Taxacom: digital camera question

[Tony Rees]

Hi John,

Of course it depends on how big you would like to be able to print your
results - e.g. at 300 DPI, a 1 MP image (approx.) would still print up to
about 4 x 3 inches, a 4 MP image up to about  8 x 6 inches, and a 8 MP
image up to about 12 x 9 inches before quality falls off... For many
journal plates, they would be a composite of smaller images than (say) 10 x
8 inches, so small files would still get you there. On the other hand if
you want something to go on the cover of "Nature" at large size, or just to
create an archive of high quality images, large is definitely better!

I was intrigued enough by this topic to look further into the old
chestnut of "film vs digital" in which, as alluded to above, I believed
that up to around 12 MP, 35mm film beat digital, and above that, the other
way around (unless you go up to medium format etc.). I did a little test to
see at what point quality loss became visible on a scanned - actually
digitised with a micro 4/3 format, 20 MP resolution Olympus mirrorless SLR
- 30 year-old slide, taken probably at 100 ISO in good light outdoors -
copy put up at
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FFile%3AMaritime_Museum_%252B_James_Craig_1990.jpg&data=05%7C02%7Ctaxacom%40lists.ku.edu%7C8a89896b60934a02b60a08dcbcdf9e48%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638592916858640335%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C60000%7C%7C%7C&sdata=3X6b46dMLT98Dnw2tIy9jbQYhm%2FYHu9UTZ9ywxcz4Mg%3D&reserved=0
, So, I digitised this at 20 MP including some of the slide mount; after
cropping the latter off, I was left with 4,908 × 3,234 pixels (15.9 MP). I
then down sampled this to 2 smaller sizes and enlarged a small portion of
each image to see when quality loss would kick in. The answer seems to be
that 8 MP is a little visibly worse than 16 MP, and 4 MP definitely worse,
at least when "pixel peeping", see detailed enlargement comparison at
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpostimg.cc%2F2V6Rxtn9&data=05%7C02%7Ctaxacom%40lists.ku.edu%7C8a89896b60934a02b60a08dcbcdf9e48%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638592916858640335%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C60000%7C%7C%7C&sdata=fiRMHSv0%2BWyHPy1G2v1cSG7UQNLb1F3pUCM4gZUnS3k%3D&reserved=0 . So this tells me that maybe 16 MP of digital
may well be needed to equate to a good slide (transparency), for those of
us ancient enough to use this as a yardstick; however that may of course
not be necessary unless you wish to print to very large sizes (would equate
to 16 x 12 inches in this example).

Apologies if the above is too much of a diversion for some, however in the
overall context of "how much resolution is enough" for digital images I
thought it might have some value...

Regards to all - Tony

Tony Rees, New South Wales, Australia
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fabout.me%2FTonyRees&data=05%7C02%7Ctaxacom%40lists.ku.edu%7C8a89896b60934a02b60a08dcbcdf9e48%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638592916858640335%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C60000%7C%7C%7C&sdata=7qcmu%2BbxGqlHJgO6il%2FtH8EXjEAP3nsxFepzfmZTaFE%3D&reserved=0


On Thu, 15 Aug 2024 at 11:34, John Grehan via Taxacom <taxacom at lists.ku.edu>
wrote:

> Thanks Tony and Paulo, as well as an off-line respondent. It looks like I
> will be able to afford up to 18 megapixels. As for the microscope - yeah,
> you get what you pay for. But there is no way I can afford what I see in
> university or museum facilities. But right now I have a microscope that is
> over 50 years old (Kyowa - Japan) and used a small hand held digital camera
> which sometimes produced some barely adequate images. So at least I will
> now be better off to some degree. Through the kindness of a couple of
> university and museum colleagues I have been able to get stacked images for
> some important dissections.
>
> Cheers, John
>
> On Wed, Aug 14, 2024 at 6:17 PM Paulo Buckup <buckup at acd.ufrj.br> wrote:
>
> > Hi John,
> >         To achieve 300 dpi, each square inch in the final page requires
> > 90,000 pixels. So, a full letter size page (or equivalent in PDF)
> requires
> > over 8 megapixels. Allowing for some loss caused by cropping blank space
> > around your specimen, you need at least a 10 megapixel camera for a full
> > page image.
> >         Keep in mind that if you do any resizing or rotation of the final
> > image, the relationship between the pixels in the original camera sensor
> > and
> > the final image is lost, and the quality is severely reduced. So, if you
> do
> > rotating or resizing in photoshop you will need a 40 megapixel camera to
> > avoid individual pixel blurring.
> >         In my experience the "cheap" microscope cameras do not meet
> > traditional publication requirements (but will be accepted for
> publication
> > in open access journals by careless editors, mostly because PDFs are only
> > evaluated using monitors that have a resolution way below the 300 dpi
> > standard).
> >
> > Cheers,
> >
> > Paulo Buckup
> > Museu Nacional, UFRJ
> > Brazil
> > -----Mensagem original-----
> > De: Taxacom [mailto:taxacom-bounces at lists.ku.edu] Em nome de John Grehan
> > via
> > Taxacom
> > Enviada em: quarta-feira, 14 de agosto de 2024 11:45
> > Para: taxacom <taxacom at mailman.nhm.ku.edu>
> > Assunto: Taxacom: digital camera question
> >
> > Hope someone on Taxacome has microscope camera expertise that can help me
> > with a question concerning digital camera capability meeting publication
> > needs. I am looking at buying a 'cheap' (less than $1,000 US) dissecting
> > microscope and digital camera through Amscope. They have cameras ranging
> > from 1 to 20 megapixels, but I have no idea how that relates to dpi where
> > publications usually require at least 300 dpi. Can anyone clue me in on
> how
> > to know what megapixel size will likely work to give me a sharp enough
> > image
> > for publication? Currently looking at a 5 megapixel camera which brings
> the
> > setup well within my limits whereas 10 megapixel goes just over.
> > Any enlightenment much appreciated. I am a total moron when it comes to
> > digital camera tech.
> >
> > Thanks.
> >
> > John Grehan
> >
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