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Need advice in buying micro equipments

 
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Yousef Alhabshi



Joined: 04 Feb 2011
Posts: 168
Location: United Arab Emirates

PostPosted: Fri Feb 11, 2011 9:03 am    Post subject: Need advice in buying micro equipments Reply with quote

Hi,
I've been into macro for a while & thought to give it a try with microscope photography...
I hope to find some answers to the following questions..

1- In one of the topics somebody mentioned that it's preferable to get a 20x ELWD than the LWD.. & it would be fine to have to have the LWD for lower magnification than 20x.. so is it really ok if i go for the 10x LWD?
2- I'm planning to get used "Nikon BD Plan 20x ELWD" & "Nikon 10x LWD".. can someone tell me what's the estimated prices for these two & whether if there are any better options? & if not any points should i consider in the two mentioned above?
3- Does it really matter to have a cheap Bellows over an expensive one?

I believe this is all i need to know... suggestions & advices are appreciated Very Happy

cheers,

Yousef
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Charles Krebs



Joined: 01 Aug 2006
Posts: 5713
Location: Issaquah, WA USA

PostPosted: Sat Feb 12, 2011 8:36 pm    Post subject: Reply with quote

Yousef,

It sounds like you are interested in using a microscope objective on a camera bellows, and not an actual microscope...correct?

If so, a couple of responses to your questions. There is a lot in the forum about this but not gathered in any one place. It has begun to be pulled together a little here:
http://www.photomacrography.net/forum/viewtopic.php?t=12147

And John ("Morfa") has put together a good piece here:
http://www.flickr.com/photos/johnhallmen/5379235010/

To briefly answer your specific questions.

Be sure to understand that there are two basic types of objectives that most of us use for this purpose.

One is a "finite" type. They are marked with the design tube length, typically 210mm for Nikon M Plan and 160mm for the few "biological" objectives that can be used readily this way. They attach to a bellows with no other optics needed.

The second type is an "infinity" design. These require an addition lens to work properly. In a microscope this additional lens is called the tube lens. They can be also be attached directly to the front of a camera lens (about 200mm is generally best, and provides the indicated magnification. People have been using them with lenses in the 150mm to 300mm range, which will provide magnifications different than marked on the objective.

Be sure to use objectives that do not require addition color correction via a corrective eyepiece. You are OK with Nikon CF series (the M Plan and BD Plans are nice). You are also "safe" in this regard with Nikon and (latest model) Olympus infinity objectives. (But Zeiss and Leica infinity objectives do some color correction with the tube lens, so these are not the best choices).

The Nikon CF M Plans and BD Plans are popular choices. The versions most commonly used here are finite type with a 210mm tube length. The 10/0.25 M Plan and the BD Plan after the outside collar is unscrewed) have a working distance of 9mm... not great, but workable. There is a 10/0.23 SLWD (super long working distance) version that generally is much more expensive. (I'm not aware of a LWD version). The 10/0.25 M Plan and 10/0.25 BD Plan can usually be gotten on eBay for between $80 and $150. At 10X there is also a newer Nikon (infinity type) objective that several people here use with excellent results. You can see it in the first link above. It can usually be purchased on eBay (when available) for about the same cost as the M Plan or BD Plan. (about $75 to $170).


As for the 20X, there are four Nikon CF (finite) versions.

20/0.40 WD=2.7mm
20/0.40 LWD WD=6.0mm
20/0.40 ELWD WD= 10.5mm
20/0.35 SLWD WD= 19.9mm

I don't know if I've ever seen the SLWD version. The others are pretty common. The working distance of the first two is too short. That's why the ELWD is desirable. Their selling price on eBay is all over the place so it is hard to say what it might cost. The last two sold went for $125 and $455. $125 is a low price. $455 is high, but it was a new objective.

Keep in mind that these are not "Apo" objectives. You will experience some color "issues" (more so with the 20X). These can often be minimized with diffuse lighting (which is best for stacking anyway). But you will often need to do some "clean-up" in an image editing program. There are Plan Apos (like the Mitutoyo M Plan Apos) that offer excellent working distances and superb color correction.... but they are not as commonly available, and they sell for much higher prices. These are also "infinity" type objectives, so they need to be used with an additional lens. There is currently a flurry of activity in the group experimenting with various combinations.

An expensive bellows is not needed. Even the best bellows do not move forward and backward in small enough, or smooth enough increments for stacking purposes with a 10X or 20X microscope objective. You will need some method of moving either the subject, or the camera/bellows unit in very fine, smooth increments. Commonly used are stages that micrometer driven, or microscope focusing stages.

One possibility is something like these current eBay listings:
http://cgi.ebay.com/NEWPORT-423-Series-3x3in-Stage-/280617580864?pt=LH_DefaultDomain_2&hash=item41561c7940

http://cgi.ebay.com/Newport-Linear-Double-Row-Bearing-UMR8-25-Stage-1-Mic-/250770526570?pt=LH_DefaultDomain_0&hash=item3a6316916a

http://cgi.ebay.com/NEWPORT-NRC-420-X-LINEAR-MOTION-STAGE-/390285973975?pt=LH_DefaultDomain_0&hash=item5adedb59d7


This lengthy topic deals mostly with microscope focus blocks. It is worth looking over:
http://www.photomacrography.net/forum/viewtopic.php?t=6070
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SONYNUT



Joined: 22 Jan 2011
Posts: 627
Location: Minnesota USA

PostPosted: Sat Feb 12, 2011 8:54 pm    Post subject: Reply with quote

you can find stages way cheaper....the last one i bought cost me 30.....what sucks is i bought some last year to resell before i knew about stacking Rolling Eyes
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Yousef Alhabshi



Joined: 04 Feb 2011
Posts: 168
Location: United Arab Emirates

PostPosted: Sun Feb 20, 2011 12:47 pm    Post subject: Reply with quote

Charles,
I really can't thank you enough for the time you spent writing me the answers of my questions Very Happy
& my deep apology for my late as i've been really busy the past days with my job Confused

Yes i meant microscope objective not an actual microscope. I should pay more attention next time...

