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Liliensternus

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About Liliensternus

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    Vacuum

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    Male
  • Location
    Bucharest, Romania

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  • Yahoo
    lilliensternus@yahoo.com
  1. Hello everyone, As a fan of this telescope i, like many others have been thoroughly impressed by the quality of this instrument versus its price. I have the gold tube Pro version which i purchased second-hand for 300 euro about 3 years ago. Ever since this telescope appeared i have had the weird feeling that those guys at Skywatcher designed this with the DSLR astrophotography in mind since the ED80's focal lenght is so good a with the pixel size of the Canon EOS range. About a year ago i also purchased the dedicated Skywatcher 0.85x reducer corrector which works like a charm, its no FSQ mind you but for the price it does the job well and rightly deserves to be called an astrograph. Bearing this in mind though i have always wondered how i could use filters on this telescope without resorting to the very expensive clip-in filters. Sure, these filters would be perfect but the price is kind of high for my taste at least. Searching through many webpages i came across two solutions: 1 - http://www.firstligh...l-reducers.html The problem with this is that you cannot mount the R/C via the threads on the focuser tube, a solution which i think is always best since it is the strongest and free from any tilt, besides that i do not know if vignetting would be an issue since the 2 inch filter one would install that far ahead of the focal plane would act as a field stop/baffle. 2 - http://www.baader-pl...ion/s17/s17.htm Really nice but too much money for a hunk of metal, a really nice hunk of metal but still. One other little bug with this is that if you were using more than one filter you would have to either buy several adaptors or try to take it apart in the dark to fit another filter in place............not the best of ideas when handling metal tools close to optical surfaces at night. The two accesories above have one thing in common, the assumption that you would have to use 2 inch filters......reaaaaaaaaly ??? Remember that the sensor in the EOSXXXD range si APS-C. Now, if you have your camera on hand and a 1.25 inch filter near by you can place the filter on top of the square recess for the mirror and see that it fits really nicely. The idea is this: You can use 1.25 inch filters with your APS-C camera as long as you bring the filter as close as you can to the sensor, obviously in DSLR's that recess is the limit. So, here is my solution to using 1.25 inch filters on an ED80 telescope fitted with a dedicated R/C and a DSLR. 1 - Take one T2 to 1.25 inch adaptor with internal 1.25 inch threads and put some masking tape on the T2 threads to make it fit snugly into the back of the R/C. 2 - Take one 1.25 inch eyepiece barrel with external threads and screw it into the 1.25 inch portion of the T2-1.25 inch adaptor and then cut off the excess length. ( i am using 1.25 inch filters from a spectrometer and these have internal 1.25 inch threads so i did not have to do the modification explained below) 3 - Take your 1.25 inch filter and remove it from the housing, put it back in reverse (the mirror like side should face the camera) and attach screw it into the 1.25 inch portion inside the T2 adaptor. Despite the fact that you might be shocked by the reduction in usable diameter of the R/C remember that the whole point of this excercise is to bring the 1.25 inch filter as close to the rectangular cutout inside the body of the DSLR as possible. Finally here are some pictures to help you understand the whole idea and some flat frames taken with and without the adaptor to check fot vignetting. Hope some of you will find this useful, i for one can cut my filter expenditures in half going from planned 2 ich narrowband filters to 1.25 inch ones. 0.85x R/C, adaptor and M48 to canon EOS adaptor Adaptor mounted inside 0.85x R/C The whole assembly including 1.25 inch narrowband filter ready to be attached to the focuser and camera. When a change of filters is required, the camera is removed, the filter unscrewed and another filter screwed in place. TESTING: WITHOUT ADAPTOR Flat frame taken without adaptor, 1/45 seconds at ISO 400. Same image as above with Auto Levels and Equalize set to default levels in PS7 portable to emphasize vignetting, desaturated. WITH ADAPTOR Flat frame with adaptor, 1.45 seconds at ISO 400. Same image as above with Auto levels and Equalize set to default levels to emphasize vignetting, desaturated. There is a small difference in the amount of lighting at the edges but given the vignetting present without the adaptor the difference is inconsequential. CONCLUSIONS: The addition of a 1.25 inch reduction to the back of the dedicated Skywatcher 0.85x R/C has little impact on vignetting due to the close proximity of the reduction/1.25 inch filter to the camera body. This makes the use of 1.25 inch filters on this telescope when used in conjunction with a DSLR possible at a significant reduction in cost for those wanting to attach filters to this particular setup. You heard it here first on SGL folks All the best Mihai
  2. You are very welcome. This solution has the advantage of being more compact and simpler to build then the classical lightboxes and cheaper than EL panels. Besides that, i love the fact that it can do double duty as telescope cover and lightbox. . All the best
