Re: 18" classic pole length for photography
Mark, I have considered the same project for my UC18. I have the Mallincam DS287m (which I really enjoy) and have been thinking about the DS432m with the 11mm sensor and 9um pixels.?? I think you just draw a triangle 18" at the mirror and 75" long and just locate the position back from the peak that will fill up your sensor with light. For me to go from the DS287m (6mm sensor) to the DS432m (11mm sensor) I need to come up with another inch and a half of shorter light path. Below are my calculations.
| 75.6 |
Focal top |
| 74.56 |
DS287m |
| 73.02 |
DS432m |
| 72.03 |
DS10cTEC |
Richard
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Re: 18" classic pole length for photography
Linton,
He told me he didn't have enough poles for his current production.
You might contact him:
telescopes@...
- Roy
On 4/17/2021 9:10 AM, Linton Guise
wrote:
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Have I missed something? Is he ceasing production??
Linton
L.J.Guise
Physics Dept.
Bedford School.
?
Mark, and all,
I just heard from Kriege and he no longer has poles in
stock. He recommended a company, Online Metals.
Roy
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Re: 18" classic pole length for photography
Hi Dragan,
Many thanks for that information, I had heard the 25” Classic had been dropped but when I looked at the website the rest of the range were still there. Luckily I have a 20” f5 classic from around 2006 which is a great scope. I tried an 18UC but I’m not
a fan.
Best wishes,
Linton
L.J.Guise
Physics Dept.
Bedford School.
www.bedfordschool.org.uk/observatory
On 17 Apr 2021, at 18:25, Dragan Nikin via groups.io <dragannikin@...> wrote:
?
Hi Linton,
?
Yes. He discontinued the Classics last year. I don't think he has any more in stock of any size.
?
As far as UC's go, he's in the midst of a production run of UC's in various apertures.
On 04/17/2021 10:10 AM Linton Guise <lguise@...> wrote:
?
?
Have I missed something? Is he ceasing production??
?
Linton
L.J.Guise
Physics Dept.
Bedford School.
?
www.bedfordschool.org.uk/observatory
On 17 Apr 2021, at 15:50, Roy Troxel via groups.io <roytroxel@...> wrote:
Mark, and all,
I just heard from Kriege and he no longer has poles in stock. He recommended a company, Online Metals.
Roy
This message has been sent through the Bedford School email Server, and is intended for the addressee(s) only. If you have received this message in error, please contact the sender, or administrator@..., and delete the email. The views expressed
are the views of the sender, and not necessarily the views of the School. The information in this message may be confidential and should not be read, copied, or otherwise distributed unless permission is given.
Bedford School is part of The Harpur Trust: a company limited by guarantee. Registered in England: Company No. 3475202. Registered Office: Pilgrim Centre, Brickhill Drive, Bedford, MK41 7PZ. Registered Charity No. 1066861
This message has been sent through the Bedford School email Server, and is intended for the addressee(s) only. If you have received this message in error, please contact the sender, or administrator@..., and delete the email. The views expressed
are the views of the sender, and not necessarily the views of the School. The information in this message may be confidential and should not be read, copied, or otherwise distributed unless permission is given.
Bedford School is part of The Harpur Trust: a company limited by guarantee. Registered in England: Company No. 3475202. Registered Office: Pilgrim Centre, Brickhill Drive, Bedford, MK41 7PZ. Registered Charity No. 1066861
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Re: 18" classic pole length for photography
Hi Linton,
?
Yes. He discontinued the Classics last year. I don't think he has any more in stock of any size.
?
As far as UC's go, he's in the midst of a production run of UC's in various apertures.
On 04/17/2021 10:10 AM Linton Guise <lguise@...> wrote:
?
?
Have I missed something? Is he ceasing production??
?
Linton
L.J.Guise
Physics Dept.
Bedford School.
?
www.bedfordschool.org.uk/observatory
On 17 Apr 2021, at 15:50, Roy Troxel via groups.io <roytroxel@...> wrote:
Mark, and all,
I just heard from Kriege and he no longer has poles in stock. He recommended a company, Online Metals.
Roy
This message has been sent through the Bedford School email Server, and is intended for the addressee(s) only. If you have received this message in error, please contact the sender, or administrator@..., and delete the email. The views expressed are the views of the sender, and not necessarily the views of the School. The information in this message may be confidential and should not be read, copied, or otherwise distributed unless permission is given.
