Tag Archives: comparison

Shock Diamonds and the F-22

Within the very high speed flows of air in an aircraft’s exhaust, you can set up a series of shock waves and expansion fans as a result of the differences between the pressure of the flow and that of the surrounding air.  When afterburner is engaged, the hot gases and the temperature changes these shocks and expansions cause, result in a diamond pattern forming in the exhaust plume.  In darker conditions, these diamonds are more conspicuous but they are visible even in normal daylight.

These diamond patterns are a function of the flow being symmetrical since most engines have round exhaust nozzles.  This isn’t the case for the F-22, though.  It has flattened nozzles with a pointed profile top and bottom.  This got me wondering what the effect is on the exhaust plume and whether the traditional diamonds are formed or whether the nozzle shape results in a different pattern of shock and expansions as they reflect within the plume.  I decided to dig in to some shots to see what I could find.

I don’t have a lot of F-22 afterburner shots.  While I have shot them a lot taking off, they often take off without afterburner.  Since they have plenty of power and burner use dramatically increases fuel consumption (and the F-22 is not over-endowed with range as it is), there is no point using burner if it isn’t needed.  Air shows are a time when they do give it plenty of burner, so that is the source of the shots.

The result of this is that there is definitely something unusual about the shock patterns.  I include some shots of F-16 and F/A-18 afterburner plumes and the normal shock patterns that create the hotspots known as the diamonds are very obvious and simple in shape.  For the F-22, things are very different with the patterns of hot zones being something more in line with the shape of the nozzle.  The way in which the patterns repeat is more complex than for an axisymmetric nozzle.  There is nothing much to conclude in these observations.  It is just something that appeals to an old aero guy like me.

A330 CEO Versus NEO Courtesy of Delta

While I had headed to SeaTac to see the 21Air 767 arrive, I hung around for a couple of other arrivals.  Delta operates a variety of long haul types into the airport and this includes A330s of the older and newer generations.  First to arrive was an A330-300.  A little while later, it was followed by an A330-900, the A330neo version.  I thought I would try and get identical shots of both jets to see how much the engine and winglet changes showed up when looking at them in flight.  Here are shots to compare the two types for you to make your own comparisons.  I think the differences are there but they are not drastic.

HDR Tech Comparison – What’s Up Lightroom?

A while back I saw a Scott Kelby video on YouTube about the HDR functionality in Lightroom and that in Photoshop.  I had assumed that they were the same prior to seeing his video but he showed that the Photoshop version of the HDR was significantly cleaner than that in Lightroom.  I was interested in how this could be but I wasn’t too concerned.  The Lightroom version was so easy to use I figured the impact was not so much that it would show up in my shots.

Then, I found out I was wrong.  I was in the cockpit of the Comet at the Museum of Flight’s restoration facility at Paine Field.  I took a sequence for HDR because the cockpit is very dark but the view out of the windows is much brighter.  It isn’t particularly important since the view outside is nothing special but I did it anyway since I was there.  The lighter shot had quite a bit of shadow noise and, when I created the HDR in Lightroom, the noise was very conspicuous on the finished version.  I decided to try it in Photoshop to see what happened.  The difference was significant.  I include both of the full shots as processed along with the section of cockpit shadow so you can see the impact.

HDR Pro Comparison

wpid12423-IMG_2448.jpgThe iPhone has an HDR function available in the camera’s software. However, it hasn’t impressed me in the past. My friend Hayman introduced me to an app called HDR Pro and I have used that as my default iPhone HDR app since. Recently, they introduced an updated version of the app called HDR Pro X. I decided to give it a go. I wanted to see what the images it produced were like, how the new controls worked and also to make a comparison with the output from HDR Pro.

wpid12425-IMG_2449.jpgThe top shot is from the new app.  The second one is the previous version.  The added control certainly seems to be beneficial and the blowing out of the higlihgts is far better controlled.  I am generally happy with the new version.  The controls could be more user friendly.  When you use Lightroom/Camera Raw all the time, anything less seems clunky!  See what you think of the results.

When Does Noise Matter?

I will freely admit I am as much of a gearhead as the next photographer.  New toys always catch my attention and then it is a matter of time before the battle is won between my sensible side or my not very sensible side as to whether I am going to get something.  The price of said item may well have an influence on which side wins that battle.

One thing that is a popular discussion for the pixel peepers is noise.  Having started off with a Canon EOS10D when I first went digital and worked through a number of bodies since – none of which have left my ownership I must confess – I have seen some steady improvement in noise reduction capabilities although not always with as much benefit to the final image as I might have liked but I digress.

A while back I was shooting at the Oceana air show with two of my buddies, Ben and Simon.  We had trekked down from DC for the show and were greeted by less than ideal weather.  The cloud base was solid and low and a bunch of displays didn’t take place.  Some did though and we still had a good day.  Given the heavy cloud, though, we were struggling for light.  I was shooting mainly with the MkIIN and was up at ISO 800 for a lot of the time.

The MkIIN is well into the noisy range at 800 and I knew that was the case but there was little option.  A while after this show, Lightroom 3 came out and it had a lot of noise reduction built in that wasn’t in the previous version.  I took a look at some of the Oceana shots to see how much better they might look.  There was a noticeable improvement and I was happy.

Why am I discussing this now, over a year later?  I was mulling over this topic for some reason, probably related to another acquisition decision, and I wondered how the printed version was affected by this noise.  There are plenty of things that I fret over in an image when looking at it on screen, usually zoomed in far too close, that really don’t become apparent at all when printing.  Is noise one of those things that looks better on paper?

I picked one of the shots from that day to experiment with.  The shot in question is this one of one of the Blue Angels taking off.  Since there was the treeline behind, the gray sky was not an issue and the burner plumes show up nicely given how dark it is so I like the shot.  Now to check it out on a print.

One of the nice features of Lightroom is the ability to mess with the print layouts.  I made a couple of virtual copies of the image and one one of them did my best to optimize the noise reduction and on the other switched it off for the most part.  On screen, it did not look great.  I then set up a page in the print module with two cells right next to each other and put the left side of one image in the left cell and the right side of the other in the right cell.  It looks like a full aircraft if I get the positioning just right.

First I printed it on an 8.5×11 sheet.  If I look closely, I can see the divide.  It actually shows more in the background than on the aircraft.  It is visible but it isn’t as noticeable as you might expect.  This had got my interest!  What about the size of the print.  I repeated the layout on some Super B (13×19) paper of the same type and printed it again.

As you might expect, this time is is a little more noticeable – hey, it’s twice the size!  However, even now, while it isn’t great, it really isn’t that bad.  We are talking about turning the NR almost off.

So, what do I conclude from this?  Well, technology is going to always get better, both in camera and on the computer processing it and I am still going to be a sucker for a new piece of kit.  However, while there is a noticeable noise difference on screen, the print is really a lot more forgiving.  Maybe I should relax about it a lot more and just enjoy the shooting, even when the light is limited.