Mosquito wing for objective testing

[TonyT]

Such wings are the best fly wings thanks to the presence of scales on the veins in addition to the minute hairs on the wing membrane. This wing is 4.0 mm long
Mosquitoes are universally available!

Fig.1 is the tip of a wing showing the hairs, modified as scales, and the minute hairs (dots) on the membrane; a micrometer scale is superimposed in the bottom left corner, 1 division = 0.01 mm (10µ)
Fig.2 show the wing tip and micrometer scale in actual pixels. This objective easily separates lines that are 2 microns apart.
Fig. 3 micrometer scale taken with same setup.

Olympus 20x SPlan Apo + 1.25x + 2.5x; Nikon D810.

[Seta]

Your systems does work well indeed. Just one question..why do you use the 1.25X intermediate piece? to get better corners?
Is not the 2.5X photo eyepiece enough?

[apochronaut]

That's a start. Might be of value for choosing between very average achromats of low power but to determine the performance of objectives such as you are using , you need features that are sub. micron. If a 20X planapo isn't crisply defining a 2 micron separation it would be so poor in it's image formation that no measuring would be needed.
If there is a feature close to the line width of Surirella Gemma or Nitzhia Obtusa , .5 um or so, that would stress a 20X planapo some.
Something around the hair follicles maybe?

[TonyT]

I need the 1.25x for DIC; too lazy to remove it for non-DIC

[Seta]

Ok, I understand..
I am considering getting one of these magnifiers to use it with nikon CFN lenses
Olympus performs the corrections on the eyepiece, so I guess they are neutral and will work with the nikon lenses via direct projection.
That 1.25x is all I would need to remove the extreme corners from the equation.

[elvis_saya]

Just wanted to say that you make really impressive mounts and images!

[viktor j nilsson]

Ok, I understand..
I am considering getting one of this magnifiers to use it with nikon CFN lenses
Olympus performs the corrections on the eyepiece, so I guess this one is neutral guess it is neutral and will work with the nikon lenses via direct projection.
That 1.25x is all I would need to remove the extreme corners from the equation.

Getting a DIC intermediate tube seems like an expensive way to get 1.25x!

Kidding aside, it might be a good idea to get a magnification changer. The BH2-CA has settings for 1x, 1.25 and 1.5x. This can be nice if you want to clip the corners on some objectives (non-plan Fluors) but not others (Planapos). It also has a built-in bertrand lens, which is very nice to have.

Alternatively you could look for a BH2-KP polarizing attachment. They can be quite affordable. That would give you the 1.25x you want, and gives you the option to easily experiment with adding an analyzer and wave plates.

The olympus BH2 intermediate tubes are designed to be optically neutral - they only correct for the increased tube length. Of course, any extra glass in the path can have some effect on the image. But I think you can safely assume that Olympus made them to a rather high standard.

[Seta]

Getting a DIC intermediate tube seems like an expensive way to get 1.25x!

Kidding aside, it might be a good idea to get a magnification changer. The BH2-CA has settings for 1x, 1.25 and 1.5x. This can be nice if you want to clip the corners on some objectives (non-plan Fluors) but not others (Planapos). It also has a built-in bertrand lens, which is very nice to have.

Alternatively you could look for a BH2-KP polarizing attachment. They can be quite affordable. That would give you the 1.25x you want, and gives you the option to easily experiment with adding an analyzer and wave plates.

The olympus BH2 intermediate tubes are designed to be optically neutral - they only correct for the increased tube length. Of course, any extra glass in the path can have some effect on the image. But I think you can safely assume that Olympus made them to a rather high standard.

Thanks Viktor; it seems a quite affordable option compared to photo eyepieces, like NFK 1.67X for Olympus or CF 2x for Nikon. I will look them up
In fact I saw a full lineof accessories featuring such 1.25X magnifier for dual heads, sketch drawing and more; are BH and BH-2 fully compatible?

This BHT project is giving lots of work (and headaches!!)but may end up like a quite versatile one

[viktor j nilsson]

Getting a DIC intermediate tube seems like an expensive way to get 1.25x!

Kidding aside, it might be a good idea to get a magnification changer. The BH2-CA has settings for 1x, 1.25 and 1.5x. This can be nice if you want to clip the corners on some objectives (non-plan Fluors) but not others (Planapos). It also has a built-in bertrand lens, which is very nice to have.

Alternatively you could look for a BH2-KP polarizing attachment. They can be quite affordable. That would give you the 1.25x you want, and gives you the option to easily experiment with adding an analyzer and wave plates.

The olympus BH2 intermediate tubes are designed to be optically neutral - they only correct for the increased tube length. Of course, any extra glass in the path can have some effect on the image. But I think you can safely assume that Olympus made them to a rather high standard.

Thanks Viktor; it seems a quite affordable option compared to photo eyepieces, like NFK 1.67X for Olympus or CF 2x for Nikon. I will look them up
In fact I saw a full lineof accessories featuring such 1.25X magnifier for dual heads, sketch drawing and more; are BH and BH-2 fully compatible?

This BHT project is giving lots of work (and headaches!!)but may end up like a quite versatile one

Yes, the BH-2 and BH intermediate tubes are directly compabile. The condenser mounts are different, but the dovetails on the intermediate tube are the same. So you can also look for a BH era intermediate tube if you want to widen your search.

Even a lot of the photo adapters are compatible all the way from BH to BH2 and BX! Not many other makers were so generous.

