Which EP for full fov solar disc?

[GUS]

Hi,

For the SV60EDS, a 60mm fl 330 f5.5, which is the lowest fl EP at which the full disc of the sun takes up the whole fov or almost? Thanks

[michael.h.f.wilkinson]

It all depends on the apparent field of view (AFOV) of the EP. Assuming a 0.5 deg solar disk, you can get the entire disk at 160x magnification with a Nagler (82 deg AFOV) or just about 2mm, but 140x is maximum magnification for a 72 deg AFOV Delos (or about 2.4mm). Using Plossl EPs you end up at 100x (3.3mm) for the 52 deg AFOV. In practice, I would go for about 60x or a 5.5mm, which will show the whole disk readily in any eyepiece. You can stretch to 120x (2.75mm) but it will not show much more detail

[GUS]

Thanks Supernova, I am just starting out at this. I learned through you that the greater the AFOV, the higher you can crank up the power and still have a full disc. I have a quark chromosphere and a 1.25" baader uv-ir cut filter on the way, as well as the mentioned scope, and I would like to binoview with the celestron BV. So for full disc I'll go with a pair of 5.5mm plossls that will also allow me to pay the rent. I would have thought that a much longer fl EP was necessary for a full disk view, like a 30mm. When I think of 5.5mm I imagine a really close-up view, let alone a 2mm, and in no case getting a full disk at those small fl's, go figure! So if you can get a full disc with a  2mm Nagler @ 82 deg AFOV, which is amazing, you can't do a close-up with it? Also you'd already be at 160x when the scope's objective supposedly only allows a useful magnification of up to 120x.. Moreover, I'm thinking if I get full disc views with 3.3mm 52° AFOV Plossls, how can I get a flare or sunspot close-up, since you can't go much smaller than 3.3mm, and at 100x you're at just about the 120x limit of the objective? Bewildered.

Which EP pair do you recommend for the sharpest zoomed-in surface detail using the BV, say at a regular and more affordable 52° AFOV? (I say 'surface' because I'm not sure if what we see is the photosphere or the chromosphere; a google search of photosphere says "The photosphere is the visible surface of the Sun that we are most familiar with." But cut-away images show that the photosphere is UNDER the chromospere, so you would think that the ‘visible surface of the sun’ would be the chromospere… Do you know?) The only decent EP I have is a celestron 8-24mm zoom; my idea is to get another one and binoview with those, ... your thoughts? Thanks again.

[Stu]

Don't forget that the standard Quark includes a x4.3 Barlow so you need to allow for this in your calculations

[Moonshane]

Bear in mind that seeing often restricts magnification in ha to <100x

[michael.h.f.wilkinson]

33 minutes ago, Stu said:

Don't forget that the standard Quark includes a x4.3 Barlow so you need to allow for this in your calculations

Important point! Add the Quark and you need a 9mm Nagler, or 24mm Plossl.

[Davey-T]

Not familiar with your BV but doubt there's much to be gained using any more than 20mm eyepieces.

Dave

[paulastro]

It never ceases to amaze me how long focal length eyepieces in a binoviewer always produce more magnification then you might think, in any telescope.

I use x2 SW 40mm Plossls in my Badder Maxbright binoviewer with my Lunt 60mm DS and it gives me a nice full disk with some nice black sky surrounding it.