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Everything posted by Lonestar70

  1. Hi Alex, The correct coma corrector for the SW200P is this one Skywatcher 0.9x Coma Corrector You will also require the M48 camera adaptor for the Nikon. Skywatcher DSLR-M48 Ring Adapter Both are available from FLO. It is arguable whether you can reach focus with the standard 200p focuser, as you may find that it has insufficient inward travel. especially since the coma corrector also works as a focal reducer (0.9x)... this will make the focus point somewhat closer to the scope. (opposite effect of using a Barlow) You could certainly find focus using a Barlow inserted into the focuser and with the coma corrector fitted into this, however the net result would be a much longer focal length (not recommended). The only other method would involve moving the main mirror cell up the OTA tube to bring it a little closer to the secondary... this will move the focus point further out on the focuser. This may not be a good option since it may effect the warranty on a new scope. If you have not already got the 200P (reference your question in another thread) then you would be better off saving a little more and going for the SW200P DS since this has been modified for DSLR photography and will certainly reach focus without the Barlow. It also has the low profile dual speed x 10 focuser fitted, which will be much better for fine focussing. I hope this answers you question. Best regards,
  2. Hi Mike, You can obtain 1/4" x 20 BSW studding, dome nuts and standard hex nuts all in stainless steel from: - http://www.stainlessautomotivefastenings.co.uk Cut the studding to length required and fit a DOME nut on one end (use a touch of araldite or loctite if you want it to remain fixed) this will replace the round head... then you can use a standard nut for adjustment/driving purposes if required. Stainless steel will be better suited to outdoor work in the cold and damp. Finding off the shelf round head bolts at 1/4" x 20 whitworth is no longer that easy... especially 4" ones... thanks to metrication. Hope this helps. best regards. Sandy.
  3. Hi Gina, Thank you for the + vote on the sliding weight idea. That would be my main fear also... especially in the dark when you cannot see the clamp positioning clearly. It's not the best clamp arrangement at the best of times.. and anyway, you have had enough heart stopping mishaps... you certainly don't need any more. I will see what I can come up with and will post the results. Probably best if I do that in the DIY section. In the words of Cptn. Oates... " I may be some time" If it works out ok and you think it would suit your set-up then I am sure I could be persuaded to make a second set. Us oldies have got to stick together you know!! :grin: Keep happy and healthy.
  4. Hi Gina, it’s so nice to finally make your acquaintance. I have been following your many exploits/projects, trials and tribulations, successes and, sadly, the occasional misfortune for some time prior to joining the lounge. They have certainly given me the incentive to get my act together and sort out a decent set-up for myself… albeit; I am unable to install an observatory. I already have a large (engineering) workshop and there is just not the room (or damagement approval) to add yet another large home for my hobbies. Orion! ... Oh yes…! …I vaguely remember him… he’s the one with the flashy sword and a bow and arrow being chased around by a couple of dogs and a unicorn whilst annoying an old bull isn’t he? Last seen up here in 1812 December 2012 due to the rubbish weather. It would be nice just to catch a glimpse of a star now and then, let alone a whole constellation…and for a whole hour … I jest of course. All we’ve had here since December is Clouds, rain, snow, howling gales, more rain… did I mention clouds? Ho hum!! Returning to the balancing issue… Yes, finding a system that suits changing the various capture equipment, more often than not having vastly different weights, is not so easy to achieve is it? … Especially when the basic ED 80 is already focuser heavy when mounted at the back of the dovetail. My current arrangement (similar to that used by Sara), being a fixed weight, is fine for my current DSLR camera set-up… but is not really flexible enough to accommodate the large changes in weight distribution if I choose (seriously being considered) to go down a similar route to you. I have already stated, my concerns with the use of longer dovetail bar with regard to bending point… and, whilst not entirely ruling it out, my current thought is to fabricate some sort of sliding weight counter balance arrangement mounted on the back of the objective end of the dovetail bar. This, hopefully, will permit, reasonably simple, re-balancing when a camera change is made, or other attachment is added, without the need to unclamp the main dovetail bar at the mount… always a risky operation in the dark… and cold. Decisions, decisions… !!!! Methinks it is time to get down to the workshop, crank up the lathe and milling machine and coble something together… Now where did I put that lump of unobtainium?? What other ideas do you have Gina? Best regards.