Putting together a system from loose parts is a frustrating and rewarding experience - and the end result can be extremely versatile, as you say. But the Olympus system is very fun, thanks to the relatitvely good interchangeability of parts, and the excellent documentation.

[TonyT]

viktor j nilsson wrote:
``Getting a DIC intermediate tube seems like an expensive way to get 1.25x! (BH2-NA)
Alternatively you could look for a BH2-KP polarizing attachment.``

How do they differ?

[viktor j nilsson]

viktor j nilsson wrote:
``Getting a DIC intermediate tube seems like an expensive way to get 1.25x! (BH2-NA)
Alternatively you could look for a BH2-KP polarizing attachment.``

How do they differ?

You mean the dic intermediate tube and the bh2-kp?

The dic intermediate tube has, as you know, a slider with a translatable nomarski prism and a fixed analyzer above + an open port.

The BH2-KP has an opening for a slider with an analyzer, and below this there is space for a wave plate:


They are both fixed, no rotation. That's why it's called the "simple polarization intermediate tube"

The BH2-PA polarizing attachment is the one intended for real quantitative pol work, it has a rotatable analyzer, space for wave plates, and a built-in Bertrand lens:



For pure visual use and DIY experiments, the BH-KP is a great way to get access to the light path above the objective. It could also be used as a starting point for DIY experiments with DIC.

[Seta]

Couple of more question about these magnifiers..
- Do you know if the optical formula changed between BH to BH-2? Can I expect same field coverage/corner quality in APS-C?
- Will I be able to use it in conjunction with the PZO MIP5 Head?

[viktor j nilsson]

Couple of more question about these magnifiers..
- Do you know if the optical formula changed between BH to BH-2? Can I expect same field coverage/corner quality in APS-C?
- Will I be able to use it in conjunction with the PZO MIP5 Head?

Olympus catalogues from the BH era suggests that you can use all the intermediate tubes together with the Superwide head (field number 26.5), which to me suggests that they were made to cover a sufficiently large field. It is still, of course, possible that the later BH-2 era equipment is slightly improved optically (or in better condition)´.

Whether you can use it with the MPI-5 head depends on whether you are able to adapt the head to you Olympus system at all. Some intermediate pieces (the Zeiss epi fluoro condenser comes to mind) have telan lenses at the top that interferes with some dovetails. But based on photos of the Olympus offerings I can't see any optical elements that look to be problematic.

See for example page 11:
http://www.alanwood.net/downloads/olymp ... e-1977.pdf

[Seta]

Thanks for the link, that is a nice brochure

[viktor j nilsson]

Thanks for the link, that is a nice brochure

You should absolutely check out ALL the BH and BH2 brochures if you haven't already done so!
http://www.alanwood.net/olympus/downloads.html

[TonyT]

Thanks Viktor.
In the Olympus catalogues the BH2-NA and BH2-KPA intermediate tubes look identical externally.
They differ internally ? The BH2-NA has a fixed analyser which the KPA lacks ?
How does one determine if the tube has a fixed analyser?
I have 2 intermediate tubes, each just has a 1.25 X marking. How do I identify which each is ?

[viktor j nilsson]

Thanks Viktor.
In the Olympus catalogues the BH2-NA and BH2-KPA intermediate tubes look identical externally.
They differ internally ? The BH2-NA has a fixed analyser which the KPA lacks ?
How does one determine if the tube has a fixed analyser?
I have 2 intermediate tubes, each just has a 1.25 X marking. How do I identify which each is ?

You mean that the bodies of the two intermediate pieces are similar? Yes, very similar. If you remove the slider, they are pretty much the same thing: a 1.25x extender with a space for a slider. I'm not even sure if the dimensions of the slot differs. Maybe it's just the slider that differs? I don't know as I don't have a simple polarizing intermediate tube to compare with, I "only" have the older BH-NA dic intermediate tube and the BH-PA polarizing attachment.

You mean you have two intermediate tubes without a slider? If you have the sliders it should be very clear what they are.

[TonyT]

I still find it confusing.
I have 2 Intermediate Tubes and 2 sliders, one a DIC and the other for a polarizer + wave plate. The sliders are interchangeable.
The intermediate tubes have 2, what look like fixed, glass surfaces, one at the top and one at the bottom. The slider fits in the slot between the 2 glass surfaces.
I assume one glass is the 1.25x magnifier; the other glass ??

[viktor j nilsson]

So you can put the dic and pol sliders in either of them? Cool, that suggests that the housings are indeed identical.

Intermediate tubes need to have two lenses. In a finite system, the objective projects a converging bundle of light that comes to focus at the intermediate image plane located 10mm below the shoulder of the eyepiece.

The first lens is a negative lens that takes the converging bundle of light and turns it into parallel rays, creating an infinity space inside the intermediate tube. The second lens is a positive lens, which takes the parallel rays and make them convergent again.

This has two benefits. The first is the the optical tube length is maintained. The second is that flat and tilted optical accessories can be placed inside the infinity space without introducing optical abberrations. If they had been placed in the light path where the light rays were convergent, these optical elements would have caused all kinds of problems.

Here's a good illustration:

[fero]

Incredible resolution, Would like to check it with my SPlan APOs, was the wing mounted in water under cover glass?

Thank you,
Fero

[TonyT]

Wing mounted in Canada Balsam, under a coverslip.
I don't think you would get the best resolution if in water.
There is an image of the same wing taken with the 100x SPlan Apo here:
http://www.photomacrography.net/forum/v ... 30&t=43394