Allan the Plumber Posted September 19, 2013 Share Posted September 19, 2013 Okay it’s getting colder and damper and this will be my first proper Autumn/Winter observing and I would like to ask about Dew control At the moment I have HitecAstro 4 channel port with 1x 8†band as well as an Astrozap dew shield. Over the last few evening out I’ve noticed an increase in moisture building up on OTA Will this be affecting the images I’m trying to take? (No moisture on main mirror) I live down near river Trent thought I better add that Since I’m not really observing with eyepieces is there any advantage to adding another heater band to OTA or a smaller band to the camera /webcam where bare metal fits into the focuser Sorry to ask have tried as usual the search topic to no avail Link to comment Share on other sites More sharing options...
Guest Kheldar Posted September 19, 2013 Share Posted September 19, 2013 Moisture on tube does not matter Heater on camera is a BAD idea unless it freezes Only worries are moisture on optics Link to comment Share on other sites More sharing options...
Brantuk Posted September 19, 2013 Share Posted September 19, 2013 You can have ice on the ota so long as the mirrors/lenses remain clear. Using the scope near a river or lake isn't always a good idea - mist can build pretty quick when the temperature and conditions are conducive to it. Cameras tend to work better at lower temperatures so I wouldn't warm any part of them up (the chips stay cooler). But it would be a good idea fitting a dew heater strip to your secondary mirror. Link to comment Share on other sites More sharing options...
Perkil8r Posted September 19, 2013 Share Posted September 19, 2013 If you are talking about the 200p you may need to consider something on your secondary mirror. I did the 5w 200ohm resistor stuck on the back of it mod, but a 12v hair dryer in between subs will do a good job. Link to comment Share on other sites More sharing options...
Allan the Plumber Posted September 19, 2013 Author Share Posted September 19, 2013 If you are talking about the 200p you may need to consider something on your secondary mirror. I did the 5w 200ohm resistor stuck on the back of it mod, but a 12v hair dryer in between subs will do a good job. Thanks for that Is it hard to get the resistor stuck on the back of the secondary I know Daz has one think Marytn did the mod for him I'm a little worried about messing around to much with the mirrors in the OTA yeah I know I'll have to clean them one day but I heard horror stories about the silver on the secondary being damaged when gluing the resistor on and damaging the fins holding it in place when fixing the leads Anyone in the group have expertise on this would love to get it done and flock the tube at the same time I'd even pay to get it done I'm so worried i'd screw up the scope if I did myself Link to comment Share on other sites More sharing options...
Perkil8r Posted September 19, 2013 Share Posted September 19, 2013 It's easy enough, I managed it and it all still works. As long as you don't drop a mirror or scratch them there's not a lot you can do that will break the scope Link to comment Share on other sites More sharing options...
Allan the Plumber Posted September 19, 2013 Author Share Posted September 19, 2013 It's easy enough, I managed it and it all still works. As long as you don't drop a mirror or scratch them there's not a lot you can do that will break the scope Okay Mike will give it a go can you advise what I need to buy and how to build ( if that's okay) Link to comment Share on other sites More sharing options...
Perkil8r Posted September 19, 2013 Share Posted September 19, 2013 I'll have a look sometime tomorrow for the thread I think I posted on it Link to comment Share on other sites More sharing options...
Allan the Plumber Posted September 19, 2013 Author Share Posted September 19, 2013 I'll have a look sometime tomorrow for the thread I think I posted on it Thank You Link to comment Share on other sites More sharing options...
red dwalf Posted September 19, 2013 Share Posted September 19, 2013 it`ll be handy when you get to Kelling Allan, it`s a good place to have a look at, and get advice about what everyone else does to keep dew at bay. i can help with the flocking but not used a newtonian scope for a long while so don`t know alot about dew pervention on secondary mirrors. Link to comment Share on other sites More sharing options...
dawson Posted September 20, 2013 Share Posted September 20, 2013 Rob, have you flocked your sct? James Link to comment Share on other sites More sharing options...
dawson Posted September 20, 2013 Share Posted September 20, 2013 Does putting a dew band and a dew shield on the main opening of a newt reduce the risk of the secondary dewing up? Or is the only way to be sure to heat the secondary up? James Link to comment Share on other sites More sharing options...
