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Alan64

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Posts posted by Alan64


  1. 8 minutes ago, Neil H said:

    That's my fault I was thinking it was just to hold mirror against the screws , I can't find a shop like you have , but Paul (wookie1965) pointed me to these 

    25mm long ,1mm wire,8mm diameter 

    https://www.ebay.co.uk/itm/Compression-Spring-Small-Various-Sizes-Up-To-10mm-Diameter-Pressure-Compressed-1/222382066727?var=521250561773

    My own, after I cut them down, were about half that length.  But cells do differ from one to another.  25mm is how long my springs were originally, therefore you might have to cut those down, as you don't want to set the primary-mirror back too far.


  2. This the pack of springs I got at my local big-box hardware...

    springs2b.jpg.3dd5a8ee7aaa40648522e442c49028a9.jpg

    That is, the likely candidates for the job from the pack.  Note how substantial, how thick, they are.  Also, compare them to the adjustment-bolt laying before them.  I chose two from the third grouping from the left, and the only ones of stainless-steel.  I then cut three out of those two to the length required...

    springs2fb.jpg.9b96c754015000b7af9266fbef495443.jpg

    I then bent the cut ends towards the remainder of the springs...

    springs-stainless2.jpg.022fb24d944b1dc75687225579b85183.jpg

    That way, they won't try to slip to the side when compressing them.

    Keep in mind that you're tensioning a 150mm primary-cell.  I don't think that the ones you ordered would tension that of a 76mm.

    • Like 1
    • Thanks 1

  3. 15 hours ago, Neil H said:

    Thanks They do compression springs on Amazon but need to work out what to get 

    You don't want the springs to be too large in diameter; not quite twice the diameter of the bolt.  You do want the springs to be difficult to compress with the fingers.  You should be able to squeeze the springs a little with the fingers, but only very little.


  4. 1 minute ago, Neil H said:

    Thanks for that do I need to get longer screws if I convert to springs

    No, not for the adjustment-bolts at least.  You want them at the same threaded length.  The lock-bolts can be as long as you'd like, and stretching back into infinity even.  I replaced all of mine with socket-heads; before and after...

    832915679_primarycell12f.jpg.15b7fa65206ae63d1706c33a6a9642b7.jpg

    I just don't care for Phillips-heads.  To me, Phillips-head screws are for permanent fastenings only, and they're not all that great for that, either.  They were developed to make driving a screw easier, and faster.  

    It didn't matter about the length of the lock-bolts when I changed over.  I wanted them a little longer.  

    You will have to adjust the length of the springs to correspond with the length of the adjustment bolts; again, trial-and-error.  You can choose just the right tension in so doing.  

    • Like 1

  5. Yes, you replace the rubber o-rings with metal springs, and as I did for this reflector...

    2026597184_primarycell12e.jpg.815126a48e3e3221261305d86402cf71.jpg

    You can see the o-ring there, at left within the image at right, and after it was removed.  It's just sitting there, waiting to be cast into the bin.

    The springs should be heavy-duty, like that used in industry, but not large ones.  You may have to cut them down in size even, and as I did.

    Trial-and-error the undertaking, but just remember, you'll defeating the manufacturer in their wanton indifference towards the consumer.

    Afterwards, it makes collimating so much easier.

    • Like 1

  6. An EQ5-class mount would be an excellent choice, and the sweet-spot among the equatorial mounts.  They do get ponderous at an EQ-3 and up.  Also, the best EQ-3 is an EQ-5.  An EQ-5 weighs only a little more than an EQ-3, yet is much more versatile in the range of telescopes that can be supported.

    • Thanks 1

  7. 5 minutes ago, Vulisha said:

    Oh sorry I ment on this part about 85° :

     

    "The DEC setting circle is fixed, and with screws, but look at where it points, and at its home-position...

    2046424220_DECsetting-circle2.jpg.58472d87b6b0e9a07bc85aba50492e03.jpg

    ...at about 85°.  You can't rotate the circle independently of the axis.  Is that correct, or does it even matter?  I know that I won't be using either circle, in a practical manner, but I want it to be correct nonetheless."

