...> wrote:
Hi Zernike Polynomial (nice!)
I have no problems using this mount with my 8" SCT. It sort of looks like a 200mm newt with the dew shield on it.
On top of the SCT, I have my 80mm APO riding piggy back plus cameras on both scopes.
My total equipment weight is 27 lbs and I have 27 lbs of counterweight as well.
If the seeing is good, I can guide to about 0.5" RMS in PHD.
--

Bill
Location: Dallas, GA
Scopes:
 Celestron C8, AstroTech 80mm APO

Mounts: EXOS II PMC-Eight, LXD75

Cameras: ZWO ASI294MCPro, ASI385


Dan Kahraman
 

Bill:

I meant yes not "yet".

Dan Kahraman

On Thu, 25 Jun 2020 at 16:18, Dan Kahraman via groups.io <dkahra213=gmail.com@groups.io> wrote:
Bill:

The answer is yet but the other challenge will be good cable management...shifting cables are a no-no so they should be held in place yet allowed "slack" within those constraints.

Dan Kahraman

On Thu, 25 Jun 2020 at 16:08, Bill Black <wcblack1020@...> wrote:
Hi Zernike Polynomial (nice!)
I have no problems using this mount with my 8" SCT. It sort of looks like a 200mm newt with the dew shield on it.
On top of the SCT, I have my 80mm APO riding piggy back plus cameras on both scopes.
My total equipment weight is 27 lbs and I have 27 lbs of counterweight as well.
If the seeing is good, I can guide to about 0.5" RMS in PHD.
--

Bill
Location: Dallas, GA
Scopes:
 Celestron C8, AstroTech 80mm APO

Mounts: EXOS II PMC-Eight, LXD75

Cameras: ZWO ASI294MCPro, ASI385


Bill Black
 

Totally agree on the cable management. It can make all the difference for refining your guiding/drift.
I route all of my cables to the center of the mount and then straight down, with enough slack all at the center.
--

Bill
Location: Dallas, GA
Scopes:
 Celestron C8, AstroTech 80mm APO

Mounts: EXOS II PMC-Eight, LXD75

Cameras: ZWO ASI294MCPro, ASI385


 

Bill / Dan
 
I'm starting to wonder if the EXOS2 doesn't like a bit more weight... :-)

Question:  What's your tolerance limit for wind?  
 
- Bob  (who keeps hearing the siren song of small Newts...)
 
--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2 290M
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


jrichard333 <jrichard333@hotmail.com>
 

Good day all,

 

I don’t know about the EXOS-2GT, but the IEXOS-100 does J.

 

JR

 

From: MAIN@ESPMC-Eight.groups.io [mailto:MAIN@ESPMC-Eight.groups.io] On Behalf Of Robert Hoskin
Sent: Thursday, June 25, 2020 4:00 PM
To: MAIN@ESPMC-Eight.groups.io
Subject: Re: [ESPMC-Eight] Can EXOS2-GT PMC-EIGHT handle 200mm diameter f/5 newt? #EXOS2

 

Bill / Dan

 

I'm starting to wonder if the EXOS2 doesn't like a bit more weight... :-)


Question:  What's your tolerance limit for wind?  

 

- Bob  (who keeps hearing the siren song of small Newts...)

 

--

Mounts: ES PMC-8 EXOS2

Scopes: SV 102EDT, ZWO 60/280 Guide

Cameras:  Nikon D5300, Altair GPCAM2 290M

Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Dan Kahraman
 

Bill:

Please post pictures of your cable management. It is a very important yet challenging topic.

Dan Kahraman

On Thu, 25 Jun 2020 at 16:35, Bill Black <wcblack1020@...> wrote:
Totally agree on the cable management. It can make all the difference for refining your guiding/drift.
I route all of my cables to the center of the mount and then straight down, with enough slack all at the center.
--

Bill
Location: Dallas, GA
Scopes:
 Celestron C8, AstroTech 80mm APO

Mounts: EXOS II PMC-Eight, LXD75

Cameras: ZWO ASI294MCPro, ASI385


Wes Mcdonald
 

I have always thought that more mass on the load would be better.  Yes you will during slew experience more tortional twisting of compliant shafts etc.  but the increase in mass will decrease resonant frequencies.  In a spring mass system the period is proportional to the square root of the mass.  So one lowers the frequency as one increases the mass.  I wonder if guiding happens better.  External disturbances might also have less influence, even wind if the mass goes up faster than the sail area.  

