Picture magnification question?

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lperepol
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Picture magnification question?

#1 Post by lperepol » Fri Feb 01, 2019 3:07 am

I have a camera mounted on a 0.5X reduction lens and am using a PH20 objective what is the magnification?
I am thinking the pictures are taken at 10 times magnification.

Looking through the eyepiece at 10x and a PH20 objective magnification is 200 times.

However, pictures taken look much more than 10 times?
1) OMAX 40X-2500X 18MP USB3 Plan Phase Contrast Trinocular LED with Turret Phase Disk
2) AmScope Trinocular Stereo, 3.5X-90X Magnification Four-Zone LED Ring Light

Jkelley1000
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Re: Picture magnification question?

#2 Post by Jkelley1000 » Fri Feb 01, 2019 5:26 am

There are a lot smarter than me in this illustrious group, but I'll add my two cents.
Magnification becomes irrelevant because the final size of the photomicrograph depends on the device it is viewed on. Projected on a wall or PC screen or a tiny cell phone screen.
PLEASE! I could be wrong about what magnification really means.

In the meantime, I would only add that my modest OMAX trinocular with 5 M camera and Toupview software on my PC via USB includes a stage calibration slide that allows me to actually insert a Metric/English ruler right on the photo which does give a true size of the specimen regardless of the size of the photo being viewed.

I don't mind telling you that I am a bit humbled by this brain trust on MicrobeHunter and hope I got that right... Hahahahah
Jimmy

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75RR
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Re: Picture magnification question?

#3 Post by 75RR » Fri Feb 01, 2019 5:37 am

At 100% they would be. Note that it is easy to stray into empty magnification with photograph final size.

Best way to to be sure is to use a Stage Micrometer.

Photograph it with each objective.

If you get an eyepiece with a Graticule/Reticle as well you can also use the Stage Micrometer to calibrate it.

You should probably get one anyway as size is an important detail in species identification.

You can either add a Graticule/Reticle to a spare eyepiece (make sure it can take one and what size is needed) or buy a no name eyepiece with one.

https://www.ebay.co.uk/itm/Cross-Dot-0- ... :rk:2:pf:0

https://www.ebay.co.uk/itm/Wide-Field-W ... rk:14:pf:0

https://tecmicroscopes.co.uk/wp-content ... ration.pdf
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

ChrisR
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Re: Picture magnification question?

#4 Post by ChrisR » Fri Feb 01, 2019 12:11 pm

+1 for a stage micrometer - or two.
If you get one which has a square grid pattern on it, it'll tell you quite a bit about how your optics are doing, sharpness wise, because you can compare across the field.
You won't get one with the desirable 0.01mm gradations with a grid, I expect, but they're much cheaper than they used to be so I'd advise one anyway.

viktor j nilsson
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Re: Picture magnification question?

#5 Post by viktor j nilsson » Fri Feb 01, 2019 1:17 pm

https://www.ebay.com/itm/171573622127

I have one of these that have both a grid and a scale, works very well and costs little.

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lperepol
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Re: Picture magnification question?

#6 Post by lperepol » Fri Feb 01, 2019 1:45 pm

Thank you all good answers. I was puzzling about a 1000x annotation on an image. The annotation does not mean much without a scale. Annotating the magnification of the objective used when capturing the image along with a scale may be better.

When calibrating a camera, are x and y dimensions the same length (horizontal, vertical, round, oval, square, rectangular)?

Some stage micrometres are pricey --> https://www.microscopeworld.com/p-1719- ... 005mm.aspx

Most likely off topic, but I ran into an issue with browsers Internet Explorer, FireFox and Google Chrome. They all can have different concepts on what the dimensions of a pixel ought to be. I cannot find the original tech doc that discusses the issue but this one is close --> https://stackoverflow.com/questions/232 ... pixel-size.
For example:
Compare.jpg
Compare.jpg (46.53 KiB) Viewed 2543 times
If one inspects the images in different browsers both are 89x89 pixels but are different sizes.
1) OMAX 40X-2500X 18MP USB3 Plan Phase Contrast Trinocular LED with Turret Phase Disk
2) AmScope Trinocular Stereo, 3.5X-90X Magnification Four-Zone LED Ring Light

Hobbyst46
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Re: Picture magnification question?

#7 Post by Hobbyst46 » Fri Feb 01, 2019 4:32 pm

lperepol wrote:Some stage micrometres are pricey --> https://www.microscopeworld.com/p-1719- ... 005mm.aspx
I own an old Zeiss stage micrometer, made of polished steel in which the glass window is embedded, and the graduation marks are super-fine, a really high level of mechanics, must have costed a fortune 70 years ago.
In addition I own a simple Chinese glass stage micrometer, like the one shown above by Viktor Nilsson, the scale marks are not as thin and elegant - yet the performance for calibration is exactly the same.
So I would vote for the simple inexpensive micrometer.
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

ChrisR
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Re: Picture magnification question?

#8 Post by ChrisR » Fri Feb 01, 2019 8:49 pm

Viktor's looks good. :)

I have one with a grid like this but 0.01mm centrally. Models come and go.
This is an eyepiece graticule, but you can tack them to a slide for stage use. (Would probably need to be upside down).
Good for lower magnifications: 181862775927
grid.jpg
grid.jpg (21.75 KiB) Viewed 2518 times

Tom Jones
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Re: Picture magnification question?

#9 Post by Tom Jones » Sat Feb 02, 2019 12:36 am

One other thing to consider is to be sure the picture/video format you want to use is the same one you use to calibrate.

Most cameras will use different pixel dimensions on the sensor for each available resolution and/or aspect ratio. That can rather dramatically change the number of pixels for a given dimension, and therefore the output image calibration.

For example, below are some pixel dimensions from the manual, for stills using a Panasonic GH4. Video resolution 4k, UHD, 2k, Full HD, etc., will all use different numbers of pixels on the sensor as well.

Setting the number of pixels
Applicable modes:
> [Rec] > [Picture Size]
When the aspect ratio is [4:3]. When the aspect ratio is [3:2].
Settings Image size Settings Image size
[L] (16M) 4608 x 3456 [L] (14M) 4608 x 3072
[M] (8M) 3264 x 2448 [M] (7M) 3264 x 2176
[S] (4M) 2336 x 1752 [S] (3.5M) 2336 x 1560

When the aspect ratio is [16:9]. When the aspect ratio is [1:1].
Settings Image size Settings Image size
[L] (12M) 4608 x 2592 [L] (12M) 3456 x 3456
[M] (8M) 3840 x 2160 [M] (6M) 2448 x 2448
[S] (2M) 1920 x 1080 [S] (3M) 1744 x 1744

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