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 Post subject: Re: Best Used Scopes?
PostPosted: Wed Apr 27, 2011 12:55 pm 
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G4Lab wrote:
If you put 15x oculars on you can still have the "standard" 10x magnification with the zoom knob set at 0.7x


yeah, exactly the same 10.5X of the above suggested setup.

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 Post subject: Re: Best Used Scopes?
PostPosted: Wed Apr 27, 2011 4:47 pm 
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The scope arrived safely yesterday afternoon.

It looks brand new with the exception of the dried lubricant. It came with 15X oculars and not 10X as reported by the seller. But that's a good thing in my mind. =D>

I didn't have much time to play with it last night but my wife and I did look at some of her Spinel and sapphire rings as well as some other loose spessartite garnets. WOW! Opens up a whole new world!

Even though there's probably no real need for more magnification, once you get to full magnification it kind of makes you want to zoom in more to see the details of those other tiny little inclusions that show up at full magnification. I guess that's where the other attachments/accessories come into play.

At what point does the additional magnification start to have a negative effect on the quality of the viewed stones? In other words, when is to much magnification a bad thing?


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 Post subject: Re: Best Used Scopes?
PostPosted: Wed Apr 27, 2011 5:03 pm 
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mitch57 wrote:
At what point does the additional magnification start to have a negative effect on the quality of the viewed stones? In other words, when is to much magnification a bad thing?


i think you have enough mag to solve the majority of issues about inclusion without adding other lenses. Neverthless, sometimes an higher mag is required mostly when looking at very tiny features. in those cases you must be prepared to have your field of view deeply reduced, inspecting at 90, 100X or more by using duplicators or more powerful oculars can be an unconfortable but sometimes unavoidable experience.

ciao and congrats for your scope! :D
alberto

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 Post subject: Re: Best Used Scopes?
PostPosted: Wed Apr 27, 2011 7:06 pm 
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If you think you want more mag, the best way is to watch fleabay for a 2x objective lens.

You could also get a pair of 20x oculars but this is not really recommendable because on a stereo it will not really reveal many new details compared with a 15x. This is for optical reasons. (Search the forum for posts on Numerical Aperture or NA. Also Google "Empty Magnification") Also 20x oculars have lower and narrower eyepoints and make the scope more difficult to use.
The intraocular distance and parfocality of the two eyetubes have to be perfect with a 20x. I have had a pair of AO 20x oculars since about 1978. I will be pleased to sell them to you because I have used them maybe once.

Any method of increasing mag will also decrease field size and the depth of focus also goes down as mag goes up. (the depth of focus is the thickness of the sharp zone in the Z or optical axis of the scope direction)
Eventually you reach a point where you need to have a fine focus knob as on a compound scope. Very few stereos have these (Zeiss and Wild) and no AO or B&L scopes ever had them. Also as the mag goes up the amount of light that is incident on the specimen is "spread thinner" so that the illumination requirements also increase. You start needing a fiber optic illuminator.

20x oculars are more properly used in the domain of scopes that have 30mm diameter oculars (ie. later model wide field scopes like Zeiss, Wild , Nikon and similar)rather than the 23.2mm diameter on your Gemolite.

I am not surprised that the oculars turned out to be 15x. That is how GIA shipped them.


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 Post subject: Re: Best Used Scopes?
PostPosted: Thu Apr 28, 2011 10:15 am 
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G4Lab,

Thanks for all the great info!

At this point I think I will wait and see. I mainly want the extra mag out of curiosity more than out of need. Sometimes I see a very tiny inclusion at full mag which I would like to zoom in on just to see what it looks like when magnified further. It would be nice if I could zoom in to have a closer look.

Then again, I don't think I would want to leave the objective lens attached all the time which would require screwing it on when I wanted to use it and back off when I'm done. Especially since I would be loosing that field of view for normal use if I left it on.


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 Post subject: Re: Best Used Scopes?
PostPosted: Thu Apr 28, 2011 7:56 pm 
Just a couple of thoughts that re-inforce the advice Alberto and Gene have been giving you.

I bought a reasonably well-accessoried gemmo microscope about seven months ago. My rig offers the choice of x10 or x20 oculars, an x2 auxiliary objective and x1 - x6.5 zoom. This gives me the option of working with x10-x65, x10-130, x20-x130 or x20-x260 ranges of magnification. Here are some lessons learned:

1. As your confidence grows in handing your scope, you may be surprised at the percentage of your time you choose to spend working happily at x10 - x30.
2. Like Gene, I would not miss my x20 oculars if they were to leave home.
3. I would miss not having an x2 objective but I may only resort to fitting it about one time in ten that I have a session on the microscope.
4. Most of what a gemmo wants to look at is appreciably three-dimensional. This makes having some depth of field important.
5. For any given level of illumination of specimen, for each doubling in magnification, the amount of light entering your scope reduces as an inverse square. Eyes and cameras are both built to adjust for this - but only up to point. Most cameras are far more limited in their automatic light handling than are most eyes.
6. Get a 150w minimum output halogen bulb cold light source. It helps for camera work at above x30 and for much working above x50, I'd say it was a 'must have'
7. Occasional working at x130 is probably a practical limit - at least with my rig.