  5. Hi Martin, Thanks for your thoughts... Yes I did consider using a longer dovtail bar, as you say it doesn't matter which way up the scope is... my main concern with this method was that is got in the way of the camera (DSLR) possibly preventing it being turned to frame the shot and the fact that the balance point would mean having BOTH tube rings forward of the attachment point to the mount... thus creating a single bending point at the mount attachment closest to the first tube ring... possibly leading to flexture since the back end of the dovetail bar would not be attached to anything behind the attachment point. By clamping between the tube rings this is avoided... as the 2 tube ring attachments work in opposition too each other... if you see what I mean. Perhaps I am being to critical/analytical in thinking this...Too much engineering training in my youth methinks... Maybe I will give it a try and see what happens. I take your point about there not being an UP in space... does it also follow that there is no DOWN... Not sure NASA would agree with us though... they would never get any of their rockets back :grin: Cheers and clear skies
  6. Hi Ed, You should only need a t-ring for your D60 like this: - http://www.firstlightoptics.com/adaptors/t-rings.html Just pick the one for Nikon and you should be in business... It is the one I use for my D90 on a 2" SW focuser. Cheers
  7. Hi there, The 8" dobsonian is a great scope for a beginner to learn their way around the sky, however, if, as you say, you wish to get into astrophotography, at some point in the future, then I also would strongly recommend getting a copy of 'Making every photon count'. It was written by a fellow SGL member... 'Steve Richards'... (AKA Steppenwolfe) and is worth it's weight in gold when it comes to purchasing the correct equipment... and more importantly not buying something not suitable. Astrophotography is a whole new ball game when it comes to equipment and I agree that the HEQ5 Pro mount would be the very minimum you should consider but, as stated above, even this would struggle with an 8" scope... for this you would certainly need to go for the NEQ6. You may be lucky and find one second hand... but don't hold your breath... and keep saving up. Where abouts are you in Western Scotland?... it would be nice to have a fellow stargazer to meet up with. All the best and clear skies.
  8. No problem John, you are most welcome. I should point out that I mis-quoted one of the dimensions (just a TAD) They should have read 70cm long x 18cm dia... ( 80cm indeed)... must be getting old. Have fun and enjoy.
  9. Good evening Sara, Thank you for your valued input ... it would seem that we both have come to the same conclusion. I am not too worried about the additional weight since, as you say, the total package is well within the limits for the mount... it just looks somewhat odd/untidy and I just wondered if perhaps a better solution could be achieved... but hey' if it gets the job done then thats what counts I suppose. I have seen some of the images you have posted on this forum, and if they came from the setup pictured above then they are a standard for me to aim for. Now... if only the grey skies, rain, snow, howling winds and yet more cloud would remove themselves from the scene, perhaps some of us here in the UK could get out and do something. Thanks again Sara, Clear skies to you.
  10. Hi Ruthie, welcome to SGL. The only silly question is the one you don't ask. We all start at the first rung and then spend the rest of our time in this life asking questions... they never stop. Just ask away. Clear Skies. Sandy.
  11. Welcome to SGL Steve. Lots of very talented people on here and they are very helpfull with advice on all things astro. Clear Skies. Sandy.
  12. Hi Gio and welcome to SGL. Another + here for the suggested items, however, you can't steal the book from the library... cos I came over on the ferry and got it first!!!!! Clear skies. Sandy.
  13. Welcome to SGL JAMCART. Another +1 for Steve Richards' book It certainly helped me to make my final choices. Best Regards and clear skies. Sandy.
  14. From one RETIRED newbie to another (SEMI-RETIRED) welcome to SGL. You will find everyone here very friendly and extremely helpfull. Clear Skies. Sandy.
  15. Hi Everyone, I hope this is posted in the right place... apologies if not. I currently use my SW ED80 pro on my HEQ5 mount and have found that balancing the thing in DEC impossible (no problem in RA), especially when it has the focal reducer/field flattener and DSLR attached, without resorting to adding a home made weight to the front end of the dovetail bar. The use of a longer dovetail bar is not really practical, since it would interfere with the focuser (now motorised) and ,possibly, the camera... and the OTA is already as far forward in the tube rings as it can be. As I am just starting to look into guiding using an SPC900 LX modified camera in conjunction with the 9 x 50 finderscope (which will add more back end weight) and, whilst I appreciate a little camera heavy is desireable,... the current setup leaves a lot to be desired. I would appreciate any suggestions any of you may have as to how else this balance might be achieved? And how much 'Camera heavy' will PHD tolerate? Best regards, Sandy.
  16. I have just weighed my own SW 150PDS (not the same as 150P) and it is 4.9Kg including tube rings, dovetail bar and finderscope... but without eyepiece. The tube assembly is 70cm long x 80cm dia (not including focuser). This is well within the capabilities of the AZ4 mount. As far as I am aware... the head section of the AZ4 can be removed and fitted to the HEQ5 steel tripod. Hope this helps. Best regards. Sandy.
