Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_beauty_night_skies.thumb.jpg.2711ade15e31d01524e7dc52d15c4217.jpg

Search the Community

Showing results for tags 'diagonal'.



More search options

  • Search By Tags

    Type tags separated by commas.
  • Search By Author

Content Type


Forums

  • Welcome
    • Welcome
  • Beginners
    • Getting Started General Help and Advice
    • Getting Started Equipment Help and Advice
    • Getting Started With Observing
    • Getting Started With Imaging
  • Community
    • Official SGL Announcements and Events
    • SGL Challenges and Competitions
    • SGL Star Parties
    • Star Parties & Astro Events
    • Celestial Events Heads Up
    • The Astro Lounge
  • Retailers
    • Sponsor Announcements and Offers
    • FLO Clearance Offers
    • Supplier Reviews
  • Astro Classifieds
    • For Sale / Swap
    • Wanted
  • Equipment
  • Observing
  • EEVA (Electronically Enhanced Visual Astronomy)
  • Imaging
  • Science
  • WADAS's WADAS Discussion Forum
  • Beaufort Club's Topics
  • Swindon Stargazers Club's Topics
  • East Midlands Stargazers''s Topics
  • Central Scotland Astro's Topics
  • SGL Cumbrian Skies's Topics
  • Herts, Beds and Bucks Group's Topics
  • SGL East Anglian Group's Topics
  • South Leicester Observers's Topics
  • South Wales Group's Topics
  • SGL Surrey Observers's Topics
  • South Yorkshire Stargazers's Topics
  • Yorkshire Astronomers's Topics
  • Devon and Cornwall's Topics
  • West Midlands's Topics
  • Essex Cloud Dodgers's Topics
  • Essex Cloud Dodgers's New equipment
  • NLO and Planetarium's Topics
  • Astronomical Society of Edinburgh's Discussion
  • Dorset Stargazers's Topics
  • Hairy Stars Club (Comets)'s Tutorials and Guides
  • Hairy Stars Club (Comets)'s General Discussion
  • Hairy Stars Club (Comets)'s Observing Campaigns
  • Hairy Stars Club (Comets)'s Analysis results
  • Hairy Stars Club (Comets)'s Useful Links
  • Pixinsight Users Club's Pixinsight Discussion Forum

Calendars

  • Astro TV
  • Celestial Events
  • SGL Calendar
  • Astro Society Events
  • Star Parties
  • WADAS's Events
  • Beaufort Club's Events
  • Astronomical Society of Edinburgh's Events
  • Dorset Stargazers's Events

Blogs

There are no results to display.

There are no results to display.


Find results in...

Find results that contain...


Date Created

  • Start

    End


Last Updated

  • Start

    End


Filter by number of...

