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mix and match scope/eyepiece brands

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Old Monday 5th December 2005, 18:22   #1
jekatz
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mix and match scope/eyepiece brands

At risk of beating a dead horse, throwing good money after bad, or just sounding like a total ninny, I could use some input from some self styled engineers. I read a review on this forum I believe where it was suggested that though not readily interchangeable, the image through an EO Raven could be improved by using another manufacturer's eyepiece. My Raven has what I would describe as a three-flange bayonet, and I notice most others do too. The two primary concerns would be:

a) the tension on the bayonet, or in other words the length from the mating surface to the flanges, which could be altered unobtrusively (in one direction) with spacers, or possibly in the other direction by having it machined, and

b) the ability of the scope to focus with the new eyepiece, or the ability to maintain the proper distance between the objective lens and the objective end of the eyepiece (clearly I have only an elementary understanding of what the heck goes on in my scope when I look through it).

Has anyone ever tried anything like this? It is an expensive experiment, but I was considering buying something like a Kowa 32x WA eyepiece and investigating what would be needed to mate it up to my EO Raven. I also am aware that the actual magnification (and other specs) will not be that listed on the eyepiece, so maybe a zoom would be better, but I am curious about what liberties people take with their scopes.

thanks
Jon
Northern CA
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Old Wednesday 7th December 2005, 10:17   #2
iporali
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Quote:
Originally Posted by jekatz
The two primary concerns would be:

a) the tension on the bayonet, or in other words the length from the mating surface to the flanges, which could be altered unobtrusively (in one direction) with spacers, or possibly in the other direction by having it machined, and

b) the ability of the scope to focus with the new eyepiece, or the ability to maintain the proper distance between the objective lens and the objective end of the eyepiece (clearly I have only an elementary understanding of what the heck goes on in my scope when I look through it).
Hi Jon,

In the absence of knowledgeable responses I thought I could throw in my opinion. I like your brave idea to try to mix and match optics: eg. I would very much like to have the Zeiss zoom on my Swarovski scope and maybe also the Leica 20x wide-angle for digiscoping . But as you are clearly aware, there are some concerns.

Without ever testing this, I would imagine that the major issue is the diameter of the eyepiece hole on the scope. Those bayonet wings should be quite easy to machine or remove (and I have heard it has been done), but if the eyepiece cannot be inserted through the hole, I wouldn't bother making it larger. On the other hand if the hole is too large, centering of the eyepiece may be difficult. Again, you may be able to adapt the bayonets, but if the eyepiece has some lateral play, all kinds of aberrations may appear in the image.

The ability to focus the setup depends on how much range the scope focuser has. If your EO Raven can focus past the moon and the stars, you may have a chance to create an adapter ring which comes between the scope and the eyepiece (something like this http://www.kendrickastro.com/astro/spt_swarovski.html). If there is not enough overfocus range, your system will not reach focus at infinity - this is what the above mentioned astro eyepiece adapter does with my Swaro on long focal length eyepieces - of course, the benefit is that close focus gets better .

You could take your scope in a store (where they sell eyepieces) and hold different eyepieces loosely on the ep-mount. If you focus on the close-up targets, you should see roughly how the new eyepiece behaves compared to your old one (in terms of magnification, field-of-view etc.). And also, whether there is any chance to fit it inside the eyepiece-mount. Do let us know, what you have found out.

Best of luck.

Ilkka

ps. The Kowa 32x's focal length is 14mm, which means that on the Raven (420mm) it should be about 30x (scope fl/ep fl = magnification)
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Old Thursday 5th January 2006, 01:14   #3
A. Leopold
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interchangeable eyepieces

Quote:
Originally Posted by jekatz
At risk of beating a dead horse, throwing good money after bad, or just sounding like a total ninny, I could use some input from some self styled engineers. I read a review on this forum I believe where it was suggested that though not readily interchangeable, the image through an EO Raven could be improved by using another manufacturer's eyepiece. My Raven has what I would describe as a three-flange bayonet, and I notice most others do too. The two primary concerns would be:

a) the tension on the bayonet, or in other words the length from the mating surface to the flanges, which could be altered unobtrusively (in one direction) with spacers, or possibly in the other direction by having it machined, and

b) the ability of the scope to focus with the new eyepiece, or the ability to maintain the proper distance between the objective lens and the objective end of the eyepiece (clearly I have only an elementary understanding of what the heck goes on in my scope when I look through it).