  17. Evening everyone, Many thanks for the warm welcome. Yes I do have a few things to keep me occupied when the dreaded clouds roll in (seems like everyday up here at the moment). Currently trying to get to grips with Guiding using my LX modified SPC900 on a 9 x 50 finder... thinking about making a small Crayford focuser for it... trying to focus with the threaded objective housing is proving to be a real pain. Ho hum!! It's all great fun. Best regards. Sandy
  18. Hi mindburner, OK then... from what you have tried and established It would certainly suggest that your regulator is a DUFF ONE. On the heat side of things: - I am not surprised that your transformer is getting very hot... it is only rated for 2.8Amps at the full 36v output. If you use the centre tap you will reduce this to 1.4Amps... yes it will probably supply the 4.3Amps you are drawing but transformer regulation will be all over the place... and it will get very hot... and will certainly give your regulator a lot of headache's trying to keep up... creating yet more heat. You need to replace it with a more suitable unit before you end up with a fire and possible injury to yourself... that is not what is required. Rapid electronics have a couple of suitable ones. 75VA 230v primary with 2 secondaries. part no. 88-3447 has 2 x 9v secondaries which can be joined in series to give you 18v. part no. 88-3449 has 2 x 15v secondaries which can be used in parallel giving 15v. Either will supply around 5Amps and not get hot and a very good price at the moment. http://www.rapidonline.com Do not try using the full secondary on your existing transformer... this will give you 36v out which is too high for your LF1038 regulator (max is 30v) and can still only provide 2.8Amps without overheating. Sorry to be the bearer of bad news. On a lighter note... thats a very nice image you have captured of M42. Best regards. Sandy.
  19. Hi again mindbender, No problem, pleased to be of some help. Ok then, even though you have a mica washer under the regulator these are prone to failure when changing things about... there should also be 2 plastic bushes to isolate the bolt passing through the device and heatsink. If you have a multimeter available then it is easy to check for a short... if you put the multimeter in Ohms mode and check between the TAB on the regulator and the heatsink/0v you should get a highish reading...1 kOhms or more... if you get a low or zero reading then check the bushes and mica washer for damage. One other check to make is to see if you have cracked the circuit board track between the output pin on the regulator and the nearest other component (probably the 300 Ohm resistor) It is easy to do this when you un-solder a connection to replace a component. You should get a zero reading when doing this test Hopefully it is just the change to a 100 Ohm resistor and change of pot that will get you up and running again. NOTE** make sure the circuit is powered down before making the above checks. Just out of interest... what is your maximum load current requirement? Best regards. Sandy.
  20. Hi everyone, from a very wet, and cloudy Argyll. I have been lurking for quite a while and thought it was time to join the club. My name is Sandy and I am a retired electronics and software design engineer. I have always had a love of astronomy and retirement now allows me to indulge in it a lot more than just a quick look around with binoculars. My main interest is in ASTROPHOTOGRAPHY and have purchased the necessary mount (HEQ5 pro) and a couple of scopes (SW 150PDS reflector and an ED80 pro refractor) along with various eyepieces, focal reducers atc. I control the mount using EQmod. I still enjoy the electronics side of life and have built my own ASCOM focuser (SGL TYPE) and power distribution board/box including Dew heater controls, flat panel control etc. I use a Nikon D90 DSLR and also an LX modified SPC900. Other interests are Model steam engines and boilers, Model Boats and wildlife Photograhy. I hope to be able to add something to the mix here on SGL. Best regards to all. Sandy
  21. Hi All, I am new here, having just joined, but have been lurking on the forum for some time. I have been following this thread with interest (as a retired electronics engineer) and I thought a couple of things may have been overlooked in the change over to the LF1083. Firstly: - have you made sure that the TAB of the new regulator is isolated properly from the heatsink?... especially if the heatsink is attached to the project case, which may be either at 0v and/or earth.... this would short out the output pin and prevent the regulator from turning on. (note... you may not get a big bang in such a case as the internal short circuit limiting would prevent the output from passing current. Secondly: - The LF1083 requires a more strict bias regime than the LM338 in that it must have at the very minimum 5mA of bias current (10mA would be best). It also requires a minimum load of 10mA. The 300 Ohm resistor in your existing circuit would only provide 4.16ma of bias current. If you change this resistor to 100 Ohms this would provide 13.75mA of bias current and also provide the minimum load current. The control pot (10K at present) is far to large to be used with a 100 Ohm bias resistor and would make setting the output voltage very touchy (sensitive)... A value of 1k Ohms - 2K Ohms would be more appropriate and would make setting easier. Hope this helps. Best regards. Sandy.
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