When we are guiding we are tracking along at a nice pace and issuing slight corrections.  Unfortunately the response of mount will be longer given greater mass... pesky time constants to final value gonna be proportional to the inverse natural frequency which higher mass decreases thereby increasing response time.  But if these times correspond to intervals lots smaller than the guide interval the advantage more mass gives for resistance to disturbances might just be a positive  overall.

Wes

--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


Dave Cherry
 

I have a SW 200PDS , no problems, pretty much always under 0.5 average in PH2

Dave
--
Scopes: Sky Watcher 200PDS, Skywatcher 72ED
Mount: Explore Scientific PMC8 EXO2
Cameras: ASI 294MCPRO Coooled, Altair guide cam + 50mm scope
Software: Sharpcap Pro ,PH2, Stelarium Startools


Jeny@
 

"Instrument specifications are payload capacity for astrophotography is 28lbs + counterweights and for visual use, the instrument payload capacity is 40 lbs + counterweights"

I think it should easily handle 200mm Newt.
--
EXOS2-GT PMC8
Orion150 Mak, Polemaster, ZWO ASI178MM


Bill Black
 

Hi All,
Here's an annotated picture of my wiring harness.
I have a Losmandy D type dovetail on my SCT, so there's a Farpoint adapter that I have on the old saddle.
All of my wires meet at the point of the old saddle screw, which has been replaced with a longer bolt so I can tie all of my cables to it.

As far as wind, if I'm at a short focal length (500mm or less) I don't have any issues with winds up to 7mph. I usually don't go out if the wind is higher than that, so I'm not sure at what point I would have issues.
At long focal lengths (2000mm +), I can see the slightest breeze, but I'm guessing that's going to happen with any mount.


--

Bill
Location: Dallas, GA
Scopes:
 Celestron C8, AstroTech 80mm APO

Mounts: EXOS II PMC-Eight, LXD75

Cameras: ZWO ASI294MCPro, ASI385


zernikepolynomial
 

On Thu, Jun 25, 2020 at 01:08 PM, Bill Black wrote:
Hi Zernike Polynomial (nice!)
I have no problems using this mount with my 8" SCT. It sort of looks like a 200mm newt with the dew shield on it.
On top of the SCT, I have my 80mm APO riding piggy back plus cameras on both scopes.
My total equipment weight is 27 lbs and I have 27 lbs of counterweight as well.
If the seeing is good, I can guide to about 0.5" RMS in PHD.
--

Bill
Location: Dallas, GA
Scopes:
 Celestron C8, AstroTech 80mm APO

Mounts: EXOS II PMC-Eight, LXD75

Cameras: ZWO ASI294MCPro, ASI385


 I've seen people on cloudy nights say that at this price point, this should be impossible. But its also 2020, so maybe we have come further than I realized.


Dan Kahraman
 

Bill:

Thanks. I like the different sources of wires coming to a common & feeding into a  larger tube.

Dan

On Thu, 25 Jun 2020 at 20:44, Bill Black <wcblack1020@...> wrote:
Hi All,
Here's an annotated picture of my wiring harness.
I have a Losmandy D type dovetail on my SCT, so there's a Farpoint adapter that I have on the old saddle.
All of my wires meet at the point of the old saddle screw, which has been replaced with a longer bolt so I can tie all of my cables to it.

As far as wind, if I'm at a short focal length (500mm or less) I don't have any issues with winds up to 7mph. I usually don't go out if the wind is higher than that, so I'm not sure at what point I would have issues.
At long focal lengths (2000mm +), I can see the slightest breeze, but I'm guessing that's going to happen with any mount.