  3. Hello Everyone, Since all work and no play makes for one sad amateur astronomer i decided to finally get my act together and construct a flatbox after realizing that synthetic flat frames will never cut it, especially under the light polluted sky of Bucharest with every kind of gradient immaginable. After scouring the internet for various solutions that people have implemented and ranging from lightweight but bulky classical lightboxes to laptop tft screens and ending with electroluminescent panels (EL panels) i decided to go with the tft laptop screen ideea. I obtained a broken laptop from work, gutted of essentials but with the screen still intact and in full working order and after dismantling it i discovered that at least that particular screen and i am assuming older models as well work by shining a high powered halogen lamp through a piece of plexiglass and are backed by an aluminium foil to aid in reflecting the light and by a number of polarized diffusers at the front. The problem with this idea was the size of screen.......somewhat larger than an A4 size piece of paper and that meant a lot of wasted space as i only have an ED 80 for imaging. Dismantling the screen proved valuable in that it furnished me with the mode of operation of these devices and gave me the idea which you see below. In as few words as possible, laptop screens work by internal reflexion of a lightsource placed on one edge of a plexiglass sheet and remove any gradient by using polarized difussers. Realizing this i odered a piece of 4mm clear plexiglass worth around 3 pounds and a strip of 15 white SMD 3528 LED lights for about 2.5 pounds bringing the total cost for this little project to a 5.5 pounds, dont think you can get any cheaper unless you already have those items. So here are the actual stages of construction: 1 - I cut out a circular piece of plexiglass 90mm in diameter and used sandpaper to give the edges and the side facing the objective a matte finish whose purpose is to aid in diffusing the light from the led's. 2 - Onto the periphery of the plexiglass i superglued the led strip using a few dabs of glue inbetween the individual led's and connected the trailing wires to a 5mm power jack making sure the connections were tip positive (since all Skywatcher instrumentation seems to use this it makes sense to take the extra bit of time with a volt meter). 3 - Cut out and glued a piece of aluminium foil to the back of the plexiglass disc. 4 - Sanded the face of the plexiglass facing the objective. 5 - Glued a piece of black paper with an internal diameter of 85mm and an external diameter of 90mm to the side facing the objective (this serves as a sort of field stop for the led's). 6 - Glued circular cutouts of the laptop screen polarizing sheets to the face of the plexiglass facing the objective and added a couple of layers of tracing paper on top securing them with scotch tape (i know it's not that pretty but it works). 7 - Drilled a hole in the top of the cover of the ED80 and fitted the 5mm female power jack. 8 - Superglued the whole assembly to the inside of the ED80 cover and left it for 3 days to allow for any outgassing of the glue. The result of this is a very compact, dual purpose lightbox/objective cover that does not take up any extra space. For larger diameters where led strips would be farther apart from the center of the plexiglass disc and hence give light frames which would be brighter on the periphery and dimmer at the center one could use an EL wire glued in a spiral onto the back of the plexiglass starting from the inside out or the other way round depending where you would want your power jack to end up... And since a picture is worth a thousand words here are some of the actual item and the results obtained with and without the flat frames. Diagram illustrating the arrangement of the the plexiglass disc, aluminium foil, filed stop and polarizing screens inside the ED 80 objective cover. Side facing the objective. Opposite side with 5mm female power jack, tip positive. With power on. And now for the actual testing. I took three images with a stock Canon EOS 500D and ED80 on the NEQ6 mount, guided with PHD guiding. The lights were shot in RAW format and show a patch of stars near the constellation of Lacerta. Lights were shot at ISO 400 and are 2 minutes long, 3 dark frames, 3 flats, 3 bias/offset frames. Images were stacked in DSS and the output files were processed with PS 7 portable edition. Flats were taken with the camera set to AV mode which resulted in exposures of 1/45 seconds at ISO 400. All images were compressed quite heavily to fit them here so please bear that in mind when you see jpeg artifacts. In photoshop, the central star has a value of 255, 255, 255 and the background and average of 20, 36, 40 (after normalization). WITHOUT FLAT FRAMES: DSS output without the addition of flat frames (central star value 245, 245, 245, background around 230) Levels ajusted, central star 255, 255, 255, background around 30 (vignetting and various lp gradients from floodlights reflecting off buildings and window frame) Synthetic flat applied to the previous image in PS7 from a blurred copy with a Median filter of 45. Same as above but with the application of a Gaussian blur filter of 250 on top of the Median of 45. CONCLUSION: In heavy light pollution in the center of a major city with numerous gradients, synthetic flats are of little use. It could be that with further work or with the use of the DBE tool in PixInsight the image could be improved, but for those of us using Photoshop for one reason or another synthetic flats under these conditions are of very limited use. WITH FLATS: DSS output with flat frames. DSS Master Flat, Adjusted in PS7 with auto leves to emphasize vignetting. PS7 output with central star values of 255, 255, 255 and background values of 30, 30, 30. Same as above but with threshold levels of 40 to emphasize gradients which are very small in the original image. With a Median filter of 35 applied to a copy of the original image and then subtracted from the original with an offset of 50. Same as above with a Threshold of 30 levels to emphasize smoother