wrose New Member
- Skill Level
- Time with Product
Dec 18, 2006
- User Notes:
Burgess Optical/TMB 4mm PlanetaryPros:
Clean, Tight viewing; Good Detail and Contrast.Cons:
Internal reflection issue; Eye relief for eyeglass wearers is closeComments:
The Burgess Optical/TMB 4mm Planetary eyepiece is solidly built, has good optics, and excellent lens coatings.
The eyepiece has a twist-up eyecup as well as the standard rubber fold down eye guard which is really nice. Both work very well.
The barrel has a wide undercut safety groove that's a little bigger than most.
Along with the stated 16mm of eye relief, a drift test of the BO/TMB 4mm showed it has a 60+ degree field of view. This makes the eyepiece easy to use in a non driven scope.
The 4mm BO/TMB has great ergonomics. It is very easy to use with excellent eyepoint. For a 4mm eyepiece, it is one of the more comfortable I've used.
In a Dob the field of view is sharp to within +/- 10% of the edge, then you get a bit of coma. In the Dob the BO/TMB 4mm showed a ring of false color just at the extreme edge of the FOV but you really have to look for it.
As many have reported, this eyepiece still has a minor issue with internal reflection even with the new retaining ring. Not anywhere near as bad as the original version with the gloss black retaining ring but it's still present. If a bright object is just outside the FOV, it will result in an internal reflection. If a bright object is at the edge of the FOV it results in a more pronounced internal reflection. With both the 6mm & 9mm BO/TMB eyepieces, the internal reflections are only apparent when there is a bright object within the FOV or just at the edge of the FOV. With the 4mm BO/TMB if the Moon is within a few minutes or so of the target object, you can still have a slight internal reflection.
Personally I don't like using this eyepiece on the Moon mostly because I feel it has too much scatter on this bright of an object (filters do help).
The 4mm BO/TMB eyepiece provided a crisp, high-contrast image of both Mars and Jupiter. As with most of this series of eyepieces, the 4mm BO/TMB has a slight amount of light scatter. In comparison to a standard 4mm University Optics Ortho and 4mm Celestron Plossl, it showed a little less scatter. Contrast and detail were surprisingly good for a $100 eyepiece as is the light transmission. With good seeing and transparency the 4mm BO/TMB eyepiece showed more surface detail with clearer boundaries than the University Optics Ortho in both my 4" APO and 12.5" Dob. Although the internal scatter tends to slightly mute colors compared to more expensive eyepieces, I felt the 4mm BO/TMB gave better (more distinguishable) variations of the surface shading than the UO Ortho or Celestron Plossl. Bottom-line is this eyepiece is a slightly better Planetary eyepiece than either the Univ. Optics or Celestron Plossl.
Stellar DSOs as viewed through my APO had a crisper Airy Disc with the 4mm BO/TMB than either the 4mm Univ. Optics or 4mm Celestron Plossl. They're so close that it was difficult to call but after several nights of viewing I'd have to say the BO/TMB is a little sharper and has a hair better definition across the entire FOV. When used on nebulas and galaxies with the 4" APO and the 12.5" Dob, it was a toss-up between the BO/TMB and the Univ. Optics Ortho. Both are slightly better than the Celestron Plössl.
The BO/TMB 4mm Planetary eyepiece is very comfortable to use, it has a nice "twist-up" eyecup with a standard eye guard, it provides much better AFOV than the other 4mm I compared it to, and provides excellent viewing especially for a $100 eyepiece. If you're in the market for a 4mm I'd definitely suggest you look at this one.Sort by