metallurgical microscope for insect photo

len · Post by **len** » Tue Apr 23, 2013 2:44 pm

Hi,
I understand that metallurgical microscope allow to use semi clear or opaque objects, are they better from normal microscope for the purpose of watching dry insects?

Thanks

Lothar-Gutjahr · Post by **Lothar-Gutjahr** » Tue Apr 23, 2013 3:21 pm

Hi Len,

this depends on the type of lenses used. I do have a Leitz Metalloplan with NPL-Lenses. The light is fed trough the same lenses used to look trough and there you will have no fun in watching things with low contrast. The elder Ultrapack system or the so called EPI-systems use coaxial ring around the lenses to guide the ilumination light. There it looks good and would be usable.
Witout knowing the microscope you have in mind, one can not answer your question.

Greetings

Lothar

len · Post by **len** » Tue Apr 23, 2013 4:18 pm

Thanks Lothar,

I'm thinking on something like this: http://www.taylorscientific.com/TaylorS ... P1897.aspx

Lothar-Gutjahr · Post by **Lothar-Gutjahr** » Tue Apr 23, 2013 10:38 pm

Hi Len,

your aim goes into a good looking piece of optical gear. But it says objectives are D.I.N lenses and there we are at the allready mentioned point.

Here i looked up a old "Epignost" which makes use of the optical path mentioned.
http://www.ebay.de/itm/Zeiss-Mikroskop- ... 56555049b3

Just to give you the idea, where the secret of a good reflective illu is hidden.
Please look at the second row of fotos. There you can see the separat path around the lenses.
If you possibly think about taking fotos from insects or even doing focusstacking, my idea is to look more for a macrostand, one can modify towards using in the range of microscopy also. Even such an old Epignost or similar could do the job.
But wait other ideas of experts writing here. I am a low budget pensioner and do my own design for all my needs. The stand of my Metalloplan got cut in pieces to make up a sturdy base for my universal foto microscope i use with automated focus stacking.

Greetings

Lothar

rjlittlefield · Post by **rjlittlefield** » Wed Apr 24, 2013 12:46 am

Len,

We could give better advice if we understood what you are trying to accomplish.

I have reviewed all your posts, and quite frankly I don't have a clue.

You've made a total of only 16 posts, starting in 2009. First you wanted advice on "How to build a vertical focusing rail". Then it was "DSLR Adapter for Stereo Microscopes". After that it was "Which trinocular should I have for insect photo?" Then apparently you bought an Amscope B390A (binocular?), discovered that the 40X doesn't do what you want, and now the topic is "metallurgical microscope for insect photo".

Let me quickly summarize the basic physics: you cannot have direct view of sharp high magnification images with significant DOF.

Any three are OK, all four is not.

So you have to decide:

a) Can you give up direct view? Then you can have sharp high magnification images with significant DOF. This is the regime of focus stacking using objectives designed for compound microscopes.

b) Can you give up sharp? Then you can have direct view of high magnification images with significant DOF by stopping down.

c) Can you give up high magnification? No problem then to get direct view with sharp images and significant DOF.

A compromise between (b) and (c) is the regime of stereo microscopes.

d) Can you give up DOF? Great, then you can have direct view of sharp high magnification images. This is a classic compound microscope.

Please excuse my bluntness, but I have the feeling that you are looking for a universal solution, and preferably one that doesn't cost much money. There is no such beast.

With that as background, let me ask: what is it that you want to accomplish?

Best regards,
--Rik

Craig Gerard · Post by **Craig Gerard** » Wed Apr 24, 2013 2:16 am

Len wrote:I understand that metallurgical microscope allow to use semi clear or opaque objects, are they better from normal microscope for the purpose of watching dry insects?

Len,

In most cases, Working Distance and illumination reflected off the sample are applicable when using metallurgical objectives. Biological objectives are usually expecting transillumination (from below through the sample) and often require a cover glass, especially when using objectives with a high numerical aperture.

If you only require a scope for "watching" or visual inspection then a good stereo microscope will be sufficient, depending on the range of magnification you require for your purposes. The item linked in your earlier post may be overkill if your subjects are initially, reasonably visible to the human eye.

