6 replies to this topic

[MountainAir]

Hello all,

 

A new RASA 11 V2 has not-so-mysteriously graced my living room.

 

I use AstroZap Flex-Heat dew shields for my other scopes, and like them.  They stay put, are easy to transport without utterly crushing them, and hold their shape fairly well.  However, I only see the aluminum dew shields for the RASA 11.  I am wondering if the Celestron 11 Sct CGE & HD Two-Notch Heated Dew Shield would work for the RASA, but thought I'd ask the community since I haven't heard back from the manufacturer or a few vendors yet.  I'm concerned about how sensitive the RASA may be to a not-perfectly-round dew shield, and also about whether I'd have any difficulty routing my Camera USB3 and 12v power cables under it.

 

The reason I'm not keen on the aluminum shield is I heard there were "fit" issues with the non-recessed screws in Celestron's recent OTAs (including mine).  I also wonder how a dew heater would work if wrapped around the aluminum dew shield (not well, I'd bet).  Lastly, a giant, round, inflexible dew shield will surely be crushed in all my trips out to my dark-sky site.  Love the idea, but a flexible two-in-one solution is what I'm after.

 

Any advice out there?  Does the Celestron 11 Sct CGE & HD Two-Notch Heated Dew Shield work with the RASA 11 V2?

 

Thanks in advance & clear skies!

Edited by MountainAir, 05 August 2020 - 09:24 PM.

[jgraham]

I use a heated Astrozap on my deforked C11 (no notches) and it works great! I also have a couple of aluminum dew shields and they are purdy, but surprisingly fragile. They bend very easily and dropping one can give it a nasty ding.

 

+1 on the heated flex shield.

Edited by jgraham, 05 August 2020 - 08:03 PM.

[andysea]

For my RASA 8 I ended up 3d printing a dew shield that would be exactly how I wanted it but It's not heated. 

I use a cooled camera and I found that the heat and air movement produced by the camera always keep the corrector perfectly dry. Is that not the case with the 11"?

[MountainAir]

For my RASA 8 I ended up 3d printing a dew shield that would be exactly how I wanted it but It's not heated. 

I use a cooled camera and I found that the heat and air movement produced by the camera always keep the corrector perfectly dry. Is that not the case with the 11"?

I am hoping that the camera generates enough ambient heat to keep the dew away (with the help of a dew shield), but I had fairly horrible experience with an EdgeHD 9.25 with a dew shield with a built-in heater running 100%.  I've seriously had to abort entire nights of imaging after needing to pull out the hair dryer every 15 minutes to get the dew to go away.  This was at 86% relative humidity, supposedly 4 degrees above the dew point.

 

Unfortunately this is my first astrograph (never even tried HyperStar with my 9.25) so I don't know how well it'll work.  11" is a whole lotta corrector to heat.

 

However, since you're based in Seattle, I'm going to trust you!  I bet you have more humidity than we do.  Thanks for the tip.  And your 3D-printed dew shield -- awesome!

[MountainAir]

Update:  Joe from AstroZap confirmed that they increased the aluminum dew shield diameter for the screws on the RASA 11 last year, so I'm expecting it to fit fine.  I'm excited to see how this works, because last night was my "second light" with the RASA and -- you guessed it -- it dewed over.

Edited by MountainAir, 12 August 2020 - 10:21 PM.

[smccully]

I have a flexible two notched Astrozap ( I think ) heated dew shield, and the aluminum double noticed dew shield. I prefer the metal dew shield personally, one reason is I use a mask for focusing a lot of times with the RASA and it holds the masks a little firmer. It also provides a little more weight for balancing, I wrap a dew heater around it as well a lot of times the heat from the camera is enough but not always. 

[MountainAir]

Update:  I picked up the AstroZap Aluminum Dew Shield, and it fits nicely.  It's annoying that these RASA screws stick out; Celestron could have recessed them, or at least used some flat-top screws the don't stick out as far.  But, the felt on the inside of the dew shield is only slightly abraded as I slide it on and off.  It is a beautiful dew shield, and on one fairly humid night the camera TEC cooler/fan did keep the dew off.

 

I also picked up a 3D-printed cable router and it just barely fits in between the dew shield and the OTA (in this case, the larger dew shield diameter to accommodate those screws actually helped).  It's quite a nice solution, through the cable router pulls off when I remove the dew shield.  I also had to position it near one of those screws, where the dew shield was slightly further from the OTA (it's in the top right of this photo).

 

I'm pretty happy with this solution.

 

Here's the setup:

Attached Thumbnails

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Edited by MountainAir, 31 August 2020 - 09:26 PM.