DR. HANNEMAN'S MINERAL COLLECTION WILL BE AVAILABLE FOR SALE IN THE NEAR FUTURE
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 Post subject: Advice on a 2nd hand GIA microscope, currently on eBay.co.uk
PostPosted: Tue Nov 10, 2020 10:22 am 
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Hi everyone,

I was hoping that one of the microscope gurus could have a quick look at a listing that's popped up on eBay for me please. My knowledge of microscopes is limited to what I've read on the various posts on this board, I don't think I've read about a "Custom A" before though.

I live in the UK so it's unusual to get a GIA scope listed on our eBay and, hopefully, luckily for me my microscope savings fund is currently at £980.00 so this one is within my reach. I'd be really grateful for any advice you might have regarding price, general quality of this particular model, what upgrade routes might be required and how easy they are? Plus finally, I'm a little concerned whether the magnification would be suitable as I've noticed a trend in the newer scopes for the magnification to creep up well beyond 40x and even get as high as 90x.

https://www.ebay.co.uk/itm/Gia-Custom-A ... d#rpdCntId

Thank you in advance,
Dan

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 Post subject: Re: Advice on a 2nd hand GIA microscope, currently on eBay.c
PostPosted: Tue Nov 10, 2020 11:58 am 
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That is my favorite GIA scope. It will give generations of good service. I note that the two fluorescent bulbs in the overhead light need to be replaced. That will add to the cost, but shouldn't be a big deal. less that $50 for the pair. Important to get the right color balance for these.

At the current price it is a bargain, let's hope it doesn't get bid up too high.


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 Post subject: Re: Advice on a 2nd hand GIA microscope, currently on eBay.c
PostPosted: Tue Nov 10, 2020 3:10 pm 
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Yeah, this is an excellent scope. Sturdy and serviceable base, good head too. If you have a friend with a 3d printer you can easily make an adapter to mount a newer head, but it is probably not necessary. The stereostar 570 is good and if really needed you can hunt down a 2x auxiliary lens for it, or 15 ultra widefield eyepieces.
I doubt it will go for 500 but you never know!

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 Post subject: Re: Advice on a 2nd hand GIA microscope, currently on eBay.c
PostPosted: Tue Nov 10, 2020 5:53 pm 
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Thank you both for the information.

Would you know roughly how old it might be? Googling around about the head, it seems quite aged! :) Are the older heads comparable to newer ones? Also, if needed, could you think of any heads that might drop straight in as an upgrade, or would they all need adaptors?

I'm sorry for all the questions and I really appreciate the help :)

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 Post subject: Re: Advice on a 2nd hand GIA microscope, currently on eBay.c
PostPosted: Tue Nov 10, 2020 10:31 pm 
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It's from the 90s or so. Newer heads may have a wider field of view but in this tier of stereo microscope other specs haven't budged much. The resolution of this head will be comparable to anything else in its tier today (its tier being medium to upper end 'routine' stereo microscopes, as opposed to higher end 'research' stereos). Some of the toppest end new routine stereos (like the Zeiss Stemi 508 or the Leica S9) will also have a wider zoom ratio and apochromatic color correction (meaning it's corrected for at least three wavelengths rather than two, so you don't get color fringing). Those would cost a lot more than the entire scope you're looking at, and if you get one you can adapt one on with a 3d printed adapter if you want one later. I haven't done it myself for this model, but I know someone who has. However that also comes with paradoxically lower build quality. There's a bit of plastic in an AO 570 but not much, and they tend to hold up quite well.

That being said, if you use it for a while and decide you need some other features (higher magnification, or particularly a trinocular head for better photography) I'd generally recommend trying to find a good used head rather than buying new. You can save a lot and get more powerful optics that way if you exercise some caution. It's not quite as easy over there as it is in the US though.

Just to give details on what type of adapter you'd need, the AO head has a round mount like a typical scope today, but it's ~98mm in diameter, while a standard one today is 76mm. It is very easy to design something to fit into that and accept a newer head.

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 Post subject: Re: Advice on a 2nd hand GIA microscope, currently on eBay.c
PostPosted: Wed Nov 11, 2020 6:13 am 
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Thanks Stephen for writing such a comprehensive answer. That answers my questions perfectly.

The listing is "collection in person only" which would mean breaking our lockdown rules in the UK, something I'm not willing to do as I feel it would be putting others at risk for my own gain. I've messaged him to try and set up a courier collection and if that is possible it's fingers crossed time. I'll let you know how I get on.

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 Post subject: Re: Advice on a 2nd hand GIA microscope, currently on eBay.c
PostPosted: Wed Nov 11, 2020 7:29 pm 
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Courier agreed so full steam ahead! :)

I seriously considered waiting the 4.5 days to see how much it went up from £500......
but 30 minutes later my willpower crumbled and I clicked "Buy It Now" as the price was almost exactly the same amount as I had saved up in the microscope piggy bank.

Good news is the seller answered all my questions, that I've gleaned from various forum posts, and it all sounds good, plus he sounds a nice guy which I think goes a long way. The only thing that hangs in the balance is whether or not it's aligned well. I'm not really sure how that works though. I've read and could carry out the process for checking it, but don't understand the physics behind it.

I'm really pleased and excited though, as my current scope (bought 6 years ago) cost £99 and is only lit from above with a single led, and has two magnification settings, no zoom.

