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Alan64

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Posts posted by Alan64


  1. 9 hours ago, Timothy Tappan said:

    Not wanting to take a drill to it. I saw an article on micro adjustment focusers but none would work on mine. May time to upgrade. Nice taste in automakers.

     

    If you like the go-to mount-head of that kit, then you might want to do something about the legs of the tripod that supports it; or rather does not support it adequately...

    Znw0tDK.jpg

    I'd suggest locating wooden legs for the kit...

    4.jpg.f6dd64947e97997a6bab03c081960340.jpg

    The tripod-hub, to which those wooden legs are attached, used to have the same legs as those of your own kit...

    2b.jpg.d6f7abf64fa7fc66ec35a32180b5101e.jpg

    Know that the manufacturers overseas are going to provide only enough to get the telescope up off of the ground.  Hence, the mount-head and telescope require a tripod that's a bit more substantial.  You can locate a new or used surveyor's tripod, with wooden or fibre-glass legs, however you would need to craft a spreader to tie them together.  In a pinch, a spreader of chain; the chain, a center-ring and whatever else to be had at your local hardware, to keep the legs from spreading out too far.  Wooden legs are the best choice; perhaps a stout pier even, albeit less mobile.

    • Like 1

  2. A 2x-barlow serves two purposes, in so far as visual-use...  

    1. The economical aspect,  in combining a barlow with 2 or 3 eyepieces resulting in 4 to 6 differing powers.  In carefully selecting the eyepieces to combine with the barlow, the goal is to avoid duplications.  For example, if you barlowed a 20mm, and for a simulated 10mm, you would not need a dedicated 10mm; and so on.  You might then choose an 8mm, 12mm, or 15mm instead.

    2. The ergonomic aspect, in avoiding a 4mm eyepiece for example, and with its tiny eye-lens and tight eye-relief.  Instead, you would barlow an 8mm or 9mm, and with their larger eye-lenses and greater eye-relief.  Now, that's when dealing with orthoscopics and Plossls.  There are eyepieces that have barlowing lens-elements built in; for example...

    PlgDWig.jpg

    Note the generous eye-lens, and for a 4mm eyepiece.  Then, compare it to this 4mm symmetrical-Ramsden...

    SR4mm3.jpg.6aa47a31f6cead3d107ef3998eacd51b.jpg

    Such enhanced eyepieces also offer slightly wider fields-of-view over Plossls.  Plossls are the current, minimum standard in performance-eyepieces, and they have come down in price considerably within the last several decades.  "MA" stands for modified-achromat, like the ones that came with our Meade kits.  Eyepieces that are less complex than Plossls, and even cheaper to produce -- modified-achromats, Huygenians, Ramsdens -- do work well with telescopes with longer focal-lengths, like our own.  Since they do in fact, the manufacturers tend to include them with all entry-level telescope kits, albeit regardless of a given telescope's focal-length.  In that enterprise, the rubbing of two copper coins together makes four or more.

    Although, that 4mm Ramsden illustrated there, from a kit, has astounded me, albeit when paired with its 127/1000 telescope.

    Don't hesitate to acquire quality eyepieces, barlows and other accessories for your telescope, for unlike telescopes those items can be used with other telescopes that may be had in future.  They're wonderfully interchangeable; and like luggage, they are with us for a lifetime.

    Plossls... https://www.365astronomy.com/GSO-Super-Plossl-Eyepieces/

    An example of a quality barlow, and one that I have myself... https://www.rothervalleyoptics.co.uk/antares-x2-achromat-fmc-barlow-lens-125.html

    Enhanced eyepieces... https://www.firstlightoptics.com/bst-starguider-eyepieces.html

    Of those, the 8mm and 12mm have been reviewed most favourably.

    That's another nice thing about telescopes with longer focal-lengths, in that you can get quality performance with all of those eyepieces, including the simpler ones, and for relatively little outlay.

    • Like 2

  3. I got this rogue's gallery with my Meade "Polaris" 114/900, and a current model...

    kit4c.jpg.18713b888bb95e41131b1819d6aff407.jpg

    accessories2.jpg.a0ea3a2c5bd66f1a7133f0c44f05dbf7.jpg

    Indeed, the plastic 2x barlow, and probably with a plastic lens(es) even, introduced considerable false-colour, and with Newtonians being 100% apochromatic, colour-free, in the first place.

    In addition, the images through the eyepieces exhibited graininess.  The telescope, however, is excellent, as I had tested it with my better eyepieces. 

