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DaveGibbons

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Everything posted by DaveGibbons

  1. Ah the Tal 25mm Plossl, If ever you get the chance to own a good example just buy it! I have had an original pair since 1998 and used them extensively as my main goto eyepiece in every telescope I have owned since then . Beautiful piece of optical glass. Stunning as a binoviewer pair.
  2. Hi Grant,

    You recently re-instated my ad"Celestron CPC 9.25 XLT GPS set up £1300" . Can the block on this topic be lifted so replies can be posted or indeed I can amend the ad if Iwish?

    cheers

    Dave 

    1. Grant

      Grant

      We can’t change the editing rules for one post - please use the report tool to request a moderator change it for you.

      Or, post a new topic and ask the mods to close the existing one.

  3. Thank's for all your advice! unfortunately the small set screw on my finder is chewed up and could not be removed. I have managed to clean the inside of the objective from the other end of finder tube. I removed the eyepiece assembly and very carefully used some baader wonder fluid with lens tissue and microfibre cloth attached to a small soft paint brush to remove all the fungus and leave the lense almost smear free...good enough for me ! cheers Dave
  4. Hi All, I picked up some Tal gear the other day, all in very good condition if a little dusty. The Tal 8x50 finderscopes are superb bits of kit but mine does have a little bit of fungal growth on the inside of the doublet objective. I have tried carefully to drift loose the retaining ring (see photo), but it does not seem to want to move. Now I have been sensible and not applied too much force but just wonder has any member taken this ring off before and was it a pain to get off. I am hapy to purchase the correct tool to remove the ring -they are about a tenner on flea bay. Just wondering if I missed something?
  5. Hi Dave, A job well done! You have far too much time on your hands in retirement! Although, not a patch on the professionally built B & Q special in the background!😉 Dave
  6. Hi all, I recently purchased a used but immaculate Skywatcher 350p non goto dobsonian. It was a little gift to myself upon retirement after 26 years at BT. This would be the largest aperture scope I have ever decided to live with, also the heaviest! Many scopes have passed through my hands over the past 40 years and I have loved most of them! I currently own an APM152mm apo refractor and a Celestron CPC 925 sct both with excellent optics . But, as my eye’s get older I find the photon’s just don’t light up the receptors that they once did and as they are only going to get worse I figured it’s now or never for larger aperture. I know some of you will be thinking why not go 16” or larger? I tend to observe every clear night possible and do not wish the set up and break down to become a chore. My garden is reasonably dark but I do use several observing positions to open up as much of the sky as possible and it is necessary for me to negotiate a couple of steps and traverse a short bit of decking, ultimately I need to be able to set up without breaking my back- more on that in a minute. So a bit about my actual scope. It came with a few modifications to improve performance and usability:- Bob’s knobs fitted on secondary Focuser tube and secondary mirror edges blackened lower tube assembly and upper cage opposite focuser flocked. I have added :- Astrozap light shroud 9x50 ra finder Telrad with 2” riser . Baader click lock adapter. It’s a sin that Skywatcher still persist in shipping dobs with a straight through finder, keeps the after market 9x50 RA finder sales buoyant I suppose! If you want to keep cost down the “essential” item in that list is the light shroud. Improves contrast and has kept dew at bay on all observing sessions so far. The standard dual speed Crayford style focuser is of decent quality and comes with 2” and 1 ¼” adapters. I just use the 2” with a Baader click lock 1 ¼ “ adapter. Focuser is super smooth and is more than up to the job. The dreaded collimation and the collapsible tube. Well I keep my tube assembly fully extended and locked permanently! It saves faffing round with the light shroud and means only a small tweek usually needed when I take the tube out to the base . My secondary is in perfect position and has not needed adjustment and I use a simple short collimation eyepiece for the primary adjustment, it is good enough to get accurate alignment. Here's the thing at F 4.5 and 14” aperture this is not the scope for splitting sub arc second doubles, it’s forte are the faint grey galaxy smudges, globular and galactic clusters and the beautiful rendition of true star colours. Yup atmosphere permitting it will easily show fainter E and F components in the trapezium but it is not a double star or planetary killer. I am learning to embrace it’s greatest strengths letting me see new objects for the first time and familiar vistas with greater detail than ever before. Mirror quality, well you get what you pay for to a degree. Inside and outside focus differ (as does every other Skywatcher mirror I have ever seen) with what appears