Convex spectacles lens isn't forming inverted image? I moved my spectacles of farsightedness away from an object and tried to look at the image formed.  It was erect.
I moved even more far but still it was erect. 
How is this possible? 
I hope my question is clear.
 A: Your spectacle lens will be converging and have a focal length in metres of $\dfrac{1}{\text{power in dioptres}}$.  
So if the power of the lens is $0.5\,\rm dioptres$ the focal length of the lens is $2\,\rm m$.  
If the place an object closer than the focal length of the lens you will get an upright, magnified and virtual image formed on the same side as the object (ie on the other side from which you are viewing).
From what have stated in your question this is what you have found as shown in case (vi) in the ray diagrams below.  
 
What you need to do is place a brightly illuminated object, a light bulb will do, at about twice the focal length away from the lens and use a screen, a piece of white paper will do, on the the other side of the lens at about 2 focal lengths from the lens and then move the screen towards and away from the lens so that a sharp image (real and inverted) is formed on the screen.
This is approximately case (iii).
If you do not know the power/focal length of your lens then you will need to find the real image position by trial and error.
A: Thus is happening because the object that you are seeing is lying between the optical centre and the first focal plane of your lens. Let me show you the diagram:

Source : topperlearning.com
And the distance from the object to your lens till which you could see that erect image is simple enough to calculate if you know the power of your specs.
The distance from the object to your lens should be less than 1/P metres (where, P is the power of your lens)
