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New BT series from Oberwerk

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#1 guangtou

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Posted 25 April 2018 - 11:50 AM

Anyone check these out at NEAF?
https://oberwerk.com...lar-telescopes/

#2 Rich V.

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Posted 25 April 2018 - 12:24 PM

These appear to be variants of the KUO BTs sold by APM.  In these models, though, the optical specs are different.

 

A non-ED 82mm model is offered which could be a good value-oriented BT that APM doesn't offer.  Interesting also is that the 82mm ED is claimed to use a 450mm  FK-61 ED doublet instead of the 470mm FPL-53 formula offered by APM in that size.  24mm clear prism aperture instead of 28mm.   hmm.gif

 

I like the picatinny rail mount built into the handle.

 

It would be nice is somebody attending NEAF that's familiar with the APMs would comment on these new offerings.

 

Rich


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#3 Mad Matt

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Posted 25 April 2018 - 01:16 PM

Different housing, different glass types, different focal lengths. I suspect these are not United Optics (who makes the APM models) but a different manufacture. Maybe there was a military tender that multiple manufactures designed prototypes for and we are now seeing civilian version from a second manufacture reach the market.

I find the following from the website to be alarming „These models also have an effective aperture that is very close to the actual objective size, with just enough baffling to eliminate the less-than-optimal performance delivered from the outer-most edge of all objective lenses.„

I applaud Oberwerks openness and proper expectation management but I suspect the erecting prisms are undersized and may negatively effect field illumination.

#4 Rich V.

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Posted 25 April 2018 - 01:31 PM

Different housing, different glass types, different focal lengths. I suspect these are not United Optics (who makes the APM models) but a different manufacture.

 

I think you're right, Matt.  On closer inspection of the photos, the housings are different; very much inspired by the Kowa Highlander.

 

Kevin has been in a joint venture for a long time with Yunnan Optoelectronics Co. Ltd., in Kunming, China in the production of his BT100s.   Perhaps this is a "modernizing" of his BT line using this already established manufacturing arrangement.

 

https://oberwerk.com...-joint-venture/

 

Rich


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#5 Mad Matt

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Posted 25 April 2018 - 01:42 PM

Your probably right Rich. One could easily assume that they are the manufactures. 😁

Good to see Oberwerk is modernizing the line... let’s hope they have a 150mm model in the pipeline

Edited by Mad Matt, 25 April 2018 - 01:43 PM.

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#6 OBERWERK

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Posted 25 April 2018 - 01:54 PM

Different housing, different glass types, different focal lengths. I suspect these are not United Optics (who makes the APM models) but a different manufacture. Maybe there was a military tender that multiple manufactures designed prototypes for and we are now seeing civilian version from a second manufacture reach the market.

I find the following from the website to be alarming „These models also have an effective aperture that is very close to the actual objective size, with just enough baffling to eliminate the less-than-optimal performance delivered from the outer-most edge of all objective lenses.„

I applaud Oberwerks openness and proper expectation management but I suspect the erecting prisms are undersized and may negatively effect field illumination.

This is entirely our own design, has been in the works for 3 years now.  I repeat once again for all the speculators- all Oberwerk binoculars, except for the Ultra Series and BT-70-45, come from our own assembly plant in Kunming.  The BT-70-45 is from another manufacturer 2 blocks from us.  United Optics has never made (or sold) an Oberwerk product.  

The prisms are huge, the effective aperture on the BT-82XL-ED is 80mm.  


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#7 Mad Matt

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Posted 25 April 2018 - 02:06 PM

This is entirely our own design, has been in the works for 3 years now. I repeat once again for all the speculators- all Oberwerk binoculars, except for the Ultra Series and BT-70-45, come from our own assembly plant in Kunming. The BT-70-45 is from another manufacturer 2 blocks from us. United Optics has never made (or sold) an Oberwerk product.
The prisms are huge, the effective aperture on the BT-82XL-ED is 80mm.


Many thanks for the excellent information. Good to have you here to replace my assumptions with facts! 👍😀

Can you tell us the effective aperture of the 100mm model? Also, can you elaborate on your decision to restrict the aperture? I assume it was to control reflections and false pupils but since we have you here it would be better to get the info first hand 😀

#8 Rich V.

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Posted 25 April 2018 - 02:07 PM

Thanks for the clarification, Kevin.

 

When comparing new product lines with existing ones, if we can only compare specifications and images provided we can't help being "speculators".   wink.gif

 

Rich



#9 OBERWERK

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Posted 25 April 2018 - 02:22 PM

Many thanks for the excellent information. Good to have you here to replace my assumptions with facts!

