seeking advice on mag ratio
/forum/topic/1156609/0



Justin Huffman
Registered: Aug 25, 2004
Total Posts: 5469
Country: United States

Hey guys - im putting together odds n ends in my kit to come up with the most mag ratio i can without spending any more dough. Here is what i intend to stack and Im wondering what type of mag ratio it will provide. or if someone has a linky to a formula that would be great thank you

PK13 (27.5mm) ext tube > sigma 150 2.8 > Reversed 50mm 1.4

thanks again



LordV
Registered: Jan 02, 2006
Total Posts: 28197
Country: United Kingdom

Well the reversed 50mm lens should give you 4:1 at min focus.
M= existing mag + fl main lens/fl reversed lens = 1+ (150/50)
The ext tube will not add too much more (around 0.4) giving a grand total of 4.4:1 approx.

Brian V.



Justin Huffman
Registered: Aug 25, 2004
Total Posts: 5469
Country: United States

wow cool thanks Brian



MarkB1
Registered: Apr 07, 2009
Total Posts: 6053
Country: Australia

I'm interested in what the working distance would be with that? I know the higher the mags the shorter the WD, and the longer the FL the longer the WD, but I never got into formula.