"Disastrous" (completely unexpected!!) 100x oil immersion objective comparison

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Macro_Cosmos
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"Disastrous" (completely unexpected!!) 100x oil immersion objective comparison

Post by Macro_Cosmos »

NA1.4 Apl Achromat condenser.
Objective and condenser oiled.
This is a disaster. Some may find the information useful. In this case, I regret to say... you do absolutely get what you paid for.
400lp/mm target.

Camera is a Nikon Z6, Olympus objectives. Centre crop at 400%.
At 100%, the FL is a tad worse than the apo. The Plan N shows very obvious CA.
At 100% in the corners, the Plan N casts colourful CA outlines, making it look like one of those retro neon signs. The FL suffers from the same fate, just not as drastic. The Apo holds up strongly, but CA is showing up.

Image
Last edited by Macro_Cosmos on Sat Sep 12, 2020 10:31 am, edited 2 times in total.

Scarodactyl
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Re: Disastrous 100x oil immersion objective comparison

Post by Scarodactyl »

A little more context might help make this more actionable. Center? Corner? Brand/appearance?

Macro_Cosmos
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Re: Disastrous 100x oil immersion objective comparison

Post by Macro_Cosmos »

Scarodactyl wrote:
Fri Sep 11, 2020 11:46 am
A little more context might help make this more actionable. Center? Corner? Brand/appearance?
Centre. Olympus objectives (as the designation illustrates), Nikon Z6.

I only use the middle of the frame, so corners do not matter to me at all.
Corners are orders worse for the Plan N, okay-ish for the FL, and really good for the apo.
The Apo does show blue and orange haloing in the corners. FL and Plan N are like those retro neon lights.

Vish_007
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Re: Disastrous 100x oil immersion objective comparison

Post by Vish_007 »

Images taken with or without coverslip ?
Vishnu

Ichthyophthirius
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Re: Disastrous 100x oil immersion objective comparison

Post by Ichthyophthirius »

Hi,

I'm not sure what to make of this. How can there be colour finging in the centre with the UPlanFL?

If the Plan N has fringes like this in the centre and in focus, it is likely defective. Could there be oil inside (not uncommon for the Plan Ns)? I don't have it myself but maybe someone could post an image with their own Plan N 100x?

Regards, Ichty

Macro_Cosmos
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Re: Disastrous 100x oil immersion objective comparison

Post by Macro_Cosmos »

Vish_007 wrote:
Fri Sep 11, 2020 2:17 pm
Images taken with or without coverslip ?
No coverslip.
Ichthyophthirius wrote:
Fri Sep 11, 2020 4:02 pm
Hi,

I'm not sure what to make of this. How can there be colour finging in the centre with the UPlanFL?

If the Plan N has fringes like this in the centre and in focus, it is likely defective. Could there be oil inside (not uncommon for the Plan Ns)? I don't have it myself but maybe someone could post an image with their own Plan N 100x?

Regards, Ichty
Fringing is only visible when viewed at 400%. At 100%, it's barely there. I have a new 10x uplanfl as well, could try and compare that.
Not sure about the plan N. I did receive it with oil leaking out and the originally working spring loaded mechanism broken, there's that. This however does align with my expectations. I've tried the 40x with the same target, the fringing is sort of similar.

Macrero
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Re: Disastrous 100x oil immersion objective comparison

Post by Macrero »

Ichthyophthirius wrote:
Fri Sep 11, 2020 4:02 pm
Hi,

I'm not sure what to make of this. How can there be colour finging in the centre with the UPlanFL?

If the Plan N has fringes like this in the centre and in focus, it is likely defective. Could there be oil inside (not uncommon for the Plan Ns)? I don't have it myself but maybe someone could post an image with their own Plan N 100x?

Regards, Ichty
I don't think there's anything wrong with those crops. The Fl (semi-apo), while significantly better corrected than an achro, will still show color fringing in areas of extreme contrast as in this case. Even the Super-Apo is showing some mild fringing. The N is a plain achromat, so no wonder it is doing much worse.

- Macrero
https://500px.com/macrero - Amateurs worry about equipment, Pros worry about money, Masters worry about Light

Pau
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Re: Disastrous 100x oil immersion objective comparison

Post by Pau »

Disastrous?

Maybe I'm too used to non optimal objectives but I tend to agree with Macrero. BTW the Plan Achro shows too poor contrast, the other two seem OK.