     

    But latitude is wrong as well in my, but i do not bother so much with that one. 

    So that circle is wrong? it should be  90° in the middle ,and i should not rely on that circle as well?

    Again, I'm not certain, as I no longer have my Japanese-made EQ-2 from the early-1990s with which to compare, therefore I only suspect, and strongly, that that's incorrect.

    • Thanks 1

  8. In that any and all eyepieces are pushed over to one side when securing with thumbscrews, then it would follow that the Cheshire, cap, or laser should also be pushed over to one side, the same side, when collimating.

    That will ensure that the centres of the 1.25" eyepieces will correspond to the centres of the secondary and primary mirrors.

    You can certainly use a centring-adaptor, but the adaptor will be required when using the 1.25" eyepieces as well, if you want everything spot on.  It's not so much an issue with 2" eyepieces, as those are at the lowest powers.  Rather, it's at the higher and highest powers where the collimation needs to be precise.

    • Like 2

  9. 3 hours ago, Vulisha said:

    Oh, I don't have heavy duty, only small ones, tried and gave up as I am not sure will it even fix whiplash.  I also noticed as you have that 90 degrees is not in line with RA axis, did you ever found an answer is that suposed to be? 

    If I'm not mistaken, you're referring to the latitude-scale...

    349066957_latitudescale.jpg.1df5001497a9292f9449b685ebb47fb8.jpg

    If so, I carefully lifted it off, and then re-glued it on as true and square as I could manage.  I used what I call a squaring-jig, and of my own design...

    520334096_squaringjig.jpg.a19f91f0f4620db4a2c09775ad9cc875.jpg

    I made it out of narrow strips of thin plywood.  It's not that crucial to correct that, however.  Now, in so far as the setting-circles, for the RA and DEC, they might as well have been printed with clown faces...

    GDP4puL.jpg

    Aside from those aspects of the mount, and of far more importance, if the RA-axis is stiff, bound up, or loose and sloppy, you will have to figure out a way of adjusting its lock-nut.  You don't have to take the axis apart, but you should at least be able to adjust it.

    I can't help but think that there is a set of sockets that have thin walls, the kind that would crack and shatter if you used them for automobile repairs.  Such a set would be made in China, of course,  The set should also be dirt-cheap, and found at discount-houses or other.  Back in the late 20th-century, here in the U.S., I used to run across sets like that all the time.  If that fails, and if you desire to defeat the manufacturer in that, then you will need the tool that I had described previously.

    • Thanks 1

  10. 13 hours ago, merlin100 said:

    I've got a Meade 4000 15mm Plossl. Would a decent 2X Barlow improve things?  The OEM one is plastic!

    Yes, I have the same 114/900...

    kit4b.jpg.e1f94583b04f95a9787cadf0fbfd03bd.jpg

    Let's take the 900mm focal-length of our telescopes and see what we get.  The planets become interesting at 150x and up, up close...

    900mm ÷ 150x = a 6mm eyepiece.  The telescope is certainly capable of reaching even higher powers, up to 200x, and beyond even whilst observing the Moon's craters, and within those, the craterlets; not to metion the walls of the craters as they slope upward.

    You can get a 2x-barlow, and combine that with a 12mm eyepiece, and for a simulated 6mm.  A 9mm can be combined with the barlow, and for a simulated 4.5mm(200x).

    In order to aid in the hunt, a 32mm Plossl is also recommended, and for your lowest power and widest view of the sky.  Once you spot something or other, you simply pop in the shorter eyepieces and get closer and closer still.

     

    • Like 1

  11. A 9mm Plossl should be allright.  Anything below that will have a tiny eye-lens and tight eye-relief.

    I have a Vixen NPL 6mm Plossl.  I have to hold my eyeball right up to the lens, to where it almost touches same, and in order to see the full field-of-view.  It can be uncomfortable to use, but the views are outstanding...

