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laptop protection

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pox's picture
laptop protection

Hi, Not sure where to post this, so here goes!

Having more or less completed my combined chart viewer/observation recording app, I plan to install it on a laptop and use that at the scope en plein air. The main problem I can see here is of damp/condensation etc possibly affecting the innards of the laptop. Has anyone else experienced problems in this direction, or am I worrying about nothing?

BPO's picture

Hi Mike,


I reckon dew could be a problem, you could set up a small fan to blow air gently across the keyboard to keep everything above the dewpoint..?

Or what about a shallow box with a lid..

Good luck with it anyhow



GTN's picture
Laptop dew

Hi Mike,

    I'm coming late to the discussion and don't know if you are planning on using your laptop in an observing structure, like a rool-off or dome, or literally en plein air.  My scope is in a shed with a roll-off roof.  When I took an exposure, the software blanked the screen and I put piece of opaque, black fabric over the screen.  The keyboard was not covered.  I surmise that the heat from the laptop kept itself dry, since the cloth never covered the fan exhausts or the keyboard.

    Have a great time with your gear!


Thom (GTN)

SDB's picture
Dew on Laptop


As you probably already know, the dew is caused by the exposed surface losing its heat to the clear sky.  The exposed surface cools to a temperature below the dew point and condensation ensues.  So, you need to observe only on cloudy nights when the sky is warmer........probably now a good idea.  ;-)

Or you can place the laptop in a 5 sided box.  The open side of the box needs to face the user.  The box needs to be deep enough to completely cover the display and the keyboard [and a little more] and the box needs to be high enough to accomodate the display and allow you to see the diaplay while the laptop is in the box.   The box keeps the keyboard from radiating its heat to the night sky and keeps the keyboard 'warm' .  One advantge is that you can drape a piece of dark cloth over the open side of the box to help retain your night vision when not using the display.  You can use a cardboard box to test out the process and then fabricate a plywood or Masonite box after you know that it works.

Donn Starkey 

PYG's picture

I dunno.  Laptops for visual observers - "you cannot be serious!".  Even with a heavily reddened screen, it will affect your vision.  Be a luddite Mike and don't do it - just don't do it!


SXN's picture
The forum needs a like button

 "I dunno.  Laptops for visual observers - "you cannot be serious!".  Even with a heavily reddened screen, it will affect your vision.  Be a luddite Mike and don't do it - just don't do it!"


pox's picture
thanks guys

Well, a nice mixture of suggestions, and no mistake. Most of my fellow visual observers say 'don't do it!' so it's tempting to take your advice. I know the visual purple in the eye takes quite a while to revivify, so I plan to have a button which will toggle a completely black window (as in 'windows') over the main screen but of course there is still the problem with the main app screen. All the charts used are red stars on black, and the main screen will also be red-on-black. It's more a question of unpeeling those suck-together charts, running ink, and other problems. A trade-off I suppose. Maybe I'll give it a try and just see!

PS - Gary... I hope you know I'm eating my words regarding the mighty reds!

MDAV's picture
Dew on laptop

On re-reading it seems you are using the laptop settings to get your red and dim the screen or to toggle a black window over the open ones. Even the dimmest settings are way too bright. 

I always set my screen to the dimmest setting but I wouldn't even consider using the laptop without that fitted red plastic screen. And all the indicator LEDs and any light leaks around the red screen get the black tape treatment.

GTN's picture



     I second Gary's comments.  The human iris closes very quickly, but it takes many minutes to open up again.  Even completely blanking the screen of my laptop and covering it with an opaque cloth during CCD exposures proved that the screen was still too bright, too often, to allow my dark vision to ever recover.  Doing visual observing under those conditions?  Visual opticide!



Ken Sikes
Ken Sikes's picture
Laptop Protection

I use a laptop with my SSP3a photometer set on a cloth to help keep it warm. I also use an Ironing board for a table as it has adjustable heights. I place a Coleman propane catalytic heater on the ground under the laptop. No dew problems or problems wit the laptop due to the cold.


Ken Sikes

MDAV's picture
Dew and laptops

Has never been an issue for me. 