Joined

  • Start

    End


Group


AIM


MSN


Website URL


ICQ


Yahoo


Jabber


Skype


Interests


Location

Found 20 results

  1. Time for yet another cry for help when it comes to choosing diagonal. I have read the many similar threads and gathered some knowledge (too many to start linking). I have come some way in my process and now that it is coming to final decisions I would like to hear from the experts. Not many of threads I have read end with the OP returning to deliver some review/verdict of his/her final decision. While I wait for response on some thread where I asked about the result, the eagerness in me forces me to write my own thread. Perhaps some of the people asking these questions before can now answer in my thread as experts!I have the Nexstar Evolution 9.25 and am currently using the stock diagonal. My eyepieces are the Baader 8-24 mm zoom and the stock 40 mm Plössl. I would also like to upgrade EPs and there I'm looking at something better in 24 mm range, as well some nice low power for more FOV. I'm following threads about EPs and SCTs with great interest for this (on CN). Can say that I'm currently leaning towards the 1.25" 24 mm ES 68° and 2" 36 mm Hyperion aspheric (if going 2" route).I'm thinking 2 alternatives (including a budget alternative for one of them). I'm looking at Baader mainly for ClickLock (and expect good optics): Baader T2 Zeiss prism with a 1.25" ClickLock EP (T2 part #08) -OR- the 2" prism with 2" ClickLock (splurging that is). The budget alternative would be to get the non-Zeiss T2 prism instead for the 1.25". Worth noting that I would like to get the Celestron f/6.3 Reducer/Corrector. This would be for future purposes of delving into EAA but of course I would use it visually as well (especially if choosing the T2 route). The reasoning for my alternatives: Go for the 2" Zeiss prism to theoretically get the best of the best in visual terms. I would make better use of the 46 mm baffle tube opening. Theoretically possible to combine with the R/C thanks to relative short light path (although not necessarily needed with 2" EPs). Downside of going to 2" accessories would be the cost, EPs, filters etc., on top of diagonal. Would not be able to spend all these costs at once. Cheaper route with T2 prism (especially the non-Zeiss), not only diagonal but also the other accessories. Cost of the R/C would be comparable to e.g. the 36 mm aspheric and give similar power and FOV with the 24 mm ES, i.e. the 24 mm would act as both. Extra plus is the ClickLock clamp for 1.25" with built in fine focusing not involving the mirror. Downside of knowing that not all light coming out of baffle tube is used. To get the wide FOV (24 mm + R/C) I'm adding glass to the optical train (theoretically not a good thing). I'm leaning towards the T2 as it would be a cheaper diagonal and for EPs I would only need the 24 mm and then the reducer instead of a 30-40 mm, so saving the expense of one EP. Then I would already have the reducer for continuing into EAA. The questions I hope the experts here can help with: The old reducer vs 2" diagonal question. With R/C and the 24 mm I can get roughly the same mag and FOV as e.g. the 36 mm Hyperion (technically 38 mm vs 36 mm and 68° vs 72°). Also reading good things about the ES 68° and with R/C the EP should behave the same. Am I missing something here? The logics say that the I would lose some contrast with the R/C (not using full opening + adding elements), correct? Possibly flatter fields though (not important now, hopefully the EP threads might tell soon enough). The Zeiss vs non-Zeiss T2? Big differences? I have read a few posts on this so most to get some updated views here (have read that Baader has changed some things over the years). Using the R/C (f/6.3) with these prisms. I know f/7 is mentioned as "the limit" but also remember BillP's test where he was happy down to f/6 with the prisms (in 2014 at least). Perhaps most important: have I missed some other obvious alternative here? Maybe I have forgotten some question here but perhaps for the best as I assume those who have gotten this far are tired of reading now. Thanks for getting here though!Thanks,Viktor
  2. https://www.astroshop.eu/telescopes/tecnosky-apochromatic-refractor-ap-70-478-quadruplet-flat-field-ota/p,57327 How to know this? I have read that with 65/420 scopes you cannot use 2" diagonals because there isn't enough backfocus.
  3. Does anybody happen to know the light path measurement for the Baader Click-lock di-electric star diagonal? Paul.
  4. Are there any advantages of using a 2" diagonal with a 1.25" eye piece vs a 1.25" diagonal and 1.25" EP, assuming both are of similar build quality? [Someone asked me this and I gave them my answer, but I wonder what others think]. James