    1180738406_VixenNPL6mm3.jpg.ec37cc61f85f68ad7d50597f354aa4cd.jpg

    It's a keeper and a half.

    • Like 1

  12. 52 minutes ago, Lordspace said:

    I was thinking of putting some tape around the barrel of the Lazer so it fits in snug without the need to use the thumb screws. I will give it a try and see what happens.

    When the Lazer is fully aligned I look down the focuser and can see that the mirrors aren't actually centered. 

    You don't want to go all the way round with a shim, for when the thumbscrews are battened down the eyepiece will be secured slightly off-centre.


  13. On 10/02/2020 at 10:38, Apollo_95 said:

    Ive had my Skywatcher 130p Heritage Dobsonian for abt 4-5 years now so not really a beginners question but I think this is a common issue when some people get a new scope. Everything has worked perfectly since I got the scope until recently. I had it out the other night for the first time since a house move last year. The problem is that the red dot finder is now no longer in sync with the eyepiece. I was initially trying to see Venus but the red dot was way off the mark. I also tried to vuew the moon & had the same issue. I know there are adjustment dials on the red dot finder but when I try to get it aligned the red dot is still too high for the object I have in the centre of the eyepiece. This is even when its on its lowest setting ie I cant make the red dot go any lower. The scope is well protected in its original box & I am not aware of it receiving any bumps. I suspect though that the mirrors are now slightly out of alignment, hence why I am asking about getting a collimator. Ive read reviews on collimators & watched the process on youtube for laser collimators but Collimators seem to be very hit & miss. Some seem to work for some but not for others. from what Ive read some collimators need to be collimated first. Ive called the camera shop I bought the scope from to see if they would collimate it for me but they dont & Im struggling to find somewhere that would do it for me as I would prefer a professional take a look at it before I start tinkering. Has anyone else had this issue? Any suggestions or assistance would be very much appreciated. Thanks Andrew

    Laser-collimators are generally used for larger and longer Newtonians on Dobson mounts.  The cheaper lasers usualy have to be collimated first, and can be more trouble than they're worth.  I have one myself, and it is difficult to collimate, and before I can use it for a telescope.  In any event, I don't use one to collimate my smaller, shorter Newtonians, like your own.  Instead, I use a Cheshire and a collimation-cap, both, and during a single procedure.  

    Cheshire... https://www.firstlightoptics.com/other-collimation-tools/premium-cheshire-collimating-eyepiece.html

    Beware of cheaper Cheshires, as the cross-hairs may not be aligned correctly, and cannot be corrected.

    Collimation-cap... https://www.firstlightoptics.com/other-collimation-tools/rigel-aline-collimation-cap.html

    In the case of Newtonians, the peep-hole and cross-hairs of a Cheshire act as those of a sight-tube, and aid in centring the secondary-mirror directly under the draw-tube of the focusser...

    420722200_secondarycoll.2.jpg.62395c272f8e5ab3f11c18c952251167.jpg

    Then, adjusting both mirrors, you direct their centres towards each other, back and forth until they are aligned...

    1599447925_sighttube-081819b.jpg.1597a501c61eb45d94788f1001c0f6e5.jpg

    When the cross-hairs of the Cheshire on the outside are aligned with the mirror-image of same in the centre, and both along with the primary-mirror's centre-spot, you're golden.  I then use a collimation-cap to verify, and tweak further if necessary...

    2141104978_collimationcap-081819b.jpg.f9c4ad852ebdbf081510f6801385afee.jpg

    When tightening down the primary's lock-bolts after adjustment, the cap allows you to keep an eye on the alignment to ensure that nothing shifts out of position when tightening.

    Note how the lighter circle is not centred within the larger black circle.  It's askew, off-centre.  That is normal for a short Newtonian(f/4, f/5).  It is known as the secondary off-setting, and it occurs during a normal collimation procedure.  There's nothing you have to do to accomplish the off-setting.

