First of all hello everyone!
Picked up my 8" Skywatcher Dob today and assembled in no more than 30mins. Very simple to assemble. The only things that disappointed me was that supposedly it should have included a rubber o-ring for the finder scope which it didnt, and locking screws for the pri mirror (I think) which were absent also. Also one of the blades on the spider was slightly bent which I was able to straighten up with slight pressure.
Also picked up some colour filters (red, yellow, orange, green), an Acute Imager and a 17mm and 40mm EP. There were no 2x barlows available, but I hope to get one this week when stock arrives.
After a quick and nervous collimation adjusting the pri mirror I was satisfied that the collimation was acceptable for first use and was ready to try out my new toy eagerly awaiting the cloud cover to clear up.
Soon as it got dark and the moon was clear of the tree in my back yard the viewing began.
Started with trying all different EP's(10mm, 17mm, 25mm, 40mm) and getting used to the rotation and slewing of the scope and mount.
WOW, staring at the moon in the 10mm eyepiece left me awestruck. I had no idea what to expect and I was simply amazed!
Then followed Mars, the Orion nebula and star clusters to the south. Wow!
A good 1-2 hour session before the clouds built up and I was very pleased.Cant wait for the 2x Barlow.
A few questions I have:
1) Has anyone tried the Acuter Imager? I tried it out but could never get a focused image. I was using the extender piece that came with it which may have been the problem(should have used the shorter piece).
Tip: Vista did not like running the software(PhotoLib2002) until I changed compatibility mode to Windows 98, then it worked without a hitch.
2) Should the Skywatcher Dob include locking screws on the pri mirror? All I have are 3 adjustable screws.
3) The allen key bolts on the sec. mirror were very tight and I was quite afraid to try and loosen them and try to improve the collimation.
Ive seen some people say do not touch the sec. mirror and only adjust the pri mirror. Is this true? If so why?
4) As the Dob is more so point and view, are there any recommended addons/finder accessories,mods etc?
2 - Does its have threaded hole for locking screws? As long as the springs on the collimation screws are stiff enough you shouldn't need locking screws, I took them off my lightbridge.
3 - Once the secondary is aligned properly you generally won't have to adjust it often, normally just the primary.
4 - Not sure what finder comes with the skywatcher, is it a straight through? A Telrad or rigel quikfinder (1x finders) can be a very handy addition for putting yourself close to your intended targets. With eyepieces etc I recommend getting used to using what you've got for a little while and find out what you like . I assume you've got a collimation tool, other things are red torch, star atlases etc, observing chairs are a great addition too...there is a lot of things you can spend money on, so go slow.
With a dob, in the future you may look into making up manual setting circles to help locate fainter objects.
1. the extender could be the problem. try removing the adapter and extender, winding your focuser right in and then hold the camera as close to the focuser (or inside it if you can) and see if it will come closer to focus. Alternatively try using a barlow. The problem may be that your mirror may be too far down the tube for imaging with that particular camera.
3. If your secondary has a center bolt, make sure you loosen that first or you will find it very difficult to adjust the three outer screws. I'd suggest seeing if you can find someone in your area that has a newt that can show you how to adjust the secondary. It is 1000 times easier when you can see someone else doing it first
Er...Paul, aren't exactly familiar with the Sw's secondary mechanics but am wondering why (in my humble opinion) you're recommending leinid loosen the sec's centre bolt to adjust secondary screws: if it's the usual set-up the centre-bolt's a spring-loaded "toggler" and the only reason to play with it is to centre the sec in the focusser....?
I'm assuming it is similar to the Bintel 12" dob secondary. When I was shown how to adjust that we needed to loosened the center bolt to adjust the secondary screws (after adjusting height and alignment to the focuser) as we couldn't get any adjustment with it tightened. It may well be different with the Skywatcher.
Got me confused there Paul (I hope this isn't making it worse for you leinid!)