Can you tell us the effective aperture of the 100mm model? Also, can you elaborate on your decision to restrict the aperture? I assume it was to control reflections and false pupils but since we have you here it would be better to get the info first hand

Effective aperture of the 100XL-ED is 96mm.  19x on the 82mm, and 25x on the 100mm was as low as we needed, therefore 24mm prism aperture was enough.  BTW, no fingernails :)    


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#10 Mr. Bill

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Posted 25 April 2018 - 02:28 PM

Kevin....good news on the updates of your binocular line. 

 

waytogo.gif


Edited by Mr. Bill, 25 April 2018 - 02:29 PM.

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#11 Rich V.

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Posted 25 April 2018 - 02:32 PM

Many thanks for the excellent information. Good to have you here to replace my assumptions with facts!

Can you tell us the effective aperture of the 100mm model? Also, can you elaborate on your decision to restrict the aperture? I assume it was to control reflections and false pupils but since we have you here it would be better to get the info first hand

I would love to see a BT design that minimized the prism reflections around the exit pupil found in the KUO BTs.  It appears with KOU a trade-off was made to minimize prism baffling to satisfy those looking for greatest clear prism aperture/ illumination over those looking for the cleanest views without unwanted reflections swimming past in the FOV.

 

The Miyauchi and Kowa offerings mentioned as inspiration to these new Obie BTs incorporate internal prism baffles that eliminate most of the annoying reflections but cause some amount of illumination fall off at the edges of the fields even though operating at full aperture.  I can't help wonder if that's always a design trade-off?  

 

I look forward to hearing more about the performance of these new BTs after they reach customer's hands.

 

Rich



#12 GamesForOne

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Posted 25 April 2018 - 03:01 PM

An obvious question:

 

I wonder if 90 degree models will be forthcoming?

 

I have a love/hate relationship with my new APM 100mm 90 degree after a decade of using 45 degree binocular telescopes, including the BT-100-45. The 90 deg setup is great for 40 degree elevation or higher, but honestly it gets incrementally more painful for me when looking closer to the horizon.

 

The COG looks like it might be lower than the APMs from the pictures, which would make use with a lighter-duty fluid head easier. I think the mounting shoe on the APM is at least 1/2" too tall.

 

One big plus in Oberwerk's favor is USA stock that doesn't require expensive shipment from Germany.

 

---

Michael Mc


Edited by GamesForOne, 25 April 2018 - 03:08 PM.


#13 Mad Matt

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Posted 25 April 2018 - 03:20 PM

Well, if 4% and 3% aperture loss for the 109 and 82mm models respectably is a good trade off for eliminating finger nails as long as the manufacture is open about it. (Might want to consider adding an “effective aperture” spec to the additional information page 😊)

Rich, without doing an actual ray trace and just thinking it through, a baffle at the amici prism entrance acting as a aperture stop could actually still facilitate a good field illumination. The illumination does not start to drop until the aperture stop and the edge of the objective start to block off axis light simultainiously.

If I am not mistaken and in a simplified manner, you can visualize this as the light cone pivoting off-axis with the fulcrum at the aperture stop as opposed to the edge of the objective full aperture.

Edited by Mad Matt, 25 April 2018 - 03:21 PM.


#14 Mr. Bill

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Posted 25 April 2018 - 03:47 PM

An obvious question:

 

I wonder if 90 degree models will be forthcoming?

 

I have a love/hate relationship with my new APM 100mm 90 degree after a decade of using 45 degree binocular telescopes, including the BT-100-45. The 90 deg setup is great for 40 degree elevation or higher, but honestly it gets incrementally more painful for me when looking closer to the horizon.

 

The COG looks like it might be lower than the APMs from the pictures, which would make use with a lighter-duty fluid head easier. I think the mounting shoe on the APM is at least 1/2" too tall.

 

One big plus in Oberwerk's favor is USA stock that doesn't require expensive shipment from Germany.

 

---

Michael Mc

APM says it will have a fully stocked US distributor in the near future.



#15 OBERWERK

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Posted 25 April 2018 - 03:54 PM

An obvious question:

 

I wonder if 90 degree models will be forthcoming?

 

I have a love/hate relationship with my new APM 100mm 90 degree after a decade of using 45 degree binocular telescopes, including the BT-100-45. The 90 deg setup is great for 40 degree elevation or higher, but honestly it gets incrementally more painful for me when looking closer to the horizon.