    Did your Meade 114/900  come with a .965" visual-back, eyepieces and barlow?


  4. 32 minutes ago, Louis D said:

    Only if the objective lens of the DSLR is smaller than the eye lens of the eyepiece; otherwise, you'll get vignetting.  Cell phone cameras work great with just about any eyepiece due to their tiny objective lenses and "fast" focal ratios which capture all incoming light bundles.

    Those are the times where you'd simply zoom in to capture the full field-of-view.  In any event, the goal would be capturing individual objects, not vistas so much.


  5. Prime-focus imaging with a DSLR requires a LOT of researching, trial-and-error, and monetary outlay.  It is usually those individuals who dwell under light-polluted skies who are compelled to image rather than observe with eyepieces, but I've digressed.

    A mount required for imaging with a DSLR is of prime importance.  Unlike our eyes and brains, which can compensate for tracking errors, the shakes and wobbles, a camera will tolerate none of that.  The camera, and the telescope to which it's tethered, must be held rigidly, like a rock, whilst they track an object during a timed-exposure(s).  Else, the images will be soft or blurred.  The mount must be able to track the celestial sphere, and in an arc, therefore an equatorial mount is practically necessary; for example...

    https://www.telescope.com/catalog/product.jsp?productId=116276&gclid=CjwKCAiAnfjyBRBxEiwA-EECLCGiyfb1vSjrpKsiu-Bu11YjwSTDh3-Upa7mzdLXy-goIe0ewuDKgRoCSHIQAvD_BwE

    That mount supports up to 30 lbs. for visual-use, but only about 50% of that for imaging, 15 lbs.(telescope, DSLR, et al).  The mount is far more important than the telescope chosen to mate with a DSLR.  A modern DSLR's sensor, a CMOS usually, is much more sensitive than the eye, therefore large-aperture telescopes are not required.  Many start out with either an 80mm f/6 ED or triplet-apochromat refractor; a telescope with a short focal-length in any event. 

    It is more difficult to image with a Newtonian or a Schmidt- or Maksutov-Cassegrain.  Those are the mirrored options.  A refractor, with a doublet or triplet as its objective-lens, is easiest.

    It would be harder work, and more frustrating, to employ lesser components for imaging with a DSLR; but it wouldn't be impossible.  Somewhat near to the stated budget, you can choose an 102mm achromat with a 2" focusser, and a manual equatorial with its RA-axis motorised; for examples...

    The equatorial mount... https://www.telescope.com/Orion/Orion-SkyView-Pro-Equatorial-Telescope-Mount/rc/2160/p/9829.uts

    Motor-drives for the RA and DEC axes... https://www.telescope.com/Orion/Orion-Dual-Axis-TrueTrack-Telescope-Drive/rc/2160/p/7832.uts

    The go-to upgrade, to be had in future perhaps, and for greater ease in imaging with a DSLR... https://www.telescope.com/Orion/Orion-GoTo-Upgrade-Kit-for-SkyView-Pro-EQ-Telescope-Mounts/rc/2160/p/7817.uts

    The telescope... https://www.highpointscientific.com/meade-infinity-102-mm-altazimuth-refractor-telescope-209006?utm_source=google&utm_medium=cse&utm_term=MEA-209006&gclid=CjwKCAiAnfjyBRBxEiwA-EECLAbBy_jZogwsdCqK9U52ztKgfEgo_Xh63eIEgwadBofZ2xB-MozIchoCnT4QAvD_BwE

    Now, if you chose to use a webcam-type camera instead, then you can use most any telescope and mount.

    I take afocal-shots on occasion, by simply hand-holding a small point-and-shoot camera up to an eyepiece inserted into any of my telescopes, and snapping a shot, on the fly; no timed-exposures...

    sampler.jpg.37e8c91f3c255cc439bbd4acc03f443b.jpg

    Of course, with the afocal method, I'm limited to the brighter objects.  If you can hand-hold your DSLR likewise, you can use any telescope on the planet, on a manual alt-azimuth even.  All of those images within the collage were taken through this 6" f/5 Newtonian, and on, again, a manual alt-azimuth...

    420055947_6f5ra.jpg.3736291f9fa3983a3316c887247347e0.jpg

    https://www.highpointscientific.com/celestron-omni-xlt-150-newtonian-reflector-optical-tube-assembly-ota-31057ota

    If you can precisely collimate a Newtonian, like that one, you can expect very nice images, during visual-use, or whilst imaging.

    • Like 1

  6. 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.


  7. 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

  8. 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.


  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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.


  18. 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

  19. 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
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