Phase Contrast or Brightfield if all things are equal?

Here you can discuss different microscopic techniques and illumination methods, such as Brightfield, Darkfield, Phase Contrast, DIC, Oblique illumination, etc.
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rjarquin
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Phase Contrast or Brightfield if all things are equal?

#1 Post by rjarquin » Wed Aug 19, 2020 1:12 pm

Hello, I am new to this subject so please forgive my beginners question. I am very familiar with astronomy and photography equipment but I am new to microscopy. I have been offered an Olympus BH2 BHTU microscope with standard lighting or with Phase Contrast for about the same price. Aside from differences in condition, objectives (both with plan), etc., which one would you pick if you could only have one microscope?

Thank you for any feedback

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Re: Phase Contrast or Brightfield if all things are equal?

#2 Post by BramHuntingNematodes » Wed Aug 19, 2020 1:27 pm

Frequently, phase contrast objectives can also be used for brightfield work with minimal drawbacks. I believe Olympus has had several different levels of quality offered in their objectives, so any other additional info might be useful to the Olympians on the forum.
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Re: Phase Contrast or Brightfield if all things are equal?

#3 Post by Zuul » Wed Aug 19, 2020 2:10 pm

The other way to look at it is this. All things equal, upgrading a brightfield microscope to phase is much more expensive than buying a set of brightfield objectives to use on a phase microscope. The lingering question is, why is the phase scope not more? It could just be a better deal, or there could be other reasons.

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Re: Phase Contrast or Brightfield if all things are equal?

#4 Post by apochronaut » Wed Aug 19, 2020 5:05 pm

What do you mean by "differences in condition"? The original post said if all things are equal !

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Re: Phase Contrast or Brightfield if all things are equal?

#5 Post by deBult » Wed Aug 19, 2020 7:32 pm

There is a slight reduction in contrast and resolution when using Olympus phase objectives for bright field, you wil only notice the difference when comparing both on the same scope.

The observation “ upgrading a brightfield microscope to phase is much more expensive than buying a set of brightfield objectives to use on a phase microscope” is to the point.

With both scopes having the same objectives serie (SPlan are slightly better compared to DPlan) I personally would go for the Phase set (My main interest area is protozoa, algae etc: pond dipping)

Note the main advantage in SPlan Is they are wide field and can be used with an (expensive) wide field head.

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Re: Phase Contrast or Brightfield if all things are equal?

#6 Post by Hobbyst46 » Wed Aug 19, 2020 7:42 pm

Does the "phase contrast" microscope include a phase contrast condenser ?
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Re: Phase Contrast or Brightfield if all things are equal?

#7 Post by 75RR » Wed Aug 19, 2020 8:23 pm

Phase Contrast or Brightfield if all things are equal?
Your question has a simple answer - go with the phase.

It is important however that in practice, as opposed to theory, all the parts are there and that they be in good condition.

If you can post a detailed photo of each I am sure there are several members here that can confirm in practice which would be the better deal.


Not sure if you know this but just in case you are not clear on illumination techniques, Brightfield is the default standard (what I think you are calling standard lighting),

Phase Contrast is an additional illumination technique. That means you would effectively have Brightfield and Phase on that microscope.

The only potential fly in the ointment is (as mentioned above) that when using Phase objectives for Brightfield, if those are the only objectives that come with the Phase microscope,

there is a slight NA (Numerical Aperture) penalty. As said, it is only slight and nothing to worry about at what is the beginning of your adventure.
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Re: Phase Contrast or Brightfield if all things are equal?

#8 Post by rjarquin » Thu Aug 20, 2020 3:14 am

It is clear from your comments that all things being equal, the Phase Contrast model is the better choice. Its condenser''s position 0 is basically a brightfield setting. I was not aware of this. It seems that the loss of a little contrast is more than compensated by gaining the ability to use phase contrast.

Hobbyst46, you asked if the microscope comes with a phase contrast condenser. I did not know someone could sell a phase contrast model with the incorrect condenser. I will have to check on this. Thank you for pointing that out.

The phase contrast microscope is a BH-2 BHS model with an external light source/transformer. This makes the unit less compact than the other one which is a BHTU model. The BHTU model does come with a darkfield condenser option which I understand is also desirable :)

Thank you all for your feedback!

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Re: Phase Contrast or Brightfield if all things are equal?

#9 Post by Hobbyst46 » Thu Aug 20, 2020 6:09 am

rjarquin wrote:
Thu Aug 20, 2020 3:14 am
Hobbyst46, you asked if the microscope comes with a phase contrast condenser. I did not know someone could sell a phase contrast model with the incorrect condenser. I will have to check on this. Thank you for pointing that out.
I asked, simply because several times I saw eBay listings titled as "phase contrast microscope" but the smaller font print down the page admitted that it came without condenser. So, I was only suggesting to verify.
The phase contrast microscope is a BH-2 BHS model with an external light source/transformer. This makes the unit less compact than the other one which is a BHTU model. The BHTU model does come with a darkfield condenser option which I understand is also desirable :)
Phase contrast would be my first preference; plus, the phase contrast condenser of the BH-2 might be configured to include darkfield as well (at least for 10X-40X objectives), plus the high-NA phase position of the condenser yields decent darkfield with the 10X objectives. In addition, the BHS is (I think) top of the BH-2 line.
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Re: Phase Contrast or Brightfield if all things are equal?

