extension tube question

Hi Forum members:

I am wondering whether using an extension tube is a good idea for 6X6 macro

(okay, pseudo macro) work. I am not talking about real macro. I am not trying

to capture the eye pattern/detail of an insect or a tiny water droplet on a

leaf. I want to shoot some flower close ups and may be some portrait

headshots. I use Bronica SQ and I need some expert advice on whether 1:4 110mm

F4 PS lens is far superior than using the 36mm extension tube. The extension

tube would give me some flexibility, I guess. The 1:1 110mm F4.5 PS is beyond

my budget.

Another important question is how do you calculate the working distance when

using the extension tube. Theoretically I can use the 36mm tube on a 50mm or a

80mm lens. Well may be 50mm with the tube is next to impossible. I have these

2 lenses. I am planning to acquire another tele, although I am yet to decide

whether it would be 150 or 180 or 200. But which one is the lens of choice

i.e. with or without the 36mm extension tube? I understand that the longer the

lens is the smaller the magnification would be (Mag factor = extension tube

length/focal length of the lens). So a 36mm extension on a 180mm lens is 0.2X

magnification. Is it even a pseudo macro?

So I need practical advice and as usual I am seeking it here from my peers

knowing very well that by end of today or tomorrow I will be a happier

person :)) Thanks in advance. Subho

Using an extension tube with a standard lens is an excellent way to get into close-up photography.<br>Don't let the site's "theme" nor the page's ttle scare you away, but you can find formulae to calculate almost everything <a href="http://www.hasselbladhistorical.eu/HT/HTComp.aspx" target="_blank">here</a>.<br><br>Though not the working distance (subject to front lens) nor the focussing distance (subject to film), since those depends on the particular design of the lens (the position of the entry and exit pupils relative to each other, and to the first vertex of the front lens).<br><br>And not Depth of Field, because that is a mostly mythical entity, depending on too many factors for calculations to make sense.<br><br>At the bottom of the page is a link to a <a href="http://www.hasselbladhistorical.eu/HT/HTCuC.aspx" target=_blank">Close-Up Calculator</a>. It uses the particulars of Zeiss/Hasselblad lenses, but you can still get a fairly accurate idea of how extensions, focal lengths, fields of view and distances will work out.

Hi QG:

Thanks for the info. It took me a while to understand those calculations. Thats why I did not get back before this. I went out today and took some flower close ups with my 80mm lens plus a 36mm extension tube. Hopefully few of the shots will be keepers.

I faced a big problem though. Now the focus distance is very close (2-3 inches only) and it does not focus even at 6 inches from the subject. The minimum focus distance of this 80mm lens is 2.6 feet or 0.8 meter. I was hoping that if needed the set up would focus at 12 inches or so for tight headshots. I wish there is a way to do it.