Of course, your needs may be different from mine - but good luck anyway and enjoy the microworld opening up to you.


Last edited by Kerensky on Fri Apr 29, 2011 3:46 pm, edited 1 time in total.

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 Post subject: Re: Best Used Scopes?
PostPosted: Fri Apr 29, 2011 12:05 am 
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Kerensky,

Thanks for advice. Kind of what I was thinking as well. Having to take the objective lens on and off would probably render that accessory rarely use unless there was some inclusion that was really bugging me that I needed a closer look at.

Speaking of the 3 dimensional aspect of it all... I'm currently struggling trying to keep the left and right eye focused and in the picture. If I tilt my head up, down, left, or right the slightest amount one eye tube goes dark. I know I can adjust the width of the eye tubes, which I've done, but I still struggle with losing one or the other frequently. I suspect that mastering this technique comes with practice no?

You mentioned cameras! Ah ha! That was going to be my next question. Where can I find accessories for the AO 570 so I can mount a digital camera for photos? And... What digital camera should I be looking at? I've already considered the Nikon D3100. I figured I could also use it for taking gem videos as well. Which brings up another question.

Where's the best place to get one of those small rotating mirror or white table top battery operated tables? I think that's the best way to really show off those phenomenal gemy gems!

Thanks for everyone's help on this stuff! You guys are great! =D> =D>


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 Post subject: Re: Best Used Scopes?
PostPosted: Fri Apr 29, 2011 10:12 am 
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If one eyetube is going dark you may not have the scope adjusted correctly or it may have , somewhere along the way, gotten knocked out of alignment.

Turn the scope onto bright field. Have the scope sitting in the position you use it in as far as table location especially height and so on. Have an assistant observe as you adjust the interpupillary distance. The scope will project two bright circles onto your eyes. The circles should be concentric with the pupils of your irises.

Then focus at high mag on some detail using the eyetube that does not have the focusing adjustment. Then using the adjustment that is adjustable focus the other side to match, not touching the main focusing knob.

Then double check the intrapupillary distance again.

You should have less problem with blanking out then.

You can blink between left and right eye. The view is not supposed to be identical since it is the difference in the two views that generates stereopsis in your brain.

However the image must not rotate or shift up and down. If it does the scope may be out of alignment. It may shift left to right a bit. That is part of the "convergence" that
generates the 3D

For photography you have essentially two choices.
One would be to buy the AO 580 that I posted on an adjacent thread. This would give you six to one zoom and it has a photoadaptation. You would need to remove the 35mm camera and the exposure meter and throw them away. (mostly nobody is ever going to shoot film again) and make an adaptation of the digital camera of your choice.
This task is substantially identical to adapting a Bausch and Lomb SZ-7 as Alberto shows in his avatar. Perhaps he would care to take some close up photos of how he accomplished it. He uses a C mount microscope camera that has no optics of its own.

This could require having made on a lathe , a ring that on one end grabs the photoadapter and on the other grabs a camera adapter you would buy on ebay which has a projective eyepiece (usually of less mag than the 10x or 15x that are used with the eyes) and a lens mount compatible with the particular camera.

You also could simply use a point and shoot or dSLR with a lens and shoot through one of your oculars. You could sent up a little table tripod that would hold the camera in the correct position or if your camera is not too heavy buy a gadget that bites the eyetube and holds the camera there.

If your camera has Live View you could have a video flat screen to preview what you would get and confirm accurate focus.


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 Post subject: Re: Best Used Scopes?
PostPosted: Fri Apr 29, 2011 10:32 am 
mitch57 wrote:
Kerensky,

Thanks for advice. Kind of what I was thinking as well. Having to take the objective lens on and off would probably render that accessory rarely use unless there was some inclusion that was really bugging me that I needed a closer look at.


IMO, there are two real downers against keeping the x2 objective permanently fitted:
- One would lose the ability to work at x10 - x20, which I find very useful and use a lot. Firstly, this lets one examine as a whole larger features than one can at x20+. Secondly, a larger field of view and depth of focus are very useful in first finding small targets of interest (at last some of which could well otherwise be overlooked). First finding points of interest and then adjusting magnification and, maybe, illumination levels and positions is a method that works for me.
- Unless your target is pretty much flat - and you can manipulate it normal to the central axis of observation (often impossible) you will usually want work with the most depth of field you can summon up. To illustrate the point, below is pic of what seem to be growth layers on the surface of a faceted crystal of Smithsonite at x130 mag. The pic only works at all because I could align the linear feature of prime interest into nearly the right position relative to the depth of field available.
Attachment:
Smithsonite 1-08b.JPG
Smithsonite 1-08b.JPG [ 142.22 KiB | Viewed 2866 times ]


Quote:
Speaking of the 3 dimensional aspect of it all... I'm currently struggling trying to keep the left and right eye focused and in the picture. If I tilt my head up, down, left, or right the slightest amount one eye tube goes dark. I know I can adjust the width of the eye tubes, which I've done, but I still struggle with losing one or the other frequently. I suspect that mastering this technique comes with practice no?


