Are different brands of camera flashes different?

On the Photography StackExchange site, I came across an interesting question: “Factoring out all features and just considering the Quality of the light, What is the difference between a very expensive flash and a average priced flash?

I was aware that people had posted opinions on general quality of manufacturing and durability in a professional-use situation and product lifetime, and I had decided to get one of each (one expensive, one cheap).  The only feature difference that I use is the secondary lamp on the high-end brand.  Since I have them, I thought I could easily compare the results.

The Test Shots

I shot the same picture using a Yongnuo YN568EXII (currently sold for $105) and a Metz 58AF2 ($400 for those versions still for sale).  I used a tripod with the flash mounted on-camera, and fully specified the exposure as ISO 100, 1/250 second at f/22. The flashes were set to use ETTL to determine the light output automatically, with the zoom head set to 70mm, and the secondary lamp on the Metz disabled.

The raw files can be downloaded via Dropbox.  IMG_4236 was taken using the Yongnuo, and IMG_4237 with the Metz.

RAW Data Analysis

chart-measurements

The green rectangles indicate some of the regions where measurements were taken: whole-chart, lightest, darkest, and grey-background.

To my surprise, the immediate appearance of the histogram on the camera showed striking differences!  The Metz showed a substantially broader range of tonal values, while the Yongnuo showed a narrow spike dominating the display.

To get a closer look, I used RawDigger, which will give information about the real recorded values in the RAW file without any kind of interpretation going on.

IMG_4236-Sel-1813-1257-1605x1135.x

Yongnuo whole chart measurement

IMG_4237-Sel-1813-1257-1605x1135.x

Metz whole-chart measurement

Where are these differences coming from?  I’ll report only the green values because the shapes of the histogram are the same in all channels.

For middle grey, the background border areas of the card, Yongnuo (Y) shows an average value of about 702 and σ (standard deviation) is 32.  For Metz (M), the average is 852 with σ 25.  The darkest and lightest (un-numbered) patches are 68–3013, while for M they range from 55½–2417, with similar variances on each brand.

For M, the brightest un-colored base paper is not the brightest value recorded! Patches 13-A through 19-B, (C,D)-13 (cyans), and (C,D)-15 (yellows) are all brighter in the green channel.  The brightest patches on M measure as 3142, where there is a visible spike at the right edge of the histogram.  In Y, those patches are 2895, a little less than full bright, as expected.

This might be due to uneven flash coverage: I found the wall around the chart was also brighter towards the upper-right on the M, so the base-paper patch happens to lie in the corner that received the least light.  On the other hand, the wall was more slightly brighter towards the top in the Y exposure.  Since the camera was in the same position and the flash height is only about 1cm different, any effects due to angle should be the same on both.

Looking at the R,G,B values of patch L8, it is clear that the color balance is different: the Y has more blue than the M.  In the histograms for the overall chart, the M shows double peaks in all three channels where the Y only has one.  In the red channel, one peak between EV −2 and −3 (about sample value 350) while in M there is a double peak around this value; for green the situation is similar between EV −1 and −2; and for blue the peak just right of EV −2 in the Y corresponds to just the (smaller) right part of the double-peak on either side of EV −2, in the M.  The blue channel also has another strong peak at EV −1 in the M that’s not present at all on Y.  Clearly the colors are responding differently.

The overall exposure seems darker in the M photo just looking at what comes up in RawDigger, though range of values (as seen on the histograms) is the same on each, and the specific value recorded for middle gray is the other way around.  For the wall to the right of the chart, the M is also a tiny amount brighter.  But for the lower-left of the exposure, the wall is significantly darker in the M if you just look at the average.

flash-chart-wall-R

flash-chart-wall-LL

The M exposure shows a lower average and a much lower σ, but the histogram pictures show fatter distributions on the M, and double peaks.  This is confusing and not immediately obvious why, but RawDigger changes horizontal scales when moving between exposures, and the choice of scale is not intuitive.  It appears that the exposure is about half a stop lower in this region for the M.

