John Sadowsky

John Sadowsky

Charlestown, MD

John S. Sadowsky is a retired wireless system and signal processing engineer, with both academic and industrial experience. Now, I'm an amateur landscape photographer. I've done a lot of shooting in America's southwest, mostly in Arizona and southe...
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Articles

Rolling Shutter on a Planetary Scale

Rolling Shutter on a Planetary Scale

HiRise, the High-Resolution Imaging Science Experiment, is a camera on the Mars Reconnaissance Orbiter (MRO). HiRise is a project of the University of Arizona’s Lunar and Planetary Laboratory, LPL, in Tucson, AZ. The mission is to photograph the surface of Mars in...

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Noise, ISO and Dynamic Range Explained

Noise, ISO and Dynamic Range Explained

This article examines the noise characteristics of a modern digital camera. The primary spec used to specify the noise performance of a camera is Dynamic range (DR). Most expositions on DR tend to get highly technical very quickly. OK, this article gets technical here...

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A Better Histogram

A Better Histogram

The photo-histogram is probably the most ubiquitous exposure tool in digital photography; that is, short light metering itself.  It has been with us more than 25 years, and it hasn’t changed much.  The histograms we are familiar with are calculated from transformed...

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  • John Sadowsky
    John Sadowsky
    Silver Member
    Posts: 169
    Clip-In Filters?
    on: August 1, 2021 at 10:55 am

    Thanks, Jonathan!  I was also thinking these filters might protect the sensor from dust – but apparently not so much.  The difficulting of inserting and removing it in the field also seems problematic.  I may still try out a neutral density filter.

    JSS

    John Sadowsky
    John Sadowsky
    Silver Member
    Posts: 169
    Re: Cameras, Lenses and Shooting Gear
    Reply #1 on: August 1, 2021 at 9:07 am

    Does anybody have any thoughts, pro or con, on clip-in filters.  These are filters that clip in the body of the mirrorless camera just on top of the sensor.  Their apparent advantages include that they are truly one-size-fits-all – that is, one filter for ALL lenses, and there is no vignetting.  You won’t get an adjustable gradient filter, but these appear to be a great solution if you are just looking for neutral density filters.  Any thoughts?  Is anybody using these?

    A PhotoPXL forum search on “clip-in filters” turned up one post by Jonathan Sacks, 5/20/2020, who pointed out that if you do an IR conversion on an old camera, you can then buy a clip-in IR filter to recover the IR filter.  Interesting.

    JSS

    John Sadowsky
    John Sadowsky
    Silver Member
    Posts: 169
    Re: Styles & Looks
    Reply #2 on: July 31, 2021 at 3:32 pm

    This is a math geeky post – if you’re not into that kind of thing, stop reading.

    An hxw rectangle, where h < w, is called a golden rectangle if h is to w as w is to w+h, that is, h/w = w/(h+w).  The ratio phi = h/w = 1.618… is called the golden ratio.  It has several interesting mathematical properties.  For example, it is the ratio of the diagonal to side length of a regular pentagon, and it is the asymptotic ratio of successive numbers in the Fibonacci sequence.  You can read more in the Wikipedia article.

    The golden ratio, also called the “divine proportion,” has also been known to have certain artistic properties.  You may have seen the golden spiral as an alternative to rule-of-thirds composition.  It has been claimed that the Great Pyramids of Giza, the Parthenon, and the Mona Lisa were designed using golden ratio – although some of those claims are not well substantiated.  Nonetheless, the 19th century psychologist G. T. Fechner presented subjects with piles of rectangles and asked them to select the most pleasing.  They selected the golden rectangles!  So there is something to this.

    Yet none of the standard crops are golden.  2 x 3 is the closest (ratio = 1.5), then 9 x 16 (ratio = 1.77…).  It happens (and there is a mathematical theorem about this) that 610 x 987 is extremely close to a golden rectangle.  So I entered 610 x 987 into Capture One as a custom crop and started comparing it to some 2 x 3 crops.  I found the golden crop to be more pleasing.  That’s not scientific result (like Fechner’s experiment) since I knew which crop was golden.  But it’s fun, and I’m going to start using it.

