70D question

[newshooter]

This is probably going to be a really dumb question, but I am going to ask anyway.  I just bought my first dslr camera, the 70d, and it's all a bit overwhelming for a newbie.  I intend on buying one of the DVD sets that explains the cameras features but in the meantime, the one thing I haven't been able to find in the manual or by clicking through the cameras menu is this, and it's my dumb question;

I will use this camera for wildlife photography and while watching the numerous camera review videos before I made my purchase I heard where they kept talking about how this camera has a crop sensor of 1.6x and by using this feature it would turn a 255mm lens into a 408mm lens?  Ok, so is this a feature you turn off and on or is this camera just always using this crop sensor?  And I think crop sensor was the correct term?

[TCampbell]

Hi Dee,

Many of us have plug-ins installed in our web browsers which allow us to right-click on an image to look at the EXIF data (this assumes the image has EXIF data).  

In the case of your most recent moon image, the EXIF data was intact -- that's how I was able to see that it was set to f/10.  Your friend's moon image did not have any EXIF data -- whatever he used to process the image must have stripped it out.

I always leave the EXIF data in the image because I'm not shooting to earn a living off my images (I worked for a photography studio for many years... but that was over 30 years ago -- today I am in a completely different career, but do photography for the enjoyment of it.)  So I'm not too worried about someone knowing how I take a shot... to the contrary, I go out of my way to explain how I got a shot.

Flickr strips the EXIF from the image itself, but makes it accessible via a menu (so the EXIF viewer plug-ins don't work, but you can still see the data using their menu to look at it.)

[TCampbell]

I did not make up "Loony 11" - I swear.  You can look it up (though it is more obscure than the "Sunny 16" rule).  😉

BTW... if you look very closely at the upper right edge of your moon you'll notice it has a slight blue fringe.  If you look down at the lower left, you'll notice a very slight red fringe.

This is not a camera defect nor even a lens defect.  This is atmosphereic dispersion... the atmosphere itself is behaving like a "lens" and starting to bend the light based it's constituent wavelengths (blue bends more easily than red).

If you were to split the image into a "red", "green", and "blue" layer (using something like Photoshop) and then nudge the blue layer down and left, and nudge the red layer up and right (so that it all lines up nicely with the green layer) the image would actually become sharper.  You would only nudge just enough to make the fringing disappear... a few pixels at most.

This is one of the things that Registax (free stacking software -- particularly good at dealing with planetary images or lunar images) handles.  

You can actually by a device which corrects for this (Atmospheric Dispersion Corrector - or ADC) which has levers which allow you to determine how much correction you want.