braybarr

6 hours ago, 8472 said:

Mount the OTA with the focuser at the 12 o'clock position.

Although I don't use one, a dew shield may also help. I've also made a secondary dew heater.

Interesting, how would rotating the OTA to 12:00 position help? I also have a dew shield arriving today or tomorrow. I’ve seen suggestions to solder resistors together for heating but that is well beyond my skill level. 

Does anyone have experience dew heating their coma corrector? I live in a very humid area where my CC has been getting dewed over recently. What can I do?

Sorry for clogging the thread but I’m just over the moon!! I’ve had the 130PDS for a few years now and I’m just finally getting to the point of being able to image without issue. 

I’m up to 12 hours of Ha on Flaming Star Nebula and I’ve always dreamt of getting data like this. This scope is so amazing for its size. 

Elephant Trunk Nebula in OSH as well as a split of SHO and Foraxx’s (thecoldestnights.com) dynamic SHO. 

4.5h Sii and Oii, 4h Ha. Had an absolute blast with these. 

Got 4hrs of Ha data on Monkey Head recently. Boy do I love this scope. 

8 hours ago, Rob F said:

I haven’t noticed any. I keep the heater strap as far back as I can and on the middle setting so it warms the tube and doesn’t get too hot. It’s an inexpensive heater strap but does the job.

Sweet, I’ll start looking for one. Thank you very much. 

6 hours ago, Rob F said:

The swimming/shower cap I use now has helped with stray light and I think also with dew. I use heater straps at the rear of the ota and no issues with seeing on the secondary. I also have a dew shield which helps against dew and stray light, and my ota is flocked.

heater strap and diy dew shield for the guide scope helped greatly against dew and fogging of the the guide scope.

Sorry for all the questions but I’m dying to get this sorted out. Do you just use a generic wrap-around heater? I’ve heard that causes turbulence inside the tube while not actually heating the primary mirror. But if it works for you then I might as well give it a go. 

9 minutes ago, Ratlet said:

I've had my secondary dew over but never the primary.  I've managed okay with a dew shield at preventing secondary from dewing over.

Interesting. I use a dew shield, and recently the primary dewed over and the secondary was okay. Do you cover the back end of the tube with a shower cap or similar? I think that’s what I’m missing. 

Curious how many people have issues with their primary mirrors dewing over? I’m going to try using a shower cap around the back end of the scope tonight, but I’m dreading the fact I might still get dewed over. 

Seems you have to take a DIY approach if you want to heat the mirror, and that’s intimidating to me. 

1 hour ago, Jamgood said:

A shower cap over the end of the scope can help with due and also block out stray light pollution getting under there.

A black cloth and an elastic band will also do the same. 

A Dew Shield up the top will also help.

 

Awesome, I’ll give it a try. Last night I used just my dew shield. The secondary was fine all night, the primary dewed over soon as we got close to the dew point. 

I’ll try the black shower cap idea, this is getting so frustrating. I think if it doesn’t work I’ll have to attach a small fan to the back end of the scope. I can’t find heaters for 5” mirrors anywhere.

Well, I managed to remove the mirror cell with a drill in reverse. Primary mirror is looking crisp! 

Here’s to hoping this solves my dew issues and I don’t need to buy heaters… although with my luck I’m expecting to have to drop a chunk of cash. 

Good morning, everyone. I’m currently trying to unscrew the 3 screws holding the mirror cell, so I can clean my primary mirror. However, these screws aren’t budging. 

Any tips? 

11 hours ago, Jamgood said:

A dark piece of cloth and an elastic band will also do the trick. 👍

Sweet. Thank you. 

10 hours ago, Ratlet said:

Is that daylight for round the bottom?

I believe so. I’lll have to get a black shower cap for the back end of the tube. 

Sorry for the double post but there may be hope for this dew shield after all. I took a peek down the tube at the end of the night and the secondary mirror and coma corrector both looked clear. My primary mirror, however, was super foggy and looked like it was glistening. I’ve come to the conclusion that it’s because it’s extremely dirty. I’m going to clean it for the first time ever and see if this shield ends up working.

I’m still open to dew heater recommendations, though, just in case. 

Now taking recommendations for a secondary mirror dew heater, as well as a controller. I tried out a dew shield last night and it worked only for half the night. I’m feeling defeated.

Latest image with the 130PDS + ASI 1600. About 5hrs of Ha data and 6hrs of Oiii.

I have some sudden tilt I need to sort out, it bugs me a lot knowing I can have round stars in every corner. I’m also hoping to get better filters soon, these star halos are obnoxious. 

58 minutes ago, sagramore said:

Hey, which screw are you wondering about? I only see two in the image - one thumb screw and one standard Phillips / Crosshead. Neither look stripped as far as I can tell!

Oops, sorry! I took a picture of the wrong thing. I took a new one and circled 2/4 of the mini screws I’m talking about. 

Basically, I bought a dew shield that is *very* close to fitting. I think it might fit if that white ring weren’t in the way. I was going to just replace the dew shield with one that’s one size up, but now I’m wondering if I have to remove this anyway. 

Before I order the dew shield I’m looking at, I’m just wondering if I’ll need to remove this white collar looking thing? It looks like the tiny screw holding it in place are stripped or something because I can’t even tell what they are. 

43 minutes ago, Pitch Black Skies said:

FWIW I've been using said dew shield for ~6 months. It has completely stopped the secondary from fogging up.

I'm assuming you are from Bray, Co. Wicklow?

I'm in Waterford on the coast so probably pretty similar humidity.

I’m from a small city in Ontario, Canada. I live next to a Great Lake so humidity is always very high. It’s rare to be more than 2° above the dew point. I’ll definitely give it a shot, though. 

Just now, starwatcher_ch said:

It's exactly this one: https://www.teleskop-express.de/shop/product_info.php/language/en/info/p8075

I've only used it once so far... so the only thing I can say about it: its stiff enough to attach the Bahtinov mask to it for focusing. 

My hope was the dew shield will eliminate reflections I'm struggling with, especially on M57 Ring Nebula wide field. But also with the dew shield there are reflections...

Sweet, thank you. I’ve read a bit about your reflections and I hope you can sort it soon. My backyard isn’t very dark but thankfully I’ve never had any issues other than my secondary getting dewed over. I’m hoping this dew shield is effective but it gets very humid where I am. Might be the best move to just get a heater + controller to be sure.

20 hours ago, starwatcher_ch said:

I don't think so. Yesterday I did some M13 abd M57 exposures in a row, with the dew shield in place. Also I use a "swimming hat" for the primary mirror area to block stray light.

This was my initial "problem" image:

Yesterday I had the same reflection on M57 again... exactly the same position like before. But not on M13. It seems to be related to the selected field of view and most probably the CC. 

Each image is a stack of 12 sub exposures, no flats, no darks.

Hey, what dew shield is this and how well does it work for you? 

Cropped view of my current project. About 5 hours of Ha data with a 1600mm-pro and ZWO narrowband filters. This newt is so dear to me. 

22 hours ago, Pitch Black Skies said:

Hi,

I measured it in place so it's not exact but should be good enough for your purpose.

CS

Oh shoot! I’m new to this forum so I missed your reply. Thank you so much for taking the time to do this!

Can anyone tell me the size of the mirror stalk for secondary mirror?