extension tube - how to choose the right one?

[phoTOMgraphy]

hi
i would like to shoot some makro shots with my hc 150mm lens too.
just wondering how to estimate the right size for any given subject.
lets say flowers. no need to go for 1:1.
is there a rule to calculate the resulted size for this lens with each extender?

cheers
tom

[Professional]

In fact i have same question as well, because i don't have enough money to buy HC 120 macro, and my HC 80 is not great for macro shots, so i was thinking about extension tubes, so before yesterday [Tuesday] i went to a local dealer of Hasselblad/Profoto as he told me that they had bringing some extension tubes, so i went there to test them [they have only ET 13 & 26] and he told me that the company [i think he meant Hasselblad] told him that 52 is not favorite or not recommended, anyway i tested only 26 that time even i saw 13 but really i don't need to test 13 and that 26 test was enough for me to buy it immediately, so now i can do some macro shots by using extension tube 26 with 80, cheaper alternative than buying a Macro lens [but the lens in my list anyway].

Good luck!

[Dustbak]

There is a doc on the Hasselblad site where you can find which is the focussing range with combinations of extention rings and lenses. Comes in very handy! here it is: http://www.hasselblad.com/downloads/techni...nformation.aspx

For stuff like flowers my estimate is that the 13mm would be most usefull. I mostly use the 13mm, sometimes the 26, more rarely the 2 of them together, rarely the 52 and virtually never the 52 with another ring.

The zoom with extention rings makes a great close-up combo!

Unfortunately I find myself sometimes (pretty often) longing for a ring that is right in between the 13 & 26! Quite often I find that I need to be too close with the 26 that my object is out of the frame and when I use the 13 I can frame the object but cannot focus close enough  For my kind of work I should have the 120macro, I still don't know why I don't have it

Be aware when using anyting larger than the 13mm you will go on a rapid descent, you start finding out that there is no DoF left no matter what f-stop you use, next thing you know you will have bought a TC and are dreaming about the HTS as well

[phoTOMgraphy]

thanks,

that's really helpful to me - so i will try to get the 13mm 1st and then see if i need more.  

good night from europe
tom