It depends on the optical scheme used. You may just make a series of micrographs from the object-micrometer at different magnifications to learn it.

Normally there is a "calibration factor" for these cameras, if you don´t have this information, you can try with well know images (like calibration standards) using the different objective lens.

Dear Jeannie, only to complete what my foreposters said:

When using ancillary camera technique (= old fashioned camera with color slide film or B/W negative film which for sure has become extinct or is nearly died out in most research facilities) this calculation was quite uncomplicated. Objective power(lens magn.) (say 40 times) (NOT the OCULAR power/lens magn! unless you combined the camera TO the ! EYEPIECE !) x (times) Camera (=Garcia’s “calibration”) factor (say 1,25; this factor depends on a lens or lens combination within the phototubus! and sometimes perhaps can be less than 1.0!) - the latter usually imprinted on the camera /photo-tube of the microscope (or on the analog camera device), resulted in the on the colorslide- or BW-negative film = (example) magnification on film: 40 x 1.25: M=x50.

Since you indicate “magnification of the digital image” one could argue you would be able to calculate in a similar way, but there are parameters to keep in mind:

the magnification of an image will be defined (but not depending on!, see below) by the size of the CCD-target (dimension of camera’s sensor, which can be found in the specifications section of the user manual), as well as the pixel size, too. As was proposed by Sergei, IMHO the simplest way to check this for a certain camera and (formerly calibrated) objectives for a certain microscope would be, to use an object micrometer, take images for the objective lenses you have (fixed pixels width/length of image) and measure the objective micrometer length on display (magnification will differ also on display mode on your screen e.g. vs. print mode)

Christian Schunk today has given also a valuable calculation.

Eventually: cf. also @:

http://www.dpreview.com/articles/6519974919/macro-photography-understanding-magnification

or IB Physics/Digital Technology @

http://en.wikibooks.org/wiki/IB_Physics/Digital_Technology

- Magnification of a CCD is the ratio of the length of the image on the CCD to the length of the object.

- Quantum efficiency; The greater the QE, the greater the sensitivity of the devices.

- Magnification; a greater magnification means more pixels are used for a given section of the image. the image will be more detailed. Resolution; The greater the resolution the greater the amount of detail recorded. An improvement in resolution will mean a given image will occupy more memory.

- Quantum efficiency (of a pixel): is defined as the ratio of the number of photoelectrons emitted to the number of photons incident on the pixel; not every incident photon will lead to emission of photoelectron. Usually quantum efficiency is between 70 to 80%

- Resolution: Two points on an object will be resolved on a CCD if the images of the points are more than two pixels apart.

- For measuring at least “macro”-magnification of digital cameras cf:

http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/Close-Up/BASICS/Magnification.html

- Objective magnifying power of microscopes: cf.

http://www.olympusmicro.com/primer/anatomy/magnification.html

Understanding resolution, cf:

http://www.nanotronicsimaging.com/files/System%20Resolution%2010252010%20%281%29.pdf

Best wishes and hoping it helps,

regards,

Wolfgang

Hi,

may I ask a question regarding the same topic. If the microscope I use (Biorevo BZ 9000 Keyence) applies a scale bar to the microscopic image, can I use the scale bar to measure the magnification? If I measure the size of scalebar on the image (2,3 cm = 23000 um) and divide it by the size indicated by the scalebar (e.g. 200 um), does this give me the magnification (115x)? Furthermore if I am supposed to specify the magnification of an image, does one normally mean the magnification in the picture in the print version (wich would be smaller as the size was reduced to e.g. 15%) or the magnification as in the original image of the microscope?

Thanks a lot!

All the best,

Rose

Dear Rose,

Usually the microscope is displaying scale and magnification as well.

In the case of digital microscopy where there are no eyepieces, Hirox set up a standard in 1985 calculating the magnification compared to the size of an object on a 15" screen. This resulted in a table that you can find here. I believe Keyence is using the same table.

Hope it helps!

Best regards,

Emilien

Hi Emilien,

thanks for your answer. I just found out that I actually need the magnification of the microscope (not the image as displayed in the print version). In order to calculate the total magnification of the image with what would I need to multiply the objective magnification?