Has anyone ever tried anything like this? It is an expensive experiment, but I was considering buying something like a Kowa 32x WA eyepiece and investigating what would be needed to mate it up to my EO Raven. I also am aware that the actual magnification (and other specs) will not be that listed on the eyepiece, so maybe a zoom would be better, but I am curious about what liberties people take with their scopes.

thanks
Jon
Northern CA

Hi Everyone,

New forum member here. I just wanted to write and give a little two cents worth on this particular topic if I may. I recently purchased an EO Raven and am quite pleased with it...to a point. Like everyone, any zooming in past 40X and it starts to get bad, so I decided to look into switching to the fixed 30X eyepiece. So I called Eagle Optics tonight and asked about this. The first thing the gentleman told me was that, that eyepiece (the 30X) is discontinued because they could not find a decent quality fixed eyepiece for the Raven. I guess they didn't like the 30X quality. Second, I asked about a third party eyepiece, and he told me that the only one he has heard of that has worked is the Kowa 30X WA (wide angle) 66/60mm. He told me though, that it may fit a little loose. I asked him if the Raven is an older scope and he said no, that it came out in 2005. I guess they only made the two (now one) eyepieces. I hope this helps, because I am in the same boat. Thanks for your time. I really enjoy the forum and look forward to any responses.

Keith
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Old Thursday 5th January 2006, 05:28   #4
Tom Bombadil
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If someone would be using a 30X wide angle most of the time, I would probably buy something like a Kowa 66mm with their 30X over buying a Raven, then removing the zoom eyepiece and trying to use a Kowa 30X. Not much of a price difference between them at that point and you get a perfectly matched setup.

But if you still use the Raven zoom eyepiece a lot, swapping in the 30X occasionally, then you might still go that way.

Last edited by Tom Bombadil : Thursday 5th January 2006 at 05:31.
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Old Thursday 5th January 2006, 15:35   #5
Henry B
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Welcome to Birdforum,Keith.
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Old Saturday 7th January 2006, 02:02   #6
A. Leopold
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Quote:
Originally Posted by Tom Bombadil
Interesting. Being a "little loose" would mean that it wouldn't be waterproof with that eyepiece on it.
Hi everyone,

Tom, I asked him that exact question. Would the loose eyepiece conflict with the Raven being waterproof, especially around the eyepiece fitting.I also asked if it would void the lifetime EO warranty. To be honest, he really couldn't give me a straight answer. He told me he didn't think it would hurt the waterproofness, but his whole reaction made me a little skeptical about trying it without doing more research. I hope this adds a little more insight. Have a good night all, and happy birding.

Keith
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Old Saturday 7th January 2006, 02:47   #7
Tom Bombadil
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Hard to imagine how an eyepiece could be any less than a tight fit and for the scope to still be waterproof.

It would be fun to have access to all of this gear and play around with it.

It is too bad that spotting scope manufacturers have to use different mounts and threads, like cameras, instead of universal fittings, like telescopes.
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Old Monday 9th January 2006, 02:39   #8
jekatz
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Quote:
Originally Posted by iporali

The ability to focus the setup depends on how much range the scope focuser has. If your EO Raven can focus past the moon and the stars, you may have a chance to create an adapter ring which comes between the scope and the eyepiece (something like this http://www.kendrickastro.com/astro/spt_swarovski.html). If there is not enough overfocus range, your system will not reach focus at infinity - this is what the above mentioned astro eyepiece adapter does with my Swaro on long focal length eyepieces - of course, the benefit is that close focus gets better .
I at first believed that the infinity focus of the Raven would allow for an astronomical eyepiece, as it seemed to have many turns beyond a useful infinity (as tested at a vast local waterfowl refuge). However, preliminary tests with a cheap astronomical eyepiece proved you right, Ilkka; adapting an astronomical eyepiece would severly and prematurely limit the focusing range, and that is no improvement over the stock zoom eyepiece.

Jon
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Old Saturday 16th September 2006, 01:03   #9
vincent2920
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I know this is an old post but I was wondering if you tried or had any luck using another eyepiece with the Raven scope. I've had the scope for a while and also tried to get their 30x wide angle eyepiece but was also told it was discontinued. If you can also send me an email at [email protected], I would appreciate it . I don't check this site too often. Thanks alot.
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Old Saturday 14th October 2006, 01:03   #10
vincent2920
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For those who might be interested I just borrowed a Kowa 30x wa 60/66mm eyepiece from a friend and attached to my Eagle Optics Raven scope. The eyepiece fit and there is no looseness at all. There is a very tiny gap between the housing of the eyepiece and the housing of the scope but it in no way affects the fit. I guess if you wanted to you could make a little handmade washer to fit the gap. As for the results , the clarity is great , no apparent problems at all. Maybe I'm getting too old but I don't see a big difference between the Kowa 30x and the Eagle zoom eyepiece at the 20-30x power, at least not enough to lay out $200 or more for the Kowa.
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