Posts Made By: Ed Blankenship

Hello all,

I just purchased Lumicon UHC and H-Beta filters to add to my collection: Lumicon O-III and the nice colored set that comes as part of the Celestron eyepiece kit.

My question is: "Having noticed that the UHC and H-Beta have external threads, but no internal threads, Is there a reason that these filters should never be stacked ?"

I know that the Lumicon filters are achieved with special coatings instead of (or in addition to) the optical glass substrate coloration (if any), but was wondering if I put the UHC into the diagonal or barlow and then put the O-III or the H-Beta downstream in the eyepiece, would I get a better rejection of unwanted light or would I create some odd "multiple reflection" senario like a Fabre-Porro (sp?)interferometer.

Another question, "Can I use the H-Beta filter with my full aperature solar filter to get some extra detail on the Hydrogen cell granularity (of the Sun's surface) like the cool, but expensive H-Alpha filters that come with the Energy Rejection Filters ?"

Any opinions and/or experience ?

Ed

Hello all,

Well I have had an 8 inch f/3 mirror from Surplus Shed now for quite a while (Spherical, Coated, with the center hole). I was thinking I'd build a demonstrator stand for it that put a white screen at it's prime focus and have students look thru the hole in the mirror to see the image formed.

After much thought and some education, I was wondering about the old Gregorian design that uses a concave secondary mirror to get the light cone out of the hole so that an eyepiece would come to focus. Anybody got suggestions for the range of secondary sizes and f# that would work ?

Thanks in advance,

P.S. I'm not looking for high contrast, just looking for a demo setup. I'd even try a convex secondary like the SCT and Mak designs use if I could get something cheap.

Hello all,

Well, I am considering my first encounter with giving a rating of less than 5-stars. Before I type that rating text and risk over-reacting (or under-reacting), I would like to hear from those of you who value the rating system: I could just "keep my mouth shut" and watch the person's next few transaction to see how quickly one of you give them a zero instead of my "kinder-gentler" rating of more-than-zero, but less-than-five either. I've noticed a trend toward a "digital, 0 or 5, tendency from some of you" has resulted in very few 2,3 or 4 star ratings.

Or I could be bold and send them an e-mail to see if they want to "make it right" or at least "try an apology & price adjustment (to "save the rating")" like "where was my brain when I wrote the ad, but 'left out that small detail about CUSTOM, hand drill/file/sandpaper/cement, etc., etc. modification', so what was shipped was not matching what was advertised ???"

Any sage advice on how to balance my interests vs a seller's interests (they have 5 blue stars, so they are somewhat new) vs the interests of "the larger ASTROMART community" that could be helped if I can "do the right thing" over this first real disappointment ?

I'm talking about a single transaction for less than $100, so this may be "down in the noise" or it may be the first sign of a "serial seller who has a blindness to the 'full-disclosure' approach that some/many of you take in your ads.

What say you all ???


Ed

P.S. Thanks in advance for your replys.

Hello fellow ASTROMARTERS,

I have an 8 inch f/3 spherical mirror that I bought from Surplus Shed (an ASTROMART sponsor) and was thinking of trying to make a Gregorian Cassagrain scope just for the experience. My questions are, "Can I use a 75mm f/4 sperical mirror as a secondary ?" and "How bad would this design perform ?" and "What correction could I put into the system to make a "decent" performer ?"

Thanks in advance for your thoughts,

Ed

P.S. Happy Holiday Season to all.

P.P.S. Rick or Vlad, are you there ? I assume this would be "child's play" for you guys to "slam out" with your tools and experience. Don't spend any "real" time on this yet, since I'm in the "ideas flowing, but little time to build until after New Years" mode.

Steve,

Here's a couple of thoughts:
(1) be careful to get the corrector oriented back in the
same radial relation to your scope's main mirror,
(2) There are sometimes small shims that are used to
get the spacing right on the corrector, so I hope you
noticed if these were used and got them back too,
(3) the dessicant approach or the forced air (CAT Cooler,
etc.) might be a lot more effective and less of a hassle
than removing the corrector each time this happens,
(4) if you can lower the Relative Humidity at normal room
temperature (68 to 75 degrees F or 20 to 25 degrees C)
then you will have more sucess. A "rule of thumb" that
I've used is that the % RH will double for every ten
degrees C (or 18 degrees F) that you lower the temperature.

For example if you have 50 % RH at 25 degrees C, you will
have 100% RH below about 15 degrees C (thus your scope will "fog
inside"), so if you can "trap" drier air (like:the relative
humidity down to below 20 % RH at 25 degrees C) then you
can take the scope down to 5 degrees C and still have
about 80% RH inside your scope (no fogging since % RH is
still below 100% inside).
I hope that helps,

Ed

P.S. Does anyone use "dry nitrogen" to purge scope
interiors of excess moisture ???

