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Imaging with the 130pds


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28 minutes ago, Stub Mandrel said:

I have a home-made laser collimator - the key to success is collimating the collimator, luckily I have a pair of large, matched v-blocks that i can rest the collimator in and rotate it and adjust until the spot rotates but doesn't move.

I've got a Chinese one, my goodness that was frustrating to set up, 3 hours in it was still making a 2 foot circle on the wall 5m away so I completely disassembled it replaced the gromit and all grub screws with real ones not Chinese cheese ones and got it adjusted in a few minutes. 

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A very good idea with newtonians is to replace the 3 M4 colimating screws on the secondary with hand colimating screws, take a look to the ones I put on the Sw130 pds Moonlite updated. They cost between 10 to 14 euros (8 to 12 pounds) a set of three, and they definitely make life easier and faster.

I have these set on both my 130 and 200 PDS newts.

http://www.astroshop.es/accesorios-de-alineacion/omegon-premium-collimation-screw-set/p,46619

Cheers.

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4 hours ago, carastro said:

Well I have been trying to collimate it, it seems a fair bit off.  Not had a lot of experience with collimating despite having two Newtonian's before as all I ever had to adjust was the primary, but this time the 2ndry looks like it needs adjusting.  

a) The central screw on the spider is locked tight, I am not quite sure if I need to adjust this but it's not budging and I am nervous of using force.

b ) There was no hex key included with the scope so I don't have a hex key to adjust the tilt as currently I can't see all 3 primary clips in the secondary, I don't think just adjusting the primary mirror only is going to cut it.  

I have mislaid my own hex keys (assuming I have one the right size, and husband's all are attached to a ring with a 90 degree bend at the usable end.

I have been through all the packing several times to see if I have missed a hex key, yet I have a spanner and a screwdriver supplied.

Stuck now :crybaby2:

Carole 

1) Dont tamper with the central screw unless absolutely essential!

2) Hex keys are about 2 quid for a set from wilkos, buy three sets just in case you lose one or two

3) Dont use a laser, get a combined cheshire/sight tube (lasers dont tell you about secondary rotation)

4) Be prepared to take time with it, collimation is an acquired skill.

5) As for collimation, get the secondary appearing round and directly under the sight tube first. Then make further adjustments to get it lined up with the primary, then adjust the primary. If after those adjustments are done the secondary is no longer directly beneath the sight tube, dont sweat too much over it.... its a far lesser evil to have a slightly shifted secondary than it is to have one that is rotated. The only effect a slightly shifted secondary has is that it reduces the overall illumination of the CCD chip.

 

If youre still stuck, bring it along to SGL12 and I will take a look at it using my threaded collimatior (as play in thumbscrew/compression rings play a large part in miscollimation)

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I have a home-made laser collimator - the key to success is collimating the collimator, luckily I have a pair of large, matched v-blocks that i can rest the collimator in and rotate it and adjust until the spot rotates but doesn't move.

I already went down the route of a laser collimator with my Previous Newtonian, the laser collimator needed collimating, but I just could not find a suitable place to rotate it, and in switching the thing on and off so many times when i tried I succeeded in breaking the end off the laser collimator, so I bought a Cheshire and feel much more comfortable with one of those.

Louise and Susaron, those replacement bolts look a good idea, but can;t quite get my head around a thread replacing a hex key.  I am presuming they are hex keys as I could not see down the holes today when I tried.  I presume these stay on permanently.  

Rob: 

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1) Dont tamper with the central screw unless absolutely essential!

Bit unclear on this never having had to collimate the secondary before.  I thought somewhere I read that the central screw needs to be loosened in order to adjust the 3 secondary collimating screws, is that not right then? 

Current state of play is I have checked the vanes and adjusted them so they are the same length, one was about 2mm longer than the others. The secondary is round and under the site tube, but I can't see the 3rd Primary clip (well just a bit of it), so I just need to get the secondary adjusted for this, then hopefully all I have to do is collimate the primary.