Without using careful measurements of the image pixel data, a side-by-side viewing appears to have a slight difference in exposure, but upon closer inspection only some things are exposed differently and the color balance is different.  This definitely counts as a difference.

Developed Data Analysis

Loading the files into Lightroom, I synchronized changes to the two exposures. I cropped the chart so the histogram is dominated by neutrals and shows a clear peak that should be lined up in all channels. I also corrected the perspective so it’s roughly rectangular, which will simplify the later overlay comparison. Sharpening and Noise Reduction were both turned off.

The process used is 2012 Adobe Standard, and no adjustments where made to exposure.

The White Balance was set using the eyedrop tool over a section of grey background. The image is rather noisy with the color varying from pixel to pixel, visible in the loupe-zoom of the tool. So I tried a few spots to make sure it was representative, and verified that the RGB values of the neutral patches were showing the same in each channel.

The same WB was applied to both exposures, and the other exposure was visibly different, showing a color cast.  Below are screen shots put together in a collage.  You can see the histogram in LightRoom indicates that the neutral peaks don’t line up.

wb-comparison

The Color Temperature of the two flashes are different, and neither matches the Flash preset color balance.  The setting above, taken for the Yongnuo, is a temperature of 6650 with tint +10.  The Metz is about 6072 with tint +14.

Next, I compare all the colored patches by cutting strips half as tall as the patches and alternating them from different exposures.  Below, each patch, e.g. the yellow in L15, has the bottom of the box shown from the Yongnuo exposure, and the top of the box from the Metz.  In addition, the left and right edges are painted in Photoshop as pure uniform grey.

stacked-charts

After adjusting the WB individually for each exposure as explained above, it was clear from this rendering that the brightness varied across the chart, in different ways for each exposure!  I used a (different) gradient exposure adjustment on each to approximate the uniform brightness of the grey background.

Ignoring the brightness completely by setting all the “B” values to 50% and leaving the “H” and “S” unchanged, we can better see the color differences without being overwhelmed by the illumination changes.

stacked-charts-hue

Colors with especially low saturation are lost, but this shows that the only color shift is subtle: Pure blue shifts in saturation, green shifts a little in hue value, and cyan does both.  This is not something that will be noticed, so in terms of color quality of the flash I would say there is no real difference.

Note that this uses the correct white balance adjustment for each flash, individually.  What about using both at the same time, so the light sources are mixed?

stacked-charts-WB-hues
This adds a yellowing of the mid to dark neutrals, and a hue shift in the magentas.   The lightest neutrals don’t have a visible difference, and I think that would be where it would be more bothersome.  I expect the overall effect is lost in the normal color casts you pick up from other objects in the room and whatever you are bouncing off or diffusing through.

Conclusions

Both flashes have non-uniform light beams that I believe are the dominant source of differences.  In particular, the apparent difference in exposure and the visibly different texturing of the wall is due, I conjecture, to the differences in illumination angles.  A difference in diffusion, or apparent size of the light source, can affect the modeling of textures especially when the flash is near the lens.  This deserves further research.

Although I saw the in-camera histogram was quite different with one seemingly offering more dynamic range in the exposure, and the reflected light curves are also rather different in some interesting ways, they both work to reproduce colors well.  (Assuming a silver-halide technology ANSI standard IT8 calibrating target contains pigments that respond to different spectra of light in a similar manner to real-world scenes, though it was produced with the intention of mimicking the response of various prints and films. But pigments and dies used for making prints are themselves expected to look right under different lighting conditions.)

 

Hunsacker in “in Glorious RadioVozion™”

On May 16th, 2015 Tao and I attended a play at the Bathhouse Cultural Center.

HQ-DSC00142 two of us

This is on the shore of White Rock Lake, and we arrived just as the sun was setting.

HQ-DSC00129 Tao at Bath Center

I had a few minutes to use the camera.  I got the α6000 specifically to use as a “social camera” to use at such events, as mused in another post.  I was afraid the fill flash would be unusable, but it works OK for a subject distance as would be typical for such use, thanks to digital processing.  The in-camera JPEG would probably do such wizardry automatically, but I don’t use that.  Taking a full-depth 14-bit raw image file, the somewhat brightened subject could be brought up another stop.  It looks like the camera nearly overexposed the brights (the bland sky) and put out as much flash as it could manage.

