As a beginner astronomer using a Zhumell Z130 telescope with the included 25 mm and 10 mm eyepieces, I’m looking to enhance my viewing experience during my annual winter trip to the Dominican Republic. Given that I only have about 30 observing nights per year due to living in New York City, I want to keep my setup straightforward while expanding its capabilities.
I’m considering two specific additions: a Celestron Omni 40 mm eyepiece for wider, low-magnification views, and a Celestron Omni 2x Barlow lens to effectively double the magnification of my existing eyepieces. This combination would provide a broader range of magnifications while maintaining simplicity. My primary goals are achieving a noticeable improvement in image quality and expanding my viewing options without making the system overly complex. I’m curious whether this approach represents the most logical next step for my skill level and telescope, or if alternative options like a zoom eyepiece or different focal lengths might be more beneficial before incorporating a Barlow lens.
As someone who also started with a Z130, I think your plan for the 40mm and a 2x Barlow is a solid, simple upgrade path. I added a similar wide-field eyepiece for those big star clusters, and it made a huge difference in framing objects like the Pleiades. Have you considered the exit pupil you’ll get with that 40mm on your f/5 scope, especially under those dark Dominican skies?
Thanks for sharing your experience with the Z130—framing the Pleiades with a wide-field eyepiece sounds fantastic. The 40mm will indeed give a large 8mm exit pupil, which is great for those dark skies as it gathers more light for rich, immersive views, though it might slightly dim the background sky. If you’re curious to experiment further, you could try using an app like Stellarium to simulate fields of view with different eyepieces before your trip. I’d love to hear how your own setup performs on your next observing night.
As a fellow city-dweller with limited dark sky time, I completely relate to wanting a simple yet effective upgrade path. Your plan for the 40mm eyepiece and a 2x Barlow is spot-on for the Z130; that Omni 40mm will give you a wonderfully wide, bright view of star clusters. I made a similar move with my own tabletop Dob, and the jump in comfort and context was immediate—it really makes finding targets easier before you zoom in. Have you decided on a specific brand for the Barlow, or are you sticking with the Celestron Omni to match?
Thanks for sharing your experience—it’s great to hear that adding a wide-field eyepiece made such a difference in comfort and target-finding with your tabletop Dob. I’m planning to stick with the Celestron Omni 2x Barlow for consistency, as its fully multi-coated optics should pair well with the eyepiece and maintain decent image quality. If you have any favorite targets for wide-field viewing from a city, I’d love to hear your suggestions for my upcoming trip.
Thank you. The link wasn’t working earlier, but I appreciate your help.
Welcome! I can’t vouch for that specific AliExpress store, but I’ve never had issues with any of them. Just find the best deal and you’ll save money if you don’t mind the two-week shipping wait.
The small black piece on the bottom is the Barlow lens. On the Omni, it unscrews and can be threaded into eyepieces like the one you linked, giving you about 1.5x magnification.
These eyepieces are a reasonable choice. The 43° AFOV model will show good detail in larger DSOs. However, Barlows tend to make images blurrier and objects will drift out of view faster without a GoTo or equatorial mount.
Check out the astronomy.tools field of view calculator. Enter your Z130’s specs if it’s not listed, then compare your current eyepieces with the ones you’re considering—including with a Barlow lens. Choose targets you’ve observed before, like the Moon, Saturn, Jupiter, or the Pleiades, to see how the field of view changes. Aim for eyepieces that provide noticeably different magnifications rather than ones too similar to what you already have.
I would also recommend the 32mm Omni over the 40mm.
Your telescope is an F/5, so you should consider the exit pupil of your eyepieces. The exit pupil in millimeters equals the eyepiece focal length divided by the focal ratio of your scope.
For young, dark-adapted eyes, the maximum pupil size is about 7mm, which decreases with age. Calculating backwards: 7mm multiplied by 5 gives a 35mm eyepiece maximum. Beyond that, you may start to see the secondary shadow and other issues.
I recommend the 32mm Omni eyepiece, which provides the maximum field of view in a 1.25″ format. A 40mm eyepiece can also achieve this, but objects will appear smaller and possibly brighter, with the secondary shadow potentially visible.
I also used to suggest the Omni Barlow. The Omni products are decent quality and inexpensive, especially when ordered directly from China, so minor bumps or smudges aren’t a major concern.
He likely wants to observe deep-sky objects, since he’s looking for a wider field of view.
For observing DSOs, which vary in size, I recommend the 32mm Omni for its wide field of view. A 24mm Panoptic would offer the same true field but costs around $400.
A Barlow is also a practical addition unless you’re purchasing shorter focal length eyepieces, as it’s affordable and versatile.
I agree. I was considering eyepieces that offer a wider field of view, which is helpful for observing deep-sky objects like the Christmas Tree Cluster and Double Cluster.
Thank you for the detailed response. I’ll go with the 32mm eyepiece.
Should I stick with the 2x Barlow, or do you have a specific recommendation?
Welcome! I think that Barlow is a good choice. I own both the Omni 32mm and Omni Barlow, and I’ve given them as gifts too. I purchased all of mine from AliExpress.
Thank you for your input.
Is this the correct Celestron Omni 2x Barlow for the Z130?
A 40mm focal length is too long for your setup. It creates an 8mm exit pupil, which likely exceeds your eye’s maximum dilation of about 7mm. This means some of the light collected by the telescope is wasted because it doesn’t reach your eye.
If your pupil dilates to only 7mm, an 8mm exit pupil effectively reduces your Z130’s aperture to 113mm (calculated as 130 * 7/8).
A 32mm Plossl shows the same true field of view as a 40mm Plossl because they share the same field stop size. However, the 32mm provides higher magnification, a wider apparent field of view, and avoids the large exit pupil issue. A 40mm Plossl is mainly suitable for telescopes with longer focal ratios, such as F/8 or greater.
I also have the Z130 and agree the 32mm Plössl is a good choice. I tried a 38mm and it wasn’t an improvement. I use two SVBony zooms: the 3-8mm for planets and a 7.2-21.6mm that often ends up being the only eyepiece I use in a session.