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  #21  
Old 31-01-2018, 02:10 PM
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I forget the fl of mine but it would be a little long maybe near six feet.
A design with yet no measurements...
Alex
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  #22  
Old 31-01-2018, 03:23 PM
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Quote:
Originally Posted by Amaranthus View Post
Also, your image scale will be 0.63 arcsec per pixel, which is a pathway to pain for guiding (and will be heavily oversampled...)
An image scale of 0.63 arcsec/pixel is a good match for imaging small objects like galaxies. It will require good guiding but I'd argue that it's not heavily oversampled unless the seeing is consistently horrible. Image scale of 0.63 arcsec/pixel is well sampled for seeing around 2.2 arcsec. That might be better than average seeing in a lot of places but it's nice to able to take advantage of good conditions when they arise.

Cheers,
Rick.
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  #23  
Old 31-01-2018, 11:14 PM
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If your interested in putting the camera at prime focus, you could keep it simple and do what this guy does with a 14 inch.
No idea how he controls focus though.

EDIT: You wouldn't have to worry about the wind, and at a dark site, stray light shouldn't be an issue.
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  #24  
Old 01-02-2018, 12:05 AM
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If your interested in putting the camera at prime focus, you could keep it simple and do what this guy does with a 14 inch.
No idea how he controls focus though.
And I thought three struts was simple.
Focuser could be moved with a simple nut and bolt arrangement pushing it up and down...
I wonder how his images turn out?
Alex
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  #25  
Old 01-02-2018, 12:23 AM
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Alex, like what you said but with a motor for accuracy, you would need to buy a linear actuator like I've attached that pushes or pulls the camera up and down.
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  #26  
Old 02-02-2018, 08:23 AM
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Thank you Bill.
Alex
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  #27  
Old 05-02-2018, 06:52 AM
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Hmmm...
This design gave me some ideas...

I have 10" f/5.6 Newt built with Parks fiberglass tube (33cm dia) and Coulter Optical mirror (5cm thick, 4.5kg).
The OTA (with everything on) has ~12kg, a bit too much for EQ6 (yes, I know, lot of people will say the carrying capacity of EQ6 is 25kg (with counterweight), but generally I prefer not to load things up to the hilt).

To reduce the load, I built the Serrurier truss frame with 25mm aluminium square tubing, but ended with 10kg OTA (frame itself is 8kg, only 2kg weight reduction).

Perhaps the removing of the middle part of the fiberglass tube and replacing it with struts will be more weight-effective... I need to do some number crunching now.
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  #28  
Old 05-02-2018, 04:36 PM
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So...progress on by butcher shop effort.

Lifting it all up onto the mount I thought about Strongman Mike.
Wish he was there to help...

Balance is good. Had to add 3.6kg of lead (half a day forging).

Total weight of rig ended up at 20.5KG

The EQ6-R copes easily with slewing at top speed.

First issue:
I attached the Laser Collimation tool and spun the scope around at all angles.
Not a good result. It varied quite a bit.
May well be a show stopper.

Tonight will be to find focus using the moon and take a few happy snaps.

Tomorrow will attach the guide scope, and well...have no idea of how that will turn out.
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  #29  
Old 05-02-2018, 04:50 PM
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However it works out, I love the MacGyver skills on show.
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  #30  
Old 06-02-2018, 08:18 AM
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I love that show (or did).

Last night was a disaster.
The rack & pinion focuser seized.

This morning I found a metal shard in the works.
Fixed it.

Moon was still out so tried to get focus.
After an hour of pure frustration I gave up...to find...I had left the cover on the main mirror
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  #31  
Old 06-02-2018, 10:37 AM
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Isn't that the Hyperstar configuration for Maks ?

I nearly built a newt in that configuration but it would have been too long to fit in the Ob cos it was an 8" f8 mirror ( 1600mm + )
If I can find a cheap enough 8"-10" F5 mirror I may have another go with the ASI1600 on the front of it. Or maybe one of the new ASI mini cameras.
Might 'borrow' the mirror out of the Serrurier ... Could then afford the minicamera ... maybe.

I feel another project coming on ...
Should keep my big mouth shut,
I just picked up an 8" f6 for a good price. I think the seller might have aimed it at me after I enquired and told him what I was doing. Also includes a laser collimator. No diagonal. He had it as a project but gave up.

I'll modify the 8F8 OTA first, replace the front struts with 400 mm shorter ones which should make the scope much more manageable in the Ob. See how that works in a Newt configuration. Then I'll think about other options on prime focus... or I might just do that first .. hmmm.
ASI 120mc ?
!600mm with manual filter changes ?
Options ....
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  #32  
Old 06-02-2018, 04:45 PM
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Quote:
Originally Posted by bojan View Post
Hmmm...
This design gave me some ideas...

I have 10" f/5.6 Newt built with Parks fiberglass tube (33cm dia) and Coulter Optical mirror (5cm thick, 4.5kg).
The OTA (with everything on) has ~12kg, a bit too much for EQ6 (yes, I know, lot of people will say the carrying capacity of EQ6 is 25kg (with counterweight), but generally I prefer not to load things up to the hilt).