    Newtonian collimation tutorials...

    http://www.astro-baby.com/astrobaby/help/collimation-guide-newtonian-reflector/

    https://garyseronik.com/a-beginners-guide-to-collimation/

     

    • Thanks 1

  14. On 07/02/2020 at 05:47, MikeStickley said:

    Well finally I've had a non-cloudy/rainy night (albeit with nearly full moon) to give a good long test drive of my new (well 2nd hand bargain) Astromaster 130EQ out and I had fun with it and managed to get reasonable views of the Moon, Betelguese (didn't blow up), Pleides, M42 (practically compulsory I bet everyone goes for this 1st time out!) and Venus (bright but boring - not unexpectedably). Overall I'm reasonably pleased given the price I paid. I loved the view I got of the southern highlands on the moon and crater rims just peaking over the leading limb!

    I had the expected issues with the bog standard RDF that comes fitted but will just have to wait until the Rigel I've ordered arrives to get any improvement over that.

    A few queries/ niggles have arised after this first viewing session:-

    1) The slow mo controls feel a bit "gritty" and un-smooth, particularly the RA adjustment - can anyone point me in the direction of a good tutorial on giving these a bit of a service or what may be causing this? The RA seemd to have a bit of a "bounce" in it and when adjusted seemed to go briefly in the opposite direction before jerking back to moving prograde (if that's the word! - I mean following the earth's rotation in the RA axis)

    2) I'm aware the mount that comes with this scope is not the best - is the scope worth upgrading to a better mount in future? or would I be looking at replacing both the OTA and the mount, particularly if I wanted to move into astrophotography? (this would be quite a while down the line when budget allows). I guess what I'm asking is would the scope reward getting a decent mount when I've saved my pennies? and then afterwards maybe replacing the tube itself? I know I'd need at least a tracking motor to start with to get longer exposures...

    3) Any tips and tricks for a fast but accurate polar alignment? I just kind of did it by eye last night and it was good enough for what I was looking at (I think I'll need to sort the issues with the slo mo controls first to be able to judge how accurately I've aligned) Strap a laser pointer to the polar axis?

    4) I've found I've been using the scope with the tripod legs not at full extension as it seemed a little wobbly - this does lead to some rather unusual viewing positions however... Any ideas if I might be doing something wrong here?

    5) Collimation - I have a laser collimator but with there being no centre point marked on the primary have no real way to check the secondary - any hints and tips here? The scope seems to be in good order anyway so maybe no rush to dive into this for now.

    Thanks in advance for any replies 🙂 I may be away from the computer for a few hours from now so please excuse any slow responses/thanks

    Your CG-3 equatorial mount is an EQ-2.  I have a Meade, "Large Equatorial" they call it, and also an EQ-2.  Here's my thread on its renovation... 

    https://stargazerslounge.com/topic/319273-meade-large-equatorialeq-2-hyper-tuning/

    Now, you're not expected to do everything I did.  Just pick and choose according to your ability.  You may not be able to access the lock-nut of the RA-axis with a socket-wrench, to free it up if it seems too tight.  I had to use a larger pair of needle-nose pliers; heavy-duty, and to adjust or remove the nut.

    I don't have a 130/650, but I do have this 127/1000 "Bird Jones"...

    https://stargazerslounge.com/topic/340294-celestron-powerseeker-127eq/

    You might be able to glean some help from that.

    • Thanks 1

  15. 1 hour ago, Vulisha said:

    But my all of my socket wrenches weren't able to go inside nut hole, so that failed. 

    Yes, I had to use needle-nosed pliers, the heavy-duty type.  A pair of those will make it a breeze.  The lock-nut is not difficult to turn.


  16. 10 hours ago, Neil H said:

    What I think I will do is strip clean and regrease , then see how I get on if it's a real pain  with the rings wookie1965 found me a conversation plate to make it a dovetail ( I am saving for a skywatcher 200p on a EQ5 goto) so the 150/750 is only for now , I may still keep it when I have the new one , I need to weight up do I spend on this old mount or keep saving for my new one ,new one is winning right now 

    Thanks guys for all the input I will keep you posted 

    I've always held dear within my heart and mind that the best EQ-3, is an EQ-5.


