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PostPosted: Fri Feb 15, 2008 4:39 am 
I'm asking the following in the hopes someone has a proven method of coupling an Oly 510 and a Pentax PF 80 Angled Scope...

My first attempt was using the following stack:

Olympus 510 Camera
T Mount/T2 Adapter
Scopetronics Maxview 40 Eyepiece (w/ special "pentax" corrective lens)
Pentax Scope

I had thought my greatest problem would have been vignetting, but that was not as much of the problem as the one I am having with Focus. The center image is fairly sharp, but the perimeter of th entire frame is out of focus. I've tried inserting spacer tubes, but that only improved the vignetting problem. I originally bought the Maxview for use with my old Sony Point & Shoot, which provided somewhat acceptable results, but was limiting.
It was suggested that I obtain an "Old Style" Olympus 50mm lens, and utilize that with a coupling device directly to the Pentax's original 20-60 Zoom lens. I've not tried that as of yet, as I am still under the understanding (delusion) that adding more glass will only reduce the effective light throughput, and not acheive what I hope could be some brilliant results. I'm a bit further confused now that I just watched Gordon's video on Astrophotography. He's used only a tube to connect directly to his scope, but I don't think his type telescope uses the same optical principal my spotting scope does. I don't know if my problem is due to the 4/3 type camera, or possible the Pentax's needs a special "lens" to correctly place the focal point at the right position.

This is evidently an unusual request as all the Optics suppliers I've spoken with all say they have no idea what I would need to make this work. I can only assume its because the 510 is still relativley new and there is just not enough demand for a supplier to test and offer a working coupler for this setup.

Any help will be appreciated!


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PostPosted: Fri Feb 15, 2008 6:30 am 
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Hi Marc, I'm not sure this is going to help, but the type of DSLR shouldn't be a factor. If it's going to work, it'll work with any, be it Four thirds, Canon, or any other,

The trick with a telescope is making sure the light comes to focus where the camera's focal plane is, and this often involves mucking about with extension tubes. You shouldn't need an additional lens unless you're attempting eyepiece projection...

Remember that every optic is only corrected for a certain size imaging circle though, with DSLR lenses being corrected for an area which covers their sensors. Beyond this the quality would go down. Maybe your scope simply has a very small imaging circle at prime focus, hence the sharp middle and soft edges...


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 Post subject: Looking for clues
PostPosted: Fri Feb 15, 2008 3:52 pm 
Gordon...
Thank you for personally responding. I was half-hoping that you would see my post, then go back to your storage room where you have every camera, lens, and scope you've ever tested and then just put it all together and pronounce how to solve this perfectly!

Of course your explanation makes sense, and if indeed you are correct that the "imaging circle" in the scope is too small to optically mate the two, then perhaps that is why I may need this often suggested intermediate lens (eyepiece) to magnify the image from the scope to one that is large enough to project itself to the cameras image plane evenly.

I'm still hoping someone has crossed this bridge before and will still respond with their soloution. It's tough blazing new trails when no one else is along for the ride.....


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PostPosted: Fri Feb 15, 2008 10:51 pm 
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Hi marc,

I'm having a little difficulty understanding your exact optical train. I assume that the 'scope's objective lens feeds an eyepiece which then feeds the zoom lens which focuses the final image onto the camera sensor. This arrangement is shown in the section Afocal Imaging (Also Called "Digiscoping") on this TeleVue page.

I think the trick with this method is that the camera's zoom lens should be focussed at infinity. That forces the eyepiece to be at the correct distance from the telescope focal plane (see the diagram on the TeleVue page). That way the optics are all working in harmony rather than fighting each other. It probably also helps if the eyepiece is as close as is prudent to the zoom lens so that all the light leaving the eyepiece is captured.

Not sure if this helps. If my assumptions are wrong perhaps you could use that TeleVue page to tells us which imaging method you are using.

Bob.

_________________
Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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 Post subject: Optics Train
PostPosted: Sat Feb 16, 2008 4:53 am 
Bob..

