Strategies for doing AP in Florida: Dealing with limited exposure time high humidity

Dew Heater Equipment Reflectors Light Pollution Remote Astrophotography
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John Tucker avatar
John Tucker avatar

AP is somewhat challenging in Florida. Acquisition time is precious when you live 2.5 hours from the nearest Bortle 4 site, in a state with 95% cloudy nights in the summer. In the winter, heavy dew and fog after midnight are big issues. (I’ve actually had a towel become too wet to use because I left it on a picnic table for two hours after sunset. Most mornings my rig looks like it was rained on.)

I’m thinking about 3 strategies for addressing this

  • Sending a scope out to a remote hosting site - If so, which one? My wife isn’t nice enough to pay for having multiple scopes hosted 🤣. I was going to send an SCT out there but after some discussion with a guy at the Chiefland Astronomy Village, am thinking that my 360mm refractor might be more appropriate. There is the Newt, but I’m not sure how well Starfront would take care of the collimation and what’s the point of sending your fastest telescope out to a place where acquisition time is much less of an issue?

  • Increasing reliance on fast Newts. In particular, my 6” F/4 Newt is amazingly fast when I slap my Nexus focal reducer on it and take it down to F/2.8. The problem here is that it seems a lot harder to keep dew off the optics than in the case of my refractors. And I had to cut my dew shield to half-length to prevent vignetting at F/2.8. I know there are some kits out there for applying a silicon heating element directly to the back of the mirrors, but somehow this just sounds like a bad idea. A second Newt would be reasonably affordable and I have several capable mounts.

  • Running two imaging setups with identical refractor OTAs and cameras in parallel and combining data - This will be rather expensive

I have a little bit of a budget for addressing these issues, though the third approach would be a stretch.

Thoughts appreciated, especially from those who have dealt with these issues.

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Brian Puhl avatar
Brian Puhl avatar

North Carolina isn’t much different so I can speak from experience. Newts are incredibly hard to keep dry, especially once you’re pointed at zenith. Once I moved to refractors, I didn’t have any dew issues ever again.

For newts, dew was a major issue on my secondary and my corrector. The primary almost never had dew on it as long as the fan was running, although I’m not a fan of keeping the fan running the whole time. My solution was to build a custom 1 watt dew heater that I attached to the back of the secondary mirror, and I also grabbed an extended dew shield that I slapped on the end of the OTA, this mostly alleviated any issues I had with dew on the corrector. Problem I noticed is even that little bit of heat was enough to create some tube currents that never seemed to go away.

In the end I abandoned the newt for a multitude of reasons, went to refractors and never looked back. Never had to tweak them, they just worked. Give em about 45 minutes to acclimate after sundown and they’re good to go. I have two dew straps over the dewshield on my Esprit 150 with power set to auto based on the humidity sensor. I also installed a small nichrome wire over the drawtube leading back to behind the filter wheel. In most cases it wasn’t needed, but I found myself some nights getting some dew on the front of the sensor, so I put it in as a precaution on low voltage.

So while I know you aren’t keen on moving to refractors, I can tell you for sure, you wont regret it. I’ve had plenty of nights with a 10 foot tall layer of fog on the ground, imaging straight up through it without issue. You don’t want to miss out on the foggy nights, those are some of the best seeing you will get!

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John Tucker avatar
John Tucker avatar

Brian Puhl · Feb 28, 2026, 06:09 PM

North Carolina isn’t much different so I can speak from experience. Newts are incredibly hard to keep dry, especially once you’re pointed at zenith. Once I moved to refractors, I didn’t have any dew issues ever again.

For newts, dew was a major issue on my secondary and my corrector. The primary almost never had dew on it as long as the fan was running, although I’m not a fan of keeping the fan running the whole time. My solution was to build a custom 1 watt dew heater that I attached to the back of the secondary mirror, and I also grabbed an extended dew shield that I slapped on the end of the OTA, this mostly alleviated any issues I had with dew on the corrector. Problem I noticed is even that little bit of heat was enough to create some tube currents that never seemed to go away.

In the end I abandoned the newt for a multitude of reasons, went to refractors and never looked back. Never had to tweak them, they just worked. Give em about 45 minutes to acclimate after sundown and they’re good to go. I have two dew straps over the dewshield on my Esprit 150 with power set to auto based on the humidity sensor. I also installed a small nichrome wire over the drawtube leading back to behind the filter wheel. In most cases it wasn’t needed, but I found myself some nights getting some dew on the front of the sensor, so I put it in as a precaution on low voltage.

So while I know you aren’t keen on moving to refractors, I can tell you for sure, you wont regret it. I’ve had plenty of nights with a 10 foot tall layer of fog on the ground, imaging straight up through it without issue. You don’t want to miss out on the foggy nights, those are some of the best seeing you will get!

Thank you Brian. That was very specific and helpful. Yeah, I love the speed but am increasingly wondering if working with Newts in the Eastern half of the country is practical. Might have to hold that one in reserve for trips out west.

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andrea tasselli avatar
andrea tasselli avatar
I often image close to saturation point (>90% RH) and never had issue with secondary fogging and least of all on the primary (living in the east of the UK, just for reference). Shooting with the fog is bloody pointless so I won't do that, might as shoot clouds and with B7 LP it is just milky skies. The trick is to insulate the whole scope with something like Reflectix or better still camping mats with reflective surface. And the dew shield too, or make one of the same material.  A transverse dual push-pull fan with regulated speed will also help keep dew at bay in the worst situations.
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Brian Puhl avatar
Brian Puhl avatar

90% RH would be a dream. Here we pretty much exist in a balance between 98 and 99% lol. 100% means rain ofc.

John Tucker avatar
John Tucker avatar

Brian Puhl · Feb 28, 2026, 10:30 PM

90% RH would be a dream. Here we pretty much exist in a balance between 98 and 99% lol. 100% means rain ofc.

Ah, Laddie, down here in FL we’d die for 98% humidity, a virtual desiccator! In the Great State of Florida, RH not only lingers around 100% for hours on end, in coastal regions with low air particulate counts, the air can actually become supersaturated with water, leading to Rh exceeding 100%!

😆📷 Screenshot 2026-02-28 175849.jpgScreenshot 2026-02-28 175849.jpg

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Brian Puhl avatar
Brian Puhl avatar

Haha. I used to do alot of flights down to the Caribbean via Opa Locka. It always amazed me how miserable it was in Miami, but once you went further south to Puerto Rico or the Virgin Islands it would always be so much more comfortable. Florida is like living in an armpit. The only place comparable is Costa Rica, but at least it’s a much prettier place.