--

Bill
Location: Dallas, GA
Scopes:
 Celestron C8, AstroTech 80mm APO

Mounts: EXOS II PMC-Eight, LXD75

Cameras: ZWO ASI294MCPro, ASI385


 

I use this mount with my Celestron C8 with the 6.3 reducer and an 80 mm Orion guide scope on top I don't worry too much about cable management doesn't seem to matter in my instance.
I live in the high desert of southern California so usually at night my weather conditions are really nice.


Wes Mcdonald
 

Nice looking rig Kevin.

How well is it guiding?

We’d

--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


Jennifer Shelly
 


--
Sincerely,

Jennifer Shelly
AstroPorch, VA

Mounts
: ES PMC-8 G-11, ES PMC-8 EXOS-2
Scopes: ES ED127 FCD-100, ES Levy Comet Hunter, ES N208CF, QHY Mini Guide Scope, Solomark F60 Guide Scope
Cameras: QHY600M, QHY128C, QHY168C
Misc: MoonLite CFL 2.5 / High Res Stepper / V2 Mini Controller, Baader SteelTrack NT / SteelDrive II, Baader UFC, Optolong 2" L-Pro / L-eNhance, QHY CFW3-L, Baader 2” LRGBSHO CCD
Imaging Software:  NINA, APT, SharpCap Pro
Processing Software: PixInsight, Lightroom, Premiere Elements


Dan Kahraman
 

Hi Jennifer:

The Newtonian is my system. Thanks for posting this. Very neat, clean looking cable management.

Dan Kahraman

On Fri, 26 Jun 2020 at 09:48, Jennifer Shelly via groups.io <drunkendogg=yahoo.com@groups.io> wrote:

--
Sincerely,

Jennifer Shelly
AstroPorch, VA

Mounts
: ES PMC-8 G-11, ES PMC-8 EXOS-2
Scopes: ES ED127 FCD-100, ES Levy Comet Hunter, ES N208CF, QHY Mini Guide Scope, Solomark F60 Guide Scope
Cameras: QHY600M, QHY128C, QHY168C
Misc: MoonLite CFL 2.5 / High Res Stepper / V2 Mini Controller, Baader SteelTrack NT / SteelDrive II, Baader UFC, Optolong 2" L-Pro / L-eNhance, QHY CFW3-L, Baader 2” LRGBSHO CCD
Imaging Software:  NINA, APT, SharpCap Pro
Processing Software: PixInsight, Lightroom, Premiere Elements


Jennifer Shelly
 
Edited

Dan:

The system in the picture is the EXOS-2 PMC-8 and ES N208CF Newtonian.  I must admit I do not use this set up anymore because I have the G-11 PMC-8 and ES 127 FCD-100 refractor.  I was thinking about bringing it out of retirement.  

In the picture I mounted the PMC-8 box on the handle of the Newtonian and used plastic adjustable cable clamps with 3M heavy duty dual lock fastener tape. The tape was placed on the back of the clamps and on the telescope tube rings which allowed me to quickly disconnect and reconnect the cables.

As someone else mentioned the wind is not your friend with a Newtonian.  It does not matter what mount you use the wind will cause problems with astrophotography because a Newtonian is essentially a large wind catcher.

Also you want to use a dew heater on the primary mirror especially during the summer if you store your telescope in an air conditioned home and take it outside.  The primary will dew up almost instantaneously.   

One more thing....balance is key with a Newtonian.  You want to ensure you are balanced both horizontally and vertically at 90°.
--
Sincerely,

Jennifer Shelly
AstroPorch, VA

Mounts
: ES PMC-8 G-11, ES PMC-8 EXOS-2
Scopes: ES ED127 FCD-100, ES Levy Comet Hunter, ES N208CF, QHY Mini Guide Scope, Solomark F60 Guide Scope
Cameras: QHY600M, QHY128C, QHY168C
Misc: MoonLite CFL 2.5 / High Res Stepper / V2 Mini Controller, Baader SteelTrack NT / SteelDrive II, Baader UFC, Optolong 2" L-Pro / L-eNhance, QHY CFW3-L, Baader 2” LRGBSHO CCD
Imaging Software:  NINA, APT, SharpCap Pro
Processing Software: PixInsight, Lightroom, Premiere Elements


 
Edited

It guides just fine, I usually just do like 3 minute photos with it...