wulfrun

7 minutes ago, Jiggy 67 said:

I love that Jim, great explanation.....now explain the influence of dark energy on the expansion of the Universe 😀😀

Refrerring to my analogy above, someone's turning up the air pressure inflating the balloon. We don't yet know how that comes to be. 🙂

As an anology which you can probably visualise in your head. Partly blow up a balloon. Mark a red dot on it somewhere and a load of black ones at reasonable distances. Blow the balloon up a lot more. Notice that the dots have all got further from oneanother. Notice that the dots farthest from your red, reference dot have moved further than the ones nearby. The fabric of spacetime is expanding in the same fashion but with more dimensions.

44 minutes ago, Tiny Clanger said:

After many years of searching, I've found my ideal keyring torch, and it's a Fenix E05, it has all the features I want: runs on one AAA, is even shorter than the solitaire,  twist switch so it doesn't illuminate my pocket and run the cell down , can be stood on its cap to gently illuminate the tent roof if needed (altho' you can't take the front off and make it into a bare bulb tiny electric candle as you can with the solitaire !). Comes on at the lowest of 3 brightness settings, medium and bright achieved by twisting the front bezel. The single AAA lasts an amazingly long time on the low power setting.

Much the same as the L0D I've had on my keyring for years then, except mine has a strobe and SOS function on top (I don't have much use for them though). And yes they drain the battery as flat as the proverbial, nowt wasted. Strangely, mine cycles mid-low-high-strobe-SOS. Why they didn't think to start with low I don't know. Very tough bits of kit, glad to see you have at least one decent, modern one 😉

18 minutes ago, Tiny Clanger said:

So, my heavily astro modded solitaire (red finish, original bulb model) seems collimated , but reckon the lumpy PVA glue that holds the layers of red acetate to each other and the front glass may be affecting the smoothness of the light pool somewhat. Anyone know the refractive index of dried PVA glue ?

By the way, for any tactical flashlight fans out there, yes, that thumb loop is glow in the dark paracord .

Probably about 1.3 for the PVA? Time to come into the modern age. FLO sells the Chandler-branded Photon X-Light red torch, you need to splurge your 12 quid on it. I have a couple of Photon Freedom Micro-lights, one with an (interchangeable) yellow LED and one which is a "covert" (i.e. shielded-end) red. The FLO item has the same functions and for astro it would be worth the pennies. Variable brightness is a must-have, so you can use the least power suitable for star charts, lens selection box or whatever. Battery lasts ages too. The Photons I have came with a ball-head, magnetic clip that you can attach to your clothes/cap-peak/scope tube etc so highly useful.

1 hour ago, astrocanito said:

collimating...

 

Hilarious! I have one of these:

https://www.fenixtorch.co.uk/Shop/Fenix-Torches/PD-Series/13690-Fenix-PD35-V2.0.html

It has various modes - I always leave it on the lowest brightness, which is very low power. Friends have looked at it, asked "how much?" and then "how bright?" so I invite them to look for themselves. They always look into it and say "not very bright, is it?" and I invite them to hold the button on the side. This sends it into strobe mode, which is full power in a strobe/fast flash intermittent pattern. Day or night, I promise your vision will be impaired for a good ten minutes and you'll likely feel sick. I can't put the typical comment here or it'll be removed 😉

1 minute ago, Gfamily said:

And soot on the telescope eye-cup?

Or the binoculars, for a matching pair? 😉

10 minutes ago, reezeh said:

Comes in handy as a dark light too for cancelling out any unwanted light

Can't resist this one, in the spirit of the thread. Years ago, I worked in surface coatings, which included colour matching. We had a spectrophotometer in the lab (fancy colour-measuring gadget) which had two calibration standards - a white tile and a light-trap. The white tile is barium sulphate and not very interesting. A light-trap is a tube, closed at one end, matt black inside and containing a matt black cone which tapers to a very sharp and equally invisible point. Visitors would casually pick it up and ask what it was. "It's a light-trap". "Oh", first thing look into it, second thing insert finger to see what's in it. We kept the pasters nearby 🙂

16 minutes ago, reezeh said:

That torch worries me. I'm scared that I'll get sunburn from holding it when it is in UV mode 😀

Don't use UV mode then, plus I'm sure it's safe enough if you don't stare at it. Mine in that size is an L0D, no UV function but appears to be discontinued. Seriously though, Fenix torches are the bizz. You only buy once - well once for each requirement anyway! A bit like scopes, you can't have too many torches eh 🙂

Solitaire uses a bulb, that's ancient technology. You need an upgrade. I'd suggest something like this:

https://www.fenixtorch.co.uk/Shop/Fenix-Torches/LD-Series/13756-Fenix-LD02-V2.0.html

Never needs collimation. It's about the same size, runs off the same battery (which lasts a lot longer) and is at least 5 times brighter. I have its predecessor, somewhat worn but still works perfectly. Top tip: don't use on astro trips unless to find your way back, it'll ruin your night vision in an instant.