I have a Bintel 10" dob and once I've used the sec's centre bolt to centre the sec in the focusser I "fiddle" the 3 screws (actually bob's knobs for me) to set the (sec's) position. Of course, in adjusting the centre bolt in the first place to get the sec mirror aligned under the focusser, the 3 screws needed to be loosened (backed off) - from how I'm reading your post leinid these 3 screws are too tight to even loosen: this shouldn't be so, unless they are "factory set" with a drop of paint on their threads or whatever. You need to initially loosen them to fiddle with the centre bolt if that's your desire: they shouldn't be too tight to loosen unless they've frozen accidentally, or deliberately as above...
If you do loosen them to play with the centre bolt (for aligning secondary under focusser tube) they should then be tightened up after this so that the secondary alignment re focusser tube is correct - in practice this means "fixing" the 3 set screws to hold the secondary in the position that has the secondary concentric within the focusser tube outline and the oval secondary mirror appearing to be as circular as possible.
Once the 3 screws at the back of the secondary have fixed it in this alignment then the primary is "worked" on. Having said this, you will need in all probability to go back and tweak these 3 secondary screws again after playing with the primary's screws and then after that fiddle with the primary screws again also - you will find in the reiteration of this process that the 3 secondary screws will appear to be much tighter: they will have much more limited adjusting capacity unless the spring for the centre bolt is particularly weak.
Hope this helps you leinid - if you found one of the spider legs was bent and you've straightened it then I guess you really do need to adopt a "whole procedure" regimen to get everything correctly aligned. As Paul says, someone showing you is far better and easier - your local astro society/club would be very helpfull in that respect.
Just so's you don't throw your hands in the air leinid, once you've mastered the preceding you should find it much rarer to do anything more than tweak the primary's screws, unless you drop your scope.....
JethroB76:
2) Yes there are smaller threaded holes smaller than the existing screw holes.
4) Finder scope is a straight through, took me a little while to get used to it. Temp collimation tool was made out of a film cannister. Hopefully pick up a proper collimation tool this week.
sorry for the stupiidity Jethro, but can you xplain further what you mean by manual setting circles?
[1ponders]:
1) Thanks for the tip, I'll try this later on.
2) Yes Im a bit concerned on loosening the sec. mirror as yet. BTOW where I got the scope, offers lessons on this at their viewing nights every week from memory; so I will definitely take the opportunity to learn this.
Thanks for the replies. Off to grab a coffee now, and start reading!
Just so's you don't throw your hands in the air leinid, once you've mastered the preceding you should find it much rarer to do anything more than tweak the primary's screws, unless you drop your scope.....
Thanks for the tips. The collimation as far as I can tell appears to be ok, and should last me through this week I hope .
Yes, I'll most definitely look at attending some of AGWAs meetings and attend the viewing night this coming Thurs to learn collimation; and hopefully pick up a proper collimation tool and 2x Barlow.
JethroB76:
2) Yes there are smaller threaded holes smaller than the existing screw holes.
4) Finder scope is a straight through, took me a little while to get used to it. Temp collimation tool was made out of a film cannister. Hopefully pick up a proper collimation tool this week.
sorry for the stupiidity Jethro, but can you xplain further what you mean by manual setting circles?
So there is provision for locking screws, perhaps the manufacturer has uprated the springs and has done away with the locking screws , they're not critical, if your collimation holds then dont worry about it.
Manual setting circles make use of an altitude and azimuth scale on the scope used in conjunction with appropriate software to point your scope at objects in the sky. Simply put the software generates a realtime ALT/AZ coordinate for an object you're interested in and you use the scales on your scope to point at the desired object...
1. the extender could be the problem. try removing the adapter and extender, winding your focuser right in and then hold the camera as close to the focuser (or inside it if you can) and see if it will come closer to focus. Alternatively try using a barlow. The problem may be that your mirror may be too far down the tube for imaging with that particular camera.
Thanks for the tip 1ponders. The quality of the Acuter imager lacked a bit. Guess that what you get for a cheap imager.
