Skywatcher 200P Dob standard EPs Apparent FOV

[darthvader]

Does anyone know what the apparent field of view is for the standard 10mm and 25mm skywatcher eyepieces supplied with the Skywatcher Dobsonian 200P Skyliner?

I've compiling a handy little laminated reference card for my scope along the following lines:

EP / True FOV / Magnification

6mm SPL 16.2' (x200)

10mm SW ??? (x120)

11mm ES 45' (x109)

16m ES 55' (x75)

24mm ES 1^o 22' (x50)

25mm SW ??? (x48)

RACI 5.6^o (x9)

I need the apparent field of view in order to calculate the true field of view from (apparent view / magnification = true FOV)

thanks in anticipation

[rockystar]

I think they are 50. This seems right in practice in that my 18mm 68 degree gives only a slightly small True FOV and this seems to be about the difference from what I can see

[darthvader]

excellent, thanks - that sounds about right to me, that makes my table, any other useful info do you think i could include without making it to cumbersome?

EP /  Mag / Barlow / True FOV

6mm x200 x400 16.2'

10mm x120 x240 25'

11mm x109 x218 45'

16mm x75 x150 55'

24mm x50 x100 1°22'

25mm x48 x96 1°02'

RACI 9x50 x9  N/A 5.6°

[rockystar]

I've got a similar spreadsheet

I also have eye relief and exit pupil

[darthvader]

funny how these things get done when it's cloudy .... 

[John]

Remember that the TFoV will reduce accordingly when the eyepiece is barlowed.

Exit pupil is worth knowing.

Data like this helps a lot in making decisions on new eyepiece purchases - without it you can invest in something that delivers no more than you already have

[darthvader]

Remember that the TFoV will reduce accordingly when the eyepiece is barlowed.

good point

[Moonshane]

I use this. fill in the yellow bits

eyepieces and scopes.xls

[rockystar]

So exit pupil is focal length of eyepiece divided by focal ratio of scope; if I Barlow it, does that calc then become fl/barlow/fr?

[spike95609]

Different eyepieces are sometimes supplied with the Skywatchers I believe. Have you got the Super MAs like me? If so take a look at http://www.rothervalleyoptics.co.uk/skywatcher-super-ma-eyepieces-125.html. The 25mm is 50° and the 10mm 52°.