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New 11" EdgeHD
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Gary Jarrette
An interesting article.
Gary Carpe Noctem Sent from the Astro Cave via my MS Surface Pro 4 Tablet From: C14_EdgeHD@... [mailto:C14_EdgeHD@...] Sent: Friday, March 25, 2016 6:27 PM To: C14_EdgeHD@... Subject: [C14_EdgeHD] Re: New 11" EdgeHD My C11 (NON-Edge) had a loose primary that would not maintain collimation when I moved it (especially from one side of the Meridian to the other). The solution was to pull the corrector, get my hand down the tube and tighten up the primary mirror retaining ring, which I found was almost loose feeling (not anywhere near hand tight even). After that it maintains collimation rather better. It didn't completely solve my own mirror flop issue but it's smaller in magnitude now. My C11 primary is also tilted slightly and can't be corrected without more work. My 7" Meade Mak didn't have any of these problems (neither OTA has a mirror lock, and I don't "image" but I do use video cameras). I agree that the Meade is made better and has less problems in my experience. Also saw no problems on a friend's ACF 8" F10. I used his ACF for 3 years, and my Mak at 500x and 666x respectively, visually, quite often (on double stars). Regards, Alistair G. [Non-text portions of this message have been removed] |
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Hello Alistair, Thanks for yours. As you did with your C11, and the night before your note arrived here,?I?realized that?an?alignment check?at the?zenith, and then?45 or so?deg either side?might inform?the question of mirror shift. The results...?unacceptable. No OAG will fix this. This problem?has to?be fixed. The question now is, do I dive in and?resolve it, or just chill and wait for Monday to talk to my supplier and/or Celestron. How accommodating is Celestron per warrantee/assistance? I'm not afraid to dive in on these things, and as you say,? there may simply be something?that needs to be tightened up. I?have the weekend to work on it. Monday is a work day for me, and Monday night's weather forecast is looking promising, with the moon down until bed time. Just as further info, One of my concerns was that I had?piggybacked a 15lb guide scope on the OTA.?It would have been my dream combo, and now?I finally?have the mount that can easily?handle it all ... so I want it all!. So I went back to my?old 4lb guide arrangement to see if it made a difference.?The results, no detectable difference. Or more accurately the?degree of my star trails?problem?seems the same. I'll have to get the big problem fixed first before?this can be checked more definitively. Regards, Keith |
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Yes! interesting, and entertaining... I have my own horror story of flocking the inner OTA. Guess what happens to the stickum of the flocking when the OTA sets under the beating sun of?a few?hot summer's days. That's right, fractions settle on all? the inner surfaces... like?the corrector, the mirror, the secondary etc. Imo, a dew shield, whether dew?conditions dictate it?or not, is much more effective. What I think would be effective, especially for those who don't need or routinely use a dew shield,?is another baffle 1/2 way or so down?in the OTA. Maybe the manufacturers have determined that it just isn't cost effective, But?if nothing else,?it would be a great advertising point of "better contrast" than their competitors, for very little expense, and certainly more effective than flocking. For that matter, I'd like to see?a baffle?in the dew shield too. though with the flexible ones that's a little more challenging. |
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Hello Keith,
>The question now is, do I dive in and?resolve it, or just chill and wait for Monday to talk to my supplier and/or Celestron. How accommodating is Celestron per warrantee/assistance? I'm not afraid to dive in on these things, and as you say,? there may simply be something?that needs to be tightened up Since Celestron / UK dealers / UK importer has the bare faced cheek to charge 7,000 GBP for the 11 EdgeHD (11,000 USD), then I personally would not touch the insides of it until the 2 year warranty has expired! In that case the UK dealer would have to see to it. But if it was second hand, there is no way in hell that I would return it to the UK importer / dealer for service, I would always do any repair / maintenance myself if at all possible, and I would not think twice of puliing the corrector and hand tightening / checking the primary mirror retaining ring (which has found to be loose, on more SCT's than you might imagine - there are more people on CloudyNights who have had the same issue and solved it the same way). My mirror flop was very noticeably better after I tightened my "almost loose" retaining ring. Now I can retain collimation rather better between Zenith and horizon and between each side of the Meridian. Not perfect