Borg 67FL

[skc]

Not really a "discussion", but *new toy*:


Borg 67FL with reducer by Stuart Croy, on Flickr

f/2.95! Woo hoo!

[antares2063]

looks cute...guess its a purely for imaging ? or can it be used as visual instrument?

Regards,
Junwei

[KKK26]

So cute. poison

[skc]

looks cute...guess its a purely for imaging ? or can it be used as visual instrument?

Regards,
Junwei

The 67FL was announced on the Japanese Borg blog, and then on the Hutech blog shortly after, but I think the details of the sets are still not on the main site(s).

I already have a lot of Borg parts, so can use it at its native focal length (300mm) with eyepieces, so I just ordered the objective assembly and a couple other parts to use with the reducers I already have. There are sets available with suitable tubes and a helicoid to use at it's native focal length. One set is for photography - mainly birding. WIth this you get a camera adapter for your chosen mount. The other set is for astro use, and you get a 2" eyepiece adapter. Both of these sets use the 60mm diameter tubes, but you can also use 80mm diameter tubes (sold separately), and probably the "BU-1" tube too. I doubt I'll use this for anything other than astrophotography. I wouldn't be surprised if Hutech offered a bino version.

Borg is like lego. You can choose to go for a Crayford focuser instead of (or in addition to) a helicoid, but generally these are not available in a set.

The photo above shows a short 80mm diameter tube and a couple of adapters to attach the M57 helicoid to provide plenty of back focus for the reducers. The 0.7x multi reducer wasn't designed for such a short focal length, so it's only recommended for use up to APS-C sized sensors (normally it covers "full frame"). You can also use the 0.85x reducer. Apparently there will be a flattener to match the scope released next year. Presumably like most Borg flatteners and reducers it will be adjustable to cover a range of focal lengths - the current ones (excluding the new M42 one) all cover much longer focal lengths. I'm using the 0.66x DGT reducer, which is adjustable all the way down to 300mm and covers APS-C. I've not had a chance to try this out yet.

The FL (50FL, 67FL, 71FL) series objectives are Fluorite doublets (not FPL-53 or other glass) and made by Canon Optron (who also do the objectives for Tak and some of the Canon L series lenses). Pentax Optotech made the objective for the 125SD, and also the optics for the 0.66x DGT reducer (no longer available - there's now a 0.7x reducer that covers full 35mm frame). These were all described on the Borg blog/site at some point, so are "official".
The "ED" and achromat series, as far as I've been able to find out, are all made by "Fujii Optics" (http://www.fujii-kg.co.jp/) in Japan. Note the extra "i", this is not Fuji aka Fujifilm as some have claimed. I think I found this on a Japanese forum/blog, so it's not official.

Cheers,
Stuart

[skc]

So cute. poison

Yep. I think I'll sell my 180/2.8ED Nikkor, and 60ED.

[antares2063]

thanks for your detailed explanation Stuart so awesome that Borg can mix and match , as well as the detailed info on lens manufacturers

regards,
Junwei

[MooEy]

I have been trying to hold off the purchase of the 67FL...