Bedford School is part of The Harpur Trust: a company limited by guarantee. Registered in England: Company No. 3475202. Registered Office: Pilgrim Centre, Brickhill Drive, Bedford, MK41 7PZ. Registered Charity No. 1066861
|
Re: 18" classic pole length for photography
Have I missed something? Is he ceasing production??
Linton
L.J.Guise
Physics Dept.
Bedford School.
www.bedfordschool.org.uk/observatory
On 17 Apr 2021, at 15:50, Roy Troxel via groups.io <roytroxel@...> wrote:
?
Mark, and all,
I just heard from Kriege and he no longer has poles in stock. He recommended a company, Online Metals.
Roy
This message has been sent through the Bedford School email Server, and is intended for the addressee(s) only. If you have received this message in error, please contact the sender, or administrator@..., and delete the email. The views expressed
are the views of the sender, and not necessarily the views of the School. The information in this message may be confidential and should not be read, copied, or otherwise distributed unless permission is given.
Bedford School is part of The Harpur Trust: a company limited by guarantee. Registered in England: Company No. 3475202. Registered Office: Pilgrim Centre, Brickhill Drive, Bedford, MK41 7PZ. Registered Charity No. 1066861
|
Re: 18" classic pole length for photography
Here is the company that Dave recommends:
- Roy in New Mexico
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Re: 18" classic pole length for photography
Mark, and all,
I just heard from Kriege and he no longer has poles in stock. He recommended a company, Online Metals.
Roy
|
Re: 18" classic pole length for photography
Roy:
?
Yup, that works too!
?
Mark
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Re: 18" classic pole length for photography
Mark,
?
I think I'll be ordering a new set of poles from Mr. Kriege, and then start trimming them down.
?
Roy in New Mexico
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Autoguiding and PHD2 ServoCAT Gen3 connection
Thought I would post this here in addition to the ServoCAT forum. Unfortunately, there are ObsessionUsers archives to search through on this topic.
I have been working on trying to get PHD2 talking to my SC Gen3 mount running with Argo Navis on an Obsession 18" Dob (alt-az). I wanted to try some short-exposure astrophotography with a DSLR, and wanted to have more precise guiding. I am not asking "is this a good idea?", I know this is not an ideal way of doing astrophotography, and I am aware of the problems of doing astrophotography with an alt-az scope.? I want to try it anyway. My inspiration is??which can be controlled with PHD2 via a Meade LX200 ASCOM driver.?
Dave K's shows pictures from Obsession owners doing deep sky imaging with SC without derotators or a platform:?Johannes Brachtendorf from Germany and Todd Kozikowski from New Boston, but other details of their imaging procedure are not listed.
I have installed ASCOM on my PC and the ServoCAT ASCOM driver.? I can use this to control the scope via Stellarium (through "device hub") and Cartes du Ciel (through the servoCAT driver), it's quite neat.?
When I try to connect PHD2 to the SC unit, I get the error "Mount does not support the required pulse guide interface", then the connection fails. I can connect my camera and a Telescope simulator mount. I tried both the ServoCAT driver and Device Hub (where I set up ServoCAT when connecting to Stellarium), both return this error. I tried setting my COM Port which was connected to the SC unit to 9600 baud but that did not seem to make a difference. I reviewed the driver information??and did not find much help. I assume others have had success connecting, what am I doing wrong?
I tried attaching a ST4 cable to the ST4 cable interface on the SC unit, but when I try to use the motion control on PHD2 the SC unit does not seem to respond - with I am in MODE ENCODER in the Argo Navis the encoder positions do not change when I press the directional keys in PHD2. Using the ST4 cable with my ZWO ASI camera and Firecapture, autoguiding on the planet works great, so I know the ST4 port and cable work. I would not mind using a ST4 cable for autoguiding, although it seems most users prefer ASCOM control, as it provides the program with information about to where the telescope is pointing.
Anyone out there with PHD2-to-SC communication success that they can share?
Thanks
Greg
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Re: 18" classic pole length for photography
Whew! I figured both of those were pretty obvious, but hey, measure twice . . . Was NOT trying to nit-pick, just verify! I'll be ordering new poles today! Thanks SO much!