If you put a 0.17mm (#1.5) cover glass the image could improve a bit, but 400% is excessive for any lens, much more for a 100X, deeply into diffraction territory even at 100%
Pau

Ichthyophthirius
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Re: Disastrous 100x oil immersion objective comparison

Post by Ichthyophthirius »

Macrero wrote:
Sat Sep 12, 2020 3:36 am
I don't think there's anything wrong with those crops. The Fl (semi-apo), while significantly better corrected than an achro, will still show color fringing in areas of extreme contrast as in this case. Even the Super-Apo is showing some mild fringing. The N is a plain achromat, so no wonder it is doing much worse.
Hi,

I'm thinking about the opposite-colour fringing. Blue on one side, red on the other. That shouldn't be the case in the CENTRE, only in the corners. In the centre, there should be no fringing or fringing should be the same on either side of the line. I think this indicates that the objective is mounted at a slight angle.

The Plan N looks like oil damage. It's not typical for any achromat 100.

Macrero
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Re: Disastrous 100x oil immersion objective comparison

Post by Macrero »

Ichthyophthirius wrote:
Sat Sep 12, 2020 5:43 am
Hi,

I'm thinking about the opposite-colour fringing. Blue on one side, red on the other. That shouldn't be the case in the CENTRE, only in the corners. In the centre, there should be no fringing or fringing should be the same on either side of the line. I think this indicates that the objective is mounted at a slight angle.

The Plan N looks like oil damage. It's not typical for any achromat 100.
My experience is based on dry objectives, no idea about the "opposite fringing", tbh, though I don't think that would be a problem in real life shooting.
The N is certainly performing shabbier than I would expect, You might be right and there may be some oil penetration in the optics.

- Macrero
https://500px.com/macrero - Amateurs worry about equipment, Pros worry about money, Masters worry about Light

Scarodactyl
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Re: Disastrous 100x oil immersion objective comparison

Post by Scarodactyl »

Missing the coverslip seems like it should cause some serious issues, at least with contrast. Even at NA 0.75 it's a strong effect.

Duke
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Re: Disastrous 100x oil immersion objective comparison

Post by Duke »

For oil immersion objectives shouldn't be any difference between having coverslip or without it, of course, assuming proper immersion oil is used. The crucial optical properties of immersion oil, such as refraction index and dispersion are nearly identical to those of k8 standard coverslip glass, that's why it used to be referred as homogeneous immersion (H. I.). Newer synthetic oils offering even better transmission (up to 330nm), and never dry out on the objective front lens, as original natural cedar oil did.
“Thoroughly conscious ignorance is the prelude to every real advance in science.” - JCM

Scarodactyl
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Re: Disastrous 100x oil immersion objective comparison

Post by Scarodactyl »

Oh cool, that's good to know. Shows how often I use immersion objectives.

Pau
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Re: Disastrous 100x oil immersion objective comparison

Post by Pau »

Duke wrote:
Sat Sep 12, 2020 7:22 am
For oil immersion objectives shouldn't be any difference between having coverslip or without it, of course, assuming proper immersion oil is used. The crucial optical properties of immersion oil, such as refraction index and dispersion are nearly identical to those of k8 standard coverslip glass, that's why it used to be referred as homogeneous immersion (H. I.). Newer synthetic oils offering even better transmission (up to 330nm), and never dry out on the objective front lens, as original natural cedar oil did.
Hi Duke, this has been discussed in a now 6 years old thread
viewtopic.php?p=139486#p139486

In fact there are objectives marked "no cover glass" or "../0" not only dry but also (rare) oil immersion ones meant for smears
Pau

Macro_Cosmos
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Re: Disastrous 100x oil immersion objective comparison

Post by Macro_Cosmos »

I thought coverglass didn't matter much for oil immersion? I'm probably wrong. If this is or isn't the case, I'm not sure how I would go about with the testing. I can totally place a coverslip on top of the chart, but the medium between the coverslip and the target would be air instead of the many typical mountants, thus sub-optimal.

I'll clarify on "disastrous". I thought the FLs and the Apos are very similar, I thought the achromats are good enough. The results however completely warped my mind. I did not expect such as clear cut difference. Obviously 400 lp/mm at 400% is a major challenge for any kind of objective. That is the point however, that's how people test CPUs, graphics cards... items are subjected to unrealistic scenarios.

My conclusion is pretty simple, I think the Apo and the FL are on very similar playing fields. Apos are typically twice or three times the cost of an FL objective, is it worth it? My results tell me, probably not -- unless corners matter (or you get a bargain, hehe).

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