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get a combined cheshire/sight tube 

I already have one.

Quote

If youre still stuck, bring it along to SGL12 and I will take a look at it using my threaded collimatior (as play in thumbscrew/comrpression rings plays a large part in miscollimation)

Very nice of you to offer Rob, I am not currently booked for SGL12, but if my local group bottle out of the next local astro camp, I might see if I can get there at the last minute if there is a space, and if I haven't had any joy before then I will take you up on your offer, but I really need to try to do this on my own, just hope I don't mess it up altogether.

N.B. I am using Astrobabys collimation guide. 

Carole 

Edited by carastro
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7 minutes ago, carastro said:

Louise and Susaron, those replacement bolts look a good idea, but can;t quite get my head around a thread replacing a hex key.  I am presuming they are hex keys as I could not see down the holes today when I tried.  I presume these stay on permanently.  

Hi Carole

It's just the end of the threaded bit that differs - it's much easier turning thumbscrews with your fingers compared to fiddling with a hex key (and maybe dropping it - frequently!). The thumbscrews do protrude quite a lot but that's no problem. The ones with the plastic grips (on the eu site) look a bit more deluxe compared to the 365Astronomy ones.

Louise

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19 minutes ago, carastro said:

Bit unclear on this never having had to collimate the secondary before.  I thought somewhere I read that the central screw needs to be loosened in order to adjust the 3 secondary collimating screws, is that not right then? 

 

Nope, not right at all! :)

Loosening the centre screw is the worst thing you can do because it messes up the factory set up/down tube position of the secondary. If you want to adjust the three collimation screws all you need to do is loosen one of them a little and then the others should move freely. Dont make bold adjustments, just a little at a time (1/4 turn).

The only time you tamper with the centre screw is if you are squaring the focuser, replacing it, or you find the collimation is seriously out of whack from new (unlikely).

Sounds like youre pretty close already with just being able to see the third clip, just give it a little tweak and you should be there. But dont sweat too much about getting the clips perfect, the best test will be under the stars.... as long as you get round stars in all four corners (should not be hard with your cameras) thats all that matters... dont try to chase that last 2%... it will drive you bonkers!

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Astrobaby's guide has always seemed quite good though she does mention adjusting the central screw (as does Dion on his Astronomyshed video. I vaguely remember having to loosen the central screw very slightly on mine in order to adjust the hex screws... But I think I'd be disagreeing with Rob at my peril!

Louise

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Thanks Louise, I have ordered the ones you suggested from 365 Astronomy, I thought it was slightly cheaper, and possibly quicker than ordering from Spain, plus the heads being smaller might be better for a smaller scope. 

Carole 

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On 09/10/2016 at 09:31, Squiddy said:

I've read the first and last 10 pages of this thread and must say I'm impressed with this inexpensive little tube. One thing that strike me is that some of you have a camera and mount worth thousends of euro and still choose to use a €200 tube.

I've used a megrez 90 for a while now, but I'd like to try a newtonian tube with a greater aperture and I've been thinking of getting a 150PDS for some time now. So my question to you all are, is the 130PDS better  than the 150PDS, or should I expect pretty much the same result?
The increased weight is no issue as I'm far below the limit of my mount (a Celstron CGE).

Best regards, Kent

One other thing I'd add to this is this: obviously the scope, the camera, and the mount are all important when you are imaging. However you may sometimes hear old imagers say that a good scope on a bad mount will give you bad images but a good mount with a bad scope will still give you reasonable pictures. The mount and the camera are much more expensive to get "right" whereas this little scope is really punching above its weight class. This means if you couple it with some better quality mounts/cameras you can achieve the amazing things the guys in this thread are doing without spending another ££££/€€€€ on optics.

EDIT: Wow, apparently I hit "reply" not realising there were two more pages of discussion! Sorry for the completely out of place comment :)

EDIT2: Congrats on the new scope, Carole. All this chat about collimation has got me worried mine is off and wanting to get a Cheshire.....

