Wide field of view

[lobsters15]

At university decades ago I used a wonderful stereozoom microscope to look at invertebrates. It had a fantastic wide field of view. I recently purchased an Apex Explorer plus stereomicroscope. As the field of view was extremely disappointing I returned it to Amazon.
Can anyone recommend a stereomicroscope zoom or not zoom which would give me a really wide field of view?

[MichaelG.]

Some numerical indication of what you consider to be a 'fantastically wide' and/or 'disappointingly narrow' field of view would be helpful.

I find it convenient to print a few concentric circles of known diameter, for estimating the view at various magnifications.

... I will try attaching a PDF of my template this evening.

Best Wishes
MichaelG.
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Edit: For convenient reference http://www.apexmicroscopes.co.uk/apexexplorerplus.html
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Edit: Attached PDF of Concentric Circles ...
Printed at 100% these should increment by 5mm steps of Diameter [ 2.5mm steps of Radius ]

ConcentricCircles.pdf

(18.51 KiB) Downloaded 315 times

... I find these useful & hope others will.

[lobsters15]

I am sorry I don’t have numerical data.

[MichaelG.]

I am sorry I don’t have numerical data.

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No problem ... I'm sure we can get there if people measure their various 'scopes.
I can check my Nachet stereo-zoom tonight.

MichaelG.

[photomicro]

To start the ball rolling...

My PZO stereo has a field of view of approx. 45mm at x4 and 18mm at x10.

My Zeiss Stereo has a field of view of 21mm at x10.

That is the lowest the Zeiss goes.

Hope this is of some help.

Mike

[lobsters15]

Many thanks for the information. I think I will have to spend quite a lot more to get an optically superior set up with a better width of field. The Apex Explorer plus I purchased and returned cost £158. I am looking at GTvision and the model GXM -XTL which costs about £600.

[apochronaut]

Unfortunately, microscope eyepiece f.o.v.( F.N.) is not measured by the angle of view, the way telescope eyepieces are. Additionally, 18mm, 20mm etc., can be confusing, since some eyepieces have a measurement of 15mm stamped right on the eyelens housing and actually have a wider f.o.v. than 15mm. The reason for this is that the 15mm stamp, represents the eye relief, not the f.o.v.

The f.o.v. of a microscope eyepiece is the apparent f.o.v., not the actual f.o.v. A 20mm f.o.v. represents the diameter of the field, as if you were looking through a hole that was right adjacent to your eyeball. \

To calculate the actual f.o.v., from the apparent f.o.v., I use this formula
F.N. ÷ total magnification x 10,000 = actual field of view. The formula much copied on the web of F.N. ÷ objective magnification x 1000 = actual field of view only works for 10X eyepieces. Other formulas could be worked out too, or just measure with a micrometer.

W.F. is a relative term. If the manufacturer has been supplying Huygens eyepieces with a 13mm apparent f.o.v., then even 14mm, could be considered W.F. There are lots of eyepieces of 16,17 and 18mm f.o.v. marked W.F. For some years though, the default W.F. for 10x eyepieces has been 20mm. Some are still 18mm or 19mm and some are 22, Once you get to about 24mm, or greater, you have to shift your eyeballs slightly to see the edge of the field. These tend to be designated as E.W.F. or U.W.F.

15X W.F. eyepieces usually have a greater apparent field , than a 10X. Some are as great as 28mm, yielding actual fields, very close to that covered by a 10X eyepiece.

[MichaelG.]

As promised :

My Nachet stereo-zoom has 10x eyepieces
The tubes are only 27mm diameter, which must restrict the field somewhat.

Its Zoom objective is nominally scaled 1 to 4

A quick check reveals object field diameters between about 24mm and 6mm
It does give excellent quality views, but I don't think that it would qualify as wide-field.

MichaelG.
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Edit: This range, from Brunel is usefully documented:
http://www.brunelmicroscopes.co.uk/zoom-stereos.html

[MichaelG.]

I've just been 'googling' and found this:
https://www.titantoolsupply.com/uploads ... oscope.pdf

I have absolutely no knowledge of Titan or its products, but the spec. sheet is certainly interesting.

MichaelG.

[lobsters15]

Again thanks for all the advice. The Titan microscope looks interesting but I would prefer to buy from a UK supplier.

[apochronaut]

If you can find a used Bausch & Lomb Stereozoom 7 , an AO StereoStar 580 or an AO Cycloptic in the U.K., you would be well advised to consider those. Only the highest end Chinese made microscopes could possibly equal their performance, if at all. They usually don't sell very high these days-----well below their real value as a microscope.

The Stereozoom has a 7 : 1 zoom ratio and adjustable w.d., the 580 has a 6:1 zoom ratio. The Cycloptic is in a unique small club of older stereo microscopes in that it has an apochromatic main objective and several apochromatic auxiliary objectives available for it.

They all have a possible 20-22mm f.o.v. available with 10x eyepieces and even wider with the 15X.

Baker and Vickers also made excellent stereos, with stellar optics and those should be fairly well represented on the used market in the U.K. The M63 and M6100 were both excellent. The latter had the largest zoom ratio of 9:1 available, at it's introduction.

[lobsters15]

Thanks for these recommendations. It was a Bausch and Lomb I used at university all these years ago. It was excellent! Thanks again for everybody's help and advice.

[lobsters15]

I have just seen advertised on EBay a Brunel BMX 4 stereomicroscope, a microscope Brunel no longer make. It is advertised as having super widefield eyepieces. Can someone explain what this really means, do they actually increase the field of view? I thought that would simply depend on how many times the eyepiece magnifies the image created by the objective lens.The greater the magnification, the narrower the field of view.q

[apochronaut]

I don't think Brunel actually make microscopes. They would just have one of the jobbers in China supply them with whatever off the shelf stencil microscopes they are interested in and have the Brunel name put on them.

It is important to separate the concept of apparent field of view and actual field of view in ones mind.
Super wide field is one of those terms that shows up in specification literature attached to Chinese scopes. It has no specific meaning, just that the eyepieces might provide a wider apparent field than others . Yes, the higher the magnification, the more restricted the field of view but an eyepiece with a wider apparent field will always have a comparatively wider field, irregardless of whatever magnification it is contributing to.

Terms such as extra wide field and ultra wide field have relatively more meaning because they have been marked as such on certain eyepieces and although also not formal designations, have been associated with certain higher end mfgs. who had specific field diameters designated as such.