Mark
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Re: 18" classic pole length for photography
Good grief, 1/4" would be good for a scale model obsession. It is a 1-1//4", I forgot the leading 1.? Looks like also I missed a zero for tube thickness, you are correct it is 0.035. See attached image from my order from Wick's so I do not give you the wrong info, these poles are the same as the stock poles that came with the scope. I ordered eight? 5' long poles.
I checked my order for the foam insulation to make sure it was correct, see attached image. It does fit the poles correctly.
Greg
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Re: 18" classic pole length for photography
Greg:
Exactly what I'd like to do! But I've a couple questions - you show OD on the poles as 1/4 inch - can I assume that's a typo, as that's a damn small OD. Mine measure at 1.25. And the thickness on their webpage looks to be 0.035. As for the insulation - I see your spec at 1 1/8 - intentionally smaller than the OD of the poles? And I assume you used something like a little dish soap to get them to slide on? Thanks for the help!
Mark
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Re: 18" classic pole length for photography
I have done this for my 18" f4.5 classic - bought a second set of aluminum poles.
The ones that match my scope are 1/4" OD 0.35" wall thickness 6061-T6 aluminum tubing.? I bought them from , I had a hard time sourcing pipe when I did this project. The insulation on the poles that came with my scope is??4530K126 - Unslit Polyethylene Foam Pipe Insulation, 3/8" Thick, 1-1/8" Insulation ID, 6' Length, Dark Gray, I got it from .
I was doing this not for a Mallincam, but rather so my DSLR could come to focus, and to allow me to put an atmospheric dispersion corrector (ADC) between the focuser and my ZWO ASI planetary camera: I did not have enough in-travel.
I ended up shortening the poles from the stock length of 55 15/16" (I am unsure if Dave K tweaks pole length for each mirror, but that is the length of my poles) and cut them down to 52 11/16" using a pipe cutter, the thin tubes are easy to cut precisely with such a tool.? This length to allows a DSLR and a planetary camera with an ADC to come to focus, you may need to shorten yours less as the ADC requires more in-travel than a DSLR.? Mallincam should have specs on the distance between the front of the camera and the imaging sensor that you can use as a guide, you can compare this distance to the distance in a planetary camera that can come to focus on your current poles to get an idea of how much you have to shorten the poles.
These are my "imaging poles", and are labeled as such.? I did not modify the stock poles. I used a radial saw to cut the foam insulation to length at Dave K's suggestion, it worked well.
With these shorter poles and my feathertouch focuser which has a travel length of 2", my eyepieces did not all come to focus, so I bought? from Televue. I think Dave K is a Televue dealer if you wanted to get them from him. With these extension tubes all eyepieces can reach focus.
While the optical train is no longer "perfect" with shorter poles, I cannot visually tell the difference, and I can now use a DSLR, planetary cameras without or with an ADC, and all my eyepieces on the same set of imaging poles with the help of some extension tubes when I need them. I can go back to using the regular poles if I want visual-only or planetary imaging without an ADC.
Hope this helps. Good luck and let us know how it goes.? Posting final results on the forum helps all members!
Greg
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Re: 18" classic pole length for photography
Mark,
I did what you want to do with my 15” Classic Obsession to use with my MallinCam camera. ?Yes, you want a separate set of truss poles. ?Because the point of focus is different for all cameras and focal reducers (if you use one) are different, I don’t believe Dave can give you an answer. ?If you don’t want to use a separate set of poles, Mallincam has 1 1/4’ camera that will drop further into the focuser, but it does have a narrow FOV.
What I did to accommodate my DS432cTEC was to start with a set of poles that were 3/4” shorter then make smaller 1/4” cuts until I found the length that worked the best-a slow process. ?With a metal saw blade I was able to make precise cuts on my table saw until I reached a length that worked using a small file to smooth the edges. ?I ended up with a set of poles that is 1 3/4 “ shorter. ?I did need to use black electrical take to reattach the insulation pads and small pieces on double sided tape to keep them from sliding. ?
