Tuesday, 15 March 2011

GH1 vs G1 formats and RAW pixels

Having recently acquired a GH1 to replace my G1 camera one of the things I've been keen to test out is the difference between sensors of both cameras. The GH1 has a significantly different sensor to the G1 and gives significantly different results when used in RAW and changing the recording Aspect Ratio. I first read of this about 2010 on a page by Ian Burley here. I'm not sure if Ian has updated that much, but the diagrams initially didn't mean a lot to me.

Thus I thought I'd do this and publish my results of actual photographs

It has been documented elsewhere that if you use RAW and a raw converter which does not attempt to apply lens aberration corrections that you can get the following sizes from the sensor:

  • 4016 x 3016 Pixels (12.11 MPixels) (4:3)
  • 4144 x 2768 Pixels (11.47 MPixels) (3:2)
  • 4368 x 2464 Pixels (10.76 MPixels) (16:9)
  • 3008 x 3008 Pixels (9.05 MPixels) (1:1)
It would seem that the sensor is not just a plain grid but is instead a series of grids.

Now I was familiar with how my G1 performed when using RAW and converters such as dcraw to do the conversion, I got 4016 x 3016 which is a wee bit more than the standard 4000 x 3000 pixels that you would otherwise get. Nice to be sure, but nothing to write home about.

The GH1 on the other hand gives the following which really does begin to make a difference... So when you choose aspect ratios such as 16:9 the camera actually uses different parts of the sensor, and gives you more pixels not just cropping down the 4016 x 3016 to a lower height to fit into 16:9

The picture below was taken with my Olympus OM 50mm lens and I changed the recording formats. I converted and then pasted each image into an overlay as below:
You can see clearly that the 4:3 records a greater height than anything and the 16:9 records a greater width. Looking in particular at the 16:9 compared to the 4:3 we see this

So the 16:9 is recording 352 more pixels (and importantly) by actually capturing a wider area of the image circle cast by the lens.

Is this significant?

well that depends on you. If you are the sort of person who would buy a 24mm lens because a 28mm isn't wide enough then this difference is nearly the same as that.

Also, most people considering cameras suggest that APS cameras are better than 4/3 cameras because the APS camera has a wider sensor thus capturing the image better and not squeezing those pixels into a smaller area (pixel density). So here we have a 4/3 camera which shoots a format which is a little larger than 4/3 and produces an image size that is more pixels wide than an APS-C camera like the Nikon D5000 (4288 x 2848 pixels) when its wide shots you're after. Even shooting at 3:2 format (that of the APS-C camera) the image obtained from the GH1 is 4144 x 2768 Pixels which is so close to the APS-C that you can see there is nothing in it.

Then of course there is the video and the fact that the GH2 would seem to be even more again.

No wonder I keep seeing more Panasonics out there when I'm traveling


on our recent trip to New Zealand I got to meet the famous New Zealand bird the Kea

These big parrots are quite used to people and quite playful among each other:

they appear to be a green camouflage pattern when they take off you can see clearly the red under their wings:

stories of them damaging your car are not over stated, as this fellow (who seems to be known locally to the human population) hopped straight under our car as soon as we stopped before we even got out...

The Kea are actually under threat, so despite their behaviour please be nice to them, people have been responsible for taking their numbers to the threatened level both by hunting them and by the introduction of the Australian Possum (much reviled in NZ)

Thursday, 3 March 2011

RC helicopters


I've been playing with a few of the Remote Control helicopters lately, and compared to the little one I bought from Jaycar some couple of years ago things have really improved.

This little foam bodied fella was the first RC Heli I bought ...

It was unstable and never flew well ... hard to master.

Then just 2 years later they've created the coaxial type (note the two rotors)


That one is the Doublehorse 9098 ... which is very easy to fly and a bunch of fun indoors (like at the office). The coaxial actually don't need the tail rotor for turning (that's done by varying the speeds between the top and bottom rotor) they instead use the tail rotor to tilt the chopper forward or backwards ... and thus thrusting forward. You can see the difference clearly here.


Both have "balance bars" to alter the pitch on the blades to keep stability (which spinning as a gyro effectively stablise the craft).


While the 9098 was a gas inside it struggles with even the slightest "breeze" that the air conditioning can bring ... meaning not much. Further the IR control means that outside in the sunlight it gets out of range real fast.

Enter the Doublehorse 9053 coaxial helicopter.

This is nearly 70cm long and is huge in comparison to the 9098. It comes with an actual Radio control and works outside. However as standard has a few problems. For instance the upper and lower blades often collide in windy conditions and the tail rotor blade has not enough power to cope with windy conditions.

the result is crashes ...

So I've made a few modifications to mine (that are found on youtube) to make it more stable and controlable:
  • invert the mount for the bottom blade (and then flip the blades back)
  • enhance the rear tail rotor fan with greater size blades

As it happens the balance bar from a 9077 chopper fits straight on and also looks perfect too.

To address the lacking in thrust from the tail fan, I cut down the spare bottom main blades from my above mentioned 9098 and used a good plastic glue (Tarzans grip in this case) to affix them to the ends of the existing fan ... you can see that in the video below:

The inversion process for the bottom blade is reasonably easy and can be found on youtube too.

a quick test flight this morning at home shows that it works a treat


after a quick test outside at lunch in light breeze I'm still getting blade strike (brining the chopper down fast). Also for some reason the RC is intermittently getting through at some ranges meaning that when I control forward it doesn't and when I try to stop a turn it doesn't.

You can see I was having some RC responce problems as well as hear towards the end some 'clacks' of the blades striking.

hmmm ... more work needed

Tuesday, 1 March 2011

a Glacier getting bigger?

While we were in New Zealand a couple of weeks ago we visited the Franz Joseph Glacier

At the base of the glacier there is a small sign showing the retreat of the Glacier from its position in 1985 to now:

The interesting periods however are between 1950 and now, with the levels of retreat reversing in 1970 to now. You can see the glacier has grown significantly between 1970 and now.