Rols Posted March 12, 2011 Share Posted March 12, 2011 why would i want an eyepiece that was illuminated?what is the practical use?do they disturb night vision?how do they help off axis?dumb questions for those in the know, but for me i cant work it out and i dont want to buy one to find out when you guys are such a wealth of info!Thanks in advance. Link to comment Share on other sites More sharing options...
Bizibilder Posted March 12, 2011 Share Posted March 12, 2011 They have either a crosswire or graticule (engrved scale(s)) that you would not be able to see against a black background. So a small light source (often a small, red LED) is used to illuminate the wires/scales so that you can see them. The light usually has some form of control so you can vary the brightness. They are generally not used for "observing" but for things like alignment ie to find the centre of the field of view or drift aligning your mount. Sometimes they are used for direct measurement through the eyepiece (not so common a use these days!).Hope this helps. Link to comment Share on other sites More sharing options...
Rols Posted March 12, 2011 Author Share Posted March 12, 2011 Thanks for that, why would it be of help off axis? Link to comment Share on other sites More sharing options...
brantuk Posted March 12, 2011 Share Posted March 12, 2011 Finding/following guide stars using an off-axis guider for imaging. My illuminated reticle helps keep the cross hairs on the guide star Link to comment Share on other sites More sharing options...
Si W Posted March 12, 2011 Share Posted March 12, 2011 Hi Rols The illuminated eyepiece come in two basic types cross hair type which is the one I have, I use it to centre both my main scope and guide scope when i setup so the main scope and the guider are pointing in the exact place in the sky/star, no need to estimate where the alignment star is in the centre of the field, just place it on the cross-hairs. The Astrometric is quite expensive, they are laser etched, and are used for measuring double star separations, position angles, planetary diameters and lunar crater diameters and much more. Both of these use red light so wont effect your night vision.The Astrometric is the more practical of the two.Simon Link to comment Share on other sites More sharing options...
Rols Posted March 12, 2011 Author Share Posted March 12, 2011 ok so if i was using my dslr i would be able to locate centre shot with an off axis guider!?i was trying to make sure i was on the right lines and not way off the mark (no pun intended) as i was asking i thought i would make the Q+A as fool proof as possible so if i was wrong i still got a full answer.. as usual you guys never fail me.. thanks ohh and please correct me if i was wrong about using it with my cannon camera. Link to comment Share on other sites More sharing options...
Glider Posted March 12, 2011 Share Posted March 12, 2011 I don't have an illuminated version but a simple crosshair that screws into the back of an EP like a filter would.The improvement when aligning and centering was out of all proportion to the £10 it cost me.It works fine on bright stars when aligning but I can appreciate the benefit from an illuminated version on dimmer objects. Link to comment Share on other sites More sharing options...
brantuk Posted March 12, 2011 Share Posted March 12, 2011 I have the Celestron off axis radial guider. The 1000D attaches to it using a T-ring and I use an illuminated reticle in the radial ep socket. the lot attaches to the back of the CPC. The camera stays fixed on-axis of the tube and the radial arm can be moved through 140 degrees to find a guide star - the diagonal mirror can be adjusted as well. The reticle can be replaced with a guide camera if required. Hope that helps - let me know if you'd like some pics Link to comment Share on other sites More sharing options...
Rols Posted March 12, 2011 Author Share Posted March 12, 2011 perfect, i'm going to look into it a little more before i jump in, i feel the sway towards an illuminated one but only if i can get it to power from the mount! (meade)some pics would be perfect brantuk, just to see how all that fits together, if not to much of a chore?Glider, i take it from that you just use it for visual alignment? Link to comment Share on other sites More sharing options...
Glider Posted March 12, 2011 Share Posted March 12, 2011 Yes, just for the star alignment at the start of a session. Link to comment Share on other sites More sharing options...
Rols Posted March 12, 2011 Author Share Posted March 12, 2011 i'm starting to understand the issues surrounding goto telescope leveling and centering, if this makes it easier then it must certainly be worth the expense, whats a good cheap one and what would be a prefered nice one?i'm getting the idea that i'm killing 2 birds with 1 stone with this i get the initial setup advantage and then the secondary use for my picture taking! Link to comment Share on other sites More sharing options...
brantuk Posted March 12, 2011 Share Posted March 12, 2011 Here you go: In bits you have the camera -> T-ring -> OAG -> (Illuminated reticle ep in top). Click to enlarge (2nd ones a tad blurred). Hope that helps And assembled:You can of course change the illuminated reticle for a guide camera. I'm intending to use an SPC900NC and Phd guiding software if I can get it to work. Link to comment Share on other sites More sharing options...