A camera with a wider FOV does make it easier to find your target. ?If I don’t find the target on my go to or I can’t locate it in my 50mm finder, I will use my 13mm Ethos. ?TeleView does sell a 1” extension tube for the Ethos that will allow it to come to focus on shorter poles. ?Once I focus the camera in the focuser, I will lock down the focus tube, then by sliding the Ethos in the focus tube bring it to focus to find and/or center the target so I don’t have to refocus the camera when it is replaced. ?I will cradle the camera by the eye piece during this time. ?The nice thing about about this is I can use both the camera and the eye piece. ?In my opinion nothing is better than the eye piece for clusters, globular, or doubles, but the camera is best for nebulae, galaxies or with light pollution. ?The primary set up for my camera is a C8, but with minimal expense I can now use it on both.
Mike
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Re: 18" classic pole length for photography
Frank:
Yes, a second set of poles was exactly what I was hoping to do - I'd NEVER risk my primary usage! I've got Dave's book around here somewhere, but I don't believe there's anything about the mods I want to make - and the math is over my head! FWIW, I suspect I may have to think about a second secondary mirror too, but we'll see after I get to focus!
Mark
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Re: 18" classic pole length for photography
I had read about such endeavors in the past? but do not recall where.? I did read Dave craigies book on building the dobsonian reflector, though some years ago.? ?I do believe he explained the math needed to do the build but I don't remember if it had modifications.
?May I suggest you construct a second set of poles?? This way you have a choice to go visual or imaging. And also your resale value stays up. For even increases with that option?
Clear skies,? Frank Nowatzke? 22"UC Obsession?
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-------- Original message -------- From: Mark Gregory <hackaroo@...> Date: 4/2/21 12:15 (GMT-06:00) Subject: [ObsessionUsers] 18" classic pole length for photography
So I've got multiple telescopes (don't we all?) including an 18" classic. LOVE my Obsession. However, I've also got a couple of nice Mallincam video cameras, and I know that there isn't enough inward range on the focuser to bring them to focus. The focal distance is the same as most other astro cameras (and DSLR cameras). I'm thinking about getting another set of poles cut to length so I can swap them out when I want to use the camears - after all, 18" at F4.5 would be very nice, as opposed to 8" at F10. So, here's the question for anybody who has done this before - how long do the poles need to be? I have read posts in the past (not necessarily here, but possibly) about trimming the existing poles down to work with a camera, but my memory suggests that it was a multiple step process to get the length correct. But if there's someone who HAS poles of the proper length, you could save me a good bit of time and pain! Thanks! Mark
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18" classic pole length for photography
So I've got multiple telescopes (don't we all?) including an 18" classic. LOVE my Obsession. However, I've also got a couple of nice Mallincam video cameras, and I know that there isn't enough inward range on the focuser to bring them to focus. The focal distance is the same as most other astro cameras (and DSLR cameras). I'm thinking about getting another set of poles cut to length so I can swap them out when I want to use the camears - after all, 18" at F4.5 would be very nice, as opposed to 8" at F10. So, here's the question for anybody who has done this before - how long do the poles need to be? I have read posts in the past (not necessarily here, but possibly) about trimming the existing poles down to work with a camera, but my memory suggests that it was a multiple step process to get the length correct. But if there's someone who HAS poles of the proper length, you could save me a good bit of time and pain!
Thanks!
Mark
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Re: Planetarium control of SC AN control through PC or other device
Very cool Greg, thanks! I’ve been using AN/SC on my 18” Classic since I got it 15 years ago – at least once I cleaned up the installation that the previous owner had done! But there’s a number of things I’ve never tried, and you’ve got
them well documented, so I guess it’s time I did try!
?
Mark
?
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Planetarium control of SC AN control through PC or other device
For those of you with SC/AN on your Obsession scopes, I have been working on how to control the scope with Stellarium or Cartes du Ciel planetarium programs (both free) running on a PC using either a wired USB connection to the SC Gen3 unit, or Skysafari6 planetarium program (paid app) running on a tablet or smart phone by wireless connection to the SC unit via the SkyFi3 wifi device. This setup is not completely intuitive, so I thought I would share step-by-step instructions. The PDF documents are in the "Files" section of this group.
Use the instructions on "Faux alignment of telescope" in my SC/AN guide ("OBSESSION REFERENCE GUIDE 1.0 2020 07 02 Groups.pdf") to set up and test this indoors when the sky is cloudy and not waste observing time.
It is really a lot of fun if you have not done this before, and would make it more accessible for visitors at star parties as people can see on the planetarium exactly where your scope is pointing.
Let me know if you find any errors or have questions.
Greg
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Dragan Nikin
Frank Nowatzke