  5. Thanks to recommendations from this forum, I recently purchased a Bresser AR-102s/600 refractor. (I apologise for the rubbish weather lately, it is obviously my fault. ) The supplied (1.25in) diagonal is very cheap, all-plastic construction. Even the barrels. And I would like to upgrade as soon as possible. This telescope accepts 2" accessories, so I want to begin by getting a decent diagonal, then upgrade eyepieces later. I had my eye on a William Optics 2" Dielectric Diagonal, but then saw an Altair Quartz Dielectric Diagonal 2" Push-fit for almost half the price. Altair also make a 2" Lightwave Premium Dielectric Diagonal, which falls roughly in the middle of the price range. I've heard very good things about the Williams Optics diagonal. My question is what are the Altair like. And is it worth spending the extra, for what is a relatively "budget" range OTA? Recommendations for 2" eypieces that I should consider are also welcome. Thanks.
  6. Hello all, We've just discovered that the Bresser Skylux 70/700 that Santa brought to my daughter is missing one piece: the prism/diagonal. My husband went to the shop (supermarket) where the telescope was bought at a very convenient price (like 50% discount), but at this time we fear there will be no other telescopes left, so we'll probably have to options: - Get the refund for the telescope and save some money for another telescope, at a higher price - Stick with the telescope and buy the missing piece on eBay or Amazon... maybe we can find a better one which will improve the telescope performance? We have zero knowledge about lenses/telescopes, but my daughter is really interested in Astronomy (watching videos and reading about it all day long) and she was really excited when she got her first telescope... Could you please give some advice? Thanks!
  7. Celestron XLT 2" diagonal Includes 2" - 1.25" adapter SCT fit original packaging The diagonal is in excellent condition May swap for Baader Hyperion 68 degree 10mm eyepiece or Baader Aspheric eyepiece 31mm or 36mm - these must be in excellent condition with caps etc Price includes postage (1st class signed for) £110 £89 Lancashire area Cash payment or fees paid via Paypal.
  8. The clearout continues! Williams Optics 2" diagonal with carbon fibre side plates. These retail for £135, but I only want £55 of your pounds. For that I'll send this insured post. I don't have the original box, but it will be well packaged. It will include the 2"-to-1.25" adapter. There's a couple of small wear marks on the tube from use, otherwise it's in tip-top condition.
  9. A very nice condition TAL 1.25" mirror diagonal. Optically and cosmetically in excellent condition, just don't use it any more. £25 plus postage via PayPal fees paid or bank transfer. Stu
  10. Next up on the brown carpet..... ?? A very nice, Baader Maxbright T2 mirror diagonal in excellent condition, just a little dust on the mirror. This has 99% reflectivity, Sitall glass with 1/10th lambda surface accuracy. Male T2 connection one side and Female the other, both with original screw-on caps. Looking for £125 posted or £120 picked up at SGL11. Paypal fees paid or bank transfer please. Cheers, Stu
  11. This is a somewhat custom built, but very nice Denkmeier PowerSwitch. The original William optics diagonal was not in good shape when I received it, so I have replaced it with a nice Baader Maxbright Mirror diagonal, 1/10th wave lambda surface quality, T2 fittings either end. It also has a T2 quick changer fitted to allow correct positioning of the PowerSwitch. Everything is in very good to excellent condition, the diagonal just has some minor dust on it but is otherwise in excellent condition. The PowerSwitch allow you to use straight through, multiplied or reduced views with the slide of a lever, very simple, although clearly you need to refocus each time. Total cost of the components in this is rather high, probably approaching £400 or more! This would be very handy for binoviewers in SCTs or fracs with good back focus. The T2 diagonal has a nice short light path with a clear aperture of 35mm so most 2" eyepieces can be used with no noticeable vignetting. I use a 31mm Nag in these diagonala without problem. It is also handy for solar viewing with a full frontal filter, or potentially a Quark to give variable magnification, back focus allowing of course. Looking for £195 ono plus P&P via PayPal fees paid or bank transfer. I will put this on ABS too in the near future. Cheers, Stu
  12. Hi all, I was looking for a 99% reflectivity 2" diagonal with a locking mechanism instead of thumbscrews. Thumbscrews eat through my gloves and are hard to use when fingers get cold. I saw the (very expensive) Baader Click Lock diagonal and the Williams Optics bright orange locking ring diagonal, which is cheaper but still pricey - and you either dig the orange or you don't. Finally I found the Antares 2" twist lock diagonal. I got two Antares twist lock diaginals delivered to the UK from Ontario Telescopes for about £160, so the same price as a single Explore Scientific Carbon Fibre diagonal and a lot less than a single Baader Click Lock diagonal. The Antares are solid, well machined diagonals and the mirrors look bright, smooth and clean. Light transmission seems just