What is Reddit's opinion of 1.25" 2.5mm/3.2mm/4mm/5mm/6mm/7mm/8mm/9mm 58 Degree TMB Planetary Eyepiece(Come with Original Box) (TMB3.2MM)?

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> Is this brand of eyepiece obscure or how come I can't find anything about them elsewhere online?

These are a generic white label eyepiece that anyone can put their brand on, or just sell as-is. They are often branded "TMB Planetary" because they are a knock-off of the original Thomas M Beck design. Evidently he did not have the design patented or lost control of it.

You can find them all over the place:

Here they are with their "false" TMB brand on Amazon: https://www.amazon.com/Degree-Planetary-Eyepiece-Original-TMB3-2MM/dp/B07N81PPPY/

Here's an "Alstar" branded version: https://www.amazon.com/Alstar-58-Degree-Planetary-Eyepiece-Telescope/dp/B0746CBLBG/

Agena Astro sells them as "BST UWA Planetary": https://agenaastro.com/eyepieces/1-25-eyepieces/shopby/bst_uwa_planetary.html

Here's the same generic TMB set on AliExpress: https://www.aliexpress.us/item/2251832604004387.html

They're basically all over the place. Quality is so-so. Users typically report that they are sharp on-axis but some have contrast issues. You can usually find reviews here and there by searching for "TMB planetary clone review" or "58 degree planetary eyepiece review" on CloudyNights or Stargazer's Lounge.

These "aspheric" EPs are not recommended. See this comment.

The 66deg goldlines that u/Gusto88 recommended are what you'd want to look for. If you're after a 4mm EP, check out the TMB Planetary clones.

Shorter focal length eyepieces produce higher magnification. You calculate magnification by dividing the telescope's focal length in millimeters, by the eyepiece's focal length in millimeters.

The telescope has a 750mm focal length, so the eyepieces you mentioned would be this:

1. 750 / 25 = 30x magnification
2. 750 / 10 = 75x magnification
3. 750 / 6 = 125x magnification
4. 750 / 3.5 = 214x magnification

A few thoughts / pointers:

1. For me, planetary magnification starts at 120x. So you would want anywhere from a 5mm to 6mm eyepiece as your starting planetary magnification range. 5mm = 150x which is a good place to be for planetary mags in a 6" scope. It's a good balance of view brightness and magnification. On a steady night, you will see a LOT of detail on Jupiter at 150x (shadow transits, the GRS, texture in the cloud bands). Mars will easily show you the polar cap and some of the darker markings. The Cassini division in Saturn's rings is obvious, as are its different cloud bands, and 4-5 moons should be visible.

2. I would avoid any Plossl or Orthoscopic eyepiece with focal lengths as short as 6mm (and shorter). The eye relief is so short you have to jam your eye into them to see through them. I recommend a longer eye relief eyepiece from one of these lines:

* Astro-Tech Paradigm. The 3.2mm and 5mm would be good options. Great quality, not too expensive.

* The 58 degree line. These are common and can be found everywhere. Decent eyepieces that are a lot easier to look through than Plossls. The 3.2mm and 5mm from this line would also be good choices for you.

1. Mars is very small right now. It's smaller than Saturn's disk, and will be about the size of Saturn's disk when it's at opposition this fall. You really need relatively high power to see any details on it, and even then the surface features are quite subtle compared to Jupiter's. You'll have best results in early October when it will be closest to Earth.

2. Note that as you increase magnification, the view gets dimmer. Sometimes the dimmer view can help, other times its detrimental if the object is too dim.

3. Wait for planets to get highest in the sky before observing them. Viewing them when they're close to the horizon means you're looking through more atmosphere, which will distort them more.

4. Make sure the telescope is well collimated and fully thermally acclimated to ambient temperatures for best performance.