Author Topic: How-to make decent photographs for forum posts/articles/publications?  (Read 237568 times)

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Online tunk

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Re: How-to make decent photographs for forum posts/articles/publications?
« Reply #50 on: February 10, 2021, 11:55:44 am »
Big Clive just made a video about making photos of (small) PCBs:
 

Online Peabody

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Re: How-to make decent photographs for forum posts/articles/publications?
« Reply #51 on: February 10, 2021, 04:05:11 pm »
Yes, and notice that Big Clive does this with a cell phone - a Moto6 Play (very much a "budget" phone).  None of that DSLR rubbish.
 

Offline DrG

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Crop Your Photos

Which makes more sense for a post?

This,



or this (same photo cropped)?



You probably have some software on your machine (or even your phone) that can crop photos, but you can do it online - search for "crop photos online"

« Last Edit: May 20, 2021, 03:35:01 pm by DrG »
- Invest in science - it pays big dividends. -
 

Offline EPAIII

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Re: How-to make decent photographs for forum posts/articles/publications?
« Reply #53 on: July 14, 2021, 01:41:48 am »
I have not posted much to this forum yet, but I have been posting photos to other forums for over ten years. Here are some things that I have learned:

1. USE a tripod or other support for your camera. Digital cameras often use longer exposures so any movement will result in a blur.

2. Many inexpensive digital cameras have a time delay function to allow the camera user to get into the photo. Another excellent use for these time delays is to avoid the camera shake (even if it is on a tripod) that can result from the small motion of your finger pressing the shutter release button. I almost always use a two second delay when taking photos. That gives me time to get my hands off the camera and for the camera to stop shaking.

As for flash, I use it when needed and avoid it when I can. I am making my first post here in a few minutes and the photo was made with a flash. But the flash was needed and did not cause any glaring hot spots in the image.
 

Offline Zucca

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Can't know what you don't love. St. Augustine
Can't love what you don't know. Zucca
 

Online RoGeorge

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Re: How-to make decent photographs for forum posts/articles/publications?
« Reply #55 on: August 11, 2022, 08:55:23 am »
That's nice!

In terms of minimizing the pics for web, I'm using 'convert' (from the 'imagemagic' package, often preinstalled), a command line tool for Linux, good to strip the extra info and to resize the original jpegs to half (1024px wide), then compress them a little better.

The camera is an ancient Minolta DiMAGE Z1, 3MP, better than a DSLR for close up pics.  In general, cameras with a smaller area sensor give better depth of field for closeup/macro shots than a camera with a big sensor.  DoF is bigger when the sensor is smaller (small in size, not in pixels) and this is so because of physics/math, it's not just an artistic bias.

The set of parameters that worked best for me, by turning a 1.5MB (2048x1536 px) .jpg into a 30-50kB (1024x768 px) .jpg, about 30 times smaller while the quality is preserved well enough for web posting:
Code: [Select]
convert "PICT3090.JPG" -strip -matte -resize 1024 -quality 50% -sampling-factor "2x2, 1x1, 1x1" "PICT3090_s.JPG"
Same pic as in the attachment, but resized + compressed 50% using Gimp has about 80k, looks slightly better but the quality difference is noticeable only when compared side by side, otherwise the smaller one prepared with 'convert' would be just as good:



For a comparison, the original is PICT3090.JPG, 1.5MB.
« Last Edit: August 11, 2022, 09:02:06 am by RoGeorge »
 

Online magic

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Re: How-to make decent photographs for forum posts/articles/publications?
« Reply #56 on: August 13, 2022, 06:42:48 am »
The camera is an ancient Minolta DiMAGE Z1, 3MP, better than a DSLR for close up pics.  In general, cameras with a smaller area sensor give better depth of field for closeup/macro shots than a camera with a big sensor.  DoF is bigger when the sensor is smaller (small in size, not in pixels) and this is so because of physics/math, it's not just an artistic bias.
Are you sure that sensor size comes into equation and not just your numerical aperture and the size of the minimum feature you want to resolve?



The rule goes the opposite way: a compact can't match a large sensor camera for shallow DoF and diffraction-limited resolution (which is a different matter altogether, unrelated to anything above, but equally important), because the focal length and the F-number of a lens required for such feat become impractically low.

That being said, a 6x crop compact stopped down to f/8 has the same NA as full frame at f/48, so you may struggle to find a lens capable of that. But at just 2x crop on 4/3 systems there are lenses that go down to f/22.
 


Online magic

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Re: How-to make decent photographs for forum posts/articles/publications?
« Reply #58 on: August 13, 2022, 12:59:39 pm »
Well, you said that it matters ;)

The pics show once again that stopping down FF to f/5.6 produces similar effect to MFT f/2.8, as expected.
MFT f/16 would be matched by FF f/32 and FF f/16 by MFT f/8, but these variants are not shown.
« Last Edit: August 13, 2022, 01:01:13 pm by magic »
 

Online RoGeorge

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Re: How-to make decent photographs for forum posts/articles/publications?
« Reply #59 on: August 13, 2022, 06:05:31 pm »
Sorry, it was you who used the word "matter", not me.   :P
What I was talking about is visible in that comparison article linked above.

For any pair of two pics taken with the same f-stop and the same framing, but with different sensor size, look at the middle plank, and then look at the last plank:
- the middle planks are perfectly in focus no matter the sensor size
- the last plank however, is sharper for the pic taken with the smaller size sensor

If it were to compare with an even smaller than a 3/4 sensor, like a webcam sensor or a phone camera, then the smaller sensors will show the last plank even more sharper, almost as sharp as the middle plank.

For me that's a fact, visible in the pics, won't gonna argue about.
« Last Edit: August 13, 2022, 06:08:12 pm by RoGeorge »
 

Online magic

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Re: How-to make decent photographs for forum posts/articles/publications?
« Reply #60 on: August 13, 2022, 07:31:06 pm »
It's an irrelevant fact because large cameras can work with a wider range of f-stops so there is no point comparing images taken at the same f-stop as a point & shoot.

MFT at f/16 has more DoF than any phone camera on the market today. And less resolution too. Well, unless you can find one with a VGA sensor or similar ::)
 

Online RoGeorge

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Re: How-to make decent photographs for forum posts/articles/publications?
« Reply #61 on: August 13, 2022, 09:35:42 pm »
So, you admit that for the same framing and the same f-stop, the smaller sensor pics show more Depth of Field.  :D

Just that now you are trying to declare that irrelevant (after you first question if the sensor size matters).

Then you try to find an escape by suggesting f/16.  F/16 is the last pair of pics in that link, and the smaller sensor still won at DoF.  :P


For me a point&shoot is better for taking pics in the lab.  When compared with my Nikon D90 DSLR, the point and shoot Minolta DiMAGE Z1 has the DoF advantage of a smaller sensor, is less bulky, and most of all can take macro shots from as close as ~3cm.  No macro rings needed, no inverted objective, no lens changing, just point and shoot, no cropping, and can take macro shots like these straight out of the camera:







Did I won?  ;D

Online magic

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Re: How-to make decent photographs for forum posts/articles/publications?
« Reply #62 on: August 14, 2022, 05:56:13 am »
This gimmick lens can produce similar shots.
https://www.venuslens.net/product/laowa-15mm-f/

Cost and size are the only factors in favor of a P&S, have always been.
There is no performance advantage.
 


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