9mm TMB designed planetary vs 8mm BST explorer

[WayBig]

OK, I've had both of these for 3 weeks, and it's been continuous cloud. Last night there was a break in the cloud so I thought I'd try them out for comparison, in my 10inch f4.7 dob

The seeing was atrocious, mucho turbulence, making it very difficult to achieve sharp focus.

I looked at the orion nebula and spent a long time swapping between the two trying to differentiate between the performance, spotting faint dust lanes in one, moving to the other etc....but couldn't differentiate between them. (I've heard that the contrast is slightly better in the TMB, but couldn't confirm that)

Then I looked at betelgeuse, intending to test sharpness across the field of view. Both eyepieces showed a nice orange colour, but neither could get it in sharp focus, presumably due to the poor seeing.

Finally (as my fingers were getting cold) I moved over to the big J. Detail came and went due to the seeing. I think there was a transit of one of the moons in progress as earlier in the evening, with a different eyepiece, I had been able to spot a little black dot on the planet's disk, followed by a moon emerging at one side. With the explorer, I could just make out that shadow when the conditions allowed it. With the TMB I wasn't able to make it out...I watched it for a few minutes to try to negate the effect of turbulence, waiting for it to come into view but it didn't.....whether that was due to turbulence or the eyepiece I couldn't say for sure. I think I could pick out a bit more detail with the BST than the planetary in the moments where seeing improved.

Ergonomically, the TMB has a twist up and a fold down rubber eye guard. The fold down one kept coming off in my cold hands which was annoying. Superglue (other adhesives are available!) may fix that if you like modding your eyepieces, I can't comment as to whether this is a one-off problem.

So that's it, under very poor conditions, there's very little to choose between the two...but you probably knew that anyway. For the record I'm going to keep the BST because I prefer the build of it.

[sixela]

Which source did you have for the TMB designed planetary? Black barrel, or silver barrel?

[CGolder]

Nice review, I had a very similar experience with the TMB's and decided to keep the BST's. the big advantage to me is that the BST's have a larger range available and go up to 25mm. The par focal across the range comes in handy too, especially if you hard a big floppy mak or sct mirror.

[WayBig]

My TMB has a silver barrel. It's from Skies the limit.

[sixela]

Still one of the Shuzou Synta's, then. FWIW, the best of these silver barrel ones are (in my experience) the Burgess Optical ones and the TS HR Planetary ones (there are other eyepieces with the same design, but you don't know if the quality of the polish, multicoatings and the internal baffling is the same).

I do prefer the build quality of the new TMB Planetary II ones (no longer from Synta), and rumours have it that some of the glare issues that still plagued some focal lengths have been resolved in those; they're also all branded "TMB" so you know they have uniform specifications.

[Steve]

Still one of the Shuzou Synta's, then.

Are you sure Synta make those TMB branded Planetary eyepieces?

[Ags]

To be fair, the seeing must have been pretty bad to make the shadow transit largely invisible in both EPs. It would be interesting if you gave them both a try under better conditions.

[sixela]

Silver barrels are either Burgess/TMB branded, or branded differently (only people privvy to the contract between Bill Burgess and Shuzou Synta knows the details, but Shuzou Synta started selling them through other channels and that prompted Burgess to seek another manufacturer). These are made by Shuzou Synta, yes.

The new "TMB Planetary II" is TMB-branded (with TMB Optical logo) and is not made by Shuzou Synta. Burgess sold very similar ones (black tapered barrel, different details on the moveable eyeguard, slightly different eye relief, different internal baffling) as the "new generation 6mm" but no other focal lengths appeared. Again, only someone privvy to the discussions between Bill Burgess and the estate of Thomas M. Back knows the details of what happened there.

[Ags]

WayBig, have you had another chance to compare these EPs under better conditions?

[WayBig]

No, I've kept the explorer and taken the TMB back, because the rubber eye guard coming off was annoying.

I took the TMB back to Alan and told him I couldn't tell the difference....he said most people say that!