SG and sweetness of cider

So batch #3 has fermented dry. I'm going to add some apple concentrate and start fermentation again so I can try bottle pasteurizing.
My theory was that final SG should be a good indicator of sweetness but I'm looking at my notes and its proving not true. My second batch is slightly sweet and very delicious. I did stop fermentation a little early at 1.006 (OG was 1.052). (To do this I added cambden, aged and then added a few drops of yeast at bottling. It took a while but it did finally carb up.) My first batch is not sweet and stopped at 1.004(OG 1.045). .002 can't make that much of a difference. Or is it a combination of original gravity and final gravity?

So the question really is... Is final gravity a good indicator of the sweetness of cider? Can I stop all my batches at 1.010 and get a similar sweetness or does the original gravity add into the equation?
Scott

Another thought/question... Is the difference more important. If I let it drop (X?)% will it be a better indicator of sweetness.

Your SG doesn't determine sweetness, your FG does.

If you ferment dry, it doesn't matter what your starting gravity is, you have virtually no sugar left. Your FG will determine perceptible sweetness. If you are left with 1.010 you will notice a sweetness to the cider. Your O.G. - your FG just tells you the alcohol created.

If you ferment dry, i.e. and impede the yeast due to high ABV then you could roughly determine sweetness from your OG alone. i.e. if your yeast can attenuate up to say, 12%ABV, and you put in sugars that allow for 16%ABV, you would be left with roughly 4% residual sugar from your starting point, if the yeast attenuate perfectly.

Just to be certain... OG=original gravity FG=final gravity SG=specific gravity (or is it also starting gravity).
If FG is the main factor then why did my second batch turn out so much sweeter and a scant .002 more on the FG? The apples came from the same place, the first was their cider and the second was fresh pressed by me with their apples.
scott

Correct on OG and FG.

FG is the reading that allows you to tell how much sugar is left. So regarding the .002 difference and more perceptible sweetness, it could be you have a highly refined palate, or your PH and/or acids were different in that batch.

Based on your reply, it most certainly was the acid component. Your apple blend was most likely not exactly the same. Even if it was, your blend could have had more or less starch conversion to sugar, and different acidity.

Cloying sweetness can be offset by acidity (malic acid) and vice versa. If you accidentally over sweeten a cider, you can add malic acid to offset the sweet (to a degree). This is likely what you experienced. That is, likely your acidity was different from batch to batch, making sweetness more perceptible.

As a guideline, woodchuck cider has a 1.029 FG.