SAM are using a typical macro setup comprised of a StackShot, MP-E 65mm, a 2.8/100L Macro, a copy stand and two Canon speedlights....... but they also have one of these:

http://www.leica-microsystems.com/produ ... z16-apo-a/

This may be useful:
http://www.leica-microsystems.com/uploa ... age_20.mp4

Craig

*edit: added video link

len · Post by **len** » Wed Apr 24, 2013 4:20 am

Hi Rik,
Watching my post from 2009 no wonder you're confused

I'm asking different questions and attempting different approach because I always try to improve.
I'm an amateur entomologist so my hobby is to examine and photo insects.
I started with DSL macro and was pleased until decided to improve the DOF and moved to stacking, I improvised (Couldn't find proper stand) vertical focusing rail for my camera which give great quality photos with macro lens. Eventually I had the opportunity to purchase a used Stemi 2000C for a great price and replaced my old stereo microscopes, I used it most of the times for direct viewing but the magnification is not enough for very small parts (lets say ~1mm should fill the view) so I purchase the B390A and indeed disappointed that the 40x need cover glass which is not always suitable for my needs (Still the 10x is a useful to me)
Now I had another opportunity to buy a used MM-460 in a good price and was wonder if it could give me a better result than my new B390A. metallurgical microscope, EPI-systems, Phase contrast... are all new concepts for me so I try to figure what system is ideal for me.

P.S Lothar-Gutjahr mention a low contrast problem, could phase contrast lens fix those issue? or I'm way off?

Pau · Post by **Pau** » Wed Apr 24, 2013 5:15 am

Just to add few points to clarify:

- AFAIK Phase contrast is only available for transmitted illumination, and doesn't work well for thick specimens like insect parts.
- DIC may be used for episcopic illumination but only works for metallic reflective materials.

- So for reflected light the only approaches I know are:
1--- diffused light with external light sources: the most popular technique in the forum
2--- Darkfield epi illumination with BD type objectives
--- Crossed polarization to avoid reflections, both with episcopic (3)(through the objective) or external illumination (4).

For 1 and 4 you don't need a metalurgical microscope, just objectives with enough long working distance to illuminate the sample (and for NA>0.30 designed to work without coverglass)

For 3 and 4 the adequate metallurgical microscope (or a mixt one with epi illuminator) is the way

Of course another approach is to use enough flat specimens, mount them in a microscope slide and use a biological microscope. Some clearing chemicals or observation under infrared light turns the cuticule more transparent

rjlittlefield · Post by **rjlittlefield** » Wed Apr 24, 2013 10:48 am

len wrote:I'm an amateur entomologist so my hobby is to examine and photo insects.

In that case I suggest:

1. For direct view at low magnification, use a stereo microscope.

2. For photographing, use LWD (or ELWD) metallurgical type objectives in combination with focus stacking. You'll have the most flexibility by doing that outside the confines of a microscope frame, using an open setup like one of the systems linked at http://www.photomacrography.net/forum/v ... 5311#55311. At 40-50X (equivalent to 400-500X in a direct view microscope), you can get working distances of 10 mm or so, which is plenty to shine light around the objective.

3. For direct view at high magnification, you'll also be needing metallurgical type objectives (no cover glass). The MM-460 (HERE, page "13", 11 of 25 in the pdf file) will give you that in a nice self-contained package. Whether it will make you happy, I don't know. There's no way to avoid the DOF problem. At 50X NA 0.60, DOF is less than 0.002 mm and there's nothing you can do about that except fly focus up and down to build up an image inside your head that sort of corresponds to what focus stacking software would do given a stack and some time. I have no idea whether you would find that productive or not. You can get some idea what it's like by playing with the 40X in your Amscope. The MM-460 would give a much sharper image in the plane of focus, but will actually have less DOF as a result.

P.S Lothar-Gutjahr mention a low contrast problem, could phase contrast lens fix those issue? or I'm way off?

Way off. Phase contrast is a great way for dealing with low contrast transparent subjects that can be illuminated from behind, but that's accomplished by using a specially constructed condenser that collaborates with the objective to turn phase shifts into intensity variations. It has no relevance to opaque subjects.

--Rik

len · Post by **len** » Thu Apr 25, 2013 3:17 am

So if the MM-460 light system is not very good for insects watching does the only benefit over the AmScope is the LWD objectives?
Isn't it possible to put the same objective on the AmScope and use external diffused light?

And another question, can I assume as a rule that objective with cover glass correction and N.A. under 0.3 will also be sharp without cover glass?

rjlittlefield · Post by **rjlittlefield** » Thu Apr 25, 2013 7:56 am

len wrote:So if the MM-460 light system is not very good for insects watching does the only benefit over the AmScope is the LWD objectives?

