Hassy 16mm Extension tube, exposure compensation help!
I just picked up a 16mm Extension tube and I plan to use it with my 150 for portraits, and my 60mm for general close up stuff.
I saw the Calculator website, and got thoroughly confused. Can someone please explain this to me?
Can I just add 0.5 stops to the exposure and call it a day, or would that be massively off? It'd probably work fine for negatives, but If I were shooting slide...
What Calculator website? Do you have a link? 1/2 stop would probably work for the 150 but I'm not so sure about the 60mm, you might need a little more. If you have a metered prism you shouldn't have to worry too much, the TTL metering will give you a correct reading. Now, if you are using studio flash for lighting you will need to make an adjustment. As the old saying goes, "Test before photographing anything important" In situations (testing exposure) like this, a polaroid back can be useful.
For the 80, a half stop looks good according to this chart; Extension tubes
It doesn't show the 60, but a half should be good for it too.
Last edited by bdial; 10-15-2012 at 08:20 PM. Click to view previous post history.
there's the calculator thing...
I have a polaroid back, but that pretty much limits me to testing an exposure using 100 or 3200 speed film (unless I want to do some sort of equivalent exposure thing), and i've noticed that the fuji packfilms don't do long exposures gracefully. Also, the 100 looks better shot at 80, so i'm not sure if that's the film or my camera needing a CLA. Negatives look perfectly exposed, slides have yet to be developed.
It only takes three or four exposures to test in practice how much the exposure needs to be increased for the tube.
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I have the same "problem" Since early 2012 the Fuji 100 instant packfilm lost its 100 Iso down to 65/80.
Originally Posted by EASmithV
Using an extension tube or additional bellows draw beyond the infinity position is the same. In both cases you’re placing the lens farther from the film than usual.
In close-up photography we sometimes wonder, “At what point do we need to increase the exposure for the additional bellows draw?” That’s best determined by the exposure error we’re willing to tolerate. But how can we quickly determine the error so that we can decide?
On the top of page 32 of the 1975 edition of the Kodak Professional Photoguide:
“When the exposure for a close-up photograph is determined with a hand-held meter, or if exposure is found by using a guide or dial, and if the close focusing is accomplished by extending the lens, then additional exposure is required when the camera is closer than eight times the focal length of the lens.”
When the lens-to-subject distance is eight times the focal length of the lens, the required compensation is 0.39 stops. I presume that the author of the article selected an integer multiple of the focal length at which the exposure error is 1/3 stop or slightly greater as the minimum error that triggers compensation.
Here’s a procedure that works for cameras that don’t have a through-the-lens light meter:
The following table gives the exposure error and a corresponding estimate of the lens-to-subject distance in multiples of its focal length. After measuring the lens-to-subject distance and consulting the table, you can choose at what point compensation is warranted, and know by how much to compensate.
A lens of focal length f requires the following combinations of exposure increase and lens-to-subject distance given in multiples of the focal length (reckoned from the optical center of the lens):
0.1 stop, 29.4f
0.2 stop, 14.9f
1/3 stop, 9.2f
1/2 stop, 6.3f
2/3 stop, 4.8f
1 stop, 3.4f
4/3 stop, 2.7f
1.5 stop, 2.5f
5/3 stop, 2.3f
2 stops, 2f (1:1 image/object ratio)
A quick check with a tape measure and looking at the table can tell you if compensation is warranted and by how much.
Last edited by Ian C; 10-16-2012 at 10:30 AM. Click to view previous post history.