Eyepiece advice for an 8 inch Dob.

[Spile]

I’ve a 42mm GSO which works fine for large open clusters like the Pleiades although even that wasn’t wide enough for the coat hanger which was better in my finder.

[Neutrinosoup]

23 hours ago, Ratlet said:

I think if you want best bang for buck with eyepieces you can't do better than bst starguiders.  £55 a pop, 60° fov and a nice eyecup setup.  The 8mm and 12mm work really well on my 10" Stellalyra.  Not tried the 18mm, but might work well.  Does it all for less than the baader and if she one she only looses that FL rather than them all.

Those 3 eyepieces will frame a lot of DSO well and the 8mm will handle planetary most nights.

Personally I'd avoid the svbony zoom on a dob.  The fov gets down to 40° which for me is a nip too tight.

What dob did you get?  The lower power eyepieces that come with most are usually okay and recommendations is usually to replace it last. 

The Starsense (celestron) 8 inch Dob. Pretty light and fits under the stairs. The eyepiece that came with it is a basic 25mm Celestron eyepiece. I’ve got a TV Panoptic 24mm she can use when I’m there. I suppose one advantage of getting a Zoom eyepiece like the Baader/Sbvony/Pentax?? Is that she can use it if alone BUT also I can use it with my smallest refractor and tripod when we are on the road.

[Don Pensack]

On 24/12/2023 at 06:19, John said:

A hyper-wide eyepiece such as the APM 20mm 100 will show very nearly as large a true field as the 30mm UFF does but with 50% more magnification. This can be very useful under skies with some light pollution:

 

That calculator uses the inaccurate TF=AF/M formula to compute true fields.

The actual difference is a 36.3mm field stop versus a 34.8mm field stop, so the true field of the 30mm UFF is 4.3% wider than the 20mm, a bit more than shown in the illustration.

With a 1200mm focal length, the true fields should be ~1.73° versus ~1.66°, so your point is valid--the 4.2' difference isn't significant.

For the Pleiades, though, the lower magnification makes the cluster appear more "cluster-like".

For the Pleiades, the view in an 80mm refractor at 15-20x is really the best way to view the Pleiades.  It looks a lot more impressive with 2.5° and more in true field.

M44, though, would be very nice in either eyepiece, though it, too, looks better at a low power.

[John]

5 hours ago, Don Pensack said:

.....With a 1200mm focal length, the true fields should be ~1.73° versus ~1.66°, so your point is valid--the 4.2' difference isn't significant....

 

Phew !!! - I was worried there for a bit 🙄

Seasons greetings Don 🙂