Chuck, I have the G9 and love it, and your comment about the depth of field on a compact certainly makes sense, but it really doesn't match up to the 60mm EF-S on a 40D for critical sharpness.
Chuck, I have the G9 and love it, and your comment about the depth of field on a compact certainly makes sense, but it really doesn't match up to the 60mm EF-S on a 40D for critical sharpness.
Originally Posted by Daniel Browning
Daniel, don't get me started again. You know darn well that putting extension tubes on a lense, regardless of its focal lens shortens it's depth of field. Of course it's a function of subject distance. That wasn't the point.
Do you have a link? I'd like to check that out.
To me, saying "extension tubes lose DOF" is like saying "race cars cause fast driving". It makes it possible, and that's how most people use them, but it doesn't really cause it, per se. To illustrate:
Fast driving is caused by the driver accelerating to high speeds. Race cars make it possible to achieve high speeds. Another way is stock cars. It's possible to drive race cars and stock cars at normal speeds, but usually people buy them to drive fast.
Losing DOF is caused by focusing close. Extension tubes are just one way to focus close. Another way is to use a macro lens. It's possible to use extension tubes and macro lenses at normal focus distances, but usually people buy them to focus close.
Am I being too pedantic?
CombineZM is the impressive and free stacking software. TuFuse Pro is another good option. Helicon Focus is the easy-to-use commercial software (30-day demo, then $30 to $200). Stacking in Photoshop is much worse than any of those options due to artifacts.
It works best with a focusing rail, but I can get good results even with just the tripod and lens focus ring.
I'd like to say "yes, yes you are". Race cars make it possible to achieve high speeds, but they can still go slow (they have to go slow to stop to fill up, change tires, go slow again before going fast). Extension tubes, on the other hand, FORCE shorter focus distances, and therefore FORCE short DoF. You say it's possible to use extension tubes at normal focus distances, but it's a fact that infinity focus is lost, and I've never left an extension tube on "for the fun of it". The tube is a very limited-purpose tool.
We're a Canon/Profoto family: five cameras, sixteen lenses, fifteen Profoto lights, too many modifiers.
True, infinity is lost, but there's still plenty of "normal" focus range.If you focus at 1 meter, put an extension tube on, and focus at 1 meter, DOF is still the same.
Saying that extension tubes lose DOF is putting the emphasis on the wrong thing. No matter what method is used to focus closer, DOF is going to be lost, whether it's a macro lens or extension tubes. The emphasis should be on the fact that closer focus (or higher magnifications) cause a loss in DOF.
Daniel,
I'm curious as to why you'd focus at 1 meter without an extension tube and then put on an extension tube to focus at the exact same distance? The whole purpose of the extension tube would be to allow you to focus closer then the MFD of that lens not at the same distance you just focused at.
Fred~
I wouldn't.
Agreed.
My point is that extension tubes don't "cause" thin DOF any more than buying a macro lens causes thin DOF. All types of
magnification causes thin DOF. One method to increase magnification is
to focus closer. One method to focus closer is to use an extension tube.
Wow, I didn't mean to start an argument that seems to not have any actual disagreement [] I meant to suggest extension tubes just so that you could focus closer to take pictures of models... close. That way, you can get pictures that get up close (to make small things look bigger) but also don't look like a telephoto close up shot.
You'd certainly have to stop down, but you'd have to do that with a macro lense too. You'll have long exposures too, but she said she's using a tripod. I was just thinking that she likes her Macro, but the 60mm (on 1.6x no less) is contraining the field of view. To get similar quality, it's most cost effective to go with a prime, maybe even two primes, and provide the ability for macro-like magnification without sacrificing the field of view with extension tubes. Changing lenses and adding extension tubes when you need them (and taking them off when you don't) is kind of a hassle, but her subjects aren't exactly moving, and she's got a tripod most of the time anyway. That's my reasoning. I like extension tubes as an option. I think the Kenko ones I got are a good value. I'd prefer to have a 35mm macro lens, but getting 1:1 on a 35mm lens seems to require pretty much touching the subject with the front element anyway.
Point and shoot seems like a good idea, just in that it can be physically smaller, and fit into places, though she's indicated that the quality available in such a scenario isn't what she's looking for.
You could also get extension tubes for a 17-55 f/2.8 as well.
So, yeah, I'd rather have macro abilities native to the lense at the focal length, but sometimes extension tubes just allow you to do what you want to do, i.e., get closer.
If you mean "ostentatiously learned".......Yes.
Sorry, I've been away for a day taking a seminar on lean manufacturing. Boy was that fun!
Your race car analogy was quite interesting. I did some tests. It's all a mute point.
Colin, to end all of this hullabaloo about extension tubes, I did a test last night using a 50mm Takumar and a set of M42 extension tubes. I set up my 5D on a tripod and tookphotos of apicture one of my boys had drawn. Thecamera to subject distance was aboutabout 2ft. I took two shots. Onewith the aperture set to f4then f8. Next, I unscrewed the 50 and addedone "10mm" extension tube and screwed the assembly back into the M42 adapter still mounted to the front of the camera. With the lens at infinity I could not get a clear image at f8 or f16.
If you think a wide angle would work better I've got an old 24mm Soligor I can try. Just say the word. Otherwise, when a 10mm extension tube can decrease the infinity focus of a 50mm lens to under two feet, I don't see any practical use of an extension tube in the OP's case. She's looking for an inexpensive wide angle zoom with better IQ than the Sigma 17-70 she already owns. She comes here to ask for advice and the lot of us go off on tangents about extension tubes and depth of field. Her husband makes "models and props" not micro-nano-bugs. I imagine that some of the models and especially the props can be faily large. That's why the OP doesn't have enough room to use the 60mm lens. She needs more "fov" (field of view) not necessarily "dof" (depth of field). Obviously, increased dof comes from increased "fov". So, the most valuable suggestion made so far is the use of free stacking software to increase dof.
Meanwhile, back at the ranch............
ckw,will you follow up with my request from Monday?
*cough* moot point *cough* :-)
Or, as Joey from Friends said, "Moo point..like a cow's opinion--it's moo!""
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