  17. 6 hours ago, joe aguiar said:

    ok heres the video, ps i made this like 2 months ago but it didnt get posted till now and i was gonna post it in like 3 weeks time as i had others to go first, but i thought could help neil

    https://youtu.be/nY0e1MK2JV4

    joejaguar

    The thing I found most interesting within that was that you, somehow, some way, ended up with the exact same mount as the OP's, yet continents apart.  It's nigh incredible, for that's the first time I've ever seen one.


  18. 7 hours ago, joe aguiar said:

    i guess for me tho if u have only 1 scope its really not that bad using the eq3-2, just open the rings put ota in and tighten the nuts and thats it.

    joejaguar

    Well, with the rings left on the OTA, they don't add that much more when storing same.

    But if you leave the rings on the mount, that can be quite a different storage problem, not to mention the risk of the rings getting torn up in the process.


  19. 4 minutes ago, joe aguiar said:

    Great stuff allan

    So Neil up to u what to do then

    Only downfall is it will be the same cost to buy the vixen bar and new top plate, as just buying a used cg4. Then as I said in last post it's still the aluminium tripod not 1.75inche steel tripod.

    The tripod alone costs new 225 plus taxes or 100cdn used.

    Lastly the cg4 will be alot newer than the eq3-2 since that model came out as early as 2000.

    So Neil up to u what u want to do.

    Theres no right or wrong just prefrence 

    Ok Neil I will realese  the eq3 vs cg4 toinght.look out for the video u should get notice since your a member of my channel.

    Joejaguar 

     

    I don't think you could find a used CG-4 there in the UK, cheaply in any event, as most tend to go with the Sky-Watcher variants.  


  20. On 02/02/2020 at 16:12, Neil H said:

    Well my Celestron powerseeker that was sold to me as new unused ,if you remember it was more used and abused well last night the focuser went bad so it's no more 

    Got a new toy not brand new but new to me I got a pristine skywatcher sky scan 2001 on the EQ3-2 mount OMG it's so much nicer to use even the motor off the powerseeker fitted to it , just need to adjust the red dot scope and all will be good 

    The 150/750 F5 makes so much difference , any way  him up there decided I was having to much fun so gave me cloud cover . I am a very happy guy 

    Oh, you want to ensure that the RA-axis, its gear and worm, rotate freely and butter-smooth, with no slop or binding, before you use the motor-drive with it.  Given the mount's age, I would suggest a take-apart of the mount-head, both the RA and DEC axes, for a thorough cleaning and removal of the old factory-grease, and to replace that with new grease, like Super Lube.  Also, it may help to polish all of the bearing surfaces.  I use #0000 steel-wool and a light machine-oil for that, but only if you encounter any rough surfaces.


  21. And there upon the Acropolis, poised, albeit not so humbly, upon the steps of the Parthenon; and with Plato and Aristotle just within earshot...

    A flat bar, of aluminum or steel, or a dovetail-bar even, and attached to the existing saddle in place of the rings, like so...

    956442902_SGNeilssaddle2.jpg.bd07869080f3b23395da42eba459655e.jpg

    To rise to the level of the higher edges of the saddle, or just slightly above...

    521468638_SGNeilssaddle3.jpg.92d3d91bf2fe1ebfb03e323025d98ab2.jpg

    ...the bar may need to be shimmed at the ends, like so...

    786922670_SGNeilssaddle4.jpg.2e32d501d3f1899daaec4e2b1287c6a6.jpg

    ...the shims of wood, preferably of oak or walnut.  The Vixen-type saddle would then be attached to the center of the bar.  Some basic measurements would be required, but just that, basic.

    The original saddle would remain intact, no holes to be drilled into it, as if you'd want to preserve such an archaic interface in the first place.

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