I believe I am using the Focal Length Extended by Using Eyepiece Projection method as described.

Here is the link for the Maxview 40 eyepiece:

http://www.scopetronics.com/digiscoping.htm

If you scroll down, you will see a specific note on the Pentax PF80-ED and its refering to "A special Cell" to correct the optics.

So basically I am coupling the camera directly to the Maxview eyepeice via a T Ring/T2 Mount.

T mount ring & T2 adapter TO OM 4/3 E1 E300 E330 E500

EDIT: Link edited by Bob Andersson to restore page formatting

This One piece coupler has on one side an Olympus Bayonet Mount and the other side is a 42mm internal Thread that mates directly up to the Maxview Eyepiece (with the rubber eyecup removed)

Any ideas to make this work?????????


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PostPosted: Sat Feb 16, 2008 10:57 am 
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Hi marc,

So you are using Focal Length Extended by Using Eyepiece Projection thus:
Quote:
http://www.scopetronics.com/digiscoping.htm

If you scroll down, you will see a specific note on the Pentax PF80-ED and its referring to "A special Cell" to correct the optics.

As far as I can tell the only juxtaposition of "special cell" and "PF80" on the page you link to is in the paragraph (referring to the MaxView-PX) immediately below this picture:
Is the MaxView-PX the unit you are using? That paragraph goes on to say "The MaxViews are not zoom eyepieces, instead they are designed to get the most from the zoom on your camera". For those, like myself, who aren't familiar with the Sony DSC-F717 here's what it looks like:
    Image
    Image courtesy of Sony
To my mind that implies that you should be using Afocal Imaging (Also Called "Digiscoping") thus:
and that you need an adaptor to connect the MaxView-PX to the front of your zoom lens rather than directly to the camera. Mechanically possible, I'm sure, but it might put quite a strain on the zoom lens body. If the front of your zoom lens rotates during auto-focusing then you might want to disable that as well.

I hope this helps and that I haven't got even more confused. :?

Bob.

_________________
Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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 Post subject: Maxview
PostPosted: Sat Feb 16, 2008 4:08 pm 
Bob...

You are spot on as far as the setup.

The camera I originally used is a Sony DSC-P92 using Sony's Adapter housing.

http://www.camerahacker.com/Sony/VAD-PEA.html

This system was fine for the level I was seeking at the time.

Your suggestion of using an actual lens directly on the camera is one that I had begun to investigate. The 14-42 Zoom "Kit" lens is actually made of a hybrid "plastic" and I am not comfortable with coupling this via a step ring. It was recently suggested to me to pick up an old style Olympus Zuiko fixed 50mm lens (Real metal! & $10.00 +/-) and utilze this to couple to the Maxview. Theoretically this optical stack would be more likely to provide a flat and in focus view.

I'm beginning to think that the problem may be the Maxviews design, in that when I look at the Pentax Scopes Zoom lens , the last piece of glass is at the end, which then places it extremely close to the scopes mirror. The Maxview came equipped with an additional lens that screws into the Maxviews exit end. This in my mind mimics the Pentax zoom.

I'm going to call Televue and inquire what they may suggest here.

And if I may ask, how did you "Cut & paste" the pics & diagrams?


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 Post subject: Re: Maxview
PostPosted: Sat Feb 16, 2008 4:45 pm 
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marc wrote:
...And if I may ask, how did you "Cut & paste" the pics & diagrams?

I didn't. I just linked directly to the images on the TeleVue site using the [img]..[/img] tags. This is slightly naughty so I try only to do it in a good cause and always try to include an acknowledgement and link back to the original site. That's done in the hope that they gain some reciprocal benefit from the link.

I think your idea of a $10 Zuiko is very likely to solve your issue if you can fix the MaxView to the lens and you lose very little by trying it - it might even have other uses. I hope TeleVue are helpful although they may take the view that as none of the products you are using are made by them there is no reason other than goodwill why they should spend time on the issue.

Bob.

_________________
Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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