Herbig Posted March 13, 2011 Share Posted March 13, 2011 Hi, been reading this thread with interest, I've just bought a Sky-Watcher one, cost 50 quid, it's powered by 3 small button cells. I got it to take the guess work out of star alignment, but hope to use it also for guiding. Link to comment Share on other sites More sharing options...
brantuk Posted March 13, 2011 Share Posted March 13, 2011 Herbig, Did you get the OAG, or illuminated reticle, or both for that price? Link to comment Share on other sites More sharing options...
Rols Posted March 13, 2011 Author Share Posted March 13, 2011 Thanks brantuk nice to see how it all fits together, is there a product range i should buy above another?i noticed while looking that they seem to be most common from skywatcher and meade i did see one vixen also they only seem to come in 9mm or 12mm i thought this was something that would sit infront/behind your EP collection as to be used with whatever you had. i'm shocked that they are limited to the one you buy it with??i dont know what one i should be looking for now i'm going to take another look at your pictures brant so i can get my head round it again! Link to comment Share on other sites More sharing options...
Rols Posted March 13, 2011 Author Share Posted March 13, 2011 Ok moment of maddness over...the EP you decide on should be the one best suited to what you want to take the pictures of, but as far as i can work out as long as you can see the target through the illuminated EP you choose, you can centre it, its not important that you have 'PERFECT' viewing throught illuminated ep as its only the tool to get the shot centred...sorry my blonde hair took over for a moment.a quick question to tag on the end-beter to have the battery operated or the cabled? Link to comment Share on other sites More sharing options...
ollypenrice Posted March 13, 2011 Share Posted March 13, 2011 I'm a bit lost here. If you want to centre the object for taking an image, just use a fairly high power normal EP and put the object in the middle of that. Then replace the camera, take a test exposure and look at that. Nudge the mount/rotate the camera as necessary. I have never used a crosshair for framing a pic because the method above surely does it all.If you want to flip between camera and EP for framing, then you want a flip mirror system whch allows you to do just that. The EP is at 90 degres to the camera so a hinged mirror interrupts the beam heading for the camera and sends it to an EP. However, you might well not have enough back focus in many systems and there might also be an issue with respecting the reducer to chip distance where applicable.If I am missing some arcane point here, please excuse me!Olly Link to comment Share on other sites More sharing options...
Herbig Posted March 13, 2011 Share Posted March 13, 2011 Hi Brantuk, no it was only the 12mm Skywatcher Illuminated double cross illuminated one. Link to comment Share on other sites More sharing options...
brantuk Posted March 13, 2011 Share Posted March 13, 2011 This is the illuminated reticle I use:Sky-Watcher 12.5mm Illuminated Plossl Eyepiece | Telescope Accessories | Rother Valley OpticsIt's a 12.5mm ep with double cross hairs Link to comment Share on other sites More sharing options...
Rols Posted March 13, 2011 Author Share Posted March 13, 2011 If I am missing some arcane point here, please excuse me!OllyI bow to your knowledge on the subject, i am just trying to find the right things for what i'm trying to do, i think your probably right that the kits is not actaully required to do the job, but being a little green to the subject and having to ask for information always seems to lead to different opinions being put forward, i liked the idea of having the illuminated EP for setting up the guide and OTA prior to use and also 'wanted' to implement for use with my camera for planetary photos i can well imagine if the guide and scope are setup correctly i would not require the recticle but used with the OAG i think it sounds right up my street for practicality more so if i can slide an EP directly into OAG aswell and use for noarmal viewing! i could be well of the mark and if i am please feel free to correct me, i'm open to all and any advice and will always take a commecnt on board and look into another option, if knocking and nudging is the way you do it i will give it a go before i spend any money and see how i fair at it... thanks for the input.Thanks for the link brantuk, i did also find a meade that looked as nice for the money, would you say battery or cable powered if you was buying again? Link to comment Share on other sites More sharing options...
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