I was considering a couple of aftermarket 15x wf eyepieces, which would cost an additional couple of hundred. When I asked more details about the scope, lo and behold, it has 15x wf eyepieces already fitted, giving me 63x max magnification!

I can't help feeling this one was meant to be. :)

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 Post subject: Re: Advice on a 2nd hand GIA microscope, currently on eBay.c
PostPosted: Sat Nov 14, 2020 9:26 am 
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The courier company were super fast so I now have my first "real" microscope. :)

First impressions on plugging it in have given me a few worries:

I panicked a bit that the collimation (if that's the right word?) was out of alignment and I had a big problem, because going from max to min zoom and vice versa required nearly a whole half turn on the focus wheel to get things refocused. After a bit of fiddling, I've tracked it down to the left-hand eyepiece. Looking through the right only, there is no loss of focus, but looking through the left one only gives the focusing problem. By a process of trial and error I’ve discovered that pulling the eyepiece up out of its socket by about 5mm completely solves the problem.

Does anyone know what might be causing this? Is it normal for this to happen if the diopter adjustment isn’t correct?

2nd problem is that there doesn’t seem to be a diopter adjustment anywhere. The left-hand eyepiece is grooved and looks like it could be turned, but it feels absolutely rock solid. Not in a “stuck” way, but in a totally rigid manufactured kind of way. I don’t want to force it and break it.

Last problem (I promise!) is that when winding the focus up and down, the gears seem to slip slightly. There is a quiet sort of clicking and it jumps/judders a bit. Is this likely to just be a symptom of wear and tear, and would it be a simple fix?

Sorry for all the questions. If anyone can contribute any answers I’d be really really grateful. Feeling a little bit worried that I may have bought a slight dud, due to the Covid restrictions meaning I couldn't view it before buying.

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 Post subject: Re: Advice on a 2nd hand GIA microscope, currently on eBay.c
PostPosted: Sat Nov 14, 2020 10:23 am 
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Hopefully this is just a problem of getting the oculars adjusted properly for your eyes. This is something you need to do frequently as your eyes change daily.

These are G.I.A.s instructions for doing this.

It’s important to focus your microscope before you begin each work session. You
should also refocus it periodically during long work sessions. Follow these steps:
1. Turn the well light on. Make sure the baffle and iris diaphragm are closed. At
10X magnification and using both eyes, focus on the iris diaphragm, which is
near the center of the field of view. Most gem microscopes have one ocular
(usually the left) that you can focus without the focus-control knob. Remove
that ocular and look through the right ocular, keeping both eyes open.
2. Turn the focus-control knob until the iris diaphragm is in focus in your right
eye. Release the focus-control knob. Don’t touch it again until after you focus
the left ocular.
3. Replace the left ocular. Remove the right ocular and look through the left
ocular, keeping both eyes open. Hold the left ocular firmly in place and bring
the iris diaphragm into focus by turning the ring at the bottom of the ocular.
4. Replace the right ocular. Adjust the distance between the oculars for your
comfort. Confirm the focus by looking at the iris diaphragm through both
oculars at the same time. You should see a single image, and it should look
sharp and three-dimensional. If it doesn’t, repeat the focusing process


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 Post subject: Re: Advice on a 2nd hand GIA microscope, currently on eBay.c
PostPosted: Sat Nov 14, 2020 12:24 pm 
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Thank you for the advice about setup. I took my heart in my hands and gave the ocular an almighty twist to see if it was just seized up. You'll be pleased to know that it didn't come off in my hands :lol: But loosened up and is now working as it should. There were a few metal splinters and some fresh shiny metal left behind, so the previous owner must have really screwed it down hard.

With the diopter set correctly, the collimation issue is almost resolved. Whereas it was out by a whole 180° turn of the focus knob before, the difference from min to max mag is only a 10° turn now. I can live with that.

I've ordered some cleaning materials and I'm hoping that giving the focusing rack a good clean with a toothbrush might remove any stray lubricant and stop the slippage?

I've found some haziness on a few lenses, which will hopefully mean an even brighter, sharper image once they are cleaned up. I've ordered some 99.9% isopropyl alcohol and some quality cotton buds (q tips) for that job. Hopefully that's correct based on what I've read: Small amounts of alcohol and lots of fresh cotton buds.

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 Post subject: Re: Advice on a 2nd hand GIA microscope, currently on eBay.c
PostPosted: Sat Nov 14, 2020 5:22 pm 
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Glad it worked for you! I'll need to look at my 580 to see the eyepiece situation. I think there is probably an adjustment for both eyepieces which is what is needed to get the image parfocsl throughout the zoom range.
Thr focus mount probanly has a built in tension adjustment, likely with some bolts. I have onky adjusted it on bausch and lomb ones but they're broadly similar.
15x wf eyepieces are good but keep an eye out for 15x uwf ones from Bausch and Lomb. They kick the scope up a notch.
Alochol and q tips will work. Be sure to use a minimal amount of alcohol or it will leave smears.

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 Post subject: Re: Advice on a 2nd hand GIA microscope, currently on eBay.c
PostPosted: Sat Nov 14, 2020 5:46 pm 
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Thanks Stephen. I'll keep a search running for the uwf eyepieces.

I found a .pdf of the original manual online and it explains how to adjust the focus tension. It's a really neat system where you just turn the focusing knobs in opposite directions to each other. I was expecting hex bolts and all sorts!

I've linked the page with the manuals in case they are useful to anyone else.

http://mightyohm.com/wiki/resources:stereostar

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