Beginner question, do I need dew heaters?

[Coxy80]

Having bought a new scope over a month ago and suffered a month of clouds and rain I've finally been able to get out with it a bit despite super low temperatures. It has been below -10 here for quite a few nights, the last couple of nights have warmed up a bit.

I was out last night in what was maybe -3 and had my fist glimpse of a few Messier objects and throughly enjoyed it but ended up plagued by my eyepieces constantly misting up. 

Upon packing up I also notice that the main objective was also misted up. 

My question is will this happen most nights in what is a damp cold part of the UK (Scottish Borders) and will dew prevention of some sort be an essential thing to have? 

Clear sky's are rare here and don't want to waste them but also don't want to send money on something that won't be needed much. 

My equipment is a Starfield 102mm f/7 ED Doublet Refractor with a selection of Baader morpheus eyepieces. 

[Mick H]

Hi Coxy80, I use a hairdryer for a quick blast on lens and eyepieces/finder, plus its a cheap alternative.

Edited December 18, 2022 by Mick H

[Stuart1971]

1 hour ago, Coxy80 said:

Having bought a new scope over a month ago and suffered a month of clouds and rain I've finally been able to get out with it a bit despite super low temperatures. It has been below -10 here for quite a few nights, the last couple of nights have warmed up a bit.

I was out last night in what was maybe -3 and had my fist glimpse of a few Messier objects and throughly enjoyed it but ended up plagued by my eyepieces constantly misting up. 

Upon packing up I also notice that the main objective was also misted up. 

My question is will this happen most nights in what is a damp cold part of the UK (Scottish Borders) and will dew prevention of some sort be an essential thing to have? 

Clear sky's are rare here and don't want to waste them but also don't want to send money on something that won't be needed much. 

My equipment is a Starfield 102mm f/7 ED Doublet Refractor with a selection of Baader morpheus eyepieces. 

You deffo need, and will benefit from having dew bands, it’s as simple as that….👍🏻

[Franklin]

Dew heater bands don't cost a lot and they work, I'm visual only and have a 12vDC for the objective end and a small USB type at the eyepiece. Another tip, if you observe with your left eye, the finder is placed in exactly the wrong position so when looking in the finder your warm breath flows directly onto the eyepiece causing it to mist up. I've trained myself to look in the finder with my right eye in the hope of preventing this. Also, after a session try not to take a freezing scope straight back into your warm house, everything will just mist over. Find an unheated but dry place, like a porch, to let the scope warm back up gradually, caps off till dry, then store with silica packets.

[Franklin]

Nice set up btw.

[Guest]

You might try a dew shield first, you can buy on or make one out of foam and velcro cheap enough.  If that fails, now you are looking at heat.  In my environmental conditions heaters are used almost year around.  Dew, frost or ice are no longer an issue.  The trick is to use just enough heat to do the job. 

[Coxy80]

Cheers for all the helpful replies guys. I was thinking of giving these a go along with a rechargeable power pack https://www.rothervalleyoptics.co.uk/rvo-heater-bands-with-integrated-controller.html anyone used these? 

I liked the idea of not having to buy a separate dew controller. 

[powerlord]

I just use 5v USB ones for all refractors and guidescopes. About 15 quid each from amazon.

Mine all powered by dc 5v psu, but USB power banks work fine. No need for expensive 12v astro stuff.

Just search for lens dew heater on amazon.

I use these ones:

KIWIFOTOS Lens Heater Warmer Dew Heater Strip with Temperature Regulator for Universal Camera Lens Telescopes Eyepieces Heating, Dew Remover Lens Heater Warmer https://amzn.eu/d/0jiLsCp

Stu

[bosun21]

12 hours ago, Coxy80 said:

Having bought a new scope over a month ago and suffered a month of clouds and rain I've finally been able to get out with it a bit despite super low temperatures. It has been below -10 here for quite a few nights, the last couple of nights have warmed up a bit.

I was out last night in what was maybe -3 and had my fist glimpse of a few Messier objects and throughly enjoyed it but ended up plagued by my eyepieces constantly misting up. 

Upon packing up I also notice that the main objective was also misted up. 

My question is will this happen most nights in what is a damp cold part of the UK (Scottish Borders) and will dew prevention of some sort be an essential thing to have? 

Clear sky's are rare here and don't want to waste them but also don't want to send money on something that won't be needed much. 

My equipment is a Starfield 102mm f/7 ED Doublet Refractor with a selection of Baader morpheus eyepieces. 

I have a Starfield 102 and I also have all the Morpheus eyepieces. You most definitely won’t be wasting your money buying dew heaters/controller. I had my entire night totally ruined once, and that was enough for me. I now have 12v heater bands on my telescope objective, my 9x50 RACI and also my eyepiece of choice (usually a Morpheus but not always). These are powered by a 12v dynamo power supply and controlled by a 4 channel controller. I now have incorporated this arrangement for my other two scopes, and dew is now a thing of the past.

Edited December 18, 2022 by bosun21
Typo

[cajen2]

11 minutes ago, bosun21 said:

I have a Starfield 102 and I also have all the Morpheus eyepieces. You most definitely won’t be wasting your money buying dew heaters/controller. I had my entire night totally ruined once, and that was enough for me. I now have 12v heater bands on my telescope objective, my 9x50 RACI and also my eyepiece of choice (usually a Morpheus but not always). These are powered by a 12v dynamo power supply and controlled by a 4 channel controller. I now have incorporated this arrangement for my other two scopes, and dew is now a thing of the past.

