كما أنني مبتدئ في علم الفلك أستخدم تلسكوب Zhumell Z130 مع العينات المضمنة 25 مم و10 مم، فأنا أبحث عن تحسين تجربتي المرصودة خلال رحلتي السنوية الشتوية إلى جمهورية الدومينيكان. وبما أنني أملك فقط حوالي 30 ليلة مراقبة سنويًا بسبب سكني في مدينة نيويورك، فأنا أريد الاحتفاظ بتركيبتي بسيطة بينما أوسع قدراتها.
أفكر في إضافتين محددتين: عينه Celestron Omni 40 مم لرؤية أوسع بتكبير منخفض، وعُدسة Celestron Omni 2x Barlow لزيادة تكبير العينات الحالية بشكل فعال. سيوفر هذا الجمع نطاقًا أوسع من التكبير مع الحفاظ على البساطة. أهدافي الأساسية هي تحقيق تحسين ملحوظ في جودة الصورة وتوسيع خيارات الرؤية دون جعل النظام معقدًا للغاية. أتساءل ما إذا كان هذا النهج يمثل الخطوة التالية المنطقية لمستواي وتلسكوبك، أم أن الخيارات البديلة مثل عينه متغيرة التكبير أو طول بؤري مختلف قد تكون أكثر فائدة قبل دمج عدسة Barlow.
أتفهم رغبتك في تبسيط الإعداد مع توسيع الخيارات، خاصة مع ليالي الرصد المحدودة في نيويورك. شخصياً، عندما بدأت باستخدام تلسكوبي الأول، أضفت عدسة بارلو 2x وكان الفرق في مشاهدة حلقات زحل مذهلاً حقاً. هل جربت النظر في عدسات عينية بزاوية رؤية أوسع لاستغلال سماء الدومينيكان الصافية؟
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.