Red light torch - how strong?

[Vilius]

Hi everyone, beginner here.

How strong a light do you experienced observers use when observing? I currently tape some red cloth over a regular headlight. However, I think this may dim the light too much, as it becomes really hard to take notes and read.

 

But will a stronger light screw up my night vision, even if it is red? My neighbourhood is light polluted enough as it is...

[Neil H]

Hi most red light torches have 2 settings dim and bright I only use mine on dim , I seen people use red insulation tape over the light you add more if not dim enough I tried red paint was ok but I found the torch so much better this is the one I use 

https://www.amazon.co.uk/Carson-RedSight-Pro-Flashlight-Brightness/dp/B01MY4WIW9/ref=sr_1_5?crid=1WG8RDSPWGHYV&dchild=1&keywords=red+light+torch+astronomy&qid=1612781295&sprefix=Red+light+to%2Caps%2C180&sr=8-5

Even if it's on bright I don't find it upsets my night vision

Edited February 8, 2021 by Neil H

[Carbon Brush]

Ten or more years ago, I bought something very much like this

https://www.rothervalleyoptics.co.uk/antares-dual-beam-redwhite-variable-torch.html

It was branded Skywatcher. The brightness is fully adjustable by turning the knob. Rather than a hi/lo setting.
Throw the switch and you have white light for packing away.

I have two of these torches and never seen the need for a different red light torch.

HTH, David.

 

[John]

If you are looking for DSO's keep any light as dim as you can. My personal preference is no light at the scope when I'm going for the really faint stuff.

For planetary and lunar observing it does not matter. In fact dark adapted eyes are less effective in picking up subtle planetary features.

[Pixies]

My head touch on its lowest red setting is enough to read/sketch with, but doesn't adversely effect my night vision for most things. 

However, if I was on a faint galaxy hunt, I think any red light might be too much.

[Zermelo]

I have a red head torch that is fine for seeing where I'm putting things, but I sometimes struggle to read printed charts.
I was considering options when I came across this article, which goes against everything I'd previously read:

http://www.astromax.org/activities/members/kniffen.htm

Is anyone using a dim green light instead of a brighter red one?

[Pete Presland]

10 minutes ago, Zermelo said:

I have a red head torch that is fine for seeing where I'm putting things, but I sometimes struggle to read printed charts.
I was considering options when I came across this article, which goes against everything I'd previously read:

http://www.astromax.org/activities/members/kniffen.htm

Is anyone using a dim green light instead of a brighter red one?

Certainly a very interesting read

[Carbon Brush]

An interesting idea. However, being based on a 1997 idea that never caught on, I wonder if it is valid?

The idea that human eye, green vision is more sensitive than red is well established.
Green light emitting diodes (narrow bandwidth) have been arounds since the mid 1970s.
So by the time of the 1997 article, they were well established and certainly affordable.

Green illumination for goto displays has been easy enough to arrange for perhaps 40 years. Much longer than goto has been a realistic prospect for the amateur.

The graph in the astromax link is not scaled. In fact we don't even know if the y axis is log or linear.

My gut feeling is that if it was valid reasoning, the scope sellers would have been offering us 'better' green torches and goto displays years ago.

I do though await informed opinion and am happy to change my views.

David.
 

[bish]

I've one of the adjustable Skywatcher torches as mentioned by David above.  It"s been fine for me. I've been at star parties where people have a bright head torch with flimsy red film over it, and completely dazzles you.

[pete_l]

Many, many years ago an astronomer whose word I have no reason to dismiss told me that if you can make out the colour of the light from your torch, it's too bright to not affect your night vision.

[Second Time Around]

I prefer a headtorch as I can just as easily hold it in my hands or around my neck, so it's dual purpose!  This is important when with others as used as a headtorch you'll shine it into their eyes.  Headtorches can also be laid flat on a table or even tilted.  

Red light doesn't interfere with night vision like white does.  However, most lights are way too bright, so a dimmable one is very much to be preferred. 

Many of the headtorches on the market start on either bright or white light.  It's also easy to push the wrong button.  I'd therefore recommend one of the inexpensive Black Diamond range.  These can be set to always come on with the dimmest red light whatever button you push - so no accidents! 

You do need to avoid the higher priced ones that have a battery check on starting up though.  This is because it lights up an intense blue that'll ruin your dark adaption.  Additionally, those with the Powertap feature can be knocked on accidentally.

