Search the Community
Showing results for tags 'secondary'.
Found 5 results
Hi, I know that there has been a couple of threads on how to collimate a newtonian, more specific, how to center the secondary mirror under the focuser.I bought mine "Concenter eyepiece" for almost a year ago and can't praise it enough - it makes centering the secondary a breeze.Have anyone else tried this? What is your opinion?I have also read that some have questions of how accurate it is? - I might not know the answer to this question, but what I do know is that after I have been centering the secondary with the Concenter eyepiece, I finish of the collimation with the Catseye XLKP and Blackcat. The small adjustments I have to make of the secondary after adjusting it with the Concenter eyepiece tells me it is very accurate. It is just the absolute finest adjustments i have to make afterwards.I have made a video of how it works and how it looks like when I am collimating my scope. (10" f3,4 astrograph)Best regards, Daniel
Hi, I'm collimating my Skywatcher 150p reflector and have got so far with aligning the secondary according to AstroBaby's guide, however I seem to be at a conflict with the positioning in the focuser tube. It looks to be aligned up/down the main tube, but not left/right (looking into the main tube from the open end) or up/down when looking down the focuser tube with a collimating cap on. i was told to align the secondary to the middle using the spider vane adjustments, but I can't see any other way to move the mirror than to adjust the spider vanes, which would result in the secondary no longer being precisely central in the main tube. Am I missing something? I hope these photos explain it better. To my eyes there seems to be clearly a larger gap at the bottom than at the top.
I'm selling my my 70mm secondary mirror I used with my 150mm F4 newtonian for 100$ (final price). Shipping expenses (from Beirut, Lebanon) on me for free provided I use LibanPost for shipping. We can discuss using other shipping methods and maybe splitting the cost. The mirror is brand new, still have the original package and box, bought the telescope a month ago and used only twice. No scratches, not even dust (images attached). Excellent mirror, no issues whatsoever, 94% reflectivity and optimized for the offset of f / 4 Newtons, but it can be used up to f / 5. It's from TS, made in Taiwan, original price is 134 euros (including VAT) excluding shipping and custom fees. Link below: https://www.teleskop-express.de/shop/product_info.php/info/p10673_TS-Optics-Newton-Fangspiegel-D---70-mm-mit-Halter.html It does not come with the tilt screws and center screw though unfortunately. I can also sell you the spider vanes (1mm thickness) for 6 inch newtonian for 25USD. Also brand new but without the tilt screws and adjustment screws. https://www.teleskop-express.de/shop/product_info.php/info/p11056_TS-Optics-Spinne-fuer-6--Newtons---164-mm-bis-180-mm-Tubus-Innendurchmesser.html Let me know if interested. Clear Skies! Anthony <private email address removed>
Hi all. I'm hoping for some advice on a subject which I know has had a lot of air time, but which I'm still wrestling with. Firsty, I know I get dew on my secondary mirror and it has wrecked many a DSO photgraphy session. I've fitted a home made heater, and this seems to fix it. It's insulated with neoprene, and runs at a very low wattage (about 0.4W) , so hopefully not too much turbulence. Next step is to do the same to the guide scope, which also mists up after about an hour, and then maybe the primary with a very low wattage. The main puzzle for me is this: Some folk say the mirrors are huge heat reserves, and take ages to cool down, during which time they cause turbulence. But other folk say the mirrors drop in temperature rapidly and go below the dew point, and then suffer condensation. I suspect theres some truth in both statements, but this doesnt simplify how to deal with it. Probably the main consideration is that the primary is much less ikely to suffer dew than the secondary, and so they have different problems and solutions. It would be easy to say that turbulence is in the eye of the beholder, but for sure when I'm focussing - using the camera and Live View with high screen mag - there appears to be turbulence aplenty even after an hour of cooling and before putting the secondary heater on. Of course this could be atmospheric, rather than tube currents. Rather than go through all my (muddy) thinking, can I just ask some direct questions please which relate to all this. 1. Is the small amount of heat on my secondary likely to cause any significant turbulence? 2. Is the turbulence that I see on the screen likely to be caused by the OTA? 3. I havent actually seen dew on the primary - but I've read that low grade condensation can affect the reflection. Is heating of the primary maybe just unneccesary? 4. If I heat the guidescope with a belt at about 2.5W, might this adversely affect the guiding property? 5. If I use an exhaust fan to cool the primary, is there any prospect that the air current will: a. increase dew on the primary and/or secondary by drawing in more damp air? b. reduce dew on the primary and/or secondary by evaporation? I'd be really grateful for any help with this. My next step is to wire up some kind of controller, and it would be useful to know what I'm likely to need to run before doing this. Many thanks
Hi there, I'm wondering if any SGL members might have a spare secondary assembly for an 8" EdgeHD. Basically, the previous owner of my Edge did something abominable to the collimation screws which mean that they will not move. I suspect the original owner has used a threadlock product or similar on the collimation screws. I am therefore looking to replace the entire secondary assembly. Shipping the scope off to David Hinds is one possibility and I am pursuing this, however I'm also looking at other options, such as replacing the secondary assembly myself. Kind Regards Paul J.