39 replies to this topic

[Mike B]

 Antares 1.5x

https://www.scopestuff.com/ss_ebt2.htm

 

Masuyama 1.5x

https://astrohutech....-barlow-lenses/

 

Siebert Optics manufactures several barlows/telecentrics 1.5x

https://www.sieberto...cs-barlows.html

Perfect! I’m glad someone posted the ScopeStuff link! I had that Antares Twist-Lockie 1.5x Barlow, & found it quite good optically, plus the Twist-Lock feature is VERY nice! I still have its 3x brother… I used the Antares 1.5x Barlow until I got ahold of a Masuyama 1.5x, then sold off the Antares Barlow- but can still recommend it 

[Andrea Salati]

Tele Vue 1.25" eyepieces, by and large, have their focal planes 0.25" below the shoulder of the eyepiece.

Tele Vue Barlows are designed to be their stated magnifications with Tele Vue 1.25" eyepieces.

So, if you use an eyepiece with a focal plane at the shoulder, that focal plane will be 0.25" farther from the lens of the Barlow and thus yield a slightly higher power, like 2.1x.

 

If you'd like an easy way to tell the exact magnification factor of a Barlow with a given eyepiece, merely time the passage of a star on the celestial equator across the field of the eyepiece (do it 2 or 3 times and take the largest timing).

Do it again with the Barlow in place.

Time without Barlow ÷ Time with Barlow = magnification factor for that eyepiece.

That is what I did when I came up with that estimate, I used a Pentax XW 10 (you actually recommended that as it has the focal plane right at the shoulder).

[areyoukiddingme]

Tak 1.6 is excellent, though it's not difficult for more power to show up.

 

It works out at around 1.62 when I've used it with my Ethos, and comes out at 1.8x when I've used it on my Leica with the APM 2"/1.25" adapter.

[Lostinspace12]

Does anyone know of a screw-in option that can also take a filter on the bottom? I looked at several of the 2x with removable lens elements on Agena and other sites and they didn’t take filters on the bottom.

[Andrea Salati]

The Orion Tri-Mag does and when I unscrewed the optical group and added it to my Solar rig, it gave me a magnification of 1.41x

[Lostinspace12]

Thanks! Looking at that now. I’d be using it with a few higher power TV Delos. 1.4x might actually work better for me.

[Andrea Salati]

Hold on, I can attest that the "telescope end" of the Tri-Mag accepts standard filters (M28.5x0.6), I am not sure it can actually be screwed to an eyepiece like if it was a filter itself.
Let me take a look, I will get back to you.

[Andrea Salati]

I just checked, it does.

[Lostinspace12]

I just checked, it does.

Thanks again Andrea. After getting your tip, I found there are versions of the Orion shorty 2x (made in china, 2 thumbscrew), that shares similar element as the tri-mag and will take filters and screw onto eyepieces.

[Andrea Salati]

As far as I can tell from other people’s findings, the optical group is the same and only the eyepiece holder varies.

[saemark30]

Any other brands of barlows that allow lens to screw on for 2" barrel and 1.25" barrel eyepieces?

So far we have GSO 2x short barlow and Orion barlows.

 

What are the other brands that are the same as the GSO branded ones?

 

Anyone try Celestron shorty and Svbony?

Edited by saemark30, 12 April 2025 - 11:54 AM.

[triplemon]

Look on Aliexpress, there is likely half a dozen ones at all possoble quality (and price) levels below that.

But you'll be hard pressed to find one that actually screws on 2" barrels.

Edited by triplemon, 12 April 2025 - 11:49 AM.

[saemark30]

Look on Aliexpress, there is likely half a dozen ones at all possoble quality (and price) levels below that.

But you'll be hard pressed to find one that actually screws on 2" barrels.

Can you recommend some 1.25" ones on Aliexpress that has M28.5x0.6 threads that will work?

[triplemon]

Sorry, no.
I have no use for such a barlow.

Edited by triplemon, 12 April 2025 - 07:15 PM.

[saemark30]

Just for the record the Celestron 2x OMNI barlow and Skywatcher 2x barlow with camera adapter both have removable barlow lenses will screw onto 1.25" eyepieces.