Field view help needed...

Discostuy

Sorry in advance for the complete nooby question, I'm just not getting this at all:

I downloaded the StarMap app for my iphone and there is an option which allows you to enter in your telescope and eyepiece information so that when you search for something you are looking for (e.g Orion, Andromeda etc), it also shows you what it will roughly look like through your own scope.

It first asks for the scope details:
Focal Length = 1000mm
Aperture = 90mm

and then asks for the eyepiece info:
Focal Length = 1x10mm and 1x20mm
Field = ???

Its the Field part that im lost on...this is entered in degrees.
Would anyone be able to help on this?. I've googled Field of View but have just been going around in circles with equations and explanations

Popoutman

Post up the eyepiece details, and there's a good chance that the FOV would be known.

In general the cheapie eyepieces that are marked as Hxx or ARxx, or unmarked other than the focal length are about 40 degrees FOV.
Plossl eyepieces range from 45 to 58 degrees, with the expensive ones generally being larger in FOV. TeleVue and MEade series 4000 plossls are 52 degrees FOV.

Meade SWA and Televue panoptics are about 68 degrees.

Meade UWA and Televue Naglers are 82 degrees.

My guess is that the eyepieces that you have would be between 40 and 45 degrees FOV.

Discostuy

Thanks for the reply,

The eye pieces are just the generic ones that came with the scope...Celestron 10mm and 20mm...it doesn't give any other details.

The default setting on the app was 50degrees. So you reckon between 40 and 50 would be a safe bet?


Just one other thing:
The scope is a Celestron 90eq...its a beginner scope, but its serving me well.

For a scope like this, would you recommend buying better quality eye pieces? Would it make a much noticeble difference?

Cheers again.

Popoutman

If you think that you may end up more interested in the hobby in the future and you may be investing in another scope at some point in the future, then it may be a good idea to get a set if intermediate eyepieces.
I found that improved eyepieces make a really big difference to the view through a scope. The cheaper eyepieces, while being generally sufficient, can restrict views or add abberations that make the view less than it could be.
I bought a basic set of Meade series 4000 Plossls for my Lidl ETX70 and it made a big difference. Then once I resurrected an old reflector I had I went and spent money on the Meade SWA eyepieces and they made a huge difference. It's the difference between looking through a toiletpaper inner tube and looking through a ship porthole.
Having said that I've spent more on the eyepieces than I have spent on the telescope!

Here are some ideas of what can be gotten and the kind of price range:
http://cgi.ebay.ie/NEW-MEADE-32mm-Series-4000-SUPER-PLOSSL-Eyepiece-Lens-/350404272221?pt=UK_Telescopes&hash=item5195b8e05d for about €35 or so.

http://cgi.ebay.ie/Meade-Super-Wide-Angle-Okular-16mm-/160465209114?pt=Optik_Zubeh%C3%B6r&hash=item255c78c71a for €75 ex delivery.

Here's a reasonablly-priced set of Plossls + 2x barlow + filters:
http://www.firstlightoptics.com/proddetail.php?prod=revelationepset


Getting better eyepieces is usually the easiest way to improve the view through a lower cost telescope, and if/when you ever upgrade to a larger or better scope, you can bring those eyepieces with you to use on the new scope.

Here's a reasonably good guide to telescope eyepieces:
http://stargazerslounge.com/archive/index.php/t-63184.html

Discostuy

Thanks for all the info. I've had the scope a good while now, but am still at a fairly basic level of gazing.
In saying that, i'm getting more and more into it so i can see this being something i will get really into.

I'll have a look over the links you supplied now. I think i might bite the bullet and invest in some new lenses.

Cheers again.