I'm looking for advice, council & experience for the following situation:

I currently own & use an older, modest, Meade LX-10, 8-inch (200mm) fork mounted SCT as my largest and most versatile scope. I used to own a Celestron C-8 that was also fork mounted, but I sold the OTA to fund the Meade purchase so my buddy could upgrade to a 10 inch Meade LX-50.

Both scopes are/were used for through-the-eyepiece viewing of sun (with 8 inch solar filter), moon, planets and some double star viewing as well as some Messier objects. I have slowly added accessories such as a 2 inch diagonal, 6.3 focal reducer and most recently a "starlight" filter that all have SCT threads and can be used alone or in combination. I'm considering either adding yet another device into the external SCT optical path or avoiding that by upgrading my Meade SCT stock focus knob with a Feathertouch two speed (10:1) focus knob upgrade. The Celestron C8 focus knob seemed smoother and focus was achieved with less effort whereas the Meade knob seems "stiffer" and the extra effort seems to make me work harder to achieve focus (much waiting in between adjustments for Meade LX-10 to stop shaking, more adjusting, to get a good focus). Please realize that this is a totally manual scope, so I'm touching the Dec. & R.A. knobs too, but that doesn't shake the scope nearly as bad as the "stiff" focus knob.

I have done some research and find the Meade focus knob works differently than the Celestron focus knob: both move the primary mirror, but the Meade knob attaches to a small rod inside the scope that in turn attaches to the mirror whereas the Celestron knob attaches to a threaded rod that comes out of the scope (less scary to me). I saw a U-tube video that made the Celestron knob upgrade look easy, but the Meade knob upgrade looks kind of scary (reaching into the scope's interior and hooking the end of the Feathertouch onto the small rod that moves the mirror). I've read several good postings about happy Celestron owners that have upgraded using the Feathertouch, but haven't yet seen Meade owners reporting good results.

Which would be a better use of my money: (1) Achieve better fine focus with the internal Feathertouch two speed knob upgrade or (2) spend the money to put something like a Feathertouch, JMI, Crayford, etc. into the optical path and reserve the Stock Meade Focuser for "large mirror adjustments" which would open up the possibility for a motorized fine focus, but might make Polaris unavailable because the base of the forks would interfere with the longer optical path moving between the forks.

Thanks in advance for your wisdom, experience & council

Ed

I'm looking for advice, council & experience for the following situation:

I currently own & use an older, modest, Meade LX-10, 8-inch (200mm) fork mounted SCT as my largest and most versatile scope. I used to own a Celestron C-8 that was also fork mounted, but I sold the OTA to fund the Meade purchase so my buddy could upgrade to a 10 inch Meade LX-50.

Both scopes are/were used for through-the-eyepiece viewing of sun (with 8 inch solar filter), moon, planets and some double star viewing as well as some Messier objects. I have slowly added accessories such as a 2 inch diagonal, 6.3 focal reducer and most recently a "starlight" filter that all have SCT threads and can be used alone or in combination. I'm considering either adding yet another device into the external SCT optical path or avoiding that by upgrading my Meade SCT stock focus knob with a Feathertouch two speed (10:1) focus knob upgrade. The Celestron C8 focus knob seemed smoother and focus was achieved with less effort whereas the Meade knob seems "stiffer" and the extra effort seems to make me work harder to achieve focus (much waiting in between adjustments for Meade LX-10 to stop shaking, more adjusting, to get a good focus). Please realize that this is a totally manual scope, so I'm touching the Dec. & R.A. knobs too, but that doesn't shake the scope nearly as bad as the "stiff" focus knob.

I have done some research and find the Meade focus knob works differently than the Celestron focus knob: both move the primary mirror, but the Meade knob attaches to a small rod inside the scope that in turn attaches to the mirror whereas the Celestron knob attaches to a threaded rod that comes out of the scope (less scary to me). I saw a U-tube video that made the Celestron knob upgrade look easy, but the Meade knob upgrade looks kind of scary (reaching into the scope's interior and hooking the end of the Feathertouch onto the small rod that moves the mirror). I've read several good postings about happy Celestron owners that have upgraded using the Feathertouch, but haven't yet seen Meade owners reporting good results.

Which would be a better use of my money: (1) Achieve better fine focus with the internal Feathertouch two speed knob upgrade or (2) spend the money to put something like a Feathertouch, JMI, Crayford, etc. into the optical path and reserve the Stock Meade Focuser for "large mirror adjustments" which would open up the possibility for a motorized fine focus, but might make Polaris unavailable because the base of the forks would interfere with the longer optical path moving between the forks.