gradients, at 40 levels gradients are not visible. Final image with central star levels adjusted to 255, 255, 255 and background normalized to 20, 36, 40, star colors enhanced with match color. CONCLUSION: The use of real flat frames brings dramatic results and corresponds to fewer operations necesarry to remove any leftover gradients. I know that these conclusions are taken for granted by those of you with considerable experience but for someone like me it was a real wake-up call as to the importance of all calibration frames not only darks which are universally recognized as essential for a good image. From a personal standpoint i am quite happy with my little gadget despite the fact that it will not win any beauty contests, it took about 2 hours to put together and saves many more hours in processing messing about with Median and Gaussian filters. Of course, in dark sky areas, even without flats, the results are nowhere near as disastrous as those taken from light polluted areas, but gradients and vignetting are still present to the extent that i have to actually look for them in photos, but still there presence bothers me......no more after this little weekend project though. All the best. Mihai
  4. Hello, This is my the result of my first guided astrophotography session. So far i have only taken a few other photos on an NEQ5 mount with a canon 300D without guiding so i am thrilled at the difference guiding makes on an image. Canon 500D, ED80 with 0.75x reducer, guided with 70/250mm guidescope and Meade DSI 1/ PHD guiding on an NEQ6 mount. Lights - 22, 5 min subs, iso 800 Darks - 22 Offset/Bias - 22 Stacked in DSS and processed in PS using the books by Jerry Lodriguss and DugDogs tutorials on youtube. Did not pull on the histogram too much and would prefer another 22 subs at 10 minutes to pull out the periphery. Had one hell of time with saturation because it was set to 0 in DSS and took me a while to realize it. Hope you like it and i await your criticisms.
  5. Working my way up to maybe a 200mm F4 Skywatcher Quattro, the ED is beginning to show it weakness as an astrograph due to the slow speed even with the reducer...
  6. Hello everyone, As a recently minted member of SGL here is my astrophotography setup for you enjoyment. NEQ6 mount, ED80 with 0.85x reducer/corrector, 70/250 guide-scope on a tangent mount atop the ED, Meade DSI 1 guide-camera, unmodded Canon 500D imaging camera, Lenovo S10E netbook, generic gamepad. Image acquisition via DSLR Shutter, mount guided with PHD guiding, FTDI RS232 between laptop and mount, EQMOD running unde The Sky 6, processing in Photoshop. The mount has been taken apart completely and regreased with white/yellow-ish teflon based grease. The dismantling part was done with the help of Astro Baby's excellent tutorials. I have chosen to go down the route of FTDI based adaptors due to the lack of and ridiculous price when found of EQ direct adapters, for one as electronically challenged as myself it was a really easy build. The main imaging scope is the ubiquitous ED80 from Skywatcher purchased second-hand, in fact except the mount, gamepad and FTDI adapter, everything was purchased second-hand. My original setup was atop a NEQ5 but alas i should have listened to the folks here that said to purchase the best mount you can afford...sold the EQ5 after 6 months. The guide camera back then was a Synguider that i never managed to get working properly, on the other hand the DSI i have now and PHD took only 2 hours to get working properly and has been running smoothly ever since. First camera was a Canon 300D but recently a 500D fell into my lap for less than half the price of a new one and had only the test shots i requested taken with it so actually it was brand new....lucky me. Thank you for you patience in reading the above, must sound like a well known history for those of us bitten by the bug.
  7. @Scuba Mike - that's why i joined..... cant wait. @ swamp thing - before you panic its the physics behind the weapons that interests me, personally i a an opponent of nuclear weapons but at the same time i love the physics and mechanics involved, screwy i know but..... @Mr Spock - yup, Hunedoara is right, Hateg is in Hunedoara County, really small world. @Alan B - mosquitoes you mean.......ha ha ha cold chill on the back of my neck
  8. Hello to all, My name is Mihai and I am an amateur astronomer from Romania. Knowing this you are probable wondering why I've chosen to join an astronomy forum in Britain, the answer is simple.....i have known about this forum and have watched it for some two years now but only a little while ago did i decide to take the plunge as it were and sign up. Professionally i am a Geologist with a bachelors degree in Biostratigraphy (i look at bugs brought up by the drill bit and tell you the age of the rock from which they came) and beginning a majors in Vertebrate paleontology (my true love). Hobby wise astronomy and painting are up there battling one another for my spare time. I started with visual astronomy about ten years ago after receiving a home built 130mm Newtonian from another amateur. Took a break from the hobby for quite a few years but started again two years ago after a friend gave me his EQ5 mount which he bought for astrophotography but never used. I have never owned anything larger than 6 inches aperture and now i have started down the long road of astrophotography. Fear not, i already have a working setup and will not bother you with silly questions asked over and over but i will bug you good people with processing issues.... Other hobbies: Growing Carnivorous Plants, Astrophysics, Physics and construction of nuclear weapons, hiking, drinking, . Sooooo, this is a bit about me, the rest and most important bits you will find on Deviantart where i post my works, they speak better of me than i ever could.
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