 

The COG looks like it might be lower than the APMs from the pictures, which would make use with a lighter-duty fluid head easier. I think the mounting shoe on the APM is at least 1/2" too tall.

 

One big plus in Oberwerk's favor is USA stock that doesn't require expensive shipment from Germany.

 

---

Michael Mc

No plans to offer a 90-degree.  A large percentage of our sales are to customers that are using them terrestrially (home-with-a-view), 45-degree works well for all.  I designed a single-arm mount (the XL Blade), which was great with the 82mm, but not so great with the 100mm- so more work to do on that.  In the mean time, our dual-handle 5000 head on the TR3 tripod with a carbon-fiber elevator (18" of instant height adjustment) works very well.   


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#16 Rich V.

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Posted 25 April 2018 - 03:55 PM

Well, if 4% and 3% aperture loss for the 109 and 82mm models respectably is a good trade off for eliminating finger nails as long as the manufacture is open about it. (Might want to consider adding an “effective aperture” spec to the additional information page 😊)

Rich, without doing an actual ray trace and just thinking it through, a baffle at the amici prism entrance acting as a aperture stop could actually still facilitate a good field illumination. The illumination does not start to drop until the aperture stop and the edge of the objective start to block off axis light simultainiously.

If I am not mistaken and in a simplified manner, you can visualize this as the light cone pivoting off-axis with the fulcrum at the aperture stop as opposed to the edge of the objective full aperture.

Baffling between the objective up to the front prism face is good.  Most refractors have those baffles but they shouldn't cut into the light path and decrease effective aperture.  The baffles I'm speaking of are located between the Schmidt roof prisms and the rhomb turrets to block off axis light right ahead of the rhombs.  Those bright reflections in the APMs are off the rhomb faces as indicated by their angular locations around the exit pupils. 

 

Rich



#17 jay.i

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Posted 25 April 2018 - 04:29 PM

I was waiting for these Kevin!! Glad to finally see them hit the market. Thank you for stating the glass used in the ED objectives. Any chance you'll be at ALCON in Minnesota with one of the 82-EDs? I know someone who'd love to take a peek... wink.gif


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#18 edwincjones

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Posted 25 April 2018 - 04:41 PM

I wonder how long until 125mm and/or 150mms?

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#19 OBERWERK

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Posted 25 April 2018 - 04:49 PM

I was waiting for these Kevin!! Glad to finally see them hit the market. Thank you for stating the glass used in the ED objectives. Any chance you'll be at ALCON in Minnesota with one of the 82-EDs? I know someone who'd love to take a peek... wink.gif

Sorry, won't be at ALCON.  But we will be at the Texas Star Party in 2 weeks, with the BT-82XL-ED and BT-100XL-ED available for test drives.  


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#20 OBERWERK

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Posted 25 April 2018 - 04:55 PM

I wonder how long until 125mm and/or 150mms?

edj

No plans at this time.  



#21 faackanders2

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Posted 25 April 2018 - 11:02 PM

No plans at this time.

i.e. very long time.

#22 faackanders2

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Posted 25 April 2018 - 11:05 PM

Oberwerk bought out Garrett. What ever happened to the Garrett 150mm binoculars and design? Does Oberwerk own this, and just chooses not to build/sell them?

#23 duck2k

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Posted 25 April 2018 - 11:40 PM

Kevin I am glad to see these lines of new BT's.  A very nice looking bino indeed!  Thanks for the info on them.:)


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#24 GamesForOne

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Posted 26 April 2018 - 01:00 AM

APM says it will have a fully stocked US distributor in the near future.

I thought FarpointAstro.com was said distributor. They have little to no stock listed on the website and the markups far exceed the cost of ordering from APM directly even with the shipping cost from Germany.

 

The longer-term stability of Oberwerk as a USA presence for delivery, service, and support is certainly a plus.

 

---

Michael Mc


Edited by GamesForOne, 26 April 2018 - 01:25 AM.


#25 OBERWERK

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Posted 26 April 2018 - 08:09 AM

Oberwerk bought out Garrett. What ever happened to the Garrett 150mm binoculars and design? Does Oberwerk own this, and just chooses not to build/sell them?

The Garrett 150mm was produced by yet another factory.  We don't own the design, and are not interested in building more.  They were expensive yet QC was inconsistent.  They're extremely heavy and suitable/affordable mounts/tripods don't exist. More trouble than it was worth for us. 




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