as good as my Explore Scientific 99% Carbon Fibre diagonals. Naturally the Antares are heavier diagonals. So what about the twist lock? It looks thin and insubstantial in the photos so this was a bit of a punt. In actuality, the twist lock is very solid and smooth. It turns very quickly and smoothly, so is much quicker and easier to operate than thumbscrews. It also holds very nicely indeed. I have some pricey 1Kg (2.2 lb) eyepieces, some 100 degree with Green lettering on, some Explore Sceintific, and I'm pleased to report all were held very well by the twist lock and I had no fear of them being dropped, even when viewing at the zenith. I suspect I could pick up my c9.25 by the eyepiece using one of these, though I haven't yet tried. Result: an excellent choice, money well spent. Might even get a third as I'm running three scopes simultaneously on my Ercole (though I never bother changing my little ED80 from a 21mm Ethos.
  13. Sob Sob! Yesterday evening I was doing some terrestrial observation (and testing my new second hand Nagler 3.5mm eh eh! - it works wonderfully - thanks Lee), when the eyepiece holding screw of my revelation dielectric diagonal got stuck. Fortunately no eyepiece was placed at the moment, but the screw stop rotating inward or outward. I finally managed to unscrew it, by using a piece of cloth. The thread in the end is damaged and does not allow the screw to enter. I do not know whether this is a single unlucky case, but I think that the mechanism should be much more solid that this. Particularly since that diagonal was less than 6 months old.. Dunno, many people like it. I think the mirror is works well, but the mechanics (at least for the one I got) does not seem to be well built.. So, now I have a diagonal which cannot lock the eyepiece.. scary.. I know it costs more, but I will replace it with an TV everbrite. At least I can be sure that every single item passed a severe quality control.
  14. Hi guys and girls - I have just purchased an SW Equinox 80ed and I need a 2" dielectric diagonal and a 2"-1.25" adaptor for it as well - If you are having a wee clearout drop me a line Andy
  15. I checked 365astronomy's lowest-cost, made-in-China 2-inch 99% diagonal mirror, just 79€ when most 99-percenters cost at least 120€. I didn't fear any lack of resolution because of the price, when whole chinese telescopes routinely have 1/20 or 1/30 wavefront, a single small excellent mirror is nothing difficult to manufacture. Makers claim either 1/10 or 1/12 wave to remain conservative but the real wavefront in the latest diagonal production is way superior. I needed one for my newly-restored Astro-Professional 80mm f/7 semi-apo. The nosepiece wobbled a bit, however. I tried to screw it, but it wouldn't move. How can it be both loose, and stuck? I tried harder to screw or unscrew it, but it didn't turn either way. Better open it and see what's wrong from the inside. The side panels were removed without a glitch. This revealed a matte-blackened frame, but the job was not complete, some shiny black spots remained: Unlike all my other mirror and prism diagonals, the nosepiece and the other barrel are not threaded, they are held by lateral screws hidden in dark tunnels on the side of the frame, which is full-metal, single-block and very sturdy, by the way. The whole thing weighs 396 grams, an average mass for an all-metal elbow. One of the nosepiece screws was worn out, and turned without engaging anything. It's the little one on the Allen key; close to it is a functional screw with intact threads. By sheer luck I'm a guitar tinkerer as well as a telescope tinkerer, so I had 3mm Allen screws in old guitar saddles, since I substitute non-resonant zinc alloy saddles with resonant steel ones. I installed the flat-tip chrome-plated screw, and solved the issue. However most people would have returned the diagonal, causing hassle to themselves and the seller. Better do a quick check on the gear before shipping it. Aside from that , the service from 365astronomy was courteous and efficient, as always. I painted everything that's not the optical surface with blackboard paint. Went out to buy a little thing, when I came back the water-based paint was dry. Frame, anti-glare threads in both barrels, black paint for everyone. The anti-glare threads are no longer shiny, but the foam is still more gray than black. After treating it, absorbtion of light is at the max: You can see the difference between the painted section, and the part that touches the mirror, which I left as it was because the paint might stick to the mirror in time, and make maintainance annoying. Then I remembered some guitar saddles have V-tip screws that would match the V-notches in the barrels, and replaced all eight of them: This time tightnening the screws didn't make the nasty noise of rough steel tips biting into aluminum, and giving birth to tiny shards that had to be cleaned away carefully, without pressure at all. Just holding the mirror vertically and touching it with a thick stitching