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Attention Oberwerk 25x100IF owners/users....?

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#1 Glassthrower

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Posted 08 August 2005 - 03:15 PM

Hello all,

I have done a lot of reading back through the CN post archives looking for reviews and discussions about the Obie 25x100IF bino. What I found was encouraging, and I am leaning heavily towards purchasing a pair in the near future. To help me settle on this decision, I would like to hear some recent impressions from actual owners of these big binos. Most of the older posts I read were from around the time these binos first hit the market. Has there been any fluctuation in quality or performance in later batches versus those earlier models?

And lastly, what I am most interested to learn about is the crispness of the FOV. I have heard various percentage figures quoted from 75-85% of the FOV being nice and sharp. How much of the FOV appears to be crisp clean and bright before any drop-off is noted?

I know Oberwerk has a solid reputation of being a reliable vendor who stands behind their products, so I am completely confident in that respect. What I am most interested in is optical performance.

A sincere "thank you" for tolerating all of my never-ending questions...

MikeG

#2 CESDewar

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Posted 08 August 2005 - 11:40 PM

I have to say I've been most impressed with these binoculars. Yes there is some fall-off around 70% or so, but I've never found it to be an issue while observing. I have looked through binoculars that are almost three times the weight and four times as expensive, and the difference was so minor that it made me only happier that I had picked these up. The center 25% seemed just as sharp, and while the higher quality binos did not fall of as fast, it was something I only noticed because I was desperately trying to see the difference.

Of all the instruments I have, this one is my favorite for DSO hunting and the views around Cygnus are just breathtaking. The instrument was out of collimation when I got it (I now always ship via 2-day air to get better handling), but it's very easy to collimate. It needs a good mount - I actually spent about the same on the mount that I did on the binoculars - to make the best use of them (I'm a very big fan of p-mounts with a reclining chair vs. craning your neck with a conventional tripod).

All I can tell you is that if I had paid $950 for these binoculars, I would have still been happy - at less than half that - I'm ecstatic :jump: - IMHO these are a really good value. Maybe I was just lucky in getting an unusually good pair, but we'll see what others say of their experiences with them.

#3 DJB

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Posted 09 August 2005 - 02:00 AM

re: Bebs, your concern,

I have had the Oberwerk 25x100 since around January. I must agree with what has already been said so far. The FOV is at its best out to around 65* or better. Very gently degrades after that, but, it is subtle.

They appear to be extremely rugged, compared to some others. I talked to Kevin at BB, and he assured me that collimation would be checked/corrected before shipment. It was dead-on and still is.

As a Christmas gift in 2004, I had received the Orion 25x100. However, the collimation was nearly 2* off, not two arc minutes, but two degrees, nearly the full, actual FOV. Probably happened during shipment at the Christmas rush?

Orion made it right and received the bino back with a full refund. I had the option of Orion accepting the bino and correcting the problem and returning it to me. Problem was--Orion promised to check/correct collimation first time round, so I opted for a return and refund. I continue to deal with Orion.

Kevin (BB) holds the Obies to a higher standard, which pays off in the end. A real deal, in my opinion!

Regards,

Dave.

#4 Bill Huot

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Posted 09 August 2005 - 03:05 AM

I bought one of the early ones last October. I don't know if the later batches are better, worse or the same as mine.

This was my first bino bigger than 10X50. My first reaction was Wow! at the sheer size and weight of the thing. My impression was that it is big, and sturdy, and probably designed to survive being run over by a tank. However, when I looked through them, my heart sank -- they had arrived very badly out of collimation. Very badly out! My first reaction was to return them despite the royal pain in the butt it would be to send them back across the border from Canada.

Fortunately, I had been lurking in Cloudy Nights long enough by that time to know that collimation - or conditional something-or-other -- is fixable by the knowledgeable user. I had already read -- but not understood -- the instructions on Oberwerk's website and in Edz' article. After re-reading them a few times, and an exchange of e-mails with Kevin for clarification, I was ready to give it a try. It took about an hour of trying to find the little screws and cautious adjusting and readjusting before I saw only one flagpole in my binos. By that time, my eyes were exhausted. I didn't even try looking at the stars for several days, waiting for my poor strained eye muscles to get back to normal. During that week I felt rather discouraged.

When I did finally take them out under the stars they lived up to my hopes/expectations. The Obie makes small faint fuzzies into big bright fuzzies, and shows lots of little jewels in the open clusters. My impression is that the view is nice and crisp (although, not as much so as in my more-recently-purchased Fujinon 16X70). I can't say at what % from teh centre the sharpness deteriorates. Whenever I've used them I've just enjoyed the view and haven't tried to analyze it. My general impression is that it is all pretty sharp. I'm sorry that I can't give you a better review of their optical performance than to say that because of the increased magnification I see much more through them then through the Fuji, even though the Fuji's view is crisper.

A few weeks ago I took them out and they were out of collimation again. I don't know what caused it -- I don't recall them having gotten knocked about or anything. Oh Oh!, I thought, remembering what my eyes felt like the first time. I didn't try to fix the collimation in the dark. So the next day it was back to looking at the flagpole. But this time, it just took one tweak -- probably less than a minute -- to set them right. My eyes didn't hurt a bit. I don't know if I was just lucky, or I'm a collimating prodigy, or whether collimation is easy once you get the hang of it. But next time -- and I suspect that there will be a next time -- I'll be willing to try to do it in the dark.

The pricetag of magnification, of course, is a tiny FOV. I still have trouble telling what I am pointing at unless there is a notable landmark in the vicinity. So now I cheat and use a red-dot finder. I just rubber-band it on, and the dovetail self-aligns with the curvature of the barrel. That makes aiming really easy. Be sure to budget for one of those gadgets.

Oh, and don't underestimate the weight thing. They do need a sturdy mount. (See my comments on the Couch Potato Telescope.)

The bottom line is that I am really happy with my Obie 25X100. Its very good value for the money.

#5 EdZ

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Posted 09 August 2005 - 08:42 AM

All of these notes are culled from posts I have previously put up concerning the Obie 25x100. there are too many posts to find all the stuff I've written on these binoculars.

Obie 25x100 - I was able to observe a 7.3 arcsecond double (11 Mon) still cleanly separated at about 50% to 60% out from center for an apparent resolution of 183 arcseconds. That's really very good central area resolution performance and at the 60% out mark exceeds the capabilities of the Celestron 25x100 by nearly a factor of 2. It also exceeds the capabilities of the Oberwerk 22x100 which at very best achieved a resolution of 310 arcseconds at 60% out.

Between 70-75% out the resolution falls off rapidly. At 70% out from center, the resolution in the Obie 25x100 is equal to what the Fujinon 16x70 can see at 80% out.

By 80% out in the Obie 25x100, resolution drops off considerably and is equal only to that seen in the Nikon Action extremes at that point. However is is still very much better than the Celestron 25x100 at 80% out. By 85% out the image is poor.

Ob25x100 Collimation was dead on, but there is a difference in barrel field of view overlap. It took quite a bit of work to get the fields to match and then recheck the point source collimation to insure it matched. I've seen this in several binoculars now and it is very disconcerting. The binocular will have point sources perfectly overlapped, but the field of view in the barrels is not the same. the eyes can't deal with this. This needs to be reworked. The barrels should first be set to match the field of view, then point source collimation can be set more precisely.


With the Oberwerk 25x100 IF, the moon has a thin yellow band. When eyes were moved off axis the band would change to blue and purple and become thicker. Staying on axis really minimized the CA and it was no more objectionable than some other binoculars.


I’ve been out about 10 times in the last 7 weeks with these new Oberwerk 25x100 IF. Regardless of what other binoculars I had out, each one of those nights I recorded a number of objects with the 25x100IF. I’ve seen some pretty nice objects with these binoculars. Here is a sampling taken from some of my observation notes with some comments about how I saw those objects.

Probably every night I took a look at Saturn. No particular detail is seen other than the ring system is easily seen separated from the disk at both ansae. Titan is always seen. On the night of Apr 4, it appeared to me I observed one moon directly north and one moon directly east. No CA is seen when observing Saturn with the Obie 25x100IF.

Jupiter is regularly observed with two distinct equatorial bands, even low in the sky. On Mar25, at about 10PM, I noted the positions of three moons all to the same side on the east. After a period of observation, I saw that very close in towards the disk, on the same side, was the 4th moon. Based on Jupiter’s current size of 44 arcseconds, I estimated this close moon at a distance of about 6 to 8 arcseconds from the disk. Later I researched that Io was about to start transit at 10:13pm, entering from the east. Jupiter did show a bit of red CA, not at all objectionable, and it did not interfere at all with the detection of Io.

A number of nights were used to gather star counts on M44, Praesepe. What I find really interesting is the different nature this cluster takes when viewed thru 8 to 10 different sizes of binoculars. The swarm of the beehive takes on a whole different perspective viewed thru 25x100 binoculars. M44 has 100 members brighter than mag 10.9. On various occasions I counted 70, 80, 100, 114 and 117 stars in the swarm. I suspect the 25x100 is seeing close to mag 12. Some of the fainter members never become visible in 15x70s, 16x70s or 20x80s.

I have recorded stars in Cr399 all the way down to mag 11.9.

I had these mounted on a ScopeStuff 2D Binocular Mount Head attached to a 3130 Bogen head on a 3011 tripod. In my opinion, this binocular is way too much overload for that equipment setup. The whole setup would take about 15 to 20 seconds to stop shaking every time I moved it. I had all the screws tightened about as much as I could and still it wasn't enough to keep this binocular from moving. This is definitely a case where you will spend more for the mount than you will for the binocular.

The vertical mount post is too short. That means the binocular barrels rest on top of the tripod head and there is limited range to slide the vertical post for balancing. When pointed up, it didn't seem to pose any problem. I would have preferred a taller vertical post similar to the post on the older 20x80 Deluxe. I added a 1” extension post obtained from ScopeStuff. It solves the problem very nicely. With the 1” post this binocular mounted on a Bogen 501 head attached to a Bogen 3246 tripod is the perfect portable large binocular setup. I use mine often while seated. The elevator crank, panning and altitude tilt motion is fluid, smooth and without shake.

In M44 the stars are all spread apart and it is a measure of light gathering, LM. In M67 the stars are dense, close and difficult to pull out of the glow of the background. While M67 still shows the light gathering, in some instances it may be more a measure of contrast. M67 is more like a faint glow that you can pick stars out of with a little more magnification. M67 at lower powers is nothing more than a glowing smudge in the sky, 2,500 Light years away. In the Obie 25x100IF, 20 stars can be seen resolved and the background glow of the hundreds of remaining mag 13 and mag 14 stars is bright. M67 has no stars brighter than mag 10. A Burgess 20x80 could only see 4 stars in M67, A Fujinon 16x70 saw 6. Only the 100mm binoculars are seeing stars deeper than mag 11.0.

There is much more posted here in this forum in observing reports, sharpness across field, What can be seen, Star counts in M44 and other places I can't remember.

edz

#6 Glassthrower

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Posted 11 August 2005 - 08:11 PM

I'd like to thank everyone for sharing their observations and impressions of this bino. I'm all but settled on these as my next bino purchase. Unless anyone can suggest a better 100mm bino in the ~$500 price point....

Thanks again and clear dark skies...

MIkeG


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