Yup. Practice makes perfect. You have the kit you bought and the eyes that God gave you. Now you need to make them work together in harmony.
1. If your scope came with instructions for setting up optimum focussing in a stereo zoom scope, follow these carefully and completely. If there are no instructions, ask by PM someone who uses the same optics as you for a few lines of instruction on how best to set it up. You will need to repeat this procedure from time to time - or at least I do.
2. If you do not have a pair of rubber cuffs on your oculars, I recommend that you get a pair. With these fitted, your eyes are properly positioned when your eyelids are in contact with the cuffs- so no bobbing about. With your eyes in that position, then use the inter-ocular distance adjustment to produce a single image of your field of view and which comfortably accommodates the bridge of your nose.

Quote:
You mentioned cameras! Ah ha! That was going to be my next question. Where can I find accessories for the AO 570 so I can mount a digital camera for photos? And... What digital camera should I be looking at? I've already considered the Nikon D3100. I figured I could also use it for taking gem videos as well. Which brings up another question.


Enough (from me for the mo) :wink:


Last edited by Kerensky on Fri Apr 29, 2011 3:53 pm, edited 1 time in total.

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 Post subject: Re: Best Used Scopes?
PostPosted: Fri Apr 29, 2011 10:56 am 
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Something like the D3100 is a little heavy to add onto the AO focusing mount although the tension can usually be adjusted. The Nikon F mount is one of the easier ones to find adaptations for, like the C mount. But you need to expect to spend a couple of extra hundred dollars to make that adaptation.

Remember you have two adaptations to make. The mechanical. (holding the camera where it needs to be.) and optical (projecting a sharp , parfocal with the oculars and correctly magnified [so that it covers the sensor and maximizes the optical AND camera resolution as well as is possible] image onto the camera sensor)

The problems you and Owen have been alluding to regarding auxiliary lenses can be easily solved by buying a Wild or Wild clone swing out auxiliary lens. In 90% of the cases these optics are optically compatible and so you have only to find one and make or have made a mounting ring which will screw into the front of your scope and have a surface for the auxiliary to clamp onto. Again the 580 would solve that problem too with its increased zoom range.

I bought a set of these , which are Wild clones but I consider it an excellent buy.

http://cgi.ebay.com/NEW-2x-Stereo-Micro ... 2eb187591a

http://cgi.ebay.com/NEW-1-5X-Stereo-Mic ... 2eb11f6ba2

http://cgi.ebay.com/NEW-0-5X-Stereo-Mic ... 2c589a8800

It would be a simple matter to deploy them to the front of an AO stereo.


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 Post subject: Re: Best Used Scopes?
PostPosted: Fri Apr 29, 2011 4:16 pm 
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My scope came with a pair of plastic, not rubber, cups which should accomplish the same thing.

On the camera, I think I will give my Nikon Coolpix point and shoot a try and see if I can take some photos through the oculars as suggested.

As usual, you guys are right on top of it with all the answers.

Thanks!


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 Post subject: Re: Best Used Scopes?
PostPosted: Fri Apr 29, 2011 4:32 pm 
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The AO oculars have hard plastic eyeshades not rubber.

There are gadgets you can buy that will clamp to the ocular tube and hold a camera like a Coolpix. The telescope company Orion has one. There are others. You can hook the Coolpix video out to a screen.

http://www.telescope.com/Accessories/Ad ... p/5338.uts

Focus your Coolpix at infinity and zoom to get the coverage you want.


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 Post subject: Re: Best Used Scopes?
PostPosted: Sun May 01, 2011 4:06 pm 
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Do I leave the eye shade on when I attach the camera? Which ocular tube should I attach it to? The left or right one or does it matter?


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 Post subject: Re: Best Used Scopes?
PostPosted: Sun May 01, 2011 5:46 pm 
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It is generally considered desirable to have a lens hood or eyecup in place if they don't interfere. It is good to block stray light from entering the camera.

It does not matter which side you put the camera on. You might try both sides and see if one or the other allows you to look through the uncamera'd ocular if you wish to. Most people prefer their dominant eye over the non dominant.


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 Post subject: Re: Best Used Scopes?
PostPosted: Sun May 01, 2011 7:15 pm 
You might think to take a look at another approach.

Take a look at some of the digital cameras built especially to use *in place* of one of your scope's oculars. These cameras are lightweight in comparison to a stand alone camera. There will be less mechanical wear and tear in the constant fitting and unfitting that is going to come your way. Also the mating of camera and pod is stable and entirely secure.

To use one of these, simply lift one of your oculars out of its socket and place the snout of the camera into the vacated socket. A adapttot sleeve you will get from the camera seller custom-fits the camera snout deep into the ocular barrel of your particular optical pod. Most cameras of this sort come with software that allows them to interface directly with a laptop via a USB link. This lets you use the (relatively) large laptop screen for viewing, making use of the remaining ocular or the small screen built into the camera unnecessary. Camera controls are also transferred to the PC solving little side issues like camera shake from a manual shutter release.


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