For astronomy just look for models without  a battery check and without Powertap technology.  There are 2 suitable models - the Spotlite 160 and the Cosmo 250. You may also find the newly discontinued Cosmo 225.  BTW, the so-called Astro models aren't suitable for astronomy as they don't have a red light! 

Wiggle have a special offer on the Cosmo 250 at the moment for only £15.  Go to https://www.wiggle.co.uk/black-diamond-cosmo-250-headlamp?lang=en&curr=GBP&dest=1&sku=102436075&kpid=102436075&utm_source=google&utm_term=&utm_campaign=Shopping+-+All+Products&utm_medium=base&utm_content=mckv|sRffJGoLJ_dc|mcrid|490894957190|mkw||mmt||mrd|102436075uk|mslid||&mkwid=sRffJG

[GSmith]

On 08/02/2021 at 09:44, Vilius said:

Hi everyone, beginner here.

How strong a light do you experienced observers use when observing? I currently tape some red cloth over a regular headlight. However, I think this may dim the light too much, as it becomes really hard to take notes and read.

 

But will a stronger light screw up my night vision, even if it is red? My neighbourhood is light polluted enough as it is...

I was in the same situation and ended up saving some red cellophane from the Christmas Quality Street chocolate box. Two red sweet wrappers folded in half (4 layers) and the taped onto my head torch is about right for me with the moon out. My torch, bought online from Alpkit, has different brightness levels to fine tune. Six layers is good for as dark as it gets with my light pollution. 

You don’t need to get a specialised torch straight away and now have a good excuse to eat more chocolate. Win all round!

[Nyctimene]

Agree with David  (CarbonBrush). A dimmable red-white torch is the best allrounder, and not pricey. Have a look :

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p3461_TS-Optics-dimmbare-Rotlicht--und-Wei-licht-LED-Lampe-Astrolampe.html

I've added two layers of  deep red acryl to make it usable when searching for faintest DSO's.

Stephan

 

[Vilius]

It hadn't occured to me that different light levels are suitable depending on what I'm looking for in the sky! Does seem like an adjustable torch is the best solution then. Thanks for the input and links everyone!

[Gfamily]

In terms of head torches, the best one I've found is this from Energizer - a big advantage is that it has two buttons - one for red beam and one for white beam. 

https://www.batterystation.co.uk/brands/energizer-batteries.html?_bc_fsnf=1&Product+Type=Head+Lights

[Kimboman]

I purchased two army surplus torches with 90 degree head ,these were supplied with one ,clear one red and one green filter.

I also have an ex br signal torch which also has the same range of filters at the turn of the on off switch well cheap and work well

[Tiny Clanger]

5 hours ago, GSmith said:

I was in the same situation and ended up saving some red cellophane from the Christmas Quality Street chocolate box. Two red sweet wrappers folded in half (4 layers) and the taped onto my head torch is about right for me with the moon out. My torch, bought online from Alpkit, has different brightness levels to fine tune. Six layers is good for as dark as it gets with my light pollution. 

You don’t need to get a specialised torch straight away and now have a good excuse to eat more chocolate. Win all round!

Alpkit and chocolate 🙂  that combo gets my vote any  day !

I've spent more on lovely alpkit stuff than I have on astro kit ... so far ...

Heather

[Waddensky]

On 08/02/2021 at 14:15, Zermelo said:

Is anyone using a dim green light instead of a brighter red one?

Here's a link to a research paper by Ken Wishaw arguing that orange is actually slightly better than red to preserve dark adaptation. And because of the improved contrast, it makes charts easier to read too. The subject was also discussed in a 2019 issue of Sky & Telescope. That's why some of the stargazing apps I use have an orange/amber night mode. It's still a topic of discussion, apparently 🙂.

I use a Rigel Skylite at the telescope, it has white and red leds that are fully dimmable. I've put some tape over the glass to diffuse the light a bit more. They are excellent.