to be a turned down edge evident, par for the course on a big machine figured mirror, no hand finishing here! No other aberrations other than some surface roughness as usual. The mirror coatings themselves are immaculately applied. Difficult to give a true evaluation as I have not had good seeing conditions in the past month since purchase and it also takes a long time to reach thermal equilibrium. I am quite sure it is representative of a typical large Skywatcher mirror and am satisfied with the quality it offers. In practice the views of the Orion Nebula and the double cluster nothing short of spectacular. M35, M81/82 best I have seen them. Nebulosity around the Pleiades is superb. Dark lane can be glimpsed in M31 and I am certain when better positioned overhead M51 the whirlpool galaxy will show the nature of it's spiral arms. This is why I bought the scope. Coma is most definitely evident in lower power eyepieces but it does not bother me that much,You may well differ. I may try a coma corrector at some point but I will not worry if I never do. Now for the weight issue. It is heavy and you do need to consider this very carefully as it literally can be a back breaker. I keep my scope in an unheated workshop/shed and I move it in two pieces.The built up base approx 80lb and the permanently extended OTA about 60lb . Although the base is built to be taken apart with hand knobs and captive nuts aiding this operation. I find it a bit too fiddly and opt to pick it up in one lot. Now I do have a bad back, but I also train a lot with weights and have above average body strength and find If I use the two cut outs in the front board and not the side handles I can lean back slightly and keep the base close to my body and manage the 15m or so to the garden. Again the tube assembly can be carefully picked up using the bottom of the truss brackets as grips, keeping it close to my body it is manageable for me without much trouble. I must stress for many this will not be an option so either a permanent position outside or full breakdown of the base (5-10-min) would be order of the day. The biggest issue with the scope apart from weight is excesive stiction on initiating movement with the altitude bearings, again a long standing complaint with Skywatcher dobs for as long as I can remember. I found cleaning both side bearings and nylon bushes with Isopropyl alcohol and then apply a few small drops of mineral oil helps minimise the jerky motion. Once done I can hand guide at over 500x with a 3mm eyepiece keeping ahead of a stars motion. The azimuth became nice and smooth once I cleaned the accumilated dust and grime from the lazy Susan roller bearing and put a drop of oil on each roller. Overall I am more than happy with the £750 I initially paid for the scope and it compliments well with what I already have. Cheers Dave
  7. I like many others Paul love the majesty of a clear dark night but hate the deep dark day's of winter , if only we could live in perpetual spring! 🌝
  8. It probably won't but I would not be surprised if you find it give's it a good run for it's money though ! Whatever your view on Orion Optics, they produce some excellent Newtonian mirrors that are often superb performers especially the F6 8" mirror set with Hilux coatings . They are a good deal sharper with smoother optical surfaces than the average Chinese mirrors. Expensive if you buy new though! Used is the way to go as you have done and good for you for getting one with a high spec. I remember having an 8" 1/6th wave and the views it gave of Saturn and Mars at favourable opposition are still ingrained in my memory many years later. Sure you will love it !👍 Dave
  9. Hi, I don't think that is acceptable even though a little dust makes no difference to optical performance it would bug the hell out of me! I don't think it is representtive of what to expect from a premium Skywatcher product from a state of the art optical manufacturing facility(so we are told). regards Dave
  10. Hi All , This will be a fairly brief comparison of 3 different diagonals I have had the opportunity to test in the same telescope over 2 nights and 5 hours observing . It is purely my opinion on what my eye's tell me whilst viewing a range of objects . It is not scientific or technical in any way and I was not intending to write this but thought someone may find it of interest! I recently purchased an as new Skymax pro 150 Maksutov . Technically second hand but it had never been out of the box in anger and never mounted or viewed through . It is the latest version with standard SCT threads on back along with the natty green dovetail. I always find “first light” exciting as all is about to be revealed . Will I be disappointed ? Will this particular set of optics be up to scratch? Will it do what is says on the tin? In particular I was keen to try it out with my Altair lightwave 2” sct fit 99% reflectivity diagonal. As we all all know the standard mirror diagonal is not the best , right? Many people have commented on this over a number of Astro forums and it is often stated as the first “upgrade” you must do. So out goes the scope about 5pm..Out of centrally heated house into near zero temperature . Figure minimum hour's