I used three different adjustments: the foreground subject, color-correction of the landscape, and bring out some visible color in the sky.  The problem with fill-flash, even if it could get the exposure to match with a full-sized external dSLR flash, is that the light doesn’t match; in this case, about 500K too blue.  The camera’s built-in processing might be confused that the sunset was giving pink highlights to the lake!

The theater only has 116 seats, non-reserved, so we hurried in.

HQ-DSC00182 Curtain Call

Here is a photo of the curtain-call (when I was allowed to take photos).  You can see that the set was for an entirely different play, and the microphones are dressed to look in-period, and (if you are familiar with the series) that the people are not in black&white makeup.

This was not just a reading, either.  Deadline! was presented in the manner of an in-period radio show, with an announcer and “sound artist”.  The players dressed in-period, except for their socks I was to learn.

HQ-DSC00171 sound artist

Here is a picture from the side, to show the sound effects and radio announcer performance area, which is blocked in the previous picture as it’s in the back of the stage.

The pipe is a period prop; the Apple laptop is an anachronism, but served great for a neutral color reference in the photo.  They used all live effects except for the music, I’m told.

After the play, they had a Q&A with the audience.  Here is Kurt explaining something in depth.

HQ-DSC00208 cast discussion

I tried to find a shot where Barbra is smiling, but her expression of perplexity only deepened and became more pronounced the longer Kurt continued talking.  It appears the sound artist is taking an interest.

The “live radio” format as a presentation in itself is something I’ve seen before, in Alien Voices.  I saw them (on TV) do War of the Worlds, and it featured live “practical” sound effects as an integral part of the live show.  I suppose that’s different from their normal audio books, which are sound only.

 

 

Diamond’s “Found” Photos

See the previous post for the story.

Diamond positioned himself at the main entryway of this office building, watching people go in and out and getting spotted himself. Someone took this and, after looking for lost pets online, forwarded it to us via MMS message to the phone number on the flier.

Diamond_Found_IMG_0258

A perfect travel postcard

Someone else posted on a regional lost pets group of Facebook and also forwarded us a copy, as seen in the last entry. Here is the full photo, and you can see Brendan and his family’s car reflected in the window!

Diamond-Found_IMG_0260

A busy receiving line! Diamond is about to meet Brendan.

Brendan-edit-2

Sure, you can take a picture with me!

And here is Brendan meeting Diamond. He offered Diamond a cracker, which is a good way to make friends with a hungry bird.

Brendan-edit-1

Diamond’s “Roughing It” Vacation

Diamond

Friday

On Friday, April 10 2015, everything seemed normal.  Tao was out grocery shopping and I gave Diamond his dinner.  He acted normal and content, sitting on his deck (pictured above).  I expected Tao to be home soon so I stayed downstairs, putting away dishes and other small chores.

When I heard her coming, I watched by the door and when she got right onto the porch I opened the front door.  Diamond took off, and bolted out the door.  He was not trying to reach Tao, but flew over her head and to one side, full speed ahead.  I was in shock, not believing what I just saw so quickly.

That is simply not like him.  He doesn’t boldly explore new places, even within the house.  He sticks to a few favored places and is shy about being somewhere else with me, and never on his own initiative.

I expected he must be very close to the front of the house, as when he’s scared he will just grab on, hold still, and stay quiet.  The loud lawn machines across the street would scare him, and I expected to find him in the trees or landscaping directly in our front yard.  Shock turned to worry when a broader search did not find him.

After dark, I knew Diamond would not be active at all but needs to roost.  Parrots don’t have good night vision and can’t get around in the dark.  We decided to make some fliers, so I quickly put something together in Photoshop and took it to a nearby FedEx Office store for printing in bulk, before the closed at 9PM.