I just recieved my 8" skywatcher dob and on the primary mirror there are three Phillips head screws (for adjusting) and three small black hex grub screws to lock the primary mirror.
At first i did not notice these, but i had a closer look and they were there.
I just recieved my 8" skywatcher dob and on the primary mirror there are three Phillips head screws (for adjusting) and three small black hex grub screws to lock the primary mirror.
At first i did not notice these, but i had a closer look and they were there.
Hi Juliano, had a closer inspection and yes there they are! And first glance the look just like threads, but upon a closer look with the torch, yes they are the hex bolts (locking screws)
One thing that confuses me is that I was able to adjust the primary mirror with the silver screws and these locking threads didnt seem to have any impact on the locked mirror?
The scope is brand new, so Im not sure whether this is normal, or the locking screws should not affect the primary mirror adjustment at all when turning the adjustment screws.
So when collimating. Must the hex screws be loosened fully? and screws adjusted. Then afterwards must these be screwed up with slight tension ?
Would it be that these locking thread bolts arent tesnsion tight at the moment and that is why adjusting the silver screws allowed the mirror to be adjusted?
I cannot tell you about the Skywatcher. But for my two GSO OTAs, I only tighten the three primary mirror locking screws for transport. I loosen them off when the tube is in place on the base, collimate and away I go for the evening. The 8" is as supplied, the 12" has had the "Bob's Knobs" treatment, including stronger springs on the primary. When all is done, I tighten them, just until they are touching the mirror cell, then pick up the OTA and put it into the car or trailer. It seems to me that the only issue is whether the primary mirror will hold collimation as the altitude of the OTA is changed. Both mine seem to hold collimation well enough without tightening the three "locking" screws.
Here is what the previous owner of my 12" wrote about this end of the scope:-
".......the primary mirror collimation springs were too soft. This spring floppiness made primary collimation a bit erratic: the mirror and inner cell would clunk about with altitude changes – and not hold collimation, obviously – unless all three springs were near maximal compression. As discussed below I easily remedied this by changing over to heavier springs from Bob’s Knobs. Others have used heavier springs purchased at local hardware stores with equal success. In addition to the collimation bolts there are three locking bolts which are designed to push against the inner frame of the cell and secure the mirror in that position. That is, the position after turning the last collimation bolt, dynamically balanced against the force of the springs pushing the mirror ‘up’ and the collimation bolts holding it ‘back.’ These locking bolts work well, but they definitely do not lock the mirror exactly in the same place. This is easily confirmed by checking your primary mirror collimation as you tighten a locking bolt. If you lightly tighten each bolt the same amount the collimation drift is minimal, but it does drift and if you are fussy you will have to deal with this. It is easy to over-tighten these bolts, but tighter will not incrementally improve your collimation ‘lock’ and I have to believe that super-tightening these bolts can’t be a good thing for the cell, either."
Eric
Quote:
Originally Posted by leinad
Hi Juliano, had a closer inspection and yes there they are! And first glance the look just like threads, but upon a closer look with the torch, yes they are the hex bolts (locking screws)
One thing that confuses me is that I was able to adjust the primary mirror with the silver screws and these locking threads didn't seem to have any impact on the locked mirror?
The scope is brand new, so Im not sure whether this is normal, or the locking screws should not affect the primary mirror adjustment at all when turning the adjustment screws.
So when collimating. Must the hex screws be loosened fully? and screws adjusted. Then afterwards must these be screwed up with slight tension ?
Would it be that these locking thread bolts arent tesnsion tight at the moment and that is why adjusting the silver screws allowed the mirror to be adjusted?
WOW, staring at the moon in the 10mm eyepiece left me awestruck. I had no idea what to expect and I was simply amazed!
A few questions I have:
![[1ponders]'s Avatar](../vbiis/customavatars/avatar45_9.gif){kind=avatar}
leinad.
, they're not critical, if your collimation holds then dont worry about it.
