School Me on AO Darkfield

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rnabholz
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School Me on AO Darkfield

#1 Post by rnabholz » Thu May 19, 2016 3:24 pm

I have an AO Ten that I would like to outfit for high magnification darkfield, and have some questions.

I have what I believe is a 214f condenser, missing the centering screws and the collar

1. Anybody point me to a replacement part for the centering screws, original or otherwise that will work?

2. What is the function of the collar? Is it simply to prevent extraneous light from passing, or does it serve another purpose?

The scope has a Cat 1079 100x oil objective. If I understand correctly, I needed a Funnel Stop to make it work. I commonly see AO darkfield kits that come with 2 funnel stops and thought I read that they are different sizes.

1. What size do I need for my 1079?

2. Anybody know where I can get one?

3. Is there a Plan 100 that will work in this system, and dies it also require a Funnel Stop?

4. Do any other objectives require funnel stops?

My 10 has the 20w 1036 illuminator. Will that get the job done?

Thanks for any help

Rod

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Re: School Me on AO Darkfield

#2 Post by apochronaut » Thu May 19, 2016 9:15 pm

Post a picture of the condenser. Condensers made for the later microscopes, the 100 series and 400 series did not have centering screws, because the yoke has them already.

The collar probably doesn't do anything. Perhaps on the 10/20 there was a possibility of flare from the illuminator but it might have been more of a precaution rather than a necessity. I don't see such a structure on other condensers, not even AO DF condensers. Perhaps there was a concern , due to the gray finish, it being more reflective than black. Earlier and later stages and substages were black.

The 214F type condenser, spanned the period between the 15/35 scopes to the 10/20 scopes. Funnel stops were included in kits, for various objectives that could be used with that condenser. This included 160mm achromat , fluorite and apochromat objectives as well as 1079. The 1079 funnel stop is identified by having a part # stamped on it, 214-79. They are fairly available. I have one. There is a member I know who also has one available...in fact the whole objective in mint condition.

Planachro objective cat.# 1014 has an iris diaphragm. It is a better option. There is a member who has( had, not sure about now) one of those for sale.
No other objectives require N.A. reduction.

The 20 watt illuminator will do the job for all objectives except the 100X objective. You can get a sort of DF with 20 watts but you have to leave the iris open on the 1014 quite a lot to get a bright enough image, so it ends upo being a sort of grayfield. Generally speaking you need a 100 watt 20. 120 or 420 to do the job right. There is a cheap 120 on ebay right now, sans optics.

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Re: School Me on AO Darkfield

#3 Post by zzffnn » Thu May 19, 2016 11:16 pm

Rod,

To add to apo's comments:

Any objective NA higher than 0.85 needs iris or funnel stop.

Iris is far better, due to flexibility, especially for mounted diatoms. The darkfield (DF) NA you need can be anywhere between 0.65-1.1 and it changes from diatom to diatom. Funnel stops are fixed at around NA 0.85 (and setting that can be too conservative), while iris can be stopped at anywhere in its range. I have seen difference between DF NA 1.1 from 0.85.

Too much DF NA gives bright out-of-focus halos. Too little will kill resolution.

I have a machinist friend custom made me a set of funnel openings (edit: because we did not have an iris option). Each opening size (or DF NA) will cost around $20-$25 for a set of rear/drill, if your machinist does not already have that size. We chose to go in steps of NA 0.15 (0.65, 0.8, 0.95, 1.1) and made two caps.
Last edited by zzffnn on Fri May 20, 2016 12:33 am, edited 1 time in total.

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Re: School Me on AO Darkfield

#4 Post by rnabholz » Thu May 19, 2016 11:43 pm

Thanks Apo and zz.

Well I believe that I was incorrect with that I had - I was trying to recall from memory, and think I got it wrong.

Here are the pics
DFC1.jpg
DFC1.jpg (115.76 KiB) Viewed 3495 times
DF2.jpg
DF2.jpg (93.08 KiB) Viewed 3495 times
DF3.jpg
DF3.jpg (117.12 KiB) Viewed 3495 times
I think that this was for the older stands - it appears to be too small for the yoke on the 10.

So I will be starting from scratch. I am well pleased with this 10 - Would an Ortho Illuminator provide adequate illumination?

Phil - if the 120 I found was the one you were meaning, it is missing the lamp and nosepiece, not sure what sort of challenge and expense that would be.

If you could PM me and steer me towards that 100x Iris, I will give it a serious look, the usability with diatoms has recently become important to me ;^). I like the idea of a Plan objective in that range as some forms may stretch to the edges.

Thanks guys, I regret the bad information but appreciate a great deal your help.

Rod

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Re: School Me on AO Darkfield

#5 Post by zzffnn » Fri May 20, 2016 12:35 am

Rod,

apo will correct me if I am wrong:

The top lens of that condenser can be screwed out and fit into a base that fits your stand, say 214F's base for AO10.

Also, we made funnels tops, as we had no iris option for our objective. Otherwise we would have bought an iris objective.
Selling my Canon FD 200mm F/2.8 lens

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Re: School Me on AO Darkfield

#6 Post by rnabholz » Fri May 20, 2016 2:42 am

Thanks zz.

I wonder if this one will fit my Spencer 33? That might be fun to play around with.

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Re: School Me on AO Darkfield

#7 Post by zzffnn » Fri May 20, 2016 3:07 am

rnabholz wrote:Thanks zz.