We left a few fliers at houses immediately surrounding ours, and I went a few blocks perpendicular to our street as well.  It was at this time that I met some neighbors:  one person a few doors down the block, and a family hanging out on the driveway behind the alley, and a man next door to that.  The whole time up to that point, nobody was visible on the street except for lawn-care professions (who would not stop using the scary leaf blower, BTW), and even knocking on doors I found nobody home to answer.

Tao posted on Craig’s List, which turned out to be useful (I think).

Saturday

Early in the morning, as birds were just getting up and becoming active, I went out to distribute fliers.  Since the binoculars were broken, I took a telephoto lens on my camera, which I thought a good idea anyway since I might examine a photo more carefully when I could not make out details though a shaky live view.

I also set out a portable speaker in the back yard, playing Tao’s voice in a loop.  If he can’t tell which house is his because he doesn’t know it from the outside, he might hear a familiar and distinctive sound and come that way.

Tao also distributed fliers, in a different direction.  I printed out a map to mark our routes and keep track of what’s been covered.

Sunday

I set out a plastic milk crate that he finds irresistible and just has to perch on and investigate.  I put it on the grill counter, near the back door, which is too close for wild birds but is an area he watches with great interest from his window.  I added to that a small stainless-steel bowl of nuts.  Again, shiny metal is something wild birds would be fearful of, but to Diamond that’s where food is found.  (It had not been taken by wild birds, so I suppose that’s right).

Monday

Tao passed out more fliers in the early morning before going in to work.  She has different hours on different days and Monday is a “later” morning.

I got a call from someone who found a flier that day reporting that he heard a parrot the previous afternoon.

That gave me renewed hope.  I used the last of the fliers in that area, at the same time of day.  It is common for him to call for a while in the late afternoon before evening, as do some wild birds.  So I tried to find his voice when that afternoon’s Social Chorus started.

I saved 3 fliers in reserve.

Tuesday

At last!  I got several calls in the early evening saying that Diamond has been spotted at an office building across town, 2 miles away!IMG_2458

When I got photos, it was unmistakable that Diamond was alive and doing OK, just a couple hours ago.  I heard that he was seen at this building from about 5:00PM, and that he had approached a woman in brown scrubs who met a kid.  Now it’s both exciting and frustrating, as the family who witnessed that interaction thought to look for Lost Pets online while waiting for the dentist, and did find my flier.  The people who saw Diamond and also found me did not know the people Diamond approached did not find me.

I went to the building and looked around, and left the last of the fliers where hopefully it make a connection the following day.  Most of the offices were already closed.

Wednesday

Early in the morning, we went out to that building again.  Looking around, I saw that there were numerous trees on the property, an open underground parking area, and the lot was adjacent to parkland featuring a creek.  The Google satellite view like I saw on my phone is shown below, with the red dot marked where the photo above was taken.

Office-Building

So, it’s a nice place for birds, as far as suburbs in this climate go.  I looked around, hoping I would find him still in the area, but also hoping I wouldn’t because he went home with someone.  I hoped this was it, because we were expecting severe weather starting in the afternoon.

When people started arriving, Tao asked them if they knew anything.  At last, we found someone who identified the woman in the brown scrubs, and had seen Diamond still riding her shoulder as she came back into the building.  She called her, and related that Diamond was not with her after all, but a different family was going to try to take him in.  She didn’t know who that was, but knew which office they were at.

The office in question opened at 9:00AM, so we waited until the proprietor came in.  He called the people who we knew intended to take in Diamond, and it went straight to voice mail.

Finally we heard back, and learned that Diamond went home with them and spent the night safe.  The only thing remaining was to go there and pick him up.

Tao and I had driven separately so she could go directly to work later.  Just to make things more exciting, my phone navigation was not working well:  it kept losing the GPS signal and the program would lock up for several seconds at a time.  It would show me behind the actual position and possibly in the wrong orientation, so I kept missing turns.

Tao had arrived ahead of me, and when I got there Diamond was sitting quietly on her shoulder.

Home at Last

So, Diamond spent 4 days and 4 nights in the rough, wild suburbs, and one night at a nice Roost and Breakfast.  I suppose people started spotting him and taking photos all of a sudden because that’s when he wanted to be found.  He spent an hour in public watching people enter and leave the building, before approaching someone.  He must have been considering who looked friendly, having to decide before it got late.

