Empty magnification? Lenses that fit my setup?

[Ludvig Friberg]

Hi there!

I just recently got hold of a Olympus bh-2 with some simple Olympus lenses. Yesterday I finally got the photo eyepiece in the mail and started to experiment a bit. I set it up so that its sharp in the oculars and the camera at the same plane. It seems very sharp when I view in the oculars with my eyes but I feel that the image ending up in my pictures could be a bit sharper. Looking at the liveview all zoomed in on my camera I can see that its never really tack sharp. I am assuming this is the fault of my lenses and not the NFK. I am building a adapter to try out some other lenses this evening so that will be interesting to compare. But it will not be the same magnification. I dont have a sea of cash so I am looking for something that I can use in the 2-10x range that gives ok results. I am mostly looking at photographing 3d things at the moment but slides with coverglass will also be of interest down the line. Since I will be stacking i think planar focus plane is not so important? Here is some pictures of my equipment:

[Alan Wood]

Ludvig

This recent post should help to reassure you:
http://www.photomacrography.net/forum/v ... hp?t=33406

Photos taken through a microscope need to be sharpened a lot in your editing software (Photoshop Elements, Paint Shop Pro, etcetera).

Alan Wood

[ChrisR]

Of your Enlarger lenses, the Rodagon 50mm f/2.8 should be best, followed by the 80mm El Nikkor.
Reverse them for above 1:1, particularly the 50mm.

The NFK is a high magnification, at 3.3x. That means you're losing the edges of your frames I expect.
2.5x suits 24 x 36 better
or the expensve 1.6x for APS.

[Ludvig Friberg]

Mr. Wood!

I would like to thank you for your fantastic online resource on Olympus microscopes.

So would you say that this is as good as it gets? How much does the design of the objective play? I assume that my objectives are made for looking at slides with coverglass and not 3d shapes. I would really like to try and get a bit more resolution for subjects of the size of small insects. What would be the next step?

Best Regards

Ludvig Friberg

[Ludvig Friberg]

Yes it is cropping a bit using the 3.3 but this camera (a7s) is fullformat and only 12MP. Even without this crop from 3.3 the sensor would be outperforming the resolution quite a bit. I intended to use a canon 5d3 but if there is no more resolution to get I think I will use the sony for its very good lightsensitivity.

[Charles Krebs]

With a full frame camera I would keep an eye out for the 2.5X NFK. The less you magnify the objective's image (but still "fill" the camera frame) the better your images will look from a resolution standpoint.

Also keep an eye out for objectives with higher numerical apertures for a given magnification. For example your 4/0.1 with the 3.3X NFK will give you 13.2X in camera with (in "photographic" terms) an effective aperture of f60. If you were to use a 4/0.16 objective with the 2.5X NFK you would be getting a 10X magnification in camera at an effective aperture of about f31. When it comes to diffraction losses the difference will be very noticeable.
In the first case the smallest detail you can hope to resolve is about 3.4 microns in size. In the second case the smallest detail you might resolve could be about 2.1 microns.

[ChrisR]

Charles - a "Have you tried" - because I expect you have, and Ludvig needs more parts.:

Without an NFK, and ignoring parfocality, what image size can you get on a sensor by direct projection - I'm assuming metalwork gets in the way?

Then a "What If" - you add a teleconverter to the camera body (possibly would need a short tube between)?

We've mentioned this possibility before but I can't find an answer.

Could this be a way to fill Ludvig's sensor better?
I realise it loses NFK "Korrection" - but may be worth a try, particularly at low NAs.

Ludvig, I'm guessing that a man who likes to play with enlarger lenses may have a teleconverter .

[Ludvig Friberg]

Thanks a lot for your help!

Is there anything special I should consider when buying lenses for this? Is it only Olympus I should look for so as to fit with the NFK CA correction and perhaps other things?

Also I am not ruling out getting some infinity objectives and a 200mm tele if that would dramatically increase resolution.

Best Regards

Ludvig Friberg

[ChrisR]

Look at Alan Wood's site for the Metallurgical objectives.
They don't use the (0.17)coverslip the Biologicals need.

At NA up to about 0.25 it doesn't matter, but if you go to higher magnificaitons such as a 20x NA 0.4, it starts to. You'll also want to check the Working Distance of the objectives. At anything below a few mm, it gets difficult to illuminate the subject.

For the scope with NFKs you'd stick to Olympus, but if you use an objective on a camera with tubes/bellows, then Nikon finites are better.
If you use a 200mm camera lens then it would be Nikon or Mitutoyo infinites.


If you find a Nikon 2.5x projection eyepiece, you could then probably use Nikon finite objectives on your scope, though there may be a non-parfocality issue. (Focus through eyepieces may not be correct for the camera). With Live View that's not necessarily a killer. Someone here must have tried it .

[Alan Wood]

ChrisR wrote:

Look at Alan Wood's site for the Metallurgical objectives.
They don't use the (0.17)coverslip the Biologicals need.

The BH-2 metallurgical objectives (MDPlan and MSPlan) are infinity-corrected so they need to be used with a tube lens as well as NFK photo eyepieces.

The BH metallurgical objectives (M and MPlan) are finite, 210mm tube length, and should be used with FK photo eyepieces.

Alan Wood