Basically yes. I expect that the MM-460 would have generally smoother mechanics, a more rugged build, and better eyepieces, but for your application those seem like minor improvements with a (probably) high price attached.

Isn't it possible to put the same objective on the AmScope and use external diffused light?

I can't tell. According to the descriptions, both scopes seem to be DIN spec, but that just means RMS threads and a 45 mm parfocal distance. It could still be that one is finite and the other is infinite, in which case the objectives would not function correctly if interchanged. Optical correction for chromatic aberration is another potential mismatch, though less serious than the finite/infinite issue.

If you want to go with direct view through high mag LWD objectives, then getting a system built to do that is the safe way to go. My concern is only that you understand what capabilities you will and will not be getting. My arsenal does include high mag direct view capabilities, but due to the DOF issue I don't find it helpful. Your needs and preferences may be different.

And another question, can I assume as a rule that objective with cover glass correction and N.A. under 0.3 will also be sharp without cover glass?

Correct. Below NA 0.30, the effect of cover glass is too small to be seen by eye.

--Rik

len · Post by **len** » Thu Apr 25, 2013 8:56 am

Hi Rik,
I'm well aware of the DOF problem and will probably be fine with 40x objective (Does it consider high mag?) , thanks for your concern.

As far as I can see in the PDF it's probably finite system since the infinite system is mention explicitly in other models. But I do see that it has Kohler illumination which I don't have in my scope, is it such critical feature?

If different system has different color correction does it mean I always have to install objectives from the same brand of the scope? I'm thinking maybe to just replace the 40X objective of my AmScope with something more appropriate?

rjlittlefield · Post by **rjlittlefield** » Thu Apr 25, 2013 9:46 am

len wrote:But I do see that it has Kohler illumination which I don't have in my scope, is it such critical feature?

Köhler illumination applies only for transparent specimens. It describes some details of how light is beamed directly into the objective by a condenser system. Even there the significance seems to be more for marketing than practical difference. Many scopes cannot be configured to give true Köhler illumination, but generate fine images anyway. I have no experience with either Amscope or the MM-460 so I don't know how much difference there would be.

If different system has different color correction does it mean I always have to install objectives from the same brand of the scope?

No. This is an area of subtle gradations. Many modern objectives are designed to require no color correction in other optics. All those are interchangeable (given proper tube length etc). For objectives that do require correction, the amount of correction is specific to the manufacturer. Those will give greater or lesser degradation, typically color fringing, depending on how much mismatch there is.

I'm thinking maybe to just replace the 40X objective of my AmScope with something more appropriate?

That can be done. Be prepared to spend more for the new objective than you did for the entire Amscope.

--Rik

len · Post by **len** » Thu Apr 25, 2013 12:28 pm

rjlittlefield wrote: That can be done. Be prepared to spend more for the new objective than you did for the entire Amscope.

That doesn't sound encouraging...
I searched a bit the net for 40X non cover objective but found only infinite objectives. such this http://www.ebay.com/itm/Olympus-LWD-NEO ... 2c5b6d6154 (btw: what if f=180?)

Do you have any recommendation for a relative cheap finite non cover objective?

Lothar-Gutjahr · Post by **Lothar-Gutjahr** » Thu Apr 25, 2013 1:05 pm

Hi Len,

here now my question: What do you want to use the 40 fold lens for. To give you an idea how sticky the look for high magnification may be, have a look in this thread. http://www.photomacrography.net/forum/v ... hp?t=19757
,
I have given away a large microscopic setup to get a hold of that U.W.L.D-lens from B&L. I am still experimenting with different setups. Right now after buying original B&L eyepieces it starts looking more reasonable. This lens is sitting under a bellow right now, topped by a tube for the eypiece and the adapter to my Canon. This bellow is positioned by stepping motor means and adjustable in hight to 360 mm. I use mainly Zeiss Luminar lenses 40 and 16 mm and all sorts of microscopic lenses. This ultra long working distance lens was the biggest challenge the last two years. It would not fit to any normal microscope of mine.

Other interesting LWD-lenses would be the 8x an 16x planapochromates from Zeiss Jena. I dont know if there is a 25x also. What i want to point out, is the fact, its verry hard to find this ideals in one machine. Also $$$. Homebrewing comes trough the back door.

Greets Lothar