Thanks in advance for your wisdom, experience & council

Ed

Hi All,

After today's trip to Dr. Alison {last name left out} O.D. to confirm that my eyeglass prescription is stable again this year, I have a few questions for you guys & gals who have the wisdom of years and experience and connections:

(1) What corrective eyeglass lens material is best for Astronomy: Glass, Polycarbonate or Other (fancy, new = more expensive) ?
(2) What options can you suggest for polishing that would be better than what I've been getting thru Dr. Alison's usual supplier LAB ?
(3) I've avoided contacts for several reasons: (A) Finger in eye = YUK !!! (B) Until recently, not avail. for ASTIGMATISM (see below) ?
(4) What coatings do you recommend and where can I get "better" coatings than Dr. Allison's usual 4 choices ?
(5) Trifocals are a necessary compromise for every day, but not good for astronomy AND
Bifocals work better because I need to see the star charts AND focus "at infinity" thru the eyepiece AND
Single vision glasses are a "mixed bag" since I "see better" but switching back and forth is A PAIN !!! SO
What do you guys and gals recommend and choose to use ?

Using my Vision Service Plan thru my employer, I've been getting a yearly eye exam, new frames (titanium), lenses (polycarbonite) and "anti-reflection" coatings in Bifocals for the last several years and keeping them "pristine" in my eyepiece cases, so that I can get the most of my VSP AND my astronomy equipment when I'm observing without a "cleaning detour" each time I observe because my Four year old Trifocals that live on my face during all daylight hours ARE ALWAYS DIRTY !!! Today I just ordered up a "spare" pair of Trifocals that maxed out my VSP and my copay was over $200 as well.

You should know that my prescription is zero spherical & 1.25 Diopter of cylinder (in one eye) and 0.5 spherical & 2.5 Diopter of cylinder (in my "dominant" other eye), so I need correction when observing unless I'm looking at my favorite object (M-57, The Ring Nebula) which looks just fine either corrected or uncorrected !!!

Because of the need to view thru my eyeglasses, I've stayed away from eyepieces that trade away eye relief for more field of view. My nicest eyepieces are Radians and Vixen Lanthanums that I've purchased here on Astromart. The one exception in the "Nice Eyepiece Department" is my 55mm, 2 inch Televue Plossl (which has PLENTY of eye relief due to the LOW POWER of a 55mm Plossl and does a nice job on the whole moon or the whole sun even with an f/10 SCT since 2000mm / 55mm is only 36 power !!!).

I have considered trying the Televue product specifically designed to address ASTIGMATISM, but they are "spendy" enough that I'm not ready to go down that road UNLESS they are HIGHLY RECOMMENDED: What are your experiences and opinions on these "uncle Al" solutions ? What eyepieces do you eyeglass wearers like and use ?

Thanks for reading this far and sorry for my verbosity.

Ed

Hello Mrs. WIlliam Kinslow (& All),

You have my heart-felt condolances and prayers. Brenda we are so sorry for your loss. Wish I could help, but I'm way too far to help in person.

I googled Jacksboro, TN and confirmed that the nearest mid-sized city is Knoxville, TN where I-75 and I-40 cross. Then I googled "Astronomy near Knoxville, TN" and saw that there are several active astronomy organizations listed in/near Knoxville, TN. My brother used to live in Asheville, NC which is somewhat nearby Knoxville, TN as well, so I was reasonably certain that looking for an active group of people who do astronomy could be located as close as Knoxville, TN. The four web pages I saw gave me a positive impression that someone from one of these organizations might be more help that you have already received here. The four first results in my google search looked promising and especially the university listing "UT Knoxville - Dept. of Physics & Astronomy . . "

I would support what others have suggested here about getting and staying organized by using a spreadsheet, making specific ads (including photos) for specific items and having an impartial adviser who can assist with price-setting and possibly interposing in cases where scammers surface. I wish people who scam widows could be appropriately discouraged.

Using recently sold similar items here on Astromart (& the CN site too) is a recommended resource as well. It would be good if someone from Knoxville could be located who could assist you. Maybe someone who reads these forum posts knows a trustworthy person from that part of the Astromart community could jump in here.

Very Best Regards,

Ed Blankenship

P.S. I'll keep praying and thinking good thoughts about you and your situation.

P.P.S. I would think it very appropriate for you to post a question about specific equipment (AND A PHOTO) here in the Equipment forum with a title such as "What's this ?" and expect that someone here would know what it is and help you write an appropriate description. I have a couple of people here on Astromart who either currently own one (or 2 or 5) or have owned one (or 3 or 7) in the past. Some people have over 1000 good 5-star ratings here and know lots of experts all over the world. I think you came to the right forum (my opinion only).

Nice views of Jupiter from the Pacific North West - Moons are 2 & 2 and equitorial bands are nice thru my 8 inch SCT at 100x. Seeing isn't great (I tried 200x, but had to back down). Pleasing view at 50x to 100x.