Second Time Around

Hi, my wife Peggy and I have just arrived at the nearby Bungalow Farm B&B and will shortly be having a meal at the King's Head in Cubbington. We hope to meet some of you tomorrow. Steve

As you say, probably not for a fast Dob. However I'm very pleased with my Baader Hyperion Zoom. The only downside is the narrow field of view at low powers, which of course is what this new wide angle eyepiece is for.

I mentioned earlier in this topic about https://www.bbastrodesigns.com/diagonal.htm as a way to calculate diagonal size. What I should have added that inputting the parameters into the calculator is easy except perhaps for one - the distance from the centre of the secondary to the focal plane. Apologies if I'm teaching Grandma to suck eggs but the focal plane is where the image from the primary mirror is in focus. To determine where this point is take the eyepiece out and rack the focusser in as far as it will go. Then point the scope at the moon. Take a piece of white card and gradually move it away from the focusser until you can see the moon in focus. Then measure the distance the card is from the tube of the scope. Add that to half the diameter of the tube and that gives you the "diagonal to focal plane distance" to enter into the online calculator. It sounds more difficult than it is. If I can do it anyone can!

Thanks, Louis and Paz. I'm somewhat disabled so am limited to short observing sessions thus I imagine comfort is going to play a big part. It also means I'm limited to this particular scope for my light bucket. I found that with the Orion Optics UK Dobs I can manage a 10 inch, but am limited to an 8 inch with other makes, due to both weight and bulk. I'd therefore like to get the best quality views I can, and so cost is well down the list of considerations. Due to inexperience I don't yet know what I'm looking for - eyepieces have certainly come a long way since Ramsdens and Kellners my first time round! I suspect that I'll end up with the 22mm Nagler, but I'd like to try lots of other candidates. Thanks again for the input and please keep comments coming - I've got a lot to learn!

For easy calculation of diagonal size plus lots of useful info on the subject I use this: https://www.bbastrodesigns.com/diagonal.htm

Many thanks for the advice and all the trouble you've taken, Louis! Luckily I don't have presbyopia, just myopia. I've found the most practical way for me to observe is without my glasses as I can then also focus on a tablet showing Sky Safari as well. I keep my glasses on a cord round my neck and put them on for a naked eye view. The 20mm Pentax has now arrived - I just need a clear night to try it. Thanks for the heads up on the AstroTech and the APM; I'll certainly look into these. Does anyone any experience with these plus a Dioptrx? Has anyone tried a 21mm Ethos with a Dioptrx? Given that the Dioptrx reduces the effective eye relief will there be enough? Any other suggestions gratefully received.

Hi, apart from buying from the classifieds this is my first post here. I've recently returned to astronomy after several decades and, amongst other things, just bought a used 10 inch tenth wave f/4.8 OOUK Dob and an Explore Scientific Coma corrector. I've measured my dark-adapted pupil size at 4.5mm, so I'm after trying various wide field 20 to 22mm eyepieces, but as I have astigmatism will be using a Dioptrx. I've got a 20mm Pentax XW on the way, and have also shortlisted a 22mm Nagler and 22mm Vixen LVW to try if I can find them secondhand. Any comments on the above 3 would be appreciated. Are there any other eyepieces I should consider in this focal length that'll take a Dioptrx? Many thanks.