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Oberwerk 25x100 Deluxe

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#1 Fiske

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Posted 23 June 2021 - 06:42 PM

I might as well start a topic on the OB 25x100 Deluxe because I am totally fascinated with the darn thing. lol.gif

 

I've had it for a few weeks now and fell in love with it pretty much from when I got it out of the shipping package. From my astronomy binocular collection several of the traditional binocular sizes stand out to me as ideal -- wholly a subjective thing, I just like them. Those are the 15/16x70 and 25x100 binoculars. The other size I have a serious commitment to is 10x50, but in that range I have struggled to find an instrument that suits me. The best in my collection is the Fujinon 10x50 FMTR-SX, but to make it more comfortable for me Nikon wing cup adapter rings need to be inserted in the eyecups. I find the eye relief too long given the eyecup size, exactly the opposite problem many observers experience I guess.

 

Anyway, back to the 25x100. The one thing I don't love about it is the eyepiece filter rings (sorry JG!). They have sharp edges and are not spectacle friendly. But Kevin sent me replacement focuser rings that do not have filter adapters (like those that come with the OB 20x65ED). Installing them was the work of minutes. The focuser rings are held in place with three set screws. The eyecups need to be pulled off to expose them. I positioned the rings at the + indicator (so all three screws could be easily accessed). Loosened the screws, removed the rings, slid the new rings in place, tightened down the screws and put on the replacement eyecups.

 

Replacement focuser rings before the eyecups were installed. One of the set screws is visible.

 

OB 25x100 Replacement Focuser Rings
 
Replacement eyecups installed.
 
OB 25x100 Replacement Eyecups
 
Original focuser rings w/eyecups.
 
OB 25x100 Filter Focuser Rings
 
When installing the new focuser rings I made sure to align the plus symbol with the mark on the eyepiece barrel. It would be a simple matter to tweak the diopter scale settings by loosening the focuser rings and shifting the scale left or right as necessary to calibrate it at zero or whatever mark one desired. 
 
Fiske

 

 


Edited by Fiske, 23 June 2021 - 06:56 PM.

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#2 ECP M42

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Posted 23 June 2021 - 07:39 PM

For a thousand whales, Fiske!

... you are as accurate as a German, despite living in Kansas  lol.gif

 

Good job! waytogo.gif   ... now they are suitable for your needs.

 

But the optical performance of these eyepieces, how are?


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#3 Fiske

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Posted 23 June 2021 - 09:07 PM

That is a high compliment, ECP. Thank you! grin.gif

 

I am extremely pleased with the optics. Observing the moon a few evenings ago -- waxing gibbous 90% illuminated -- slight yellow/purple fringing could be seen along the rim of the moon but well controlled and not in the least objectionable.

 

Also, following the suggestion of ihf in this post I defocused one barrel of the instrument and found that the focused star was nearly centered on the unfocused star, and then refocused the first barrel and defocused the second and confirmed that the focused star, again, was close to center on the defocused star.

 

I also had a nice view of STF 1608 in Ursa Major and also a recent favorite pair near M56 -- HD 180240 and SAO 86973 8.6/8.81 37.5" pa 331.6*, which while not technically a double star is still a lot of fun. I could just detect the blue and yellow tints of the two stars. More details in this Double Star forum post.

 

Fiske


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#4 ECP M42

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Posted 24 June 2021 - 03:17 AM

Sure Fiske, it was meant to be a compliment.

 

I'm glad the new 25x100 is collimated, but I guess you didn't purchased it to look at the moon. My Deluxe 10x50 also has some yellow and blue fringes on the Moon, but not in an exaggerated way. I noticed that it seems to color even the brightest stars, so it's all a nice vibrant kaleidoscope of false colors and true colors of the stars.

 

To look at the Moon, you should try to mask the lenses to at least 40mm. This greatly increases the overall sharpness and perhaps slightly decreases the radial ACs you see (yellow / indigo) as well. 

With my 25x70, I use 37mm masks ... and it is still very bright! 

 

 

Is the 25x100 field of view totally flat or is it more like 10x50?


Edited by ECP M42, 24 June 2021 - 03:19 AM.

