f1.7- f1.8 aperture difference?

[johnjess]

Hi all, I am thinking of buying a 50mm lens for my Sony A200. Have been looking on ebay and have looked at the Minolta 50mm f1.7 and the Sony 50mm f1.8. As a newbie can someone tell me if the Minolta will let in more light as it is f1.7 as opposed to the Sony's f1.8 or is there no real difference. I am edging toward the Minolta in any case (price/ availability) but just wondered what the difference is. Thanks in advance

 

[mastertrinity]

theres no difference however the new sony version has digital optics to minimise CA and enhance IQ etc while the minolta 50mm is a film lens and so doesnt have some of the advance optics that the sony has. TBH i would go for the minolta mainly due to better build quality and cheaper, theres not much difference between them.

 

[TriggerHappy]

This might be of interest in terms of what people think of both lenses. f/1.7 will let in fractionally more light than f/1.8 but it's only a quarter (1/4th) of a stop faster so 1/200th of a second exposure with f/1.8 would be 1/250th of a second with f/1.7.

At least I think I've worked that out correctly

 

[Mud]

16.49% I think. log_{sqrt(2)}(1.7/1.8) = log(1.7/1.8)/log(sqrt(2))

 

[TriggerHappy]

16.49% I think. log_{sqrt(2)}(1.7/1.8) = log(1.7/1.8)/log(sqrt(2))

Looks more scientific than my approach

 

[TheTimeChamber]

Looks more scientific than my approach

Even better than my planned approach of saying 0.1 and leaving the thread very very very quickly

 

[Mud]

Looks more scientific than my approach

I gave too much 'accuracy' to be honest, I bet f/1.7 isn't a very accurate figure.