thread. Metal dust would either fall or stick to the thread. Barrels that don't screw into the frame are maybe easier and cheaper to manufacture, but they also allow the top barrel to be oriented freely, so you can place the eyepiece locking screw where it's most ergonomic for you, nice. During the changes I noticed the mirror is translucent at certain angles, so much so the silicone blobs that glue it to the frame are visible through it. That's not easy to photograph, though, here's the least failed attempt: There is no metal film on the mirror, just the dielectric layers. Surprised me first, but then it came to my mind that all our interference filters for light pollution or imaging are also mirrors, but selective mirrors, so no wonder. Time to reassemble the diagonal, and test it. But before that, I realized I had never shown the old-new Astro-Pro, so here it is. The setup, completed by a 34mm/68°, a bargain from First Light Optics, seems to have all its components matched together pretty well: The contraption at the front is a sliding, tilt-lock (I'll describe it in detail in a future thread) 500 gram counterweight. But it proved too light for the 34mm anvil, I'll make another 700 gram tilt-lock, same as for my triplet. When the finder is in place the need for a heavier weight at the front will be an emergency. The diagonal I expected had the 365astronomy logo, this one bears the Starguider brand, proof we live in the time of clones. My usual artificial star is flashlight-mounted but fainting batteries have interrupted experiments, so I relied on my bass amp's on/off diode this time (best compact amp I heard among 13 or 14 others, thanks Ampeg!). It has a very intense purplish-white shine that would prove very useful for testing a particular feature related to this thread's title. But a quick quality test with the Ronchi grating, first. The finding was both reassuring and expected: Straight sharp lines with a trace of barrel curvature (intrafocal), and no strange color effects, exactly identical to what I saw with the proven GSO diagonal. Excellent. Note the overwhelming blue-indigo-violet light given off by the diode, that makes all refractor testing harsher. Hey, what was that talk about a hidden secret filter, you ask, that's been bogging you since you read the title of this thread? You see, price was not the only thing that interested me in this diagonal. APM of Germany also sells a clone of it, however they display something others don't, a reflectivity chart: Reflectivity of the Zenitspiegel, zenith mirror with blaue Seitenteile, blue sideplates. Another rebrand. Unlike other, more costly dielectrics with 99% efficiency over the whole spectrum and a flat reflectivity diagram, this one absorbs some violet, it has dips in the beginning of the curve. And my semi-apo has some unfocused violet light that might as well not reach my eye. That 400 nanometer to 435-440 nanometer range semi-apos have a tough time with. We'll make a cheaper dielectric layering, but since it can't be efficient over all colors, we'll taylor it so the inefficiency sits in the violet part, the engineers surely said. I knew the effect would be present, but to what extent? Would it be beneficial or just detectable? Enter the super-violet amp diode. Aimed at with a TS/Nirvana/William 4mm/82° clone. Intrafocal defocus, 2 turns of the small wheel in the two-speed focuser: Left: filtering dielectric, right: full-spectrum dielectric. Left: Outer halo is thinner and bluer. Inner disk is extremely pale pink. Outer ring of the disk shows. Right: Outer halo is broader and more violet. Inner disk is pale purple. Outer ring is washed out. The extra defocused light reduces contrast. The first pattern is preferable because it resembles a "white" full-apo a tad more; the whiter the pattern (paler colors), the better. The less difference between disk color and halo color, the better. In achromats the disk is hard lime green, and the halo is hard violet, strongly differing colors. Intrafocal defocus, 3 turns of the small wheel in the the two-speed focuser: These patterns are more readable thanks to the larger defocusing. Left: violet-absorbing dielectric, right: full-spectrum unit. Left: overall disk is pale indigo, two rings are distinct inside the halo. Right: overall color is pale violet, only one ring can be made out inside the halo. Some contrast is lost to the blurred violet light spread over the pattern. All photos done at 400 ISO, no treatment, not even a crop. Visually, either in focus or outside of it, the effect is the same as in these shots. Violet is fainter. I looked at targets as harsh as the superviolet amp diode: mercury vapor lamps over a parking lot. The violet halos appeared a bit larger and in a bolder tone with the full-spectrum (and 50% more expensive) GSO mirror. Switching to the Starguider, mercury lamps were surrounded by a tighter region of blurred light, and it was more pale indigo than true violet. The purple in defocused images was fainter, too, either outside or