Quark H.alpha EP - scope, eyepieces and FOV etc

[Mark at Beaufort]

The reports by a few members show that this is a quality product. Although I may attempt some solar imaging my main interest would be visual.

The information on the Quark states that the best performance would be with a refractor between F4 and F8. To obtain a Full Disc requires a focal length of 450mm or below. The Quark has a built in 4.2x barlow.

My Astro Tech APO is 102mm and 709mm FL which with the Quark would become 2978mm and F29.2.

I have looked at several EPs to gauge the possible FOV and using the TeleVue chart (attached) shows that with either a 24mm Panoptic or the 32mm Plossl I should be able to 'just about' get a Full Disc. The Angular diameter of the Sun varies from 31.6 to 32.7.

I suppose you also could use a 0.5x focal reducer attached to the EP.

I would welcome opinions on my calculations or general views on my proposal.

[michael.h.f.wilkinson]

Full disc also depends on the effective blocking filter diameter. I have heard that the full disk is only visible in scopes with focal lengths up to 450mm, although the TV76 apparently can just see it (480mm F/L), and therefore I hope my 80mm F/6 will also work

[Mark at Beaufort]

Thanks Michael never thought about the possible restriction caused by the blocking filter.

[Peter Drew]

That is why the Quark has a larger than average blocking filter as standard.