though, and it's always much worse on my C11 than on my Meade Mak (which has just a little itty bit of mirror flop at 333x or 666x, which is very small), and there was almost none on my friend's 8" ACF (Aplanatic SCT). This is all at 700x in the C11, 500x in the ACF 8", and x666 in the Mak. After I regreased the baffle slider in my C11 with Rocol Molytone MTS 1000 grease it still did not make the issue any better (a clay thickened MoS2 grease). Note that I am not talking about mirror shift due to focussing in these aforementioned. BTW My Mak had horrible mirror shift due to focussing that was almost completely solved by regreasing with this MTS 1000 grease. Not sure what the other person was trying to say when they linked to a SCT myths article after my post. My C11 collimation WAS changing markedly, how is that a myth LOL... BTW Celestron USA's accomodation isn't the problem so much as the turn around time (8 weeks, so I hear IIRC). Celestron and Meade USA wouldn't be much use to me, they are 8,000 miles away, return shipping and service would cost 1/4 of the new scope LOL. Best Regards, Alistair G. |
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Robert Shartrand
¿ªÔÆÌåÓý? I have an 11 year old C14 @ F5 guided with a piggy backed 4¡± F7 Stellarview refractor mounted on? an AP1200 and I get excellent up to 20 minute guided sub exposures. I use a SBIG Remote Guide Head in the refractor and a SBIG ST8xme imager in the C14. I can image for hours losing a FEW exposures due to mirror flop or differential flexure. When any flop or flexure occurs I usually lose one sub exposure as the mount corrects quickly. I don¡¯t get much flexure in the refractor because of the carbon fiber tube. The C14 is covered with insulation. The mirror flop only occurs when crossing the Meridian. I do not need to worry about finding guide stars and I can use any filter on the imager. I¡¯ve tried a couple of OAG¡¯s and got tired of looking for guide stars long ago. With my present setup, I can be guiding and imaging in minutes. Clear skies, Bob ? ? Sent from for Windows 10 ? |
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Hello Alistair, Omg, 7000 GBP? Something just not right there... An open?Invitation/opportunity for black marketers I would think. Or?a lot of sales of nearly new scopes, bought off Astromart, CN, etc. Is that because of the VAT? or other factors? I don't want to get too far afield here in this thread, but?if I can't get this problem satisfactorily resolved, I may have a?nearly new scope for sale.? In fact it'll come with a big improvement right out of the box. That adaptor for 3.29" to 2" SCT thread.... the first thing I did was put it on my Lathe and bore it out from 1.54" to 1.8. Do the math... it's a 37% improvement. How much do we amateurs pay just?to get a couple of points better? What?would you pay to get 37% less vignetting to begin with??When you look at the thickness of some adaptors out there, I could probably?go to 1.9" and get 50% improvement.?What's the point of including a nice 2" 23mm?FL,?82deg FOV EP, that will be cut off above the knees from out of the box? Yes, I'm venting. I am not happy. Oh I'll get it all straightened out. I have to.?Too much at risk of going down the tubes. I'm sure others have already figured out tricks and tweaks to do so.?I just resent?having to risk voiding my warrantee to figure out what's wrong,?and?fixing?it. Thank you Alistair for your experience and help. At a minimum, I have to resolve the mirror movement to as good as what I've become accustom to with?my nearly 20yr old Meade. It sounds like you do dbl star work, with the magnifications you're talking about? Unfortunately, 10-15minute photographic uses are even more?demanding. Regards, Keith |
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Thanks Bob, I'm sure there are?hundreds?if not?thousands of imagers who are successfully using a guide scope arrangement?at the focal lengths we're talking about. And they're using it for all the reasons you mentioned.? That's an interesting combination you have. Very good for detailed imaging of galaxies, PN, planets, detailed views of larger DSO's, and more. What do you use?to get f5? How much, if any fall off in quality?to the sides (or even?the corners) of that chip do you get? Mosaics? Upgrading to a carbon tube is in the background of my mind too, but I'm concerned about the?stresses, strains, and?differential flexure of a carbon tube locked between a pair of?aluminum?mounting plates? You mentioned insulating blanket around the tube, but I assume there's more to it?than this? My test of a 4lb vrs 14lb piggybacked guide scope didn't appear to make any appreciable difference, but my main problem is swamping any detailed comparison. Your?setup is encouraging. Keith |
