December 5, 2014 – Upgrading the Mak, Part 1: eyepieces, the mount, and dew

When I got the Mak, I still had 3 eyepieces that I had used with my Bird-Jones scope – the 26mm and 9.7mm Meade 4000 Super Plossls that came stock with the scope, and a 4mm Celestron Omni Plossl that I had bought to get some high power out of the Bird-Jones.  See, back in the olden days – meaning the late 70s and early 80s – Plossls were new and sought after.  They gave wider-field views than the standard “Modified Achromats” and Kellners that came with the scopes of the time.  In other words, back in the day there was a lot of oohing and aahing over a new Plossl.  I had no idea that the world of eyepieces had changed so dramatically in 30 years so that now a Plossl is practically the bottom of the barrel in terms of acceptable eyepieces.  But the 4mm still works, and is currently pulling high-power duty on the Mak.

The Mak came with two eyepieces itself – a 9mm and a 25mm.  Not only was there no identifying information on them whatsoever except for the focal length, the Celestron website had no information on what kind of eyepieces they were, either.  However, after emailing Celestron, I just learned today that both eyepieces are actually 3-element Kellners, so it was a little bit of back to the future for me.  Using these eyepieces now, I’ve gotten very good views from them.  In fact, I think that the 9mm was a bit sharper on the moon than my 9.7mm Plossl, believe it or not.

This made a total of 5 eyepieces, two pairs of which very much duplicated each other – the 25mm and 26mm, and the 9.7mm and the 9mm.  Now the goto function on the Mak was pretty accurate, but sometimes it would put the object just outside the field of view and I would have to go hunting for it.  The 26mm was actually not giving me the maximum true field of view possible in the scope.  A 32mm Plossl would; it would give me about a 34% increase in the amount of the sky I would see all at once.  That’s pretty substantial.

Off to eBay I went to get the 32mm.  While any old 32mm Plossl would do, I wanted to try to stay within the same line – the 4000 Super Plossl series – so that the eyepieces would be parfocal.  This means I would not have to change focus when switching between any of the 3 eyepieces.  Or at least, not change focus much.  I got one for 35 bucks, lickety split, and I quickly learned that there’s parfocal, and there’s “parfocal.”  Oh well, but no biggie.  The 32mm works great, and gives me super sharp views.  More importantly, as I had hoped, the wider true field of view was very helpful, as the goto was now putting objects in view perfectly, time after time.

While one of the main reasons was because of the larger area of sky I could see, another important reason was because I had taken better care in leveling the scope.  The mount has a spirit/bubble level built right into it that makes leveling a breeze. It seems like taking that extra couple of minutes to get that bubble dead center really helped, because a better-leveled scope is a more accurate scope.  The third and fourth reasons were that I was inputting the exact time from NIST and my exact latitude and longitude from Google Maps into the NexStar hand controller.  I figured every little bit helps.

After a few observing sessions, where I did marathons of double star observing and open cluster observing, seeing about 30 of each over two different nights – thank you goto! – I quickly decided I wanted something in between my 32mm, which gives me 48x, and my 9.7mm, which gives me 159x.  The 26mm and 25mm didn’t do too much in filling in this yawning chasm, because they gave me 59x and 62x. I wanted something right in the middle, around 100x – a 15mm EP.  I didn’t want to get another Plossl, because they have an apparent field of view of just 52 degrees, which would limit my true field of view accordingly.  I wanted something a view that is a bit wider than that just in case the object was a little bigger, because at that magnification and that AFOV, the TFOV would be about half a degree.

I asked around on the boards I frequent – Astronomy Forum and Cloudy Nights – and got some recommendations.  One EP that kept on coming up was the Astro-Tech Paradigm Dual ED and/or the Agena Starguider Dual ED.  These two EPs are clones of each other, meaning they’re made in the same factory and the manufacturer just stamps different names on them, but they are optically the exact same EP.  The “Dual ED” refers to the use of 2 elements of “extra-dispersion” glass out of the 6 elements in the EP.  This is a hallmark of quality!  They also have a 60 degree AFOV, which was right where I wanted to be, an improvement over the 52 degree AFOV of the Plossl.

