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Archive 2013 · Extension tubes and (different) lenses - effects or not?
  
 
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p.1 #1 · Extension tubes and (different) lenses - effects or not?


I have a (hopefully) quick question -- does the effects of using an extension tube for macro work vary per the lens?

I did my first serious macro work last weekend in several years. I was using the canon 135mm f/2.0 and an extension tube (the longest standard canon one, maybe about an inch long?). I had the extension tube on most of the time, but I took it off occassionally.

In the past, I'd used the same extension tube with a 70-200 f/2.8 non-IS (mk1) lens, a 24-70 f/2.8 (mk1) lens, as well as a few others. It would do it's job, and never seemed to make anything noticeable as far as the character of the image otherwise. At least if it did, I never really noticed it.

When I went through my photos, it seems like the ones with the extension tube are just 'different'. Like a little different 'bokeh character' and maybe how the sharpness / focus looks as it falls off. Most of them aren't really directly comparable b'cos the ranges don't overlap (without the tube the lens cannot focus closer than around 3 feet). But the ones that are close, again, they just look different.

Word of mouth (in person) I've heard conflicting things here, most insist it doesn't matter but occasionally someone tells me it does or that you at least need to look at the use of extension tubes on a per-lens basis.



Mar 27, 2013 at 08:14 PM
molson
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p.1 #2 · Extension tubes and (different) lenses - effects or not?


Access wrote:
I have a (hopefully) quick question -- does the effects of using an extension tube for macro work vary per the lens?

I did my first serious macro work last weekend in several years. I was using the canon 135mm f/2.0 and an extension tube (the longest standard canon one, maybe about an inch long?). I had the extension tube on most of the time, but I took it off occassionally.

In the past, I'd used the same extension tube with a 70-200 f/2.8 non-IS (mk1) lens, a 24-70 f/2.8 (mk1) lens, as well as a few others. It would do it's
...Show more


The depth of field is inversely proportional to image magnification, so all else being equal, your shots with the extension tube used to allow closer focus/higher subject magnification would show a much shallower depth of field (greater falloff of sharpness) than without it.



Mar 27, 2013 at 08:30 PM
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p.1 #3 · Extension tubes and (different) lenses - effects or not?


Yes, the ones that are very close with the extension tube compared to the ones that are farther away without the extension tube, they look different as I'd expect them to look different. But what about the ones where the ranges overlap, but they still seem to look a little different?


Mar 27, 2013 at 08:34 PM
Tenn.Jer
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p.1 #4 · Extension tubes and (different) lenses - effects or not?


This is my understanding, given with the knowledge that someone with more accurate information will jump in to correct me, but no one is answering yet, so I'll get started...

Indeed, every lens has different characteristics (MFD, depth-of-field, etc.) when combined with extension tubes, varying with the size of the tube(s), the length of the lens, and the aperture used...apparently, no lens will retain infinity focus, and the minimum focus distance (mfd) is reduced. Admittedly, I couldn't tell you exactly why/how this works, but I do know that UWA lenses may not focus at all, since the minimum focus distance may end up within the lens itself - mfd is measured from the sensor, after all...

Here's a handy table of reference for extension tube use with different lenses:
http://www.bobatkins.com/photography/eosfaq/closeup.htm
Also, Brian Carnathan always mentions the magnification values of tubes in his reviews of Canon lenses, here:
http://www.the-digital-picture.com/

As I said, many will have clearer information, and will jump in soon, I'm just getting the ball rolling...

Jerry

(see, it happened while I was still typing! )



Mar 27, 2013 at 08:53 PM
Monito
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p.1 #5 · Extension tubes and (different) lenses - effects or not?


Extension tubes have air in the optical paths. Lens that are focused by extending the elements when the focus ring is moved have air in the optical path. So for those lenses, there is no difference.

However, some lenses are focused by moving elements intermally. The front element does not move in or out. When extension tubes are used on those lenses, the optical relationships change because the front element is moved in one case and not the other.

That could change the 'look' of the images, even in cases where the subject is the same distance from the sensor plane.

I think there are some internal focusing lenses that don't move the rear element either: all the focusing occurs by moving internal elements.



Mar 27, 2013 at 08:54 PM
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p.1 #6 · Extension tubes and (different) lenses - effects or not?


Ah that makes a lot of sense, internal focusing might be what I'm seeing here.


Mar 27, 2013 at 09:19 PM
kezeka
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p.1 #7 · Extension tubes and (different) lenses - effects or not?


Not a super detailed overview, but Carnathan has this:

http://www.the-digital-picture.com/Reviews/Canon-EF-25mm-Extension-Tube-II-Review.aspx



Mar 27, 2013 at 09:30 PM
Sheldon N
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p.1 #8 · Extension tubes and (different) lenses - effects or not?


My 85 f/1.2 looks pretty crazy when you throw a 12mm extension tube on it, especially wide open. It's the internal focusing + tube combo that really changes things. Makes the 85L into a glowy/wild soft focus lens.

This shot of my daughter was the 85L + 12mm tube at f/1.8








Mar 28, 2013 at 03:07 AM
 

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Netgarden
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p.1 #9 · Extension tubes and (different) lenses - effects or not?


I havn't experieced any noticeable distortions in macro, using two macