Posts Made By: Ed Blankenship

Randy Ward said:

Howdy!
My name is Randy and I was a member here many years ago as MrCoaster. I'm looking to get back into observing so here I am back at Astromart. In 1999 I purchased a Televue Genesis SDF from an Astromart member (15 years ago!). I remember very well. We drove over 900 miles round trip to pick it up. It was an awesome scope that served for many years but I recently sold it before we moved from California to the heart of Texas.

Now I want aperature. I got the fever! Browsing the internet I see that scope prices are much more reasonable now than 15 years ago. I'd love a big dob but a decent SCT might be in my price range. I particular enjoy the moon and planets so the long focal length is very appealling. I'm just starting to do some research so any advice much appreciated!

Cheers!

-Randy

Welcome back Randy,

I am biased toward the 8, 9.25 or 10 inch SCT because of the reasonable cost, general purpose versatility and portability. Ask yourself about how cost vs aperature vs portability balance for you. Do you need/want goto ? How heavy of a setup do you want (Fork mounted, a 10 inch SCT is MUCH HEAVIER than an 8 inch SCT) ?

I recently picked up a nice used 8 inch Meade OTA with a Feathertouch Focuser upgrade for a reasonable price here on Astromart and matched it up to a used iOptron German Eq. mount with goto capability for a very reasonable price (less than $999 for both). That makes 2 Meade 8 inch SCTs for me as I've had a Meade LX-10 (fork mounted with only a clock motor) for quite a while that has served well for a low initial cost ($600).

A friend got me started in Astronomy with his 8 inch (which I later bought from him) so he could upgrade to a 10 inch LX-50 Meade (APERATURE FEVER !!!). Some days he regrets the big step up in weight of the 10 inch Fork Mounted LX-50 and wished he had the 8 inch back, but he can see objects I can't because of the extra light gathering capability.

I really like the goto capability that is now available a a much more reasonable cost than only a few years ago. The idea of having a goto mount that can quickly get me to more objects per hour is a big deal for me now.

Some thoughts to consider,

Ed

James Adams said:

I'm doing outreach solar viewings with my 5" f8 achromat with a Coronado 60mm etalon / BF15 combination. My 40mm Plossl is a tad weak, and my 20mm Burgess W.A. is too strong; any suggestions for a *budget* 26mm to 32mm or so W.A. eyepiece? Not sure if a 30mm Plossl would have adequate F.O.V.

Thanks

The short answer first: I think a standard 30mm Plossl would work fine for you to frame the full disk of the sun with enough sky between the Sun's edge and the eyepiece's field stop. You could even try a 26mm Plossl and get acceptable results in my opinion. Andy's suggestion of the 28 RKE is a good one in my opinion.

Now for the long answer: What I have in my eyepiece collection (much more limited that Andy's or Rod's) is (1) a very modest Celestron 32mm Plossl (I have several) that you can find used here on Astromart pretty often because it was the longest focal length of the set that came in the Celestron eyepiece & filter set that came in the nice silver case. I use this 32mm with a C-102, f9.8 and it gives me a nice moon with some sky to frame it in. The 40mm gives me more sky (which is what I think you meant by "My 40mm Plossl is a tad weak"). The other eyepiece I would reach for in my eyepiece case is (2) the Celestron Ultima 35mm (which may be harder to find on the used market these days. It would be a nicer quality eyepiece, but may be too much of a collector's item to put out into an "Outreach" situation and might be too much sky for me.

In my 8 inch, 2000mm f10, SCT, I use a 2 inch Televue 55mm (that I bought from Andy to step up from a 50 mm Surplus Shed 50mm) to "nicely frame" the full moon's disk or (with the full aperture solar filter) I enjoy the Sunspots with a very comfortable amount of sky surrounding the sun's full disk like you seek, if I understand your situation.

Doing the math, 2000/55 or 2000/50 gives around 36 or 40 power which is a nice, comfortable half degree disk (sun or moon) framed by what I think is about right amount of sky in my scope with the 55mm or the 50mm (40 mm isn't enough field of view for me to enjoy the full disk, the field stop is just too close). With your 125mm * f8 gives you about 1000mm focal length being half of what I'm used to, so, I would say Andy's suggestion of a 28mm is really close with the RKE's generous field of view (or it might be a little more sky than I would like). I would try a 26 mm Plossl and see how you like it as a very low cost experiment and adjust the power from there.

My final thought is about field of view vs eye relief: I need to use my glasses to observe because I have astigmatism bad enough to need the glasses to correct to get decent views. That means that I go for eyepieces that have about 20mm or more of eye relief. For outreach, this delights the others who need glasses, but I find that I have to "coach" the better sighted to back away from my eyepieces enough to avoid the "blackout" that comes from "missing the exit light with the pupil" light by being too close.

Best regards & Clear skies,

Ed

Oh and did I forget the filter that can almost double your viewing pleasure ????? A full aperature white light solar filter, of course !!!!!

Cheers,

Ed

Another thought would be to put a motor on the stock focuser: Orion AccuFocus Electronic Telescope Focuser is $80 and would do the work for you (by pushing a button) at a less expensive price than an upgraded focuser would cost you. I am really spoiled by my scopes with Feathertouch (R), but I'm going to try the electric focus add-on for a Celestron C-102 that I've had kicking around for several years.

Clear skies,

Ed

Hi Matthew,

I have three similar Meade 8" f/10 SCT scopes. One is fork mounted and the other two have a dovetail that lets me mount either one on a GEM or a GPS IOPTRON MiniTower.

As far as objects you can see with such a scope, there are many: (1) The Ring Nebula (M-57) in Lyra is a great view in your scope. You may want to get a 24mm and a 14mm to fill in between your 40mm and your 8mm. The 8mm is near or past the upper limit of my sky most of the time. I have both 9mm and 10mm eyepieces that get used more than 8mm.

Another good object (also in Lyra) is the Double-Double which is near Vega. You should be able to resolve all four stars in good seeing with your 8mm eyepiece. Use the 40mm to get the Double-Double in the center of the 40mm and then pump up the power (2000mm/8mm = 250 power).

Mizar and its visual companion in the handle of the Big Dipper (middle star in the dipper's handle) should be able to be seen with the un-aided eye and then with the 40mm (50 power). Then put the bright star, Mizar, into the center of your 40mm eyepiece and look carefully for Mizar's small companion by swapping in the 8mm.

Toward the end of the week, you should get great views of craters on the moon's light-dark boundary (the terminus) with both the 40mm and the 8mm.

I have an 8-24mm Zoom made by Vixen which lets me adjust for the best view in a given night's sky and then (only if the sky permits) I swap in a 10mm, 9mm or 8mm whichever is best in the zoom.

If you wait for new moon and take your scope to a dark site, M-51, M-81, M82 and M-101 are all available in a scope like yours and mine.

Clear Skies,

Ed

8) Nice write-up Linton,

Yes, I have been doing some recon. work and have my "plan A" neighborhood picked out on the "Magic line-of-greatest totality" and am going to introduce myself to some of the people on "that" street (which I'm not sharing !!!) later this year, so I can secure a good viewing spot for the 2 minutes of "TOTALITY" that we're getting in Oregon. Interstate 5 crosses that "magic" line just South of Salem Oregon and I bet some of the people on the Interstate will be very surprised when totality hits them. I'm sure it will be in the news, but lots of people will not understand even with the media coverage.

Thanks for posting Linton !!!

I concur with both Rolando and Tom: You need to balance the load directly over the center of both axis or you will be working the motors and gears of your mount very hard to overcome the unbalanced load. First impression: you are overloading the top ADM dovetail and your motors & gears in your mount. Looks cool, but . . .

You should also consider the concentrated stresses in (what I assume are) only two, small screws that are holding the ADM dovetail onto your SCT frame. If these work loose over time, you could risk your nice refractor to a fall (and the sudden stop at the ground, ouch !!!). Just the right strength of thread lock just might be in order ?

You might get a "lot of bang for the buck" by putting the weights on the bottom (near the SCT's rear) on a matching ADM dovetail (again with the due diligence for the two screws). The Idea is that the second ADM dovetail holds an adjustable counterweight (or three) out away from the tube as far away from the SCT's center axis as possible without hitting the base of the fork (ie. fat weights that stand away from the SCT's tube near the rear of the scope, but just clear the base of the fork give the most torque than weights that are nearly flush with the SCT's lower surface.

Can someone please sketch what I'm trying to express and post the torques of that he's got now and show the counter-torques necessary to balance this for all the elevation angles ? I can viaualize this, but don't have the CAD tools or skill to make a sketch of what's in my head. Sorry.

Hello Leslie Weston,

I have a working LX-10 that I still use, so I can relate to your experience. As a simple entry level 8 inch SCT scope it was a good choice for me and has served me well for years. I have upgraded the tripod and upgraded the focuser, but the basic simplicity of the LX-10 is something I still appreciate.

I don't have any personal direct experience with either the LX-90 or the LX-200. What I do have is a somewhat parallel thought process of planning for the day when my LX-10 with the simple 9V battery powered RA drive quits running.

What I have done is to buy another used Meade LX-10 Optical Tube Assembly (OTA) here on ASTROMART (Classified #866693). This second OTA already had a Vixen size dovetail mounting bar installed. I also bought an IOPTRON MiniTower mount (also used here on ASTROMART in Classified #881470). Pairing these two gives me the same optics in my LX-10 mated with a new GPS equipped mount. The GPS is a really nice upgrade that allows me to use the older Meade SCT technology with a more modern mount that has a future.

So if you still have your LX-10 OTA, you should give some thought to buying a modern mount and adapting your OTA to a modern GPS mount. If you look at my Rating Given section in my user profile, you can find Classified #881470 and Classified #866693 which have photos to give you an idea of what can be had here on ASTROMART.

Some food for thought,

Ed

Thanks Tom for posting. I always appreciate your optical experience shared here in the forums. I recently picked up a Personal Solar Telescope (PST) used here on ASTROMART. My IOPTRON MiniTower can hold an 8 inch Meade SCT on one side and the PST on the other side, so I can switch back and forth between "White Light" and H-alpha under the same viewing conditions which is very satisfying to me and my family who aren't astronomy "nuts" like me.

But as a part of my setup, I always verify my SCT's full aperature solar filter by interposing it between my eye and the sun and moving it around looking for pinholes that may have developed since last use. Now that you shared that (in theory) I should be able to see sunspots, I will take some more time and look for them as part of my verification process.

Thanks for the tip !!!

Ronald Fleming said:

Is it necessary to ship a c14 and it's broken corrector for repair. My thought is I should dismantle the broken corrector and remove it before shipping to Celestron for repair. Ideas?

It would help us to advise you to know more about what you mean by the phrase "broken corrector", so could you describe in more detail your corrector's current condition or maybe even post a photo ???

My first thought is that, during shipment vibration and shocks, the corrector could get worse and a large piece could "crash into the primary mirror" or the scondary mirror could "come loose" and ruin the primary. So as a first impression, I'd advise separating the corrector and secondary from the primary, so no additional harm can occur to the primary.

My $0.02 off the top of my head,

Best regards,

Ed