#10 Post by 75RR » Thu Aug 20, 2020 6:21 am

rjarquin wrote:
Thu Aug 20, 2020 3:14 am
This makes the unit less compact than the other one which is a BHTU model.
More compact/smaller footprint is just dealer speak for less illumination. Go for the BHS
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Re: Phase Contrast or Brightfield if all things are equal?

#11 Post by deBult » Thu Aug 20, 2020 10:13 am

The external transformer listed worries me: to my understanding the BHS does not need one for brightfield and phase (I’m a BHTU user). This may indicate a failure in the base normally supplying the power.

http://www.alanwood.net/downloads/olymp ... manual.pdf

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Re: Phase Contrast or Brightfield if all things are equal?

#12 Post by Hobbyst46 » Thu Aug 20, 2020 11:25 am

...The phase contrast microscope is a BH-2 BHS model with an external light source/transformer...
Actually, there should be just a 100W halogen illuminator, fed directly from the mains 220V/110V, without separate transformer.
And, from personal experience, it is not large, and does not add significantly add to foot print.
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Re: Phase Contrast or Brightfield if all things are equal?

#13 Post by apochronaut » Thu Aug 20, 2020 12:16 pm

All things are not really equal with the two microscopes. The BHS is a 100 watt microscope with an external transformer. It also has potential for a 6 place nosepiece. It may already have one. With phase it is the clear candidate. Since it has a 100 watt illuminator, it can also be easily adapted to high resolution DF, which the BHTU cannot. With a 6 place nosepiece you could carry 4 phase objectives and 2 excellent BF objectives of your choice for a relatively flexible and complete system, or if the nosepiece is full, it may already have one or two BF objectives?

You don't mention whether either of them have trinocular heads?

You need need more details.

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Re: Phase Contrast or Brightfield if all things are equal?

#14 Post by rjarquin » Thu Aug 20, 2020 6:14 pm

Awesome feedback!

I bought the BH-2 BHS with 4,10,20,40 and 100 Splan objectives. Actually the 100X objective is a C S Plan 100x, 0.95, 160/0, and I understand NC stands for No Coverslip (no oil necessary). I don't know if the oil version would be more desirable to reduce possible aberrations or not. The microscope was purchased without actually seeing it but after asking a lot of questions. I am familiar with the optics and mechanical issues in photography and astronomy so I am hoping I will get a keeper. I look forward to discovering the micro world and contributing to this great resource!

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Re: Phase Contrast or Brightfield if all things are equal?

#15 Post by apochronaut » Thu Aug 20, 2020 10:03 pm

You had mentioned that the BHS was the phase microscope. How many of those objectives are phase and is it a phase condenser?

The 100X .95 no cover objective has limitations. Places where many fast smears need to be done like them because there is no cover, no oil and the work can be completed quickly. They have limited value to a hobby microscopist.

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Re: Phase Contrast or Brightfield if all things are equal?

#16 Post by Scarodactyl » Fri Aug 21, 2020 12:07 am

I wonder if it could be turned to metallurgical style epi work. Probably too little wd for even oblique lighting to be very feasible.

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Re: Phase Contrast or Brightfield if all things are equal?

#17 Post by apochronaut » Fri Aug 21, 2020 2:31 am

AO produced the cat.# 1866 40X .55 planachro and the cat. # 1867 100X .95 planachro as no cover objectives for flat thin subjects in diascopic microscopy. There was probably some acceptance for smears etc. but they were high end optics and had a pretty big sticker price. I also have seen a few epi microscopes equipped with the 1867 and the catalogues for the epi scopes published after their release , list the 1867 as a 100x option, so I am extrapolating that the Olympus no cover 100X might be capable of the same sort of shift.

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Re: Phase Contrast or Brightfield if all things are equal?

#18 Post by rjarquin » Fri Aug 21, 2020 5:01 am

Apochronaut, all of the objectives are phase contrast. The person I bought the microscope from may be able to swap the NC S Plan 100x, 0.95, 160/0 no cover objective for a regular Splan 100X PL... besides the possible lower quality results of an air only objective, are there other practical concerns i.e. parafocality with the non NC objectives and the ability to use covered slides with the NC objective?

You also asked if it has a phase condenser. This is the image that I received:

Image

The picture shows the phase turret with a condenser and I am assuming it is a phase condenser, right?

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Re: Phase Contrast or Brightfield if all things are equal?