To reduce the load, I built the Serrurier truss frame with 25mm aluminium square tubing, but ended with 10kg OTA (frame itself is 8kg, only 2kg weight reduction).

Perhaps the removing of the middle part of the fiberglass tube and replacing it with struts will be more weight-effective... I need to do some number crunching now.
Bojan that looks magnificant.
If you want to loose weight have you looked into drilling out stuff.
Even at current weight it will work on eq6 if on a pier and if you balance for the region you shoot.
But you want remote but you can still balance for a particular region even remote.
I have been thinking but I dont know if the 12 inch is still there as the house has been empty and in the bush etc.
I have been thinking three carbon fibre struts but you would loose via primary mirror coverage..need to work out viable pole diameter and what it might take away and how to manage difraction which I think I could do...maybe.
Anyways I would like to rescue that mirror even if I have to build a new scope around it..
I probably will need a block and tackle the mount is the least of my worries.
I have been slack the cube obsrvatory has not progressed I have to get it up a floght of stairs and I keep putting it off.
Still have to decide on which roof or lid design to go with.
Alex
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  #33  
Old 06-02-2018, 04:53 PM
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I am thinking round poles will cause difraction problems forgeting area loss...so I am thinking a like ban the bomb templete at the top could be cardboard really that may fix it ..
Alwx
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  #34  
Old 06-02-2018, 06:43 PM
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Even with 1inch rods you would lose 15 %
I expect you would have to brace them with wires maybe fill them with foam back each russ up with a series of smaller poles...thats it...
Say a 1 " pole secured to a 3/4 inch to a half to a quarter and thst may do it and if so it would little weight...and maybe hold the mirror in a little different using carbon fiber foam sandwich. ..and maybe wrap the poles in carbon fibre ...
Alex
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  #35  
Old 07-02-2018, 06:12 AM
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Polyurethane foam was definitely planned.
Holes ø7mm in centre of the each rod, from where the rod was filled from can.
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  #36  
Old 19-02-2018, 10:56 AM
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Quote:
Originally Posted by Amaranthus View Post
Peter, not to be a spoilsport, but 20kg is going to be too heavy for the EQ6-R for imaging, especially at that focal length. A good rule of thumb is to try not to go much beyond half of the mount’s rated capacity for astrophotography. .....)
Barry (& Rick), I think you were right.

After 8 hours of testing it sort of worked.
I had to re balance & collimate at the same attitude as the target.
And then re calibrate PHD as well.

Soon as I moved the scope it was all over.

Too much hassle.

I did get a result however:
http://www.iceinspace.com.au/forum/a...e.php?a=223972
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  #37  
Old 21-02-2018, 12:12 PM
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Bojan,
if you're not prepared to image with 12kg on an EQ6R, you might as
well get an EQ8, and be done with it. The 6 is rated for a payload[not total
load] of 20kgs; 12kg is only 60% of that, which is just fine, the 6 will cruise along. The 6 is not rated to 25kg including weight[s], it is rated to 20kg
carrying the necessary weights to balance that payload, which will be at least three 5kg weights, plus an extension shaft. I ran just over 10kg on my
HEQ5 for years with no problems.
raymo
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  #38  
Old 21-02-2018, 12:37 PM
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EQ6 (I have two, one donated by Avandonk couple of year ago, I am using it when in Ballarat) may just work for my 10" Newt, especially because I plan to house it under the dome...
It is just my feeling the rating (20kg) is a bit optimistic (for imaging), I tried to load it once with my Newt (12kg, mount was on tripod) and, well, it was OK, it didn't break down but it was swaying a bit when pushed.
Maybe the situation will be better when on pier.

EQ8 is still too expensive... however if something good comes my way, I will take it :-)





Quote:
Originally Posted by raymo View Post
Bojan,
if you're not prepared to image with 12kg on an EQ6R, you might as
well get an EQ8, and be done with it. The 6 is rated for a payload[not total
load] of 20kgs; 12kg is only 60% of that, which is just fine, the 6 will cruise along. The 6 is not rated to 25kg including weight[s], it is rated to 20kg
carrying the necessary weights to balance that payload, which will be at least three 5kg weights, plus an extension shaft. I ran just over 10kg on my
HEQ5 for years with no problems.
raymo
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  #39  
Old 21-02-2018, 01:12 PM
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Yes, 20kg is too much for imaging, but over the years I have used several
sixes for imaging with payloads of 12-15kg with no problems. I even put
12.5kg on my HEQ5 once, and whilst it was obviously at its limit, it did the
job without complaining. Its not really the weight that limits these mounts,
they are pretty solid, its the windage, its amazing the load they will carry when on a pier.
raymo
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  #40  
Old 21-02-2018, 08:38 PM
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Sorry it didn't work out Peter. But definitely don't give up on imaging with a fast newt - they are great. And remember, image scale rules, so get that right. It means matching your focal length with your camera specs.
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