[wibblefish]

On 08/02/2021 at 10:48, Neil H said:

Hi most red light torches have 2 settings dim and bright I only use mine on dim , I seen people use red insulation tape over the light you add more if not dim enough I tried red paint was ok but I found the torch so much better this is the one I use 

https://www.amazon.co.uk/Carson-RedSight-Pro-Flashlight-Brightness/dp/B01MY4WIW9/ref=sr_1_5?crid=1WG8RDSPWGHYV&dchild=1&keywords=red+light+torch+astronomy&qid=1612781295&sprefix=Red+light+to%2Caps%2C180&sr=8-5

Even if it's on bright I don't find it upsets my night vision

I had this one as well, very good (and it has a glow in the dark handle in case you drop it :P) with the two step dimming unfortunately mine has not lasted longer than 4 months  

I purchased the one below as a replacement and its a bit more substantial but lacks the dimming function so I am not sure if it will be to bright (though a few reviewers said they use it fine for astronomy). I have yet to be able to use it but fingers crossed soon!

https://www.amazon.co.uk/gp/product/B07MMV7BF8/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

Since they finally came back into stock (albeit they are from US so I am not sure if I will need to pay import fees on arrival) I ordered myself an Orion Dualbeam waterproof lantern which seems to get very good reviews.

https://www.amazon.co.uk/gp/product/B071Y4FWSP/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Edited February 10, 2021 by wibblefish

[Second Time Around]

A very interesting, dare I say illuminating, paper!

[Neil H]

Hi i have 6 of the torches you link but white light super bright so i hope they dimmed it down some be uninteresting to hear what you think of it  

Edited February 10, 2021 by Neil H

[Physopto]

There are far too many people who walk around using overly and very bright red light head torches. They tend to think it is OK because it is red light !

Not so at all. A bright Red Light  will decimate your night vision and that of any folk unfortunate enough to be within the line of the beam and even if not in the direct beam. If you use a Bright Red light torch for working on your Astro setup make sure no one is likely to be in the visible vicinity. Otherwise use a very dim red head torch to barely be able to see items around you. That way your night vision will not be as badly affected. Any light red or any other colour, will affect your and others astronomers night vision.

There are times when a white light is necessary, but please warn others before you light up or get covered to do whatever is needed. Dropping a small absolutely needed  item (screw, glass, or other item) in the grass and trying to find it by red light may be the end to your only chance of good nights astronomy.

I know it may not be a popular opinion, but for those who spend half an hour or more trying to get their night vision at its best, it only takes one brief flash of a Red or other light to have to start all over again. I have been as guilty as most of these errors and strive not to do so.  I find the worst thing is having the head torch on and it being so dim, then forgetting it is on. Then accidentally looking up a someone ! Oops!

[BCN_Sean]

Never really actively thought about this, but my usual lamp is a very weedy reddish maglite and the batteries in that are usually rotated off something else.  If I'm not using that, I'm quite partial to using a dob of photo-phosphorescent tape/paint on things (cable ends, screw heads, port markers and the like), a habit which I got in to when I "lost" a camera setup in a field at night whilst doing some long exposure work.

[Orange Smartie]

On 08/02/2021 at 17:32, Second Time Around said:

 

Wiggle have a special offer on the Cosmo 250 at the moment for only £15.  Go to https://www.wiggle.co.uk/black-diamond-cosmo-250-headlamp?lang=en&curr=GBP&dest=1&sku=102436075&kpid=102436075&utm_source=google&utm_term=&utm_campaign=Shopping+-+All+Products&utm_medium=base&utm_content=mckv|sRffJGoLJ_dc|mcrid|490894957190|mkw||mmt||mrd|102436075uk|mslid||&mkwid=sRffJG

Thanks for the heads-up on this @Second Time Around. Just bought one of these and it looks excellent. 

[Tiny Clanger]

On 10/02/2021 at 13:04, BCN_Sean said:

Never really actively thought about this, but my usual lamp is a very weedy reddish maglite and the batteries in that are usually rotated off something else.  If I'm not using that, I'm quite partial to using a dob of photo-phosphorescent tape/paint on things (cable ends, screw heads, port markers and the like), a habit which I got in to when I "lost" a camera setup in a field at night whilst doing some long exposure work.

I use something similar, mostly because I'm thrifty (or possibly just mean) and had a lovely little maglite solitaire (bulb version, I imagine the newer ones are LED ?) which had become redundant through acquiring brighter more efficient white light torches for non astro use..

Rather than just buy something new, I cut a circle of red acetate and stuck it to the lens with PVA glue (which is white, but dries to  transparency) .One layer of acetate gave a nice bright red light ... too bright in fact, so a second disc went on top of the first. Now the light is dim, very dim, but it does not affect my eyes adjustment at all, and is just sufficient to see things when the torch is held a couple of cm away. 

I also use a turn of glow in the dark tape around the bottom of my tripods legs and to mark the top of my kit boxes, and glow in the dark cord on the zip pulls of bags etc : I originally got the glow in the dark cord to make easy to find tent door zip pulls, it is great stuff .

Heather