Fortunately, right at this time, a used 15mm Paradigm came up for sale in the Cloudy Nights Classifieds.  I think these classifieds are every bit as good as those at Astromart, and better yet for someone who’s unemployed, unlike at Astromart, there’s no $15 initiation fee to use them!  I bought the new 15mm EP for just 40 bucks, shipping and PayPal fee included.  Nice!  So now I had 103x and 0.6 degrees TFOV.  Perfect.

I had to wait a day for the clouds to clear before I tried out the new EP, but it quickly turned disastrous.  Unbeknownst to me at the time, the Paradigm has something called a safety groove in the barrel of the EP.  This is to prevent the EP from falling out as you move the scope up and down if you haven’t secured it properly by screwing it into place in the diagonal.  That night, I had first light with the Paradigm.  I looked at an open cluster to test it out, and it looked pretty good.  As I pulled the Paradigm out of the diagonal to put the 32mm EP back in, the screw in the diagonal caught the safety groove, and I pulled the telescope up as I took it out.  The telescope has a clutch in altitude (up and down) so that if there’s too much pressure on it, it’ll just move.

Now, especially with the existence of this clutch, this pulling up on the telescope and moving it shouldn’t have had any effect on anything, other than that at that point, I had to realign the scope.  However, as I immediately proceeded to do so, the azimuth (left and right) motor refused to engage.  Or more accurately, it didn’t engage for about 11 seconds after I pressed the button, and it now made a whining noise.  Uh oh.  Again, the altitude shouldn’t have any effect on the azimuth, but here it was.  Or maybe it was just an amazing coincidence that the motor failed at this precise moment.  Well, good thing Amazon has a 90-day return policy during the holiday season, AND I had saved all the boxes and packing materials specifically in case anything ever happened.  Back it went.

Amazon has a terrific return policy in that they trust you and will send you out a new one without charge even while they’re waiting to get the old one returned.  Isn’t that great?  The new one arrived in just 2 days, working perfectly.

In doing my research on this scope, I had learned that the SLT mount was just a little undersized for the scope.  In other words, it was beefy enough or sturdy enough to support the weight of the tube without persistent vibrations that took a while to settle down.  Celestron uses the SLT mount on a couple of other lighter telescopes; the 127 is the heaviest of these.  However, in my research, I also learned that a lot of these vibrations could be avoided:

  1. Go around the tripod and tighten up every screw by a quarter turn, to make it more solid.  Just a quarter turn, however, because you don’t want the metal screw to crack the plastic that it’s in.
  2. Don’t extend the legs to their full height.  The lower to the ground it is, the less it has a chance to vibrate.
  3. Put the scope on anti-vibration pads.  These are rubbery type discs that the scope sits on that quickly dampen any vibrations the scope might experience.  Don’t bother with the Celestron ones for 40 bucks; Home Depot sells these super-cheap at $1.48.
  4. Put a weight on the accessory tray, or hang a weight off of it.  This lowers the center of mass of the entire scope, making it more difficult to get vibrating.
  5. Inject epoxy into the cracks in the tripod where the plastic meets the metal, again, to try to stiffen these connections and make the tripod more stable.

I have done 1 and 2, and that definitely works pretty well to keep the mount stable.  I also plan on doing 3 and 4, especially once I do the first important upgrade to the scope – buying and installing a finderscope, which will increase the weight of the tube on top of the scope.  But I have no plans to do number 5, because I’m a lame-o and I wouldn’t know how to inject epoxy into a tiny little crack anyway.

Another upgrade is to get a dew shield.  I’m observing from a rooftop in Manhattan, which is the Indian word for “land of no grass.”  (Yes, I’m kidding.)  I have no dew whatsoever.  However, if the dew shield is black – and it should be – then it can act in the same manner as flocking does, which is to reduce the entry of stray light into the tube.

I haven’t decided yet whether to buy a dew shield off of eBay for about 25 bucks, or to make one myself.  It supposedly can be made from any foam-type material.  You simply roll it up, stick on some velcro strips on both ends, and bang, instant dew shield.  But I’m not the craftiest person in the world, and I do want the thing to look good.  I’ll have to head over to the craft store and see how cheap it is before I decide.

But the big upgrade is a finderscope.  More on that in part 2!

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