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"C14 @ F5 guided with a piggy backed ..." That would be 70" FL (C-11 at prime = 110").? What is your avg and best FWHM (in arcsec)?? I do not argue that piggy-back is impossible for larger SCT but that it is difficult to achieve (at least initially) and the results are usually less than optimal in terms of angular resolution (esp if it requires a reducer).? But resolution isn't valued by everyone and once the piggy-back is reasonably debugged it becomes a convenient method. As a point of reference,?my primary interest is DS resolution so I use?OAG/AO or EMCCD with 14"?to obtain fwhm =?1.4" when seeing permits and 1" when seeing is good. Here is an example: Stan |
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I think the writer said coma is not the main problem, and did?acknowledge that there is some. But he wandered?between the?photographic and visual perspective, with not a lot of warning. The eye is much more forgiving. I agree with you, coma is an issue photographically, which accept for the small chips, would be immediately apparent?doing a?with/without CC comparison.?A either the Baader MPCC or TeleVue's Paracor made my native f6.3 SCT usable over 2/3 of a full frame DSLR, instead of less than 1/2 |
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Well, so far I'm still in the Meade camp, that is?for sure. But I see this as Ford vrs Cheny, Honda Civic vrs Toyota Camry. Etc.? Hopefully once I get this star drifting problem resolved, I'll be able to say the C11 EdgeHD at f7?is better photographically than a 10"?classic Meade?at native f6.3, outfitted to f7.25 via a TV Paracor. It aught to be. It better be. |
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I'd have to disagree that guide scope?problems are endless. In my experience, and I see one other poster's, in the 1800mm FL range, they are all resolvable, reasonably. And once they are, one can for the most part go on to reliable, consistent, acceptable, results. But I also?agree, OAG covers a lot of minor sins.?When you add in?all the other things you mentioned,? including?AO (which it looks like has really advanced thanks to ever better?IS technology) you are?approaching?top of the line.?Such a?combo?is something to dream about, but only?after I've?cleared up the current problems, and recover financially from?the latest outlay. Regards, Keith |
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" Beware that there have been several reports of supposedly defective Edge reducers. " Oh no..... Lurking in the background, evident from my 1st night out, are?small but obvious?red and blue flaring in mid frame stars, similar to coma. I? hope this is not a?inherent problem with the FR, or?the native F10 either. This is actually one of the problems I worried about. Especially?when you look at?all those elements needed?for their custom FR. Difficult to imagine that the spot size would remain well in hand across the length and breadth of the?plane.?It's hard to predict actual photographic results looking at their (cherry picked?)?advertised?and white page spot diagrams. |
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I have spent the better part of a year trying to figure out why I had coma issues with my focal reducer on my Edge HD14. I thought my imaging train was wrong in terms of respecting back focus specs and read the Celestron white paper over and over and tried various combinations of spacers. Surely, this $700 sophisticated optical part could not be at fault and since I was a beginner in astrophotography, I was doing something wrong. Then I tried a friend's focal reducer on my scope and suddenly, all my images were perfect. I went back to my retailer, exchanged the focal reducer and never had a problem since then. I had just lost a year of imaging with my setup, Hard learned lesson.
Roger M¨¦nard Montr¨¦al, Canada |
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The Orion trapezium.. Impressive Stan, Just out of curiosity, is it possible these days, in one shot, with a Meade/Celestron?SCT to get Sirius and the pup? I've been out of astrophotography for a number of years now, but at the time?I left (for a stint of visual fun and accomplishment), Mars and its moonlets were possible. I'm talking one shot, not over/under exposure combos.? Since my side trip to the visual,?CCD wells have gotten deeper, anti-blooming better, bit depth greater,?pixel/FL/aperture matching more sophisticated,?AO much much?better, and patience and persistence have supplanted over?eagerness. So...? How about it? Keith |
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That really sucks. Especially for?a beginner. There are just so many issues to deal with. Astrophotography, no matter how it is advertised, just?is not easy. Compliments and admiration?for sticking with it. How are you doing now? You are about the same latitude as I, and have as few, maybe fewer good nights as I. Those mountains seem to create a lot of clouds. It is difficult to know when a product is performing within spec, and when?there is?an issue. Thanks for letting?us know that there shouldn't be?reducer issues. And question it if it does. Regards, Keith |
Roger Menard