TMB 2.5 mm Planetary II is the shortest eyepiece offered by TMB Optical, a company created by the renowned apochromatic refractor designer, Tomasz Back.
2.5mm Eyepiece TMB Planetary II is designed to achieve maximum contrast, detail and resolution when observing bright objects such as the Moon and planets, both on the optical axis and at the edges of the field of view. This eyepiece is characterized by a high transmission of light and minimal reflections. This allows you to achieve very high magnification with high quality mapping of objects in the reflex focuses , reflectors and catadioptical systems with good viewing conditions at the astonishing low price of the eyepiece.
This eyepiece is not recommended for f / 10 catadioptrophic telescopes, because with 1/4 millimeter exit and a dark image, the effects will not be unsatisfactory. We recommend this eyepiece for bright (f / 4 - f / 5) lenses, both spotlights and refractors.
For example, for the refractor 6 "f / 5 (eg Bresser R-152/760) we get a lunar - planetary magnification equal to 304x, and thus the maximum useful magnification for this telescope, similarly in popular Newtons 12" f / 5 (GSO Dobson 12 " , Sky-Watcher Dob 12), we will reach the maximum useful magnification, i.e. 610x, which is obviously used in good conditions of atmospheric stability and after proper cooling of the telescope's optics.
Removal of eye relief of 12 mm is surprisingly good for the eyepiece with such a short focal length. Vignetting occurs only in people who need to wear optical glasses during observations and it is small. Also, this is not a major disadvantage, because the TMB Planetary II series glasses are dedicated to observing planets, double stars, etc. objects that are compact and stay in the middle of the field of view, where the human eye has the maximum sharpness of the image.
For telescope owners on Dobson assembly and other telescopes without drives, very small color fission and low level of other aberrations allows observation of planets drifting through the whole field of view (own 58 ° field) of the eyepiece, thus maximizing the observation time of the object between further telescope shifts.
Although the eyepiece is optimized for observing the subtle details of the Moon and planets, the eyepiece characteristics allow equally efficient use of the eyepiece for separating compact double systems or observing globular clusters.
| • Focal length: || 2.5 mm |
| • Field of view: || 58 ° |
| • Distance of the exit pupil: || 12 mm |
| • Diameter of binding: || 1.25 inches |
| • Anti-reflective layers: || FMC |
| • 6-element eyepiece |
| • Weight: || 142 g |
Logo variability: depending on the delivery from the factory, the eyepiece is either without a logotype or with the StarGuider logo