#19 Post by PeteM » Fri Aug 21, 2020 5:39 am

It's a phase condenser - and a valuable set of phase contrast SPlans.

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Re: Phase Contrast or Brightfield if all things are equal?

#20 Post by 75RR » Fri Aug 21, 2020 5:56 am

.
Plenty of very useful information on Alan Wood's site:

http://www.alanwood.net/downloads/olymp ... ochure.pdf

http://www.alanwood.net/olympus/downloads.html

Do note that you will be needing a Phase Centering Telescope to center the annular rings. You might ask the seller, he might be feeling generous.
Last edited by 75RR on Fri Aug 21, 2020 1:07 pm, edited 1 time in total.
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Re: Phase Contrast or Brightfield if all things are equal?

#21 Post by Hobbyst46 » Fri Aug 21, 2020 7:30 am

Enjoy ! A phase condenser and phase SPLANs - wow! also, non-phase SPLANs are great objectives.
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Re: Phase Contrast or Brightfield if all things are equal?

#22 Post by apochronaut » Fri Aug 21, 2020 12:29 pm

That all looks very positive. Go for the swap. Even though , the 100X no cover objective is a great objective for it's intended applications it will be a mismatch in your scope. An SPlan 10 PL or another phase type should not be too hard to find. You may never need a 100X phase objective but there also was a 4X and since you have at least a 5 place nosepiece, you could put some BF objectives in there.

The most common Olympus phase objectives are the A . The SPlan will be about twice the price of the A. The A are not plan. Olympus had/has something called relief phase. A relief phase objective will be marked RP after the magnification. Yours are PL, which stands for positive low(contrast). There were also NH(negative high), NM(negative medium) and PLL(positive low low). There is nothing wrong with mixing phase types in a nosepiece but the individual types are usually more or less functional with certain specimens. Generally speaking, negative contrast is used for low contrast subjects and positive contrast is used for higher contrast subjects.

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Re: Phase Contrast or Brightfield if all things are equal?

#23 Post by rjarquin » Sat Aug 22, 2020 5:22 pm

It turns out that the NC Splan 100 objective is not a phase objective :( All the other objectives 4x,10x,20x,and 40x are phase PLs. He did say he got good results with the No Cover version using the brightfield setting and that he had no trouble with covered slides or parafocality with the other objectives. I just wonder if it is just good for observation but perhaps not so good for micro-photography...
Thank you for all your tips!

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Re: Phase Contrast or Brightfield if all things are equal?

#24 Post by deBult » Sat Aug 22, 2020 5:30 pm

Read Apochromat previous post please.

Go for the swap even to a none phase 100* objective.
This one is only (but very) usefull in obsevering (blood) smears without coverglas: a very specialist and niche field of microscopy.

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Re: Phase Contrast or Brightfield if all things are equal?

#25 Post by 75RR » Sat Aug 22, 2020 6:07 pm

deBult wrote:
Sat Aug 22, 2020 5:30 pm
Go for the swap even to a none phase 100* objective.
This one is only (but very) usefull in obsevering (blood) smears without coverglas: a very specialist and niche field of microscopy.

One can always ask but unless there is a problem, the the sale is done. Time to haggle was before the buy. It's done now so don't sweat it.

You have a good microscope that looks to be in good condition with very good objectives. That is a great start to microscopy. Enjoy it!
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Re: Phase Contrast or Brightfield if all things are equal?

#26 Post by rjarquin » Sat Aug 22, 2020 7:56 pm

Yes, I had read apocronaut's excellent info about the various phase objectives. I still wondered though in which ways the NC objective was not a match but you made it more clear. I contacted the buyer and he is switching the NC objective for a non phase SPlan 100X Oil objective. Thank you!

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Re: Phase Contrast or Brightfield if all things are equal?

#27 Post by rjarquin » Sat Aug 22, 2020 8:29 pm

75RR wrote:
Sat Aug 22, 2020 6:07 pm
One can always ask but unless there is a problem, the the sale is done. Time to haggle was before the buy. It's done now so don't sweat it.
You have a good microscope that looks to be in good condition with very good objectives. That is a great start to microscopy. Enjoy it!
The seller reconditions Olympus microscopes. I asked him to swap the objective and now I am getting a non phase Splan 100X. I am looking forward to discovering the world that lives in the brackish waters of our nearby Marsh. It is an unusual marsh as it has tidal sea waters but also a spring of permanent fresh water.
Image

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Re: Phase Contrast or Brightfield if all things are equal?

#28 Post by 75RR » Sat Aug 22, 2020 9:10 pm

rjarquin wrote:
Sat Aug 22, 2020 8:29 pm
I am looking forward to discovering the world that lives in the brackish waters of our nearby Marsh. It is an unusual marsh as it has tidal sea waters but also a spring of permanent fresh water.
Image
That looks interesting! Looking forward to seeing your discoveries.
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