FOV templates

[wookie1965]

Does anybody know where i could download some templates to print off please as this will help with my observing experience as i am struggling thank you.

[wookie1965]

Does anybody know where i could download some templates to print off please as this will help with my observing experience as i am struggling thank you.

sorry would help tell you which ones i want FOV templates.

[Freddie]

Not sure if this is the kind of thing you mean

http://www.12dstring.me.uk/fov.htm

Hope it helps

[wookie1965]

Ive been on there i want to download them so i overlay them on my star charts so i can see exactly what i`m seeing and compare what i`m seeing through the finder and then the eyepiece, thank you anyway.

[Mike73]

You need to work out your true field of view (TFoV) the easiest way is to add your telescope/EP details into this and then add that TFoV to what ever software you are using.

[acey]

You also need to know the scale of your star charts.

Example: for a particular eyepiece you find your true field of view is a quarter of a degree. You have a star chart whose scale is eight centimetres per degree. Then the template would be a circle two centimetres across. If your chart is on a computer then the scale depends on your screen size.

If you can specify your scope, eyepieces and star chart then it can all be worked out easily, and all you'll need is compass, pen and a transparent sheet to draw on.

[acey]

Your sig says you have a Skywatcher 150p, which I believe has focal length 750mm, and you have a 32mm plossl. Then the magnification is 750/32 = 23.4. The apparent field of view of the plossl is probably 52 degrees, in which case the true field is 52/23.4 = 2.2 degrees. All that's needed now is the chart scale. Your sig mentions Turn Left At orion - I don't have that book and a quick google doesn't tell me the scale - it ought to say it somewhere in the book.

[acey]

I just found a scan of the book online (presumably illegal so I'm not giving a link) and I see that the charts show a circle representing a finder. That's probably a seven degree circle. Measure its width with a ruler and divide by 7/2.2 = 3.2 to get your plossl field of view. Draw a circle of that diameter on a transparency and put that over the finder charts in the book. If the circle's not really 7 degrees it will say so somewhere in the book.

[wookie1965]

Acey your a star with your calcs is that a circle of 3.2 cm diameter and ive just sent for Pocket Sky Atlas by Roger W Sinnott i dont know what the chart scale is for that i will wait until its delivered and look. How can i work out my fov of my finder thats a 6x30 do you know.

[wookie1965]

The finder circles are 6cms diameter in turn left

[acey]

Your finder is probably a 7 degree field - you could verify it by timing the passage of a star across the FOV then doing a bit of calculating but let's call it 7.

I just did a quick measurment on my copy of the Sinnott pocket sky atlas and it's 4.8mm per degree. So a 7 degree finder field will be a circle of diameter 7 x 4.8 = 33.6 mm on the page - call it 3.4cm. You need to set your compasses to half that distance (1.7cm) to draw it, which might be a bit fiddly. Alternatively use a printer and fiddle until you get the required width.

For Turn Left, if the circles represent a 7 degree finder field and yout finder is 7 degree then those circles show you the field you'll see. Just try comparing what you see in the sky with what you see in the book and you'll be able to figure out if they match. The tricky part is that you won't see exactly the same stars in the sky as in the book - one or other will have more stars. You need to get used to "filtering out" the faint ones - which soon comes with practice.

[acey]

Incidentally when you get your copy of the Pocket Sky Atlas you'll see that the charts have lines analogous to latitude and longitude on a terrestrial map. The "vertical" scale (called declination) is in degrees, with a "horizontal" line being drawn every ten degrees. That will help give you a sense of how big seven degrees (your finder FOV) is on the sky: a bit less than the distance between those lines.

[wookie1965]

Thank you very much for that hopefully tonight i can go out and find a couple of things i have been struggling with i.e m51.m57,m81and m82

[acey]

Good luck with those - M57 is easiest to find though it's small. The Pocket Atlas will certainly help once you get that, it's great.

[wookie1965]

Yes i thought that that`s why i sent for it, i have got turn left a Planisphere and Stellarium with the Pocket book i do not think there is anything else i can get to help me.

[Astrosurf]

I thought Stellarium has an occular plug-un to give FOV? I haven't tried using it yet. I think you need to contact the owner to get it. I'm sure someone will be up in a minute to confirm or deny!