inside of focus. The patterns resembled less those of achromats. Try viewing the original images by clicking on these pics, constrast will be neater, and colors will be truer. The filtering quality of the diagonal might not seem much, but bear in mind the eye sees variances better than my phone camera does, and the targets were overloaded with purple light. Sorry, no Moon, no white Sun and no stars available for a real-world test. Only skies so overcast, a ceiling so low, the colors of lamps underneath paint the clouds. Pale green over a stadium, orange over the industrial. Turbulence was supernaturally absent at the onset of the nightscape testing, at 140x I didn't comprehend what I was seeing cause the image didn't have the slightest tremor, but things were brought so much closer. Normally such enlarged things shimmer a lot but this time around they were still, something I always associate with small magnification. I was confused for seeing opposite things in the same time. Some time later a more "normal", but still very slight tremor presented itself. The only problem I found in this secretly filtering diagonal is they don't advertise it as such. It might not be as efficient as a Baader Semi-Apo filter, but its reduced reflectivity makes it cost less, and makes it double-duty as a chromatism filter. Achromat and semi-apo owners should be told that. While comparing chromatism between the new diagonal and the proven GSO, I also checked sharpness, brightness and contrast (outside of these chromatic effects). At times one seemed to have the minutest edge, other times the contender seemed a shade superior. When this occurs it means both are equal. They charge 1/3 less for the Starguider-365astro, though. Catadioptrics also have a little chromatism arising from the single "lens" acting as the corrector plate. I wonder if this discreetly filtering diagonal could help there, too; no one would put a Fringe-Killer or Semi-apo filter in their catadioptric, they would filter out too much good light. Who knows if this affordable mirror could improve contrast there? How about you people experiment and research a bit? I have done my part.
  16. I've recently bought a cheap diagonal, but the image seems not collimated. When the star is out of focus, I don't see it as a ring, but as a ring with one side thinner than another. Without the diagonal the image is perfect. I'm using an SCT, and have never had to collimate it. Is it even possible that a diagonal is poorly collimated? Is there a way to fix it? http://agenaastro.com/gso-1-25-90-deg-99-dielectric-mirror-diagonal-compression-ring.html
  17. Hi All, I have the following for sale, originally bought for a full PST mod that was never done: Coronado PST - £430. Boxed. Vixen A80M - £150. Includes tubes rings, dovetail and focuser but no box, finder or diagonal. SOLD. 90 mm D-ERF - £200. SOLD. Filter holder - £8. Homemade and bought off a SGL member. Fits the 90mm D-ERF and has a internal diameter of 105mm the other end. SOLD Solar Finder - £15. SOLD. WO Dielectric Diagonal D-DIG2 - £35. Boxed. Bought to be used on the Vixen before the scope was modded. SOLD. All are in excellent condition and do not include postage. Collection preferred for the scopes. Cheers, Jon
  18. Last part of my spring clear out - See anything you need just drop me a line and we can sort it out for you. Payment by Paypal or pick it up in Edinburgh in person and save the p&p. Cheers gang - 9x50 Unbranded metal RACI finder with Skywatcher compatible dovetail with rings - £35 + p&p - Unbranded Red Dot Finder (moulded plastic) £5 + p&p - 1.25” Celestron star diagonal £15 + p&p - 2” TS mirror star diagonal with brass compression rings £40 + p&p Extended slow motion control for RA/DEC on EQ mount (never used) £8 + p&p
  19. Ok Team, I'm on the hunt for a diagonal, but before I push the 'buy button' I would like to know a couple of things! 1, Is there any point in buying a 2" if all my EP's are 1.25? 2, How important is the quality of the diagonal in the overall scope set up? I guess I may be answering my own question with the quality one when I tell you that I recently bought a Meade HD 60 6-Element EP of a well known second hand site... The quality views through that EP are fantastic (I'm saving for another) However, I was looking through a standard issue diagonal, so will a dielectric improve my pleasure? Thank you...
  20. FOR SALE: William Optics 2" Dielectric Diagonal This is a used William Optics 2" Dielectric Diagonal that I no longer require as I have moved to a DOB. It is in excellent condition with only a few very small dust spots visible on the mirror surface. It has been well looked after and regularly blown with a rocket air blower after use to keep it in top condition. It comes with the original William Optics 2" to 1.25" adaptor and original William Optics end caps. See https://www.firstlightoptics.com/diagonals/william-optics-2-dielectric-diagonal.html for more information. NOW SOLD
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.