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Dog Star
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Reged: 08/01/05
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Loc: UK
Oberwerk 8x40 Mariner - brief review
      #1131369 - 09/04/06 11:23 AM

Having owned an Oberwerk 8x40 Mariner for a few weeks now I thought I’d share my impressions. I ordered them from BigBinoculars.com and they took about 2 weeks to reach the UK after the usual processing time in UK Customs and the Post Office. The binoculars arrived very well packed and padded.

On opening the box I was quite amused by the retro-looking black vinyl case; very shiny black ‘leather look’. At least a functional case is provided.

The binoculars themselves are very squat with fat prism housings. They happen to fit my hands perfectly. For me this makes the view extremely steady. Looking through them for the first time I was a bit disappointed, but then I realised they were very slightly out of collimation (not surprising after a journey from China to the USA and then to England). A very small turn of one collimation screw (less than a quarter turn) transformed the view. The 8.2 degree field gives and apparent field of view of 66 degrees which is quite impressive. I had expected very obvious distortion and/or softening at the edges but was pleasantly surprised. The edges are soft but the view is so wide this only affects your peripheral vision so the overall impression is still very nice. What really surprised me was the performance in the central 25% of the field. Looking at craters along the terminator I had one of the sharpest views I’ve ever seen in an 8x binocular. The central performance left my old 8x and 7x binoculars for dead. I had to pull out the Nikon 10x42 SE to get a better view. However, it’s not all plain sailing. I find eye-positioning is quite fussy to get the sharpest view. Also, I was rather surprised and disappointed to find that these are NOT REALLY AN 8x40. What do I mean? I noticed very quickly that the exit pupil is nowhere near the 5mm it should be in an 8x40. After a few attempts at measuring it I’d say it’s closer to 4mm meaning that the binocular is operating as an 8x32. Looking into the objectives I can see a small baffle that looks as though it’s cutting down the aperture and is the most likely culprit. Having said that, they’re still extremely bright for there size. In fact they’re so bright I wonder if there’s some special glass in there somewhere. The other thing that makes me wonder about the glass is the colour rendition. In daylight the colour reproduction is superb and clearly beats some of my expensive birding glasses (which is rather vexing !) in a direct comparison when viewing waders up to 100m away. Whilst I was looking at the light-path I also noticed that internal construction is very clean and all optical surfaces seem to be multi-coated as stated. The coatings appear to be even and of good quality.

At first I found the focussing to be lumpy and stiff with plenty of delay when changing direction. After a couple of days I introduced a very tiny drop of WD-40 into the top of the focuser and kept on using the binoculars normally for another few days. This seemed to do the trick and now the focussing is much smoother with hardly any delay.

Despite these set-backs I’m still very impressed with my purchase. Resistance to flare is excellent, central definition is superb, eye relief is good enough for use with glasses on, they’re bright and built like a tank for very little money.

Edited by Dog Star (09/04/06 11:53 AM)


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charen
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Reged: 05/28/05
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Re: Oberwerk 8x40 Mariner - brief review new [Re: Dog Star]
      #1132493 - 09/05/06 12:12 AM

Good 'mini review' - re. 'your small baffle behind the lens issue', I though I had the same concern with my Meade 9x63's. I measured the clear aperture to be about 58mm - I was positive there was a baffle behind the main lens reducing the aperture, it was black and I could see it plainly, however, I was assured by a experienced binocular repair technician that this is a 'optical illusion' and when you remove the objective lens of the Meades there is no baffle and there is a clear 63mms of aperture. He says this 'optical illusion' occours with other binos as well. He himself admits it 'looks' like there is a baffle but it is not there. Could this explain your impression of there being a baffle also ?

Edited by charen (09/05/06 06:44 AM)


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patter1
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Re: Oberwerk 8x40 Mariner - brief review new [Re: charen]
      #1132667 - 09/05/06 03:44 AM

You could measure the exit pupil to see if you're getting full aperture. Dog Star, did it measure a full 5mm?

I have an 11x56 binoc whose exit pupil should be 5.1mm, but measures to 4.6mm. One possible explanation would be that the magnification is much closer to 12x than the 11x it's supposed to be. But I doubt that, because presumably then it would've been called a 12x56 rather than 11x56.

I've also seen that appearance of a baffle right behind the objectives. If the exit pupil measures as it should, then I suspect it could be the reflection of the binoc's dew shield.


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DJB
Carpal Tunnel


Reged: 02/23/05
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Re: Oberwerk 8x40 Mariner - brief review new [Re: patter1]
      #1132705 - 09/05/06 05:47 AM

Hi Dog Star,

I have an OB 8x40 as well, and I concure with your observations.

When measuring the exit pupil, it is somewhat difficult. I use a flexible lab precision scale in "the vicinity" of the EP; it is difficult to get it precise when one's eye is too far behind the exact EP plane and estimating the measurement (depends on our eyes). The projection method onto a thin paper material is sometimes more conclusive.

I have to agree, that for the $$$, it is a good bang for the buck.

Best regards,
Dave.


