plotting - ArrayPlot and non-integer PlotRange

There seems to weird bug regarding non-integer PlotRange in ArrayPlot. For example...

ArrayPlot[
   Table[Sin[x/50 π] Tanh[y/50 π], {y, 100}, {x, 100}],
   DataRange -> {{0, 1}, {0, 1}},
   PlotRange -> {{0, 1}, {0.5, .9}}
]

gives an error:

Value of option PlotRange -> {{0,1},{0.5,0.9}} is not All, Full, Automatic, a positive machine number, or an appropriate list of range specifications.

The same code works, if one of the plot range parameters for y-axes is turned into an integer.

Did I do smth wrong? Is there a workaround?

I need to use array plot as ListContourPlot is too slow for large datasets and MatrixPlot has the same problem.

I am using Mathematica 8 64 bit version on linux.

Edit

After some more testing I see, that it works whenever PlotRange includes at least one integer. For example PlotRange -> {{0, 1}, {0.5, 1.2}} works as it includes 1. So one possible workaround is just to scale the range, such that max-min would be larger than 1.

But I am still looking forward, if anyone finds a way to have shorter than 1 range on the axes. Dirty way would be just using manual 'Ticks'.

Edit 2

Possible workaround.

As I wrote in the previous edit, it works, then the range includes at least one integer. So one could just scale the range. Here is a naive hard-coded example how it might be done.

ArrayPlot[
   Table[Sin[x/50 π] Tanh[y/50 π], {y, 100}, {x, 100}],
   DataRange -> {{0, 1}, {0, 1} 10}, 
   PlotRange -> {{0, 1}, {0.1, 0.8} 10}, 
   FrameTicks -> {Table[{y, ToString[y/10 // N]}, {y, 1, 8, 1}], 
   Table[{x, ToString[x // N]}, {x, 0, 1, 0.25}]}, 

   AspectRatio -> 1
]

This means that I have bypassed the only side-effect of scaling the range, which is messing up the tick labels.

I would submit it as a solution, when I have waited my 8 hours and there is no nicer one proposed.

Answer

Here is a workaround that works in V7,8,9,10 (the underlying problem persists):

Show[
 ArrayPlot[
  Table[Sin[x/50 π] Tanh[y/50 π], {y, 100}, {x, 100}], 

  DataRange -> {{0, 1}, {0, 1}}],
 PlotRange -> {{0, 1}, {0.5, .9}}, FrameTicks -> All]