Staurastrum coronulatum

[Olympusman]

[carlos.uruguay]

Very nice

[RogelioMoreno]

Nice desmids.

Rogelio

[Olympusman]

Thanks, guys. I'm buying a 60X objective to better shoot these desmids. I have an Olympus 60X but it is a piece of junk (lots of flare and very poor contrast). I really don't want to get involved with oil objectives, though I have some and have found the procedures to be ponderous if not unprofitable.

[Ichthyophthirius]

Hi Mike, May I be so bold as to suggest that, rather than getting another objective, you could have a look at your camera adaptation first?

Your images taken at low magnification are OK but the ones at higher magnification are too grainy and have low contrast. You posted images of all these interesting histological slides; however, they should have come out better. Even with a simple digital camera you should be able to approach pictures that show what you see through the eyepieces.

Maybe we can give some advice. What camera, microscope and objectives are you using? Maybe you could post a picture of your set-up? Do you have other cameras available that you could use?

Regards, Ichthy

[Olympusman]

Icthy,
I am uisng a an Olympus E-420 on a Swift M3300 scope with a generic 10X relay lens. I have an amlost comlpete set of Olympus NFK eyepieces, but I have had bad problems with magnification and parfolaltiy.
I have tried a number of condensers and have setled with the one I am presently using.
I think the biggest problem is that the field condenser on my scope does not have a field diaphragm, so I cannot get true Koehler illumination.

[Ichthyophthirius]

Hi Mike, The lack of a field diaphragm is not ideal but it's not prohibitive either.

Ideally, please post an image of your microscope so we can work out some ideas. The Swift M3300 has a trinocular tube? What is the outer diameter? Are the objectives all Olympus (160 mm tube length, 45 mm parfocal length)?

If both are the case, the easiest would be the following:
NFK eyepiece - camera objective (prime lens) - Olympus E-420

What camera objectives do you have? For an APS-C camera, you would combine a 10x eyepiece and a 40mm to 50mm camera objective to get a good coverage. So in your case you could try different combinations, starting with an NFK 5x (10x eyepiece equivalent) + 25mm Zuiko objective (50mm equivalent for your chip-size).

I can also suggest a mechanical connexion but only if you post a photo of the microscope, otherwise there are too many variables.

Do you have a stage micrometer? It's usefull for tests.

Ichthy

[Olympusman]

Ichthy,
On the photo tube on the trinocular I am using a 10x widefeild objective. For relay lenses, I switch between an Olympus OM 50mm f1.4 and for more coverge an Olympus OM 28mm f3.5.
I have tried the NFKs, but the results were uneacceptable.
Yes, I have a stage micrometer and used it to go through all of my objectives to test for field flatness and chromatic aberration. From these tests I settled on the four objectives I am now using. I have a 4X generic a 10X Olympus, a 20X generic 0.40 160/.17 and an Olympus DPlan 40x 0.65 160.0.17.

[Ichthyophthirius]

Is the eyepiece in the phototube parfocal (by eye) with the eyepieces in the binocular tubes? Use the 4x objective for that test. If not, does it become parfocal if you lift it up?

Do you have an Olympus 10x high eyepoint eyepiece that you could (temporarily) use on the photo tube? Could you post an image of the stage micrometer taken with the Olympus DPlan 40/0.65?

[Olympusman]

Ichthy,
Looks like you are on the right track. Test shots with the 40X Olympus objective trying different eyepieces in the photo tube. The first is the generic eypiece I have ben using. Note the severe chromatic aberration, especially on the right.



Next is an Olympus WHK 10X/20L
Slightly better results


Next is an Olympus NFK 5X LD 125



Much cleaner and better contrast. I had previously tried my other NFKs but they were not parfocal. I had this lens on another scope and hadn't tested it on the Swift M-300D, but it is parfocal with minimal CA and better contrast. We'll see how it goes.
Thanks for your help.

Mike (AKA Olympusman)

[Ichthyophthirius]

Hi Mike, Nice improvement with the NFK 5x! Which camera objective did you use?

The NFKs can't be used to visual observation. To test the parfocality, you can only use the Olympus WHK 10X/20L. It should be parfocal with the binocular eyepieces (eyepieces without diopter adjustment). If it isn't, the tube length of the photoport might be wrong.

The images are very helpful. Do they show the entire shot or just a crop? If this is the entire field, than there's another problem: The CA should be concentric. However in your 3rd image, the blue fringes face to the top. Looking at the entire field, they should face inwards, towards the center.

Regards, Ichthy

[Olympusman]

I used a Olympus OM 50mm f1.4.
I think what remains of the CA could be attributable to the substage condenser. The Swift doesn't have a lot of leeway for centering the condenser. I have tried a number of condensers and this is the best I have come up with.
This is the entire image frame -- no cropping.