I wonder if this one will fit my Spencer 33? That might be fun to play around with.
Jim,

Based on what Jim "apatientspider" said in my previous thread (in which you will find a condenser with a highly similar dovetail mount), it should:

viewtopic.php?f=16&t=2955

You may want to take that condenser to HomeDepot and search in the screws that they have. They likely have some fitting (imperial unit) ones.
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Re: School Me on AO Darkfield

#8 Post by apatientspider » Fri May 20, 2016 3:14 am

Rod,

Yes, you are correct - that darkfield condenser was for the older stands like the models 13 and 33 as well as some others from the 1920's thru 1940's. Beginning with the models 15 and 35 in the late 1940's the substage yoke was changed to a larger diameter and fitted with a nub to engage a notch at the back of the dovetail collar or ring on the condensers. If you can find the later size dovetail collar or have one made, you can make this condenser fit later models of scopes. However, beware, because even though it will fit the yokes of later series, it may not be tall enough under the stage. This one you have should work on models 15/35 and models 2/4. It may even be tall enough for the 10/20. Pretty sure though that even though it can be made to fit the model 110/120 substage yoke if fitted with the proper notched collar, it will not be tall enough. However, the condenser element itself could be put on a different mounting base and then it would probably work.

Yes, the ortho-illuminator will easily light a darkfield condenser. It will light you up as well, if you aren't careful. :D

Edit: And I see Fan has much faster fingers than I do.


Jim

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Re: School Me on AO Darkfield

#9 Post by rnabholz » Fri May 20, 2016 3:19 am

Thanks Jim.

Not sure what you meant about the Orthoilluminator? Do you mean that they are quite bright, or are they somehow dangerous? In ways other than dropping one on your toes?

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Re: School Me on AO Darkfield

#10 Post by zzffnn » Fri May 20, 2016 3:27 am

Orthoilluminator can get burning hot.

My condenser with dovetail highly similar (if not identical) to yours fit on AO4, but could not be perfectly centered under 10x objective, though it is about 85%-90% there. Not much difference at 20x objective or above, so much so that I though it was a perfect fit at my first test (then after Jim reminded me, I looked very carefully and found that flaw). But I am not sure if my condenser or scope were original (unmodified by previous owner).
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Re: School Me on AO Darkfield

#11 Post by apatientspider » Fri May 20, 2016 4:18 am

rnabholz wrote:Thanks Jim.

Not sure what you meant about the Orthoilluminator? Do you mean that they are quite bright, or are they somehow dangerous? In ways other than dropping one on your toes?

I meant that they are very bright - perhaps dangerously so, if you were to look at either the extra bright photo setting, or even the regular setting, for a length of time without one of the included filters in the turret wheels.

And as Fan said, they do get hot. Not only does the housing get very uncomfortably hot to the touch, but the concentrated light itself can be hot enough to damage some specimens if the filters aren't used - same as the old research lamps. I have an old A.O. model 370 (can on a stick) lamp that will melt vinyl plastic at 18 inches. DAMHIKT.

Jim

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Re: School Me on AO Darkfield

#12 Post by apochronaut » Fri May 20, 2016 2:17 pm

I thought you had a 110, Rod? The 214F will work on a 110 but it is a bit sloppy, because it has the dovetail that ended with the 10/20 series.That collar helps it sit level but you have to remove the centering screws because they overlap the existing ones in the yoke.
The condenser you really want is a 1096, if you have a 110. It is designed for the 100 and 400 series yoke and is a better condenser than the 214F anyway. It has a broader field due to it's toric lens and also seems to give a more highly resolved image. It probably works at a higher N.A., although AO doesn't say what that is. There is a 1096A, which is an updated version of the older toric condenser, the K2172 but even though it looks very much like the 1096, it has centering controls and the older dovetail. If you have a 10, then those are the ones you should be looking for.

I wouldn't worry too much about the ortho illuminator. Yes, it has heat but at that distance, it doesn't get into your work. It would also be fairly easy to retrofit it to 100 watt halogen , with a variable power supply.

The 120, you found, sounds like the one, I was referring to. There is a 5 hole nosepiece on ebay too. You will need a 10 amp 12v. power supply.

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Re: School Me on AO Darkfield

#13 Post by apochronaut » Fri May 20, 2016 2:36 pm

zzffnn wrote:Rod,

To add to apo's comments:

Any objective NA higher than 0.85 needs iris or funnel stop.

There are no AO infinity corrected objectives with an N.A. above .85, with the exception of the 100X objectives.

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Re: School Me on AO Darkfield

#14 Post by rnabholz » Fri May 20, 2016 7:23 pm

Thanks Apo,

I do have a One Ten. I would consider a 1096, but I have been watching for one for sometime now and have not seen one show up.

That said, my thinking was that the One Ten would stay as is for now, I really like that stand as it is today, and as discussed it's light source may be a bit anemic for highpower DF.

I already have this nice 10, and with the addition of a condenser and funnel stop, I could make it a dedicated darkfield stand. And, depending on how efficiently (read cheaply) I am able to source the condenser and funnel stop, I should be able to spring for an Ortho Illuminator, with the plan to ultimately, in Phase Two, grab one of those nice Plan Iris 100's.

So in Phase One I get a dedicated darkfield stand with a high power, photographically capable light source on a solid stand that is ready to go at the flip of a switch (No condenser changes, alignment, etc).

I am thinking I can pull Phase One together for a couple hundred bucks which I think would be much higher if I switched stands to satisfy the lighting issue.

Make any sense?

Thanks,

Rod

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Re: School Me on AO Darkfield

#15 Post by apochronaut » Sun May 22, 2016 10:11 pm

You should be getting an email from the owner of the 1014 , if he's interested.

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Re: School Me on AO Darkfield

#16 Post by rnabholz » Mon May 23, 2016 11:10 am

Thanks Apo.

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