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#5 Fiske

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Posted 24 June 2021 - 11:11 AM

The 25x100 is quite flat -- meaning minimal field curvature -- compared with the 10x50 Deluxe. I don't know about totally, but it is sharp close enough to the edge of the FOV not to matter. Partially I believe this is a consequence of having a narrower FOV compared with the 10x50, 2.4 degrees for the 25x100 versus 6.5 degrees for the 10x50. Field curvature is much easier to control in narrower FOVs. In fact, of the three OB Deluxe series binoculars I own -- 20x65ED Deluxe, 20x80 Deluxe III, and the 25x100 Deluxe, the FOVs range from 3.25 to 2.4 degrees and the edge performance in all three is superb.

 

Thanks for the suggestion about masking. Sooner or later I will give that a try. wink.gif

 

Fiske


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#6 Fiske

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Posted 24 June 2021 - 11:43 AM

I am going to add a brief comment about my 10x50 struggles, which is a bit OT here but I had a significant realization about this last night and this is a follow on to the comment in my first post in this topc.

 

Despite hazy, not super great skies, including a full moon and some clouds, I spent time with the 10x50 Deluxe, 10x50 Ultra, 10x50 Fuji, 10.5x70 Resolux, and 12x50 APM binoculars comparing views (looking at edge performance) both with uncorrected vision (-5.50 sphere in both eyes) and corrected vision wearing glasses. What I realized is I have been underestimating the negative impact on optical performance in focusing binoculars for my nearsighted, uncorrected vision. The Resolux, Fuji, and APM are the sharpest of the five binoculars. These three are sharp to between 85 and 90% of the FOV when I am not wearing glasses, which is good enough not to be irritating to me in normal observation. Wearing glasses, all three are sharp about to the edge of the FOV. The Ultra without glasses is sharp only to about 50-60% of the FOV, which is apparent and annoying to me. BUT, with glasses, the same instrument is sharp to 80-85% of the FOV, which is perfectly acceptable. Moreover, the Ultra is comfortable for me with glasses, meaning I can see the full FOV without straining. This varies from user to user but I prefer less eye relief than what may be the average. The Ultra is easily my most comfortable hand held binocular. I have been stuck on the idea of using it without glasses (because doing so adds a certain immediacy to the experience), but now realize the trade off is not worth it. When I really want to observe sans spectacles, I'll just use one of the other binoculars. 

 

What really helped me see the issue is that the Deluxe is only sharp in the center of the FOV for my uncorrected vision -- as soon as a star is moved from the center it immediately shows softening. Noticing that, I thought wait a minute! Kevin wouldn't be saying that is acceptable performance. With glasses the performance is much better -- sharp to 60-65% of the FOV. Not as good as the Ultra, but the Deluxe 10x50 is priced at $180 USD -- $100 less than the Ultra. For it's price point, the Deluxe 10x50 is a good value IMO. It's far better optically than the first 10x50 I used for astronomy, which was a Nikon Lookout IV that seemed perfectly sharp to me at that time. wink.gif The Fuji 10x50 (the only binocular with a comparably wide FOV -- 6.5 degrees), costs more than 3x the Ultra -- $850 USD as of this post.

 

I've wrestled with this aspect of binocular astronomy -- comfortable hand held viewing with a 10x binocular -- more than about everything else put together. lol.gif Hopefully, that has been resolved now.

 

Fiske


Edited by Fiske, 24 June 2021 - 11:44 AM.

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#7 ihf

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Posted 24 June 2021 - 11:52 AM

I realized a while ago that my astigmatism kept getting worse from visit to visit. Hence while I really do like wide fields optics that do not support glasses are out. Fortunately I can deal with relatively small eye relief, but 82' eyepieces are uncomfortable and 100' are out. Unfortunately that also means that while I can use my Nikon E2 during the day, it really is not the experience it should be (struggling with taking glasses off and putting them away). So the glasses stay on and the binos that don't support it don't get any use anymore (or won't be purchased). Now we have a rationalization for the NL, don't we? Ha! 


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#8 duck2k

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Posted 24 June 2021 - 11:59 AM

I have not peered through my 25x100 Obies in awhile. I have a great mount for them too. They are a fun binos. watching.gif

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Edited by duck2k, 24 June 2021 - 12:01 PM.

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#9 Echolight

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Posted 24 June 2021 - 12:16 PM

I guess the whole binoculars are TOO BIG to fit in a picture!  Not enough FOV?



#10 Fiske

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Posted 24 June 2021 - 12:52 PM

I realized a while ago that my astigmatism kept getting worse from visit to visit. Hence while I really do like wide fields optics that do not support glasses are out. Fortunately I can deal with relatively small eye relief, but 82' eyepieces are uncomfortable and 100' are out. Unfortunately that also means that while I can use my Nikon E2 during the day, it really is not the experience it should be (struggling with taking glasses off and putting them away). So the glasses stay on and the binos that don't support it don't get any use anymore (or won't be purchased). Now we have a rationalization for the NL, don't we? Ha! 

Be sure to post that on the Rationalization topic. lol.gif  (Kind of wish I had named it Binocular N+1 Thought Processes.") grin.gif

 

I never even considered 100 degree eyepieces. And have always found 82 degree eyepieces at the limit of what I consider comfortable. I actually prefer 70 degrees to 82. Kevin Busarow told me that his preference is the 70-76 degree range.

 

Fiske


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#11 ECP M42

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Posted 24 June 2021 - 02:54 PM

Thanks for the interesting answer, as always. 

 

The 25x100 is quite flat -- meaning minimal field curvature -- compared with the 10x50 Deluxe. ... Partially I believe this is a consequence of having a narrower FOV compared with the 10x50

This certainly affects. But I also consider the different eyepiece of the 25x, which is most likely the same (or similar) as the two 20x you have.

 

And thanks also for the 10x mini test, below  wink.gif



#12 Rich V.

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Posted 24 June 2021 - 03:02 PM

Since FC is a function of focal length, just the difference in focal lengths alone between a 100mm and a 50mm bino would have a large effect on the amount of FC, even if they used the same exact eyepieces.


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#13 ECP M42

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Posted 24 June 2021 - 03:29 PM

Since FC is a function of focal length, just the difference in focal lengths alone between a 100mm and a 50mm bino would have a large effect on the amount of FC, even if they used the same exact eyepieces.

Right Rich, and in fact you could also consider the field flattener, which I believe all the models mentioned have. It is difficult to find the final cause. Fiske also pointed out that the curvature changes based on the use of the glasses ...



#14 Fiske

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Posted 24 June 2021 - 08:14 PM

The new Oberwerk stabilizer upgrade for the PM1 has been installed. It reduces oscillation in the counterbalance arms when they are extended. To install it, the stabilizer bar was detached and the two mounting plates installed on the counterbalance clamps -- the original screws were removed and longer screws provided with the stabilizer were used to attach the plates. No drilling was necessary. Then the stabilizer bar was reattached to the mounting plates. An elegant and practical enhancement for this superb mount.

 

PM1 Stabilizer

Edited by Fiske, 24 June 2021 - 08:16 PM.

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#15 Rich V.

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Posted 24 June 2021 - 10:29 PM

That's certainly a simple fix, putting a tie bar between the two arms to keep things rigid.  I'd wondered about that.   I trust all the new production will be equipped with that modification in place.  waytogo.gif


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#16 Fiske

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Posted 24 June 2021 - 10:32 PM

Kevin is introducing a PM2 mount, designed for heavier binoculars I understand. He suggested it would be a good choice for the 100XL-SD, but I am still going with the Manfrotto 117B and XL 240 fork. wink.gif 

 

Looking forward to more details about the PM2, though.

 

Fiske



#17 jprideaux

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Posted 26 June 2021 - 07:28 PM

Kevin is introducing a PM2 mount, designed for heavier binoculars I understand. He suggested it would be a good choice for the 100XL-SD, but I am still going with the Manfrotto 117B and XL 240 fork. wink.gif

Looking forward to more details about the PM2, though.

Fiske

I really like the manfrotto 117b and the OB 240 fork mount. In my case , since I added a vixen dovetail receptor and needed more dept to accommodate my refractor binoviewer set-up, Keven let me swap out the side pieces for the longer side pieces in the fork for the 280mm version. Anyway, I really like the fork and I think the tripod is the perfect balance between robustness and portability. I like the thicker crank-shaft as opposed to my Ob 5000 tripod. I now use my ob 5000 tripod for a different lighter set-up. I think you made some good choices for your 25x100!

Edited by jprideaux, 26 June 2021 - 07:29 PM.

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#18 Fiske

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Posted 27 June 2021 - 11:03 AM

Thanks so much, JP. grin.gif

 

Rich V's evaluation of the 117B was not a small factor in my choice of that mount. wink.gif And robust portability was precisely my goal in choosing it, so your confirmation of those characteristics is welcome.

 

Fiske




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