No dew but empty pockets! 🤣

[bosun21]

2 minutes ago, cajen2 said:

No dew but empty pockets! 🤣

Isn’t that always the story 😂

[Guest]

We dumps hundreds of dollars into eyepieces and other accessories, no reason not to dump some money in proper dew control if you need it. 

Edited December 18, 2022 by Mike Q

[powerlord]

Ah.. The 'Must get the best for the best fallacy' . Many a pound lost there for sure.😂

But yes to answer op. They are 100% required.

In summer mine are on low, on winter on high. I don't even bother looking at dew points anymore just always use em.

[Coxy80]

15 hours ago, powerlord said:

I just use 5v USB ones for all refractors and guidescopes. About 15 quid each from amazon.

Mine all powered by dc 5v psu, but USB power banks work fine. No need for expensive 12v astro stuff.

Just search for lens dew heater on amazon.

I use these ones:

KIWIFOTOS Lens Heater Warmer Dew Heater Strip with Temperature Regulator for Universal Camera Lens Telescopes Eyepieces Heating, Dew Remover Lens Heater Warmer https://amzn.eu/d/0jiLsCp

Stu

Do you think a power bank like this would power a couple of the usb strips in your link? 

https://www.amazon.co.uk/gp/product/B0BBGPMT2H/ref=ox_sc_act_title_1?smid=A1TW3I98UKHHWA&th=1

[powerlord]

On high they pull about 10w (2a at 5v) each.

so 20w for both on full.

That one is probably in reality about 15ah (not 30 for that size), so IF it can provide 2a to each it will last 15/4 = nearly 4 hours.

On low they use a lot less, don't know exactly, but prob about 25%. so would last maybe 16 hours.

In reality, if you can run em on medium heat, I think you won't be far off getting a night of imaging out it for 2 probably.

though I think I'd stay away from ones that can't even spell Univeral properly 🙂

If in doubt, get 2 - always useful to have. And if they are rubbish, it's amazon so you can always return them.

stu

 

[Carbon Brush]

The Amazon powerbank seems to suffer the same 'specmanship' or 'bamboozle the buyer' or 'economy with truth' of a lot of these products.

My interpretation is that it has 30Ah of lithium rechargeable cells - 3.7V or thereabouts.
In round figures this is about 10+ cells of the 18650 type. Though we don't know the cell type.
If we assume these numbers, this is 3.7 x 30 = 111 watt hours in the pack.

Using a boost convertor you step 3.7V up to 5V, assuming 80% conversion efficiency gives...
111Wh x 0.8 = 88.8Wh at the ports.

Next they talk about delivering 20W, which is 5V at 4Amps to the USB A ports.
They are vague about whether it is 4A total, or 4A per port. I suspect the former.
A USB type A connector carrying 4A is going to heat.

So in reality you have 5V 2A available at each port - which governs the size of the heater.

How long does it last? Probably a bit over 4 hours on full power, proportionally longer if you reduce power.

Caveat. Lithium cell capacity is often quoted as a particular temperature and a particular discharge current.
If you stray from these values the capacity is reduced.
I tend to assume 75% of the claimed value - unless I have the cell manufacturers data to provide a more accurate assessment.

A caution about return if it doesn't do what is claimed, or is faulty. Normal amazon 'no arguments' may not apply.

Many carriers refuse to take batteries in parcels from individuals. Business, yes - sometimes.
In this case the batteries are enclosed in the box, not loose, so you should be OK.
Unfortunately Post Office counter staff, and even some international shippers don't understand this distinction.
I once had an international shipper 'bounce' a 50Kg shipment because of a little coin cell that was in a holder. Never used him again.

Then if the item is faulty, not just a poor performer, you are into more hassle.
People who will take a package containing potentially faulty lithium batteries are as common as purveyors of hens teeth.
I once had an argument with amazon on a return with installed lithium cells that did not work properly.
Amazon wanted to refund me £3 or £5 or whatever return postage cost.
I told them to tell me which carrier would accept faulty lithium - and they couldn't.
In the end they refunded the item and left it to me to dispose of the lithium content.

Now if you buy a branded powerbank from an astro retailer, or branded product from a manufacturer (Tracer for example) things are much easier.
The stuff from China sold by amazon and others - caveat emptor!

HTH, David.

 

[powerlord]

I've returned batteries from amazon - no bother - they pay shipping usually with Hermes or whatever, and even make sure that the address label you print has the correct 'contains batteries' label.

No usb port can pull more than about 2.1a within the spec. Some cheapies will put that limit across 2 ports so you do need to check that - ones that support usb C PD will usually be good because they are used to providing more amps over usb c.

capacity wise, just go by rough cost and size - that's yer best bet. And as I say, for the @5v capacity divide by 2 and a bit.

I usually measure the power banks I get by fully charging and discharging through a power meter. I usually find that 24-30ah ones come in at around 12-14ah @5v.

I'd certainly never buy an astro powerbank - they are ridiculously over priced for what they are imho. But I suppose some folk do so what do I know. 🙂