Maybe the following equation when using a 2x-objective?

total magnification of the microscope= 2x (objective) x lens magnification x tube factor

However, I then would need to find the lens magnification and tube factor specified somewhere by biorevo bz 9000 E.

https://www.cambridge.org/core/journals/microscopy-today/article/guidelines-for-understanding-magnification-in-the-modern-digital-microscope-era/E99CB37B30B5DCF7654A17A44A6A682F

Dear Rose Fröhlich , the problem is that I can't find any actual information on the Microscope you use...so it might be an 'older vintage' microscope (what I found in one scientific article source is that that microscope is / was a Germany-made product...true?). So no technical information available (guessing you are not in possession of a Technical Data sheet or a Operations/user Manual (any more...or do you have one?).

The cambridge.org - >Microscopy Today< article by ROSE and DOPPLER, 2018 is quite extensive and detailed...-and naturally a huge source of knowledge...

>>....total magnification of the microscope= 2x (objective) x lens magnification x tube factor....>....total magnification (using a compound microscope [ roughly ]) = 'image magnification factor' (in German: 'Massstabszahl, definition see below', 'number' e. g. 40x as engraved on the objective itself): = magnification at the real intermediate image plane >....total magnification (using a compound microscope [ roughly ]) =

'image magnification factor' ( 'number' e. g. 40x as engraved on the objective itself) x magnification factor' (in German 'Maßstabszahl' or "Vergrößerung") of the ocular lens (e.g. 10x or '25x' ) = magnification of the real intermediate image as the 'optical image produced for the human eye'

Dear Wolfgang,

Thanks you ever so much for this detailed answer! I am very glad for your help!

Your are correct. I do not have a manual or data sheet at hand. However, I found this on the internet: https://docplayer.org/45773303-Neu-revolutionaere-fluoreszenz-mikroskopie-inklusive-hellfeld-phasenkontrast.html

DWow Thanks you ever so much for this detailed answer! I am very glad for your help! my technical understanding of the digital microscope- maybe different Teams are used for the technical information needed.

I will then probably need to find the information on the microscopic itself and go back to the laboratory, where I took the pictures.

'image magnification factor' ( 'number' e. g. 40x as engraved on the objective itself) x magnification factor' (in German 'Maßstabszahl' or "Vergrößerung") of the ocular lens(e.g. 10x or '25x' ) = magnification of the real intermediate image as the 'optical image produced for the human eye'

Dear Rose Fröhlich Rose, you are welcome.

Apologies for my late reply...("noch andere Baustellen" (:-)).

Just to answer your last Q-sentence (bitte nicht als "Belehrung" verstehen! ): >>So this would be what I need to specify the magnification of the optical images produced for the human eye, being the total magnification of the microscope, correct? A4 > A5, etc.) you are confined to get back to the digital/electronic microscope you used and ask supervising staff personnel for the right and correct data.

For that I wish you good luck and all the best.

PS: for my personal 'nosiness' I sent a request/enquiry for an Manual of Operation or User's guide(manual for their discontinued biorevo bz 9000 E Light microscope (a pdf if available) to Keyence (for your convenience only) :

KEYENCE CORPORATION OF AMERICA

KEYENCE CORPORATION OF AMERICA

Phone:+1-888-539-3623

E-mail:[email protected]

https://www.keyence.com/

In case I get an answer, you'll immediately will get mail (:-))

Best regards, Wolfgang

(private: [email protected])

Hello Wolfgang,

thank you ever so much for your detailed answer.

It is funny though that my university requires the magnification, even though this today with an electronic microscope is rather difficult to calculate correctly, especially if they don't specify the exact magnification type they want. However, we assumed that the magnification of the microscope itself is what I am looking for- so of the picture it saves as a .tiff (and not the magnification of the picture in the final document/print). I will need to get in contact with the lab staff and ask for help and information about the needed parameters.

Thanks for all your help and have a great day!

Rose

Hi, dear Rose, thank you for the information you provided (also with the brochure I was able to download....Unfortunately the Technical description in that pdf tells that for the respective electronic light microscope (which meanwhile has been discontinued as per KEYENCE website) the >>Software for displaying the 'scale' ('Maßstab', cf. there on p-23-) is 'N/V'

Thanks Wolfgang! I will do that!