Condenser Question

[Plasmid]

Hello, I need some help on figuring out which condenser and how to use it. My Microstar IV came with an Abbe 1970, it does not have a slot for a filter and so I opted to purchase a AO 1087 since it comes with the slot to insert Stop Patch filters. The 1087 comes with a swing in concave lens below the condenser, which I have no Idea on what its used for, or how to use it. I have notice that the Iris plays no role in the light intensity when the swing in filter is (in) also lowering the condenser has no effect.
so a couple of questions.
Is the 1087 an oil condenser like the 1970?
What is the swing in filter at the bottom of the 1087 for?
what size stopatch filters can be used on the 1087 slot? ( the 32mm filters I have just fall right out)
how close to the underside of the slide does the condenser have to be in order to use oil immersion?
is there any advantages of using one vs the other (1970 vs 1087)
and..... the very basic darkfield stoppatch filters I do have work great with the 4x neoplan and 10x 160mm acro ( I know its not infiniti but I had an extra slot open on the nosepiece) but cannot focus with my 10x Neoplan or anything higher for that matter. What is needed in order to achieve clarity with higher power objectives, do I need better filters?
Thank you all, I know its alot but I have not been able to find much info.
Adrian.

[apochronaut]

The 1087 and 1970 are both 1.25 N.A. oil immersion abbe aspheric condensers. They both have the same dovetail and can both be used on either the AO 100 series microscopes or the AO/Reichert 400 series microscopes. Why the 1970 was not made with a filter slot the same as the 1087 , I have not figured out. It has a slot down there but not one that can receive and hold anything circular.
However, the dovetail and filter slot section of both those condenser bodies is interchangeable, by removing the two cheese head recessed slot head screws and the one exposed registration screw. So, if you wanted to put the filter slot on the 1970, you can.

Both condensers do the same things, except for 1. The 1970 has lenses of a greater diameter, so will produce a better corrected wide field. In order to get the same field coverage with the 1087, you need to swing that auxilliary lens in.
This only affects objectives of 4X and lower.

With the 4X 1731 objective the 1970 will fill the field with light. For the 1730, 2.5X objective , the 1970 also needs a swing in aux. condenser. The correct one has slightly different optical characteristics than the one fitted to the 1087 but I have been able to get the aux. condenser from a 1087 to work with the 2.5X 1730 . It just requires a little vertical adjustment.

The 1087 was never designed to be used with an objective of lower magnification than 4X. To use the #1028 2.5 X and have a fully lit field, you had to have an entirely different condenser, with a flip off top element.

What I would do if I was you, is swap the filter and aux. condenser lens over to the 1970. That way, if a 2.5X objective should come your way, you will be able to use it.

Regarding your inability to focus the 10X Neoplan. It is a shorter objective, shorter than the 4X planachro and has a fairly long w.d. of 7mm or so if I recall correctly. Your stage can be set at a height to focus other objectives and the 10X Neoplan won't focus before you hit the focus stop.
Some Microstars were set up for scholastic use and the stage might have been adjusted a little too low to avoid objective slide collisions. Raise your stage a mm or so and see if that works.

[Plasmid]

Thank you, Will definitely be doing the swap, now the diameter is 32mm, does that mean I will need a 34,33 or 35 mm filter so that it can sit on the aux holder?

[apochronaut]

You are swapping the entire dovetail section with the filter slot. The size of the filter should stay the same. I measure the bottom port for both the 1970 and the 1087 at 32mm. Whatever filters you are using should still work.
I have seen (actually own) 1970's with the filter tray. It is the same part that is on the 1087.

[Plasmid]

So I completed the swab, and was left with a couple of questions.
1. The 1087 holder fit perfectly into the 1970, however that was not the case the other way around, it seems like the inner lip diameter of the original 1970 holder is wider than the diameter of the upper stage of the 1087 and so the Iris diaphragm arm wobbles a bit since its not flushed. Not of any importance since I intend to use the 1970 primarily.That being said I did not understand If I need to leave the substage lens that came with the 1087 on the 1970? As of now my lowest objective is a 4x.
I also notice that one of the Iris was dried compared to the other that had some type of lubrication (pretty sure its Slickoneum); Is this a part that requires lubrication? And if so what type? My common sense tells me that any type of lube would overheat with prolonged used from the substage light but I could be wrong.
Thank you.

[Greg Howald]

I think I saw a swing out lens at the bottom of one of the condenser photos you have included here. You asked what the swing out filter was for. If that is what you were asking about I have an answer for you. It is rarely seen on today's scopes except for those which are most sophisticated.
Swinging in the lens reduces the n/a of the condenser lens to give better focus and contrast at magnification from 40x and above.
In some models the lens can be removed from its holder and other filters can be inserted.
Good luck with it.