Edited by sagramore
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11 hours ago, carastro said:

Bit unclear on this never having had to collimate the secondary before.  I thought somewhere I read that the central screw needs to be loosened in order to adjust the 3 secondary collimating screws, is that not right then? 

My secondary was badly rotated and the three screws jammed solid until I loosened it. Now its sorted I can collimate without touching the central screw.

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1 hour ago, sagramore said:

One other thing I'd add to this is this: obviously the scope, the camera, and the mount are all important when you are imaging. However you may sometimes hear old imagers say that a good scope on a bad mount will give you bad images but a good mount with a bad scope will still give you reasonable pictures. The mount and the camera are much more expensive to get "right" whereas this little scope is really punching above its weight class. This means if you couple it with some better quality mounts/cameras you can achieve the amazing things the guys in this thread are doing without spending another ££££/€€€€ on optics

On the other hand, the low weight of the 130P-DS means it places less of a demand on a mount.

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The secondary is definitely out on my new 130PDS, I tried all my hubbies hex keys today (removed from their springs) and none of them fitted.  I also tried to bring the primary into collimation, but it just won't work with the 2ndry out.   Am stuck until I receive those little bolts Louise recommended.  

Carole

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1 hour ago, carastro said:

The secondary is definitely out on my new 130PDS, I tried all my hubbies hex keys today (removed from their springs) and none of them fitted.  I also tried to bring the primary into collimation, but it just won't work with the 2ndry out.   Am stuck until I receive those little bolts Louise recommended.  

Carole

Um, you'll still need a hex key to remove the current bolts! a 1.5mm key seems to fit mine.

Louise

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you'll still need a hex key to remove the current bolts! a 1.5mm key seems to fit mine.

You mean I have to remove the ones that are inside those long holes?  Great, I just thought they fitted inside the ones that are there.  OMG

Carole 

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23 minutes ago, Thalestris24 said:

Um, you'll still need a hex key to remove the current bolts! a 1.5mm key seems to fit mine.

Louise

Yes they need to come out. And they can be in very tight. Get the longest shaft 1.5mm key you can. Halfrauds do them at reasonable prices... or, if you aren't risk averse, your normal key with a set of pliers on the end for added leverage. Giving them a tiny nudge clockwise can often break any bonds that have formed, allowing you to then unscrew them anticlockwise. If you do that though, it needs to be a tiny nudge, barely enough to move it at all.

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17 minutes ago, carastro said:

You mean I have to remove the ones that are inside those long holes?  Great, I just thought they fitted inside the ones that are there.  OMG

Carole 

Probably best done 1 at a time :) I have to confess that I bought the thumbscrews a long time ago but never actually got around to fitting them! :embarassed: I've been using lenses and a frac instead :)

Louise

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OK folks, well Louise's post kicked me up the backside and I made one more effort to try to find my own Hex keys, and bingo I found them in the cutlery drawer of my campervan (I looked there  before but it's a deep drawer and they were right at the back buried under other stuff and it was semi dark when I looked before).  I guess things get bumped around when I am driving it, including the cutlery - lol. 

So I had a go at collimating the 2ndry.  First time I have done the 2ndry and all I can say is I hope I won't need to do it again as it was a bit of a mare  - I am sure the replacement bolts would have been easier, but now I don't want to have to take the hex bolts out to put the replacement ones in unless the 2ndry needs re-collimating.  

I think it is all OK now just need to do a star test to confirm.  

Fingers crossed.

thanks for all your help every-one.

Carole 

Edited by carastro
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Good luck with that. Oddly enough, its also kicked me into squaring the steeltrack focuser on my 200pds this evening.... for which I need to remove the focuser and secondary (yikes!). However, getting the secondary round under the focuser is greatly aided by first blocking off the primary then using a sheet of coloured (I used red) paper opposite the focuser, then just rack it far enough so you can make out a concentric circle of colour around the the secondary in the sight tube. Then remove the blocking card and adjust to match the primary, replace the blocking card, get it concentric again, then so on and so forth until its collimated... took me about half an hour and not a laser in sight! :)

Next time its clear... which will probably be a full moon, I'll take it out for a bit of visual then bung the DSLR on it to check out the corners on a starfield or two.