cool down with this type of scope (it took over 2 hr's). Anyway first target I view is the double double using Altair diagonal. This is after an hour and I can still see the heat plume giving that distinctive wedge shape in out of focus intra and extra focal pattern although they are split well and I can already see despite disturbed view that the optics are excellent . I go back out at 8pm and all vestiges of temp difference gone , the scope is in perfect equilibrium now , so I can evaluate the optics. They are superb absolute textbook diffraction patterns on all four components and as always the Maksutov optics excel on double stars , time to chase down more and more difficult pairings. Delta Cygni next followed by the more challenging Lambda Cygni a sterner test. I am now at the limit of seeing condition and can split this sub arc second pairing but the fainter component is going in and out of that elongated smear you get when conditions are not perfect . I decide to just check with a straight through configuration that my Lightwave diagonal is as good as it looks and although requiring a contortionist pose I screw back on the original visual back and put in 1.25” adapter and 6mm orthoscopic eyepiece . Yup that diagonal is converting every photon and delivers all to my eye with absolutely no difference in view to straight through configuration . As the original visual back is now on I decided to use my William optics push fit dielectric just to see if any difference. I use the same reference doubles and pleased to say absolutely no difference in optical performance .It does sit slightly further back from the scope than the screw fit SCT but no issue with either. I now change targets and start looking at some of the tighter open clusters in Cygnus and Cassiopeia .The double cluster is just clearing tall trees and although all can't fit in the Mak's smaller field of view the stars are just pin prick jewels the deep reds of the old giant stars so beautiful , they are apo like. Anyway I am now starting to get cold so pop in for a cuppa and in my now cold conservatory sits the unloved original supplied diagonal. I decide to see just how much better my premium diagonals are so shove it outside for half hour whilst I get a warm. Back out and straight on it Lambda Cygni . The view is exactly the same ...no it's slightly better the fainter component occasionally showing as a star not a smear a clean split. Assuming seeing has improved I put William optics diagonal back in and yes it presents me with exactly the same quality of image and I mean exactly the same . I now go on a tour of all those objects previously viewed with the premium diagonals , not one iota of difference ! Nothing in terms of contrast, colour or resolution . My mind and wallet tell be there must be a difference, perhaps the good but less than perfect seeing is a leveler ? By now cold has got to me and early work in morning, session over. Next night is clear as a bell and I leave the scope and accessories in the unheated conservatory . All back out in garden at 4.30pm and start observing at 7.30 . Seeing is almost perfect . 3 hours later I can say without any shadow of doubt there is absolutely no discernible difference in optical performance not one iota visually on double stars, open clusters and Messier objects . I myself have had some really crappy quality diagonals with new scopes(mostly Meade and Celestron) but the OEM one that came with the 150 pro is excellent . Either I got lucky or Skywatcher have improved quality or perhaps the premium dielectric examples are a bit smoke n mirrors who knows ? Expensive means better right? Certainly aesthetically they are beautiful but I also rather like the rugged utilitarian look of the Skywatcher. Like I said at the start not very scientific and it may just be a case of my eyes not being able to see the minute differences between optical surfaces or maybe just maybe we convince ourselves expensive must be better . Blind testing anyone ! Cheers Dave.
  11. Hi David, I think you have made a sensible choice in keeping your C9.25. Looking at your lunar image cannot see any great advantage in going for the 180 Mak. Don't get me wrong I have actually owned 3 of them along with 3 C9.25 's. All you will gain is extended cool down times and perhaps a minuscule improvement in image sharpness and contrast and if optics perfectly collimated from factory they more or less stay permanently that way. Unless you keep in an unheated garage/shed /obsy getting perfect thermal equilibrium can actually take several hours especially if temperature is dropping away. I still love the 180 Mak and if I did not have either scope I would happily go for a used 180 purely on cost . I do think the C9.25 is slightly more versatile for general purposes at f10 and extra aperture always welcome , however as I own neither at the moment I am tempted by John in Derby's 180 Mak in the for sale section 🙂! Cheers Dave
  12. Hi Dave, A dream come true indeed. Rare as hens teeth those tripods ?! Fantastic scope for a confirmed refractor nut like you . Wish I had one ! Cheers Dave
  13. Superb, the star colours are beautiful also. Dave
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