Possibly it generates enough heat to stay above dewpoint. I've seen the scope dripping but no dew on the laptop.  But I sure have had lots of paper charts destroyed by dew. I used to laminate them but the bulkiness just got un-manegeable. 

On the effect on visual observations I do use one of those plastic red lenses.  I suppose the total amount of light put out by the screen does affect night vision but my screen is a heck of a lot dimmer than some of those red LED lights I see used- possibly more total output but less intensity.  As a general rule my limit on my 12" newt is about 14.3 from my deep sky site in Los Padres Forest. It doesn't seem to matter much whether I use the laptop or not. Seeing conditions affects me more.

Given that most of my observing is out in the boonies since there's not much point in building an observatory on my house in Morro Bay,CA.  Having all my references at hand on the laptop just beats any disadvantage. 

 I suppose the best rule is that whatever works- works!

phcoker36's picture
Dew and laptops

Check out  I have one for the laptop in the observatory which I take with me to starparties.  Works well.

pox's picture
This gives me hope! I use a

This gives me hope! I use a 14" Dob, best magnitude limit somewhere around 16 - 16.5 but of course these conditions are rare! But even so, limiting magnitude is my number 1 priority so everything (as with Gary P) is geared towards that. I always have at the back - maybe not even the back - of my mind Herschel's comments about (paraphrasing here, as I can't find the quote) 'screwing an instrument up to its highest pitch' - Maybe even the dim red screen will substitute for the red LED observing light. Anyway, I shall now give it a try. Thanks all for your helpful comments.

WGR's picture


I did not get in on the beginning of this.  So maybe you mentioned it.  But does your app update the charts on some regular basis.  Do you also access the photometry page?



Gary W

pox's picture
Hi, No, the app is purely


No, the app is purely for my observing. It uses an access database, which it also creates if it doesn't yet exist (though obviously in my case this db actually exists already, I gave it this facility just in case anybody else might be interested in the future). What I do is:

1) Scan my existing paper charts into red-stars-on-black jpg files (I may re-export these en bloc as .wmf's later) which are stored on the system.

2) When you load a chart, the app reads the system date and time into a set of text boxes, as well as the star's name and chart number (adding 1 minute to the time; that's the max amount of time as a rule between finding the star and the actual estimate).
The database includes a field which determines how many dp to use for each star.

3) Pressing the 'Enter' button converts the date/time to JD and decimal, formatting to 1 dp for non-eruptives and 4 dp for eruptives (Dwarf Novae, YSOs) and providing an acceptable AAVSO text file header.

4) Each observation logged appears in a rich text box, which is editable. Labels also show how many observations have been made, and also the last star input.

5) For this app, I also want the estimate to be recorded in a cumulative file, quite distinct from that which will be uploaded to the AAVSO database. The BAAVSS require estimates to be sent as part of the observation report, but AAVSO doesn't. However, I need this facility!

6) Pressing the 'Save' button saves the file as .txt in AAVSO format, ready to be uploaded. The file gets given a name comprising my AAVSO initials and the date. The cumulative file (containing the actual estimates) is appended each time.


I don't use the photometry page, as I'm a stuck in the mud visual observer. ;-)

As I say, really this app is purely for my personal use - the database contains all the stars on my obs programme, which will obviously differ from everybody else's; but if other folks are interested, obviously I will have to add a facility to edit or create one for yourself. Not difficult - you can do it programmatically, so you don't necessarily have to have MS Access.

Hope that's covered everything. I seem to spend more time coding than observing. One consequence of living in cloudy ol' England.

PJOC's picture
My laptop does run on the

My laptop does run on the warm side, but I've never had any problems with dew on the laptop - the internal heat is plenty to keep it above the dewpoint. 

I have had dew form on the counterweights then drip onto the keyboard.  And a little problem with some local birdlife alighting on the counterweight bar to relieve itself, missing the laptop by inches.

pox's picture
Re the birdlife... where I

Re the birdlife...

where I first observed from with the 14" was near a bat roost, and it was quite common to have them flitting acrobatically around the scope before complete nightfall! Good thing I don't mind them (in fact I actively love 'em!) although I can personally confirm that the oft-quoted piece of 'wisdom' that 'they don't get in your hair' is not true. This happened to me once, but I have to say it was very much a Steve Irwin moment - I felt quite privileged!

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