The first thing i'd say is that its pretty sunny there, generally speaking. 
If your outdoors during the day, chances are low you'll need a flash at all. 
In June normally all Thailand except the southern Gulf is in monsoon. The southern Gulf's (Samui and neighbours plus adjacent mainland coast) usual wet season is Oct into Jan. I can't speak for what the day light is like during that time however.

The recommended range for the flash isn't more than about 100mm, past that, its usefulness is limited. Using the integrated diffusion panel allows extended wide-angle coverage to 14mm.

It wouldn't hurt to have a better flash than the integrated one but it all depends on what you'll be shooting. With the 15-55mm lens i'd expect the integrated flash to do good enough.

It really depends on what you'll be shooting and what you'll be using the flash for. I used a couple of generic hand-held flashes for light painting in caves in Thailand. I thoroughly recommend them for this purpose! 

Check out the DPreview link here for details about the flash and base your recommendations around that.

Hope that helps!

PS: Interstingly, I just came back from Thailand. All my camera gear got destroyed cause my peli-case leaked -_- Watch out for the water!

Is it worth bringing a flash for a backpacking trip?
I am testing various projections to calculate areas using ICES statistical shapefiles and the QGIS field calculator. 

I am using ICES areas downloadable from the following link: http://geo.ices.dk/download.php?dataset=ices_ref:ices_areas. (Please note that the calculations described below made by both ICES and myself were made using a densified version of the data available on the website).

I have been in contact with ICES and they are getting very different results when they calculate their areas using the same projections as me. Can anyone see what I'm doing wrong with my projection or process? To change the projection of my layer I used the 'save as' option to convert it and then imported the new file into my project. 

Please see a copy of the layers 'properties' found under the metadata tab all the way at the bottom of this question. 

This is what I entered into field calculator: I am certain this is fine.



The results: the left column titled 'Area_km2' represents the correct ICES calculations and the the column on the right titled '3035area' represents my calculations which seem very wrong. Both calculations used CRS EPSG 3035 - ETRS89/LAEA.



Meta data --> Properties: 

General
Storage type of this layer
ESRI Shapefile

Description of this provider

OGR data provider (compiled against GDAL/OGR library version 1.11.0, running against GDAL/OGR library version 1.11.0)

Source for this layer
/Users/aninahenggeler/Documents/Humboldt/Thesis /High seas proposal/GIS &amp; Google Earth/ICES/NewICES densified/ICESdensifiedareasclippedat899EPSG3035.shp

Geometry type of the features in this layer
Polygon

The number of features in this layer
65

Editing capabilities of this layer
Add Features, Delete Features, Change Attribute Values, Add Attributes, Delete Attributes, Create Spatial Index, Fast Access to Features at ID, Change Geometries, Simplify Geometries, Simplify Geometries with topological validation

Extents
In layer spatial reference system units
xMin,yMin -6150.61,1579195.62 : xMax,yMax 6185275.19,7365876.42

Layer Spatial Reference System
+proj=laea +lat_0=52 +lon_0=10 +x_0=4321000 +y_0=3210000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs