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EdZ
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Re: Oberwerk 8x40 Mariner - brief review new [Re: DJB]
      #1132726 - 09/05/06 06:46 AM

Make sure when you test exit pupil the binocular was set to focus at infinity. A small 10x binocular set to close focus will havee a magnification closer to 10.5 to 10.75 and the exit pupil would get smaller due to focus.

The Oberwerk Mariner 10x60 does not have a full 6mm exit pupil. You can see what appears to be the objective lens seat inside the barrel, completely around the edges of the lens. The edges of the seat are a bit uneven around the edges. It is not a reflection from the outer barrel. However, there is a baffle half way down the objective barrel that could be the culprit. Also, the prism shelf aperture could be too small.

edz

--------------------
Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
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Dog Star
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Re: Oberwerk 8x40 Mariner - brief review new [Re: patter1]
      #1132733 - 09/05/06 07:06 AM

Just to clarify on the baffle. Yes unfortunately it's really there. When you examine the light path through the objective you can see that it's shielding the outer few millimetres of the objective from the eyepiece. I believe this is what's reducing the effective aperture and producing an exit pupil of around 4mm. The exit pupil size is clearly smaller when compared side by side with an old Swift 8x40. Perhaps one day if I'm brave enough I'll take it apart and see what happens if I remove the baffle.

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Glassthrower
Vendor - Galactic Stone & Ironworks


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Re: Oberwerk 8x40 Mariner - brief review new [Re: Dog Star]
      #1132895 - 09/05/06 10:37 AM

The baffle may reduce overall aperture, but it may also serve a useful purpose. By acting as a mask to stop-out the extreme outer edges of the objectives, it may increase the quality of the view. Stellarvue did something similar with their bigger 20x85 binoculars, which are actually a 20x90 with a 5mm aperture stop placed, in this case, in front of the objectives. The reason for doing this was stated that it increased the quality of the view. Perhaps this baffle in the Obie serves a similar function?

Clear dark skies...

MikeG

--------------------
Michael Gilmer - Member of the Meteoritical Society & Collector of Falling Stars.



☄ ⒼⒶⓁⒶⒸⓉⒾⒸ ⓈⓉⓄⓃⒺ ☞ www.galactic-stone.com


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charen
Pooh-Bah


Reged: 05/28/05
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Re: Oberwerk 8x40 Mariner - brief review new [Re: Glassthrower]
      #1134183 - 09/05/06 11:31 PM

Yes - but the Stellavues were advertised as '20x85s' binoculars - should the Oberwerk Mariner '8X40's be actually 8x48's and then stopped down to 40mm ?
8mm does seem a fair amount of clear aperture reduction esp. with this size bino. [even if CA is improved.] Sorry just being a bit pedantic.

--------------------
30 binos.
Celestron C8
Skywatcher Equinox ED120 / Goto HEQ5.


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patter1
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Reged: 01/19/05
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Re: Oberwerk 8x40 Mariner - brief review new [Re: charen]
      #1134456 - 09/06/06 03:23 AM

>>>8mm does seem a fair amount of clear aperture reduction esp. with this size bino. [even if CA is improved.] Sorry just being a bit pedantic.<<<

No, not pendantic at all. If it's true, then it really is an (approx.) 8x32, and shouldn't be advertised as an 8x40. This will continue as long as people accept it.

--------------------
Patrick

8" f/6 NewStar dobsonian
Orion Starblast 4.5" f/4 mini dobsonian
42mm SuperView, 17mm Nagler T4, some other cheapies
Omcon 7x50, Oberwerk 11x56, Olympus DPS-R 7x35, Olympus Magellan 8x25
homemade 50mm right-angle bino-scope prototype


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Dog Star
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Re: Oberwerk 8x40 Mariner - brief review new [Re: Dog Star]
      #1138421 - 09/08/06 08:49 AM

Just wanted to follow up and say that despite the effective aperture seeming to be less than 40mm, I'm still very impressed with these binoculars. I don't know if I'd recommend them for astronomy but they're quickly becoming a favourite for daylight viewing.

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Keithdrengen
scholastic sledgehammer


Reged: 02/20/08
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Re: Oberwerk 8x40 Mariner - brief review new [Re: Dog Star]
      #2345928 - 04/23/08 04:12 AM

How do they compare with Nikon Action extreme og Pentax WPII?
How is the bridge holding the oculars?
Thanks,
Carsten

Edited by Keithdrengen (04/23/08 04:19 AM)


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EdZ
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Re: Oberwerk 8x40 Mariner - brief review new [Re: Keithdrengen]
      #2345958 - 04/23/08 04:54 AM

See Small Binocular Reports _ A Dozen 8s.

edz

--------------------
Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
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Keithdrengen
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Re: Oberwerk 8x40 Mariner - brief review new [Re: EdZ]
      #2349007 - 04/24/08 12:23 PM

Thank you.
Would you gain anything by downsizing a Nikon Action EX 8x40 to 8x36, yourself? In edge sharpness for instance?

Carsten J


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EdZ
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Re: Oberwerk 8x40 Mariner - brief review new [Re: Keithdrengen]
      #2349114 - 04/24/08 01:06 PM

Hard to say what that would do. Hard to know how much of the aberration is contributed by the objective lens and how much by the eyepieces.

edz

--------------------
Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21


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