Allan the Plumber Posted September 20, 2013 Author Share Posted September 20, 2013 it`ll be handy when you get to Kelling Allan, it`s a good place to have a look at, and get advice about what everyone else does to keep dew at bay.i can help with the flocking but not used a newtonian scope for a long while so don`t know alot about dew pervention on secondary mirrors. Thanks for thar Rob going to try to set up new tent next week too and if you fancy having a look at the OTA to see how difficult to flock I don't have a good a track record with sticky backed plastic Wait till you see light box oh dear!!!!! Link to comment Share on other sites More sharing options...
Allan the Plumber Posted September 20, 2013 Author Share Posted September 20, 2013 Does putting a dew band and a dew shield on the main opening of a newt reduce the risk of the secondary dewing up? Or is the only way to be sure to heat the secondary up?James Hi James looks like heating the secondary is the best option sticking a resistor on appears to be the best thing. Link to comment Share on other sites More sharing options...
red dwalf Posted September 20, 2013 Share Posted September 20, 2013 Rob, have you flocked your sct? James not done it to the sct yet James, but it is on my list of things to do, i`ve done it to my first scope, a 130p skywatcher newt, and i`m sure the contrast was better. i used the protostar flocking paper which is highly recommended, but alas it comes from America and the guy that used to import it doesn`t bother anymore. not looked at tyhe stuff wilko`s and Flo sell yet. Link to comment Share on other sites More sharing options...
Brantuk Posted September 20, 2013 Share Posted September 20, 2013 "Does putting a dew band and a dew shield on the main opening of a newt reduce the risk of the secondary dewing up?" The dew shield is always a good idea that reduces the chances of secondary dewing up - whilst simultaneously reducing light ingress from the sides. You wouldn't put a dew band on the open end of a newt (unless you want to warm the sky lol). You would glue on a heat pad or purpose made dew heater (mines like a horse shoe shape) to the back of the secondary mirror. Link to comment Share on other sites More sharing options...
Daz Type-R Posted September 20, 2013 Share Posted September 20, 2013 Here is mine..... The horse shoe shaped heater that Kim is on about does not fit a 200P, nothing on the market does as the secondary is too small. Link to comment Share on other sites More sharing options...
xanthic Posted September 20, 2013 Share Posted September 20, 2013 Any advice on what resistor to use? I'm guessing you could also use a length of nichrome wire. Link to comment Share on other sites More sharing options...
Daz Type-R Posted September 20, 2013 Share Posted September 20, 2013 I think mine was a 5W 200 Ohm. Link to comment Share on other sites More sharing options...
Perkil8r Posted September 20, 2013 Share Posted September 20, 2013 5w 200 Ohm is the way to go. I used a resistor with the aluminium heat sink around it. It's the rating that's important but also the flatter the surface the better as it will transfer the heat to the mirror more effectively. Link to comment Share on other sites More sharing options...
BAZ Posted September 21, 2013 Share Posted September 21, 2013 Use heat rated silicone adhesive to attach it to the mirror. This doesn't have to be too high, but it stops the silicone degrading over time, also if you need to get the resistor off then you can with a sharp knife. Unfortunately if it's glued, as the previous owner of my scope did, then if a resistor fails, Iam in for some fun to remove it without damaging the mirror. Something like this will do, but it doesn't have to be rated that high. http://www.ebay.co.uk/itm/1-x-BLACK-HIGH-TEMPERATURE-SILICONE-ADHESIVE-SEALANT-20ml-HEAT-RESISTANT-300C-/290624636619?pt=UK_Crafts_Cardmaking_Scrapbooking_Glue_Tape_EH&hash=item43aa9406cb Link to comment Share on other sites More sharing options...
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