Effect of short extension tube for portraits

[ymc226]

I have a 205FCC and want to take portraits (just of the head or even closer) of my children.

I have both an 110FE, 150 FE and an 80 CFE. Also have extension tubes 16E, 32E, 56E that I could use with either but would use the 80 CFE.

I would want good depth of field to have everything in focus. What would be the difference in effect in using the 110 close up alone compared to the 80 with the short extension tube. My desire is to have a very close up of the face with it taking up most of the negative.

My plan is to enlarge it to 16x16 using 16x20 paper.

 

[Q.G.]

The 110 mm alone has a minimum field of view of just a bit more than 29 cm. That of the 80 mm unaided is a few mm wider, about 30 cm. So you do not need an extension tube on the 80 mm to get the same framing.

Stopped down to the same f-stop, given the same framing of the same subject (i.e. same magnification) DoF will be the same too.

The main difference will be in perspective: the 110 mm puts your subject about 63 cm from the front lens, while using the 80 mm the sitter is 47 cm from the glass. Both - in my opinion - much too close for a head shot.

Using your 150 mm would be the best option, i think. It needs a little help from the 32 mm tube to get the same 30 cm field of view, but then leaves about 95 cm between the sitter and the glass.

(The 110 mm, by the way, should be used wide open only. If not, you lose it's rather unique character.)

 

[eddym]

I agree with QG. I sometimes use a 10mm tube with my 150, and it gives me a nice tight headshot.

 

[Dan Henderson]

I did some tests on a mannequin head for a friend who wanted to know what setup to get for really tight head shots. To eliminate everything but the face and a little surrounding head (which is what she wanted) I had to put a 32mm tube on a 150 lens and be at just long of the minimum focusing distance. 10, 16, and 21 mm tubes got me head and shoulders at minimum focusing with a little background showing.

 

[Tony-S]

I use my 36mm tube with the 200mm on my Bronica GS-1. Tubes are nearly essential for this system because the minimum focus distances on all the lenses (other than the 100mm macro) are not that great. Of course, depth of field is one of the trade-offs of getting close.

 

[Q.G.]

I have to correct the figures i provided earlier: i assumed the 80 F lens, not the CFE. The CFE has less extension built-in, so does need some help of a tube (about 6 mm extra) to get as close as the 110 mm.
The shortest usable tube, 16 mm, is just a tiny bit too long to get the same 29 cm field of view, and you will end up having a (maximum) field of view of about 28.5 cm.


The 80 mm front lens to subject distance only changes a tiny bit: from 47 cm to 45.4 cm.


I agree that for really tight headshots, more extension and longer lenses are needed. My favourite is the 250 mm lens (either Tele-Tessar or Sonnar) with (at least) 32 mm tube. You then get a field of view of about 21 cm.
For framing as tight as that of a 150 mm lens fully extended with 32 mm tube (about 16 cm field of view), you'd need the 56 mm tube with the 250 mm lenses. The extended 150 mm with 32 mm tube puts the subject at about 58 cm from the front lens. Rather close again... Same field of view using the 250 mm lens with extension puts the subject at about 106 cm from the front glass.

 

[ymc226]

Thanks Q.G.,

I took some pictures using the 150 FE using 16, 32, and 56mm extension tubes. Didn't realize until I read in another thread that DOF can't be expanded much by stopping down so much of it shot at smaller apertures. Will need to develop and print to see how much I like the results. I assume that the longer the extension tube, the more shallow the DOF.