Ok, so I wasn't far off then. Just had a feeling it might be something more mysterious that I hadn't thought of! I did think the one with the plasic knob might be for a camera but I also figured a long-lensed SLR isn't going to sit on that happily at any sensible elevation below "zenith"?

Edit: I forgot to say thanks for the quick replies.

As per thread title, what's the purpose of these fitting points, circled in the shot below? I'm guessing the pair can be used to attach a handle but it leaves me puzzled about the right-hand one and the plastic wheel. No doubt I'll be smacking my head and saying "duh, of course!" when someone enlightens me. The same seems to found on various pictures of new scopes so I assume they are OEM fitment.

I saw 3 last night in the space of half-hour ish and a mere 2 the night before, both times close to midnight. Not as many as I'd have liked but still pretty when they came.

In this day and age, it's not beyond technology to provide adequate lighting when and where it's needed - i.e. on roads and adjacent footways. Depending where I stand, I can see up to 6 streetlights at once from my (back) garden, the most obtrusive of which is an LED on an adjacent estate. All of these lights produce enough illumination for me to cast shadows and the light is not going where it should be. Let's not even mention the rottweiler lights. I don't think it's too much to ask for streetlighting to be confined to streets and not wasted on spill areas where it's sometimes a nuisance.

I've used IPA on photographic lenses for years without issue, it's a fairly mild solvent and won't harm coatings, just don't flood it on. It's the basis of many optical cleaning solutions anyway. I think a lot depends on what you were trying to clean off - greasy or not? Dust should always be blown off as much as possible and only use soft, lint-free cloths. Probably preaching to the choir here though!

EDIT: dilute white vinegar is also something I use. Just not the malted or wine-derived sort!

The petition is to make councils add shades without needing to be asked, not to have no street lights. In fairness, if they'd use sensibly designed fittings in the first place, rather than what's most likely the cheapest, shades shouldn't be needed. The other thing they seem to do is to replace existing sodium lights with LEDs and retain the same number, rather than a complete remove-and-reinstall.

Regarding light or no light, if there's no light at all criminals are forced to use a torch/phone-light, which makes them stand out. If there is bright lighting, residents might see their activity. In both cases, there is a requirement for someone (or a camera) actually to be looking though, not always the case - and activity to be reported. Movement-activated lights are surely more noticeable, provided they aren't too frequently false-triggered and so go ignored. Still subject to someone noticing, of course.

1 hour ago, Paz said:

...but I'm still going to watch it.

You learn to tolerate it, since it's inescapable nowadays but yes, it's still very much a good watch. It remains a cut above a lot of the other pap around.

I've spotted them again tonight, I think it's the third night in a row the clouds have parted obligingly. I must have been a good boy. Sadly, their position now is such that my best hope is the bedroom window and binoculars and a short opportunity. Too low and too badly positioned for me to make a scope practical. There's small park nearby which I may brave on the 21st, clouds permitting but it'll be soggy to say the least.

I think I saw it when it was on originally but I recorded it and re-watched it earlier today. It's well worth seeing even though Horizon has moved into the "let's get a half-hour of material and stretch it to an hour program, with waffle and irrelevant footage" modern style.

18 minutes ago, 7170 said:

You don’t develop it, you take it quickly out of the can and put it on your scanner, and scan. The scanner gets the image but in the process it’s light also destroys it so you only have once chance to scan...

I recall reading about this some years ago. I might be mis-remembering but can you not drop it straight into fixer and hence keep it?

There's one kicking around on the net somewhere where it was overlooking the Clifton suspension bridge. Very impressive! The technique has been around for years, one photography area I've never explored but always been fascinated by.

At the moment we have a pandemic which is causing an increase in astro interest and a decrease in gear availability. Therefore, Sod's law requires those who failed to acquire gear due to the aforementioned circumstances should receive clear skies whilst those who managed to acquire it are punished with clouds.

You could take up cloud-spotting, whereupon the skies will be devoid. Unfortunately, it probably requires you to sacrifice all your astro gear.  😞

Just managed to get a view out of the bedroom window - they aren't well placed for me, too many houses and a streetlamp almost in line. They are getting close, not much over a degree? I managed a peek through the 10x50s and can just make out Ganymede (I assume) as well. Can't believe how all the clouds have vanished! For now!

Worth looking up the Wikipedia page on "Analemma" too, which shows the sun's position on the same time each day from a fixed location. It's a distorted figure-8.

If you mean using the same lens in the same scope but using the 2" size fitting instead of the 1.25" size I think the answer is it makes no difference unless it was vignetting before (unlikely).

2 minutes ago, Skipper Billy said:

To stop the keels of yachts rusting we use a product called 'Fertan'  https://www.fertan.co.uk/

I don't know what is in it but it converts rust to an inert product. Spray or brush it on - wait until it goes black - wash it off and paint it. Even iron keels immersed in salt water don't go rusty after treatment.

 

 

Probably based on phosphoric acid then, rust goes black when it's exposed to it - it converts it to iron phosphate, which is black.