He seems find, just tired and hungry.  The slow and careful movements make me sympathize with being sore from overdoing it.  He also looks a bit unkempt, with his feathers seeming a bit frayed at the ends.  Besides fluffing up more for warmth, he didn’t have the time to keep himself groomed in his normal fastidious manner.  In addition to the dirt on his left coverts (slightly visible in this web-quality photo),  the ends of his primaries and rectricies (tail) appear a little frayed.

Diamond-3912

Looking Disheveled and a Bit Frayed

On the earlier photo at the top of this page, you can see that when his wings are folded, the tips of his primary flight features tough the tip of his tail features. Both are iridescent indigo in the light from the photo flash.

Diamond-3912-head

Bad Hair Crown-feather Day

The chatter in the local lost pets Facebook group is that Brandon (the kid who befriended him) should get the reward.  I still need to talk to everyone involved and flesh out the details, but look for a subsequent blog post in the pets category for more.

Next in topic: Diamond’s “Found” Photos

Most Boring Product Photos

Not to long ago I was photographing some product shots for family, to put on Amazon, so I had to shoot a nice shiny object with a pure white background.  Good product shots are not always easy, and some attention to detail is nice.

As it happens, the other day I came across the most boring product shots imaginable.  Ironically, both had to do with photography.  The first was linked from this post on using colored gels on the flash to match the existing lighting. This 20×24″ sheet of Full CTO can be cut up into pieces to fit over the flash head.  Click to open expanded view just struck me as funny.  Compare with this store, which uses the technical data sheet as a product image as well.

Then I came across this one, following link from the BFT by the same poster.  Now that’s hard to beat on pure useless minimalism while still being perfectly correct.  But let me know in the comments if you know otherwise.

 

Annual Black & White Play

The famous Black and White plays… well, there’s just no way to describe it.

Here is Tao and me before the play, with my brother-in-law in the frame as well. It is traditional to dress in black and white, especially for the New Year performance. But that’s not why it’s called a black and white play.

before-show

After the show, we met with the cast.  Here I am with Nick and Nora Charles straight off the screen from the 1934 film.
after-show-thinman

Well, actually it’s the world famous detective and aspiring actor Harry Bunsnacker and his paid by the hour assistant and close personal friend Nigel Grouse, in a clever disguise.  Below I’m with Lt. Foster, the show’s straight man.

after-show-foster

My family has been attending the Pegasus Theater’s productions since 1986.  And as I stated at the beginning, it’s indescribable.

A trip to the symphony

Dressed up to go out

Since Itzhak Perlman was going to be in town around the time of Tao’s birthday, I bought tickets for that show — six months ago when I saw the schedule.

Jaap van Zweden conducts
Itzhak Perlman, violin

RAVEL Daphnis et Chloé Suite No. 2
BRUCH Violin Concerto No. 1
Itzhak Perlman, violin
TCHAIKOVSKY Capriccio italien

It turns out this was the hottest ticket in town, being a special 25th anniversary gala at the Meyerson.  As well as starting a little late, people kept making speeches and I wondered how much music there would be given the times stated!  Among the “honorary organizers” were the mayor of Dallas and Ross Perot.

There was a special award for the architect I. M. Pei which was accepted by one of his sons.  Since it consisted of a “piece of original limestone” and a chunk of crystal, it looked rather heavy to the people who did handle it.  The 97 year old architect has won every award remotely connected to his field, so it makes sense that he would just send someone to pick it up [pun intended] for him.

Another speaker was Sarah, Duchess of York which surprised me.  I didn’t think that people outside of the area were involved, but apparently the building of the Meyerson was world-wide news and interested people in the Arts from all over.

As for the music, I needn’t have worried.  They simply played until they were done, never mind the printed times for the after party.  In fact, there were two encores: Perlman played the theme from Schindler’s List, and the orchestra continued with a waltz which name I did not catch.