Greg

[apochronaut]

I think I saw a swing out lens at the bottom of one of the condenser photos you have included here. You asked what the swing out filter was for. If that is what you were asking about I have an answer for you. It is rarely seen on today's scopes except for those which are most sophisticated.
Swinging in the lens reduces the n/a of the condenser lens to give better focus and contrast at magnification from 40x and above.
In some models the lens can be removed from its holder and other filters can be inserted.
Good luck with it.

Greg

I'm not sure if you intended to but your explanation came out backwards. Yes, the swing in aux. condenser does reduce the N.A. and also increases the field coverage of the illumination beam. This allows very low power objectives, to be used with a fully illuminated field, when if used with the condenser at it's full N.A. there would be an illuminated center spot in the field. In the case of the 1970 condenser above it is down to a 2.5X with a 20mm f.o.v.
The aux. condenser limits the condenser's N.A. Usually a reduction in resolution is not apparent up to about the 10X . 25 objective but it is with 20X and above.

[Plasmid]

I think I saw a swing out lens at the bottom of one of the condenser photos you have included here. You asked what the swing out filter was for. If that is what you were asking about I have an answer for you. It is rarely seen on today's scopes except for those which are most sophisticated.
Swinging in the lens reduces the n/a of the condenser lens to give better focus and contrast at magnification from 40x and above.
In some models the lens can be removed from its holder and other filters can be inserted.
Good luck with it.

Greg

I'm not sure if you intended to but your explanation came out backwards. Yes, the swing in aux. condenser does reduce the N.A. and also increases the field coverage of the illumination beam. This allows very low power objectives, to be used with a fully illuminated field, when if used with the condenser at it's full N.A. there would be an illuminated center spot in the field. In the case of the 1970 condenser above it is down to a 2.5X with a 20mm f.o.v.
The aux. condenser limits the condenser's N.A. Usually a reduction in resolution is not apparent up to about the 10X . 25 objective but it is with 20X and above.

I see, that would explain the bothersome bright spot when using the 1970 and 4x objective right in the middle of the field, so far I had been lowering the condenser and closing the Iris as much as possible, also the diaphragm knot on the base of the platform would help,.. but with the swing filter the light is disperse evenly. Thank you all.

[jjcook]

The 1087 and 1970 are both 1.25 N.A. oil immersion abbe aspheric condensers. They both have the same dovetail and can both be used on either the AO 100 series microscopes or the AO/Reichert 400 series microscopes. Why the 1970 was not made with a filter slot the same as the 1087 , I have not figured out. It has a slot down there but not one that can receive and hold anything circular.
However, the dovetail and filter slot section of both those condenser bodies is interchangeable, by removing the two cheese head recessed slot head screws and the one exposed registration screw. So, if you wanted to put the filter slot on the 1970, you can.

...

The 1087 was never designed to be used with an objective of lower magnification than 4X. To use the #1028 2.5 X and have a fully lit field, you had to have an entirely different condenser, with a flip off top element.

What I would do if I was you, is swap the filter and aux. condenser lens over to the 1970. That way, if a 2.5X objective should come your way, you will be able to use it.

I have an 1970 with the 1971 aux lens for 2.5x (only?) and the reason it seems to not include a filter slot is that the filter would interfere with the 1971 as it protrudes into the space, as pictured:

34EA8177-802E-444D-80E1-C4095FBD8A33.jpeg (115.65 KiB) Viewed 5256 times

[hans]

I see, that would explain the bothersome bright spot when using the 1970 and 4x objective right in the middle of the field...

Pretty sure this is not normal and that you should not need any swing-in lens for the 4X with the 1970. (Unless you have cover glass oiled to your condenser -- that stand no longer uniformly illuminates the 4X.) My unmodified stand does give very uniform illumination across the entire 4X field with no really obvious differences compared to the higher magnification objectives, just a very slight color shift and falloff of intensity toward the edge of the field.

I played around a bit with the condenser and field diaphragm and was unable to produce anything like a bright spot, assuming you mean the rest of the field is still illuminated and the spot you are seeing is not the opening in the field diaphragm. You might want to take the bottom cover off and check whether both collector lenses at the front and back of the black plastic mounting piece near the bulb are present. The first lens was missing from one of my stands, apparently fell out due to bed adhesive. I never tried using it with the missing lens but it seems plausible that could cause a bright spot if the filament is no longer properly defocused.

[apochronaut]

I have seen a spot in the middle of the field a couple of times and each time it turned out to be a changed air space in the condenser. One of the lenses was loose or had dropped down to contact a lower lens. Each time it was an achromat, so a more complex lens system than the 1970. The top lens of the 1970 sits about 1/4mm above it's bezel. You might check and see if it is still up there, or I suppose perhaps the bottom aspheric lens could be loose.
There was a thread about such a thing several years ago and I cannot remember what the cause was or who posted it.


Hans is perfectly correct. The 1970 has a wider field , so does not require the aux. lens in order to fill the field of the 4X. It is used with the 2.5X and does a great job, for a great objective. That is one of the big differences between the series 100 and 400. The # 1028 34mm parfocal 2.5X objective is far inferior to the 45mm parfocal , # 1730.