TMB Super Monocentric 4mm

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Brand and Model:TMB Super Monocentric 4mm
Price ($USD):$200.00
Type:Monocentric
Focal Length:4mm mm
Barrel Size:1.25
Apparent FOV:30.0 degrees
Field Stop Dia.:0.0 mm
Eye Relief:3 mm
Elements:3
Weight (lbs):
Description:This 1.25" Super Monocentric TMB eyepiece sets new standards in image resolution and contrast that other eyepiece designs simply can't equal. It works particularly well with short to medium focal length refractors to provide unequalled lunar, planetary, and binary star views. It will also resolve compact globular clusters in exquisite detail, if the field of your eyepiece/telescope combination is wide enough to hold them. With a relatively narrow 30° field of view, it is not designed to encompass open clusters or large scale faint objects (even on a 540mm focal length instrument its field of view is less than one-quarter of a degree across). However, its unsurpassed 99% light transmission makes it surprisingly good for picking out faint and compact planetary nebulas against a stellar background. That said, the buyer should still recognize that this eyepiece is optimized for the highest possible contrast and highest definition lunar and planetary images, not deep space observing. It will reward the serious lunar/planetary observer with the best images that his or her telescope and skies are capable of producing. The highest quality and best maintained optics will benefit most from this eyepiece.

Vote Highlights Vote
TMB Super Monocentric 4mm
Eye relief is tight, and you'll need good seeing conditions to use this one, but if you want to get the most out of viewing a planet, and the sky is cooperating, this eyepiece is the one to use.

Overall Rating: 10
Optics:10 Value:10
Weight: 5 (Veritable Vote)
Date:
By:
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=484443

TMB Super Monocentric 4mm
The TMB Monocentric eyepieces (and the 4mm I am reporting on here) are simply the best planetary eyepieces I have ever used.

Positives:

In direct comparison with a Zeiss Abbe Orthoscopic eyepiece of approximately the same power, the TMB was at least the equal of this legendary "world's best" planetary eyepiece at a fraction of the cost. The TMB is critically sharp across the field, and the optical design coupled with the best possible polish and coatings yield the darkest backgrounds I have ever seen in an eyepiece.

In direct comparison with a Clave Plossol (made in 1972) and a Televue Radian, the TMB was sharper, contrastier and there was less scatter (thus a darker background) than the Clave; and sharper, contrastier and DRAMATICALLY darker in background compared to the Radian. (By the way, I still think those comparison eyepieces are fine optics and excellent for wider field applications).

Cautions:

The Monocentrics have a relatively narrow field, and the 4mm has short eye-relief. For their intended purpose, neither of these factors bothered me. When viewing the planets (these ARE planetary eyepieces) I don't use the edges of the field anyway, so I simply position my eye at a comfortable distance from the eyepiece. The background is so dark it is not troubling to me that the field is narrow; I can hardly notice WHERE the field boundary is. I find the same thing when I want to study detail on the moon. I don't need the extra field. If I want to enjoy the grandeur of a large swath of the moon I don't use a 4mm eyepiece anyway. (I would mention though, in superb seeing it is almost intoxicating to turn the drive off and watch the moon speed by in the field of the 4mm. It is almost what I would imagine it would be like to be orbiting the moon!).

I would also mention that the eye-brain combination's ability to extract detail from a visual image is a LEARNED skill. My personal experience showing others views through the TMB Monocentrics is that experienced viewers say WOW! Inexperienced viewers often do not "see" the sharper detail and higher contrast.

Cons:

I seen NO downside to this eyepiece optically or mechanically when it is used for its intended purpose.

Cosmetically I found it difficult to read the focal length (on a band around the top of the barrel) at night.

Overall impression:

I know of no better planetary eyepiece. Period. Thus my optical rating of 10. When you look at the cost of other premium eyepieces (Televue, Pentax, Takahashi etc.) or the used price of a Zeiss Monocentric or Abbe Orthoscopic, I believe the TMB's are a true bargain. Thus my value rating of 10.

Test note:

I have been an amateur astronomer for over 40 years. I used my Takahashi FS-152 as well as a friend's superb Zambuto reflector for my detailed tests of the TMB's. Test objects included the planets, the moon and double stars; testing was performed at dark sky sites in the mountains of Oregon and Washington in the USA and in the US Virgin Islands on nights of superb seeing. The TMB and Clave eyepieces I tested are mine, the Zeiss and Radian eyepieces were borrowed from friends. And please note that these are my PERSONAL IMPRESSIONS. As a retired physicist, I am well aware my testing was not a controlled scientific experiment. But I hope others will find my observations of value.

Richard Chalfan

Overall Rating: 10
Optics:10 Value:10
Weight: 3 (Unreliable Vote)
Date:
By:
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=405813

TMB Super Monocentric 4mm
Great planetary eyepiece with excellent contrast. Eye relief and FOV is minimal, but not important to me when viewing planets at high magnification. Sharp to the edge-providing bright images.

Overall Rating: 10
Optics:10 Value:9
Weight: 3 (Unreliable Vote)
Date:
By:
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=330408

TMB Super Monocentric 4mm
Hi folks,

sorry, this eyepiece is only for masochists. The optics are perfect, no question but maybe useless.
The eyerelief is 3mm and thats the problem (a real problem), intensyfied by the shape of the eyepiece upper end.
Perhaps when they copied the UO Orthos the problem could be a little bit smaller but don't dissapear.
In a world, a TMB 4mm is a 5 for me, the UO 4mm is a 4.5 , not more. I want to "see" something through my scopes. I use Pentax XL 5.2; 10.5; 21 and 40mm. For Quick looking a Leica Zoom 7.3-22mm. Now I buyed a TeleVue Nagler Zoom 3-6mm for the
maximum Magnification and was impressed by it's views. The eyerelief is a little lower then the (declared) 10mm but good usable.

Best regards and try before buy,
Lamont

Overall Rating: 5
Optics:10 Value:5
Weight: 1 (Unreliable Vote)
Date:
By:
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=327499

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