As for the objective i wrote down all your highlighted points & based on the provided info i'll pick up what suit me well...

Recently i bought "Stack Shot" device which which can do 0.01mm per step. Is it enough for a 20x objective or shall i go for one of the listed rails in your answer? although i'm not really sure but i believe as for 10x i'll be ok with the 0.01mm step.. please correct me if i'm wrong Confused

For now i'll start searching for a 10X objective as a starter till i figured out about the rail & whether the "Stack shot" is enough or i have to spend some more in getting another one.

Somehow i can't see the prices on ebay any close to what you wrote.. most of what i found like "double" the price!!!

Again.. thank you for answering me.. really appreciate it Very Happy
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Yousef Alhabshi



Joined: 04 Feb 2011
Posts: 168
Location: United Arab Emirates

PostPosted: Sun Feb 20, 2011 12:54 pm    Post subject: Reply with quote

SONYNUT wrote:
you can find stages way cheaper....the last one i bought cost me 30.....what sucks is i bought some last year to resell before i knew about stacking Rolling Eyes


Laughing
The same story here!
You just reminded me the 1st time i bought the extension tubes.. the DOF was too annoying for me which made me sell it in no time!!
When i learned about the stacking i went & grabbed another one Embarassed
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rjlittlefield
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Joined: 01 Aug 2006
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PostPosted: Sun Feb 20, 2011 1:50 pm    Post subject: Reply with quote

Yousef Alhabshi wrote:
Recently i bought "Stack Shot" device which which can do 0.01mm per step. Is it enough for a 20x objective or shall i go for one of the listed rails in your answer?

If you have the USB version of the StackShot, it can actually go much smaller than 0.01mm per step and it works OK up to 40X. See the discussion in THIS THREAD, especially the particular post HERE. Those results were obtained by driving the StackShot through Zerene Stacker. I do not know if Cognisys has released an upgrade of their firmware that provides high precision in standalone mode, but if not, I expect that they soon will.

If you do not have the USB version, then still you can talk the rail into making steps that are somewhat smaller than 0.01 mm, realistically around 0.005 mm which should be OK for 20X under most circumstances. In this case, you may need to do some "creative misrepresentation" along the lines of what is described HERE, to talk the controller into making steps of the size you need. (These restrictions may be removed in later versions of the StackShot firmware.)

--Rik
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Edward Ruden



Joined: 21 Feb 2011
Posts: 42
Location: Albuquerque, NM

PostPosted: Sun Jul 17, 2011 9:02 am    Post subject: Short vs long WD Reply with quote

Charles Krebs writes:

"20/0.40 WD=2.7mm
20/0.40 LWD WD=6.0mm
20/0.40 ELWD WD= 10.5mm
20/0.35 SLWD WD= 19.9mm
... The working distance of the first two is too short"

Selecting a long WD to allow for illumination as normal as possible, short of transmitting through the objective, is advice frequently given on this site. Regardless of WD, however, the maximum angle of illumination is ultimately limited by the arcsine of the NA of the objective, unless structural parts of the objective get in the way first. Increasing the WD by 4 time (as in going from standard to ELWD in the example above) necessarily results in a front element 4X larger too, so you gain little. The ELWD costs much more too. I just bought a factory refurbished Nikon BD 20/0.40 WD=2.7mm (cover off) with case on eBay for $95. If NA is the same, what difference does it make if 8 mm above the object is filled with cheap metal and glass or expensive shadow?

The real figure of merit, then, is the actual maximum incident angle of illumination itself, as limited by structural components. I chose the above BD specifically because this is very minimal with the cover removed. A picture of a Nikon BD plan 20/0.40 standard WD with cover off is linked. From other images I have seen, the front optic fills the cylindrical tube at the end very efficiently.

The only other issue I can think of is if the object itself has obstructions that prevent you from getting close, like legs for an extreme ventral detail of a big bug. Or, am I missing something?
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Charles Krebs



Joined: 01 Aug 2006
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PostPosted: Sun Jul 17, 2011 11:02 am    Post subject: Reply with quote

Edward,

I understand your point. Naturally the angle of "access" to light the subject is important (one of the issues I have with the Canon 65MPE at the higher mags). But that is not the only desirable characteristic. (And due to the physical mounts themselves I don't know what that "angle" is for these various objectives without doing some actual measurements).

Your last point is actually a big one. These subjects are rarely flat. It is not that unusual to find that a gangly leg, antenna or piece of wing that you are not actually imaging will contact the front of equipment that is rather close to the subject. But careful subject preparation can usually avoid this.

Such close proximity to the subject also means there is much less leeway when maneuvering camera/subject. At least for me, longer working distances = fewer crushed subjects Shocked and less time spent cleaning the front of the lens.

With more working distance you can more easily choose from, fabricate, and work with a larger variety of reflectors and diffusers. One example... something like the often used ping-pong ball diffuser is quite easy to make (actually "cut-out" and shape) and use if you have 10mm of working distance... not so much if you only have 2.7mm WD.

Ultimately, it is possible to work at those shorter working distances. So I guess my "blanket" statement that a working distance is "too short" should have been more moderate. But I still feel, if you have a choice, 10mm is far nicer to work with than 2.7mm, even if the angular approach were to be similar.
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