As usual, the live performance at the Meyerson was richer and more powerful than any recording.  That’s the exact opposite of the situation with “pop” music in venues with acoustics so bad that it’s not about the sound at all but the experience of gathering.  I think I will find a good recording of Bruch, though, which is missing from my collection.

The Joy of Reading (21st century style)

I decided to read a science fiction novel.  Not a unique occurrence, as I have thousands of them in boxes and storage and shelves.  And that’s the problem, really.  Hard drive space is already increasing faster than my reading pace, so I could store books electronically and add to them indefinitely and keep the same physical volume.

Now I’m already well practiced with using my original Nook reader.  After downloading the file, I would next import it into calibre, not just to keep track of it but to massage the data.  But first it tells me that my version is woefully out of date and I go download and install the latest, which offers many improvements and rearranges the controls.

The book’s file is a bit strange, it seems, as it was not importing right.  Easiest thing is just to load it in Sigil instead (though I suppose I could figure out the import options or use new features to edit the files and not need Sigil anymore for its use in later steps) and save it again.

A first look at the formatted ebook is fair; I’ve seen much worse from some publishers.  Why can’t they do as well as, say, Project Gutenberg, and just put the text in a file?  But I digress.  I fire up calibre’s “heuristic” processing to clean up all the junk, and use its formatting features to optimize the file for my device’s liking and my reading preferences.  Ah, but that’s set for Nook.  Well, a new software reader probably doesn’t have as many peculiar issues as an old dedicated reader, so I probably don’t need that anymore.  Generic output profile to start with, but still specify traditional print-style rendering where paragraphs are indented on the first line as opposed to having double vertical space between them.  Margins and other stuff should be taken care of by the reader software.

Normally this is where I then load the resulting file into Sigil and see if there are any bizzare features that can be fixed with a simple global search-and-replace on the HTML source, if that is still necessary.  At the least I’ll manually retouch the css file to delete stuff that ought to be unspecified so the reader doesn’t feel it’s being bossed around, and get rid of the text-align: justify line since that doesn’t work as well on the old low-resolution e-paper display.  It looks better if the horizontal spacing is optimized for letterform appearance and not also trying to get a specific length too.

On the Nook, I then plugged in the USB cable (which was charging anyway) and had calibre export to it.  But how do I read it on the Android tablet?  USB filesystem hasn’t worked for a few years now and it’s futile to try.  It doesn’t have SMB file networking built in, but there are apps for that.  I know I’ve tried a fancy file manager that includes network access, and it doesn’t work.  I use the network plug-in for the well-regarded Midnight Commander port, and it doesn’t work.  I tried a few more programs, and nothing could get past the names of the file shares, if it got that far at all.  Must be some “security” thing?

Next I try a couple features in calibre.  One is wireless device access, and I’m not sure what that does, but a couple readers and stand-alone programs allow the Android device to use it, it seems.  Well, I can’t get anything to do anything with that.  The other feature is better:  a web server interface.  It tells me the local IP address and port, so I make that into a URL and feed it to Firefox.  Success!  It lets me browse the book collection on the Android tablet, and download files via HTTP.  So, now I have the book file on the tablet.

Next question:  which reader software?  A Google search turns up a few reviews.  Mostly they don’t address the features I’m looking for, or any real features pertaining to the core function of reading stuff presented on the screen.  I don’t care which stores they are integrated with, or how pretty the book chooser screen looks and all the skeuomorphisms present.  A shame that “able to load files on local storage” is a feature that needs to be checked for!  The supplied Google Play Read for example, has its collection of things you bought from them, and no way to point to an actual file.

I end up trying two, and spend the rest of the afternoon figuring out how to make it dance with the song I sing for it.  I’m glad to say that I had success in setting font appearance and size, getting the line spacing to look right, having it show margins rather than printing all the way to the edge of the screen, and so on.

The page is looking quite presentable.  I do mean “looks”, since I haven’t actually read the first page yet.  That’s a chore for next weekend.  It does seem like a lot of effort for a book I’m not going to like anyway, but that’s why I wanted to save five bucks for a remaindered copy plus shipping.