Homemade FoV rings?

[Moonshine132435]

Not long ago I found a few pages on the internet designed to help budding astronomers find their way around the night sky.

A little trick they had was making a field of view gauge, basically a ring if copper wire on a stick which could mimic the FoV of your bins or a wide eyepiece on your starmap and so allow you to better plan an evening's viewing. Sort of like some home-made telrad rings

Does anyone know where I can find that guide again, I'm completely blanking?

[Digger1895]

Sorry I can't help with the site, but if I'm understanding correctly wouldn't it just be a case of knowing the FOV of a certain EP on a certain scope, and knowing the scale of the chart you are using?

[Moonshine132435]

That's exactly it Digger

[Moonshine132435]

And that thread title should read FoV, silly typo, sorry.

[Stu]

Title sorted. I'll have a look to see if I can find what you are after, I've seen something similar around somewhere.

As digger says though, there should be a degree scale on your map so it's a case of making circles the same diameter as say 4 degrees on the map...

Sent from my iPhone using Tapatalk

[Digger1895]

I've seen somewhere a card being used. This has a circle the size of the FOV cut out. It was on black card but would be better if it was transparent, some sort of thin Perspex, so you could plan a star hop easier. You could also use a compass like you see in films were they navigate the sea. Assuming the charts you use are all to the same scale you would only need one measurement to represent the FOV of your wide field EP. You'd need someone rather more experienced than me to give you the formula to work out that measurement. I'd be interested in seeing and trying this myself.

[Floater]

On the inside of the cover of my ring bound Pocket Sky Atlas is a scale giving the angular distance on the charts and suggests making a wire ring to match the FOV of one's finderscope.

A small shampoo sample bottle was the right size for me. Wrapped some green garden wire round the bottle to get the ring nice and circular and it's done.

[Moonshine132435]

That's great guys, very helpful. I'll have a look at my star atlas, do the math and make some wire rings.

[glowjet]

An interesting and practical way to find the actual field of view of your bins or telescope eyepiece, is to focus on any bright star near the celestial equator and place it on the Eastern edge of your FOV, telescopes should have any drive switched off and bins should be tripod mounted for stability. Using a stop watch, or the second sweep hand of a watch, clock the time it takes for the star you have chosen, from when it appears at the Eastern edge, to drift across across the centre the FOV and disappear from view at the Western edge. For accuracy you can do this three times and take the average as your answer. Divide the figure by 4 and the result is the field diameter in arc minutes, multiply by 60 and your result will be in arc seconds. Armed with this information you can draw or make your map circles to the  scale of the star maps you are using. I have put to good use the fairly thick clear plastic of some Christmas presentation boxes, drawing the scale circles in waterproof Black ink. Small sheets with a number circles so marked lie nicely on the open pages of star maps and are an essential aid when star hopping and finding your way about the night sky, enjoy

[Astro Imp]

^^^

Great idea John, thanks.

[webboid]

I use a technical drawing circle template so can use on several FOV on different scopes.

http://www.amazon.co.uk/gp/product/B0047KBVRK/ref=oh_details_o05_s00_i00?ie=UTF8&psc=1