 

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8 hours ago, Uranium235 said:

Good luck with that. Oddly enough, its also kicked me into squaring the steeltrack focuser on my 200pds this evening.... for which I need to remove the focuser and secondary (yikes!). However, getting the secondary round under the focuser is greatly aided by first blocking off the primary then using a sheet of coloured (I used red) paper opposite the focuser, then just rack it far enough so you can make out a concentric circle of colour around the the secondary in the sight tube. Then remove the blocking card and adjust to match the primary, replace the blocking card, get it concentric again, then so on and so forth until its collimated... took me about half an hour and not a laser in sight! :)

Next time its clear... which will probably be a full moon, I'll take it out for a bit of visual then bung the DSLR on it to check out the corners on a starfield or two.

 

May I recommend some clusters to see / photograph?

Last weekend with the 200PDS I visited some interesting clusters in the segment of Perseus, which are in the list of the Herschel 400, they are NGC 1545, NGC 1528  (this pair can be captured with the 130PDS and DLSR within the same field), NGC 1444 and NGC 1513.

Other OC in the zone are NGC 1520 and NGC 1664 in Auriga, the first one resembles a barred galaxy with two arms, as it has  3 +3 bright stars forming the arms.

Cheers.

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Thanks, I'll check out the clusters but with the focal length of my 200pds being nearly double that of the 130 its doubtful I will be able to fit them both in the same frame of the camera. However, I do have a 28mm EP which might cover them both visually.

For star tests I always use the double cluster - or cocoon nebula if possible becuase it sits in quite a dense starfield. My location is quite light polluted, so with that and a full moon - galaxies are usually out of the question (visually or photographically) until the Moon goes away.

lol..... me doing "visual".... now theres a novelty! :D

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getting the secondary round under the focuser is greatly aided by first blocking off the primary then using a sheet of coloured (I used red) paper opposite the focuser

Thanks Rob, yes I tried to mask off the 2ndry with card (as per Astrobaby's tutorial), but I had difficulty in getting it to stand up and the 130PDS is a bit small to get your hands in to try to lift the card.  I think I need a stiffer and larger bit of card, so I can bend it at the perimeter, this should help wedge it in the tube better. 

Not having tried the Atik cameras in the scope yet, I don't know where the point of focus will be, I see you have an Atik383 Rob, do you have any problems with the focusser protruding into the light path?  I only have Mono Atik cameras now my DSLR having died at Kelling a couple of weeks ago.  I had a 15-P until a few days ago, but wanted a bigger FOV, and my stars were flattened one side because of the focusser. 

Carole 

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1 hour ago, carastro said:

Thanks Rob, yes I tried to mask off the 2ndry with card (as per Astrobaby's tutorial), but I had difficulty in getting it to stand up and the 130PDS is a bit small to get your hands in to try to lift the card.  I think I need a stiffer and larger bit of card, so I can bend it at the perimeter, this should help wedge it in the tube better. 

Not having tried the Atik cameras in the scope yet, I don't know where the point of focus will be, I see you have an Atik383 Rob, do you have any problems with the focusser protruding into the light path?  I only have Mono Atik cameras now my DSLR having died at Kelling a couple of weeks ago.  I had a 15-P until a few days ago, but wanted a bigger FOV, and my stars were flattened one side because of the focusser. 

Carole 

I had no problems with the drawtube protuding into the lightpath because I used a custom built adaptor to sink the corrector inside the drawtube (the only one of its kind I believe).

For you the only option would be to either move the primary up the OTA a bit (to push the focus point out a bit), or shorten the drawtube by about 10mm (most people choose the latter). Or alternatively, you could not let it bother you :)

 

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