    JSS

    John Sadowsky
    John Sadowsky
    Silver Member
    Posts: 169
    Re: Slideshow on Sony Bravia TV with Apple TV 4K
    Reply #3 on: July 29, 2021 at 9:20 pm

    It is really smart.  Not to mention a really easy-to-use menu system (unlike that other OS).   Apple TV using an iPhone as a sensor will even do a color balance adjustment of your TV.  I’m sure it’s not what a real spectrometer like an X-Rite i1 can do … but hey!

    JSS

    John Sadowsky
    John Sadowsky
    Silver Member
    Posts: 169
    Re: Computers & Displays
    Reply #4 on: July 29, 2021 at 6:52 pm

    I thought I’d share my experience with slideshows on the Sony Bravia 65″, which is a 4K HDR OLED display.  It is a great TV, but, sadly, the Andriod OS is not slideshow friendly.  I tried several screen-mirroring and slideshow apps – slow response, slow rendering (momentary low-quality).  Amazingly, the Android OS couldn’t connect to Google Photos.  I spent several hours chatting with Sony support.  Their suggestions either didn’t work or gave unsatisfactory results.  The only way I found that I could get a quality slide show was to load JPEGs from a thumb drive manually into the Bravia memory.  Then I was limited to the Bravia slideshow software.

    So, I bought an Apple TV 4K brick, thus bypassing the Android OS.  It’s like day and night!

    The Apple TV brick plays the Apple Photos app, which provides some nice slideshow options.  I like the Ken Burns theme (with slight zooming and panning effects).  Apple Photos is an iCloud app.  So I just set up my Photos Albums on my Mac, and play the slideshow on the TV.  Problem solved!  But there are some details.

    Like most modern high-end TVs and monitors, the Bravia has a wide P3 color gamut, which is significantly wider than sRGB.  The Bravia spec is 99% of the P3 gamut.  Amazingly, many browsers still don’t support color management – so sRGB is still the rule on the web.  For example, if you try posting a P3 JPEG, Facebook will reformat it as sRGB (and probably resize it as well).  But my TV-slideshow is now an all Apple system, and Apple does color management right!  So, I used P3 for my slideshow images to utilize the full color gamut of the Bravia.

    The images are stored and transmitted to my Apple TV brick via iCloud.  That’s the convenience I wanted, but there is a download from an iCloud server and the brick will cash local copies to get instant rendering.  So we need compression for fast download and local storage.  Again, Apple is the leader.  They fully support HEIC = High Efficiency Image Coding.  For example, iPhones automatically store as HEIC.  HEIC is at least twice as efficient as JPEG for the same image quality, and Apple has optimized its apps (Photos) for fast rendering.

    Here is my workflow:  CaptureOne will import HEIC but does not yet export.  🙁  I export my images from C1 to TIFF as 16 bit (uncompressed) images with full resolution using the Display P3 color space.  (There are variants of the P3, but all have the same color gamut.  Display P3 is the one proposed and recommended by Apple.)  Then I open the TIFFs in the Apple Preview app from which I export to HEIC.  I adjust the quality slider to produce files 1-5 MB in size.  I then place the HEICs in an Apple Photos album, and I’m ready for display on the Bravia via the Apple TV brick.  It takes a few minutes for the images to migrate through the iCloud to the Apple TV brick.  After that, rendering is instantaneous, which is why I know the Apple TV is storing local copies.  Of course, we don’t have to get involved with that level of memory management (as opposed to the Android memory stick solution).  As with most things Apple – it just works!

    Lastly, I like the Ken Burns theme, but there is a caveat.  That theme will crop your images to fill the screen.  (Other themes, such as Classic and Snapshot, do not crop, but I like the Ken Burns theme better.)  So I crop all my slideshow images to 16:9 in CaptureOne (variants, of course) before exporting.

    I hope that is useful.

    JSS