Tele Vue Radian 3mm

[MortonH]

Looking to fill a magnification gap for planetary observing.

3mm is an uncommon focal length these days so looking for one of these older models.

Note that I already have a 3.5mm equivalent (with a Powermate) and 2.5mm would give too much magnification.

I'm specifically looking for 3mm to pull out the last bit of detail on good nights.

Cheers.

[Kunama]

AgenaAstro have 2 in stock $200 USD @

[MortonH]

Looks like a bargain until you add shipping and exchange rate. Then we're up to A$250.

[MortonH]

Came across the TMB 3.2mm on the web, so added it as an option.

[PlanetMan]

Give some thought to the Takahashi Hi LE eps as well. Although I don't have them I have looked through them and they are excellent albeit they have a modest fov

[MortonH]

I keep looking at them! But narrow fov and short eye relief put me off.

[Profiler]

Hi Morton

You are probably kicking yourself a little over this circumstance (as you had this EP) but based upon your refined criteria the best choice would be one of the Nagler Zooms which have about 10-12mm ER and can reach the optimal magnification. Indeed, give some particular thought to the 2-4 Zoom as at these high powers very fine adjustments are critical and thus the 2-4 Zoom is more gradual for such fine adjustments than the 3-6. The Radian is a nice EP but its key strength is the 20mm of ER - optically things like the Nagler Zooms or Pentax EPs are better

[MortonH]

Lots of good points. Thanks guys.

It may well be that the 219x I'll get with the 2.5x Powermate and 8.8mm Explore eyepiece is enough, so I'm not overly desperate about a 3mm eyepiece. A 7.5mm might work well with the Powermate to give 3mm equivalent, but there aren't many options, unless there are some older models I've forgotten?

The main criteria are a moderately wide field of view and reasonable eye relief.

Edit: on reflection a 2-4mm zoom might fit the bill, so might try a wanted ad for that too!

[MortonH]

Now looking specifically for a 3mm Radian. Please PM me if you have one you might sell.

Thanks.

[Profiler]

Hi Morton

I recall seeing '2' (if memory serves me correctly) on Astromart and Agena/Anacortes has them new (I think a few others). I am not certain of my information but as I understand it Televue has actually started remaking this specific fl (look at their website) as it is very suited to many of their refractors.

However, the 20mm ER is the main feature - if you are after 3mm fl but don't need the ER then the Nagler Zooms easily beat it optically