MicrobeHunter.com Microscopy Forum

Hello,

I can get some Gf-Planachromat objectives, but I'm not 100% sure of the specs.
I would like some details before deciding to purchase them.

aus JENA
GF Planachromat
25x / 0.50 ∞/0-A

My questions:
- What does 0-A mean? I guess 0 is for 'no coverslip' but this is the first time I see this A
- Can I use them for reflected light microscopy ?
- I suppose the thread size is not RMS?
- What tube lens I need? f = 200mm ? Or 180mm ?

Thank you!

Edit:
I found some information here: viewtopic.php?f=25&t=18239
It seems the system may be 250mm?
And these objectives are from 1960?
Do you think a lot of corrections are made the tube lens / eyepiece? What should I expect if I don't have the right match?

-A means it is internally corrected (ie part of the CF250 system, using a 250mm focal length tube length neutral tube lens, no eyepiece corrections).
-This one is meant for reflected light )but you could get away with transmitted light.)
-I believe they have a 25mm thread.
-250mm

Scarodactyl wrote: ↑

Fri Mar 01, 2024 10:14 pm

-A means it is internally corrected (ie part of the CF250 system, using a 250mm focal length tube length neutral tube lens, no eyepiece corrections).
-This one is meant for reflected light )but you could get away with transmitted light.)
-I believe they have a 25mm thread.
-250mm

Oh, so the A is good news.
Thanks a lot Scarodactyl!

What do you think is a good price for this kind of objectives? They seems rather old (1960 I think?).

Edit:
Note: this is the black version.

These are from the 80s from what I understand, pretty late in the Jena lineup. They come up pretty frequently on eBay. I have not tried them but reviews have been quite good.

FWIW, I adapted a Jena GF infinity zero cover 50x to Nikon infinity (25mm thread, 60mm parfocal). It does an OK job with smears (blood, chemical crystals, etc.) and no cover slip.

Oh cool, just using an m25 15mm long spacer? How did it dk in the corners being pushed down 20%?

Pretty much. I used an M25 thin spacer and a tube cut to CFI60 parfocal length, epoxied to the Jena objective. I've just used it casually for smears and it looks, visually, OK. Haven't taken photos or done any serious comparisons to see how the corners hold up. I'd think, for APS-C, they'd be decent.

I also found a very cheap BF/DF version of this objective, needing to be reduced down to 25mm and made parfocal. Haven't gotten around to using it with an epi-illuminator.
.
.

Thank you. I'll try to buy a 50x and a 25x.
They are 50€ each, seems to be a very reasonable price for this kind of objectives.

Yeah, that is a bargain.

So, I received and tested the objectives on my Olympus BH2 with the epi head.

The quality is really good and I'm pretty happy.

Using the 1.5x magnification of the magnification wheel.

GF Planachromat 50x/0.80 using focus stacking and channels alignment: By comparison my LWD MSPlan 50x/0.60 in the same conditions: Using the 1.0x of the magnification wheel, some contrast is lacking because I have to open the field diaphragm.

GF Planachromat 50x/0.80 By comparison my LWD MSPlan 50x/0.60 Note: I'm not taking images in the best conditions for the Olympus objectives. I'm using a eyepiece camera so no eyepiece corrections... But chromatic aberrations are fixed in post processing using focus stacking.
Same problem for the GF Planachromat, I'm using the 180mm tube lens of the BH2.

I made a 3d printed adapter to fit the M25 objectives.

Hello,

So I finally bought the complete set from the same seller (sadly, no 100x oil in the set) and I got a weird objective.
The one on the left: No infinity symbol on it: 1 x 0,03 spez/-A

I tried it with the same setup than other objectives but I don't have any image.
Any idea what is this "spez" ? And how to use this objective?

There is also a small "wheel" to move the front element.

Thank you

onilink_ wrote: ↑

Fri Mar 22, 2024 8:03 pm

Hello,

So I finally bought the complete set from the same seller (sadly, no 100x oil in the set) and I got a weird objective.
The one on the left:
jena GF planachromat.jpg

No infinity symbol on it: 1 x 0,03 spez/-A

I tried it with the same setup than other objectives but I don't have any image.
Any idea what is this "spez" ? And how to use this objective?

There is also a small "wheel" to move the front element.

Thank you

The "Spezial" is for use with the Jenaval scopes with a special condenser : (page 8) https://www.zeiss.com/content/dam/Micro ... enaval.pdf

I think the condenser is called "Aplanat 0.12", it's a rather elaborate process.

EDIT: by the way, I think there's a 100x 1.2 oil on eBay right now, no bids so far, starts at 49€ (+import taxes, shipping etc).

I think the 1x also required a special upper lens like some Nikon cfi60s did a generation or two ago (1x macro).

shutterbug wrote: ↑

Fri Mar 22, 2024 8:55 pm

The "Spezial" is for use with the Jenaval scopes with a special condenser : (page 8) https://www.zeiss.com/content/dam/Micro ... enaval.pdf

I think the condenser is called "Aplanat 0.12", it's a rather elaborate process.

EDIT: by the way, I think there's a 100x 1.2 oil on eBay right now, no bids so far, starts at 49€ (+import taxes, shipping etc).

Thanks! I'm using epi illumination so I think Scarodactyl is right.
I'm missing a upper lens. It remains to know its characteristics.

I'll have to look at the documentation a little better.

Frequently a 1x compound objective will need a contrast cap, especially for reflected light applications.
A polarizer is placed in the light path, and the contrast cap is mounted over the front of the objective. It is essentially a 1/4 wave plate that can be rotated for the best contrast as you observe the sample

wabutter wrote: ↑

Sat Mar 30, 2024 4:32 am

Frequently a 1x compound objective will need a contrast cap, especially for reflected light applications.
A polarizer is placed in the light path, and the contrast cap is mounted over the front of the objective. It is essentially a 1/4 wave plate that can be rotated for the best contrast as you observe the sample

Good to know! I'm just adding a polarizer so it's perfect timing.

But atm I have no image at all, not even a semblance of a blurred image, so I'll have to figure out the specs of the missing upper lens.

Also, I'm not using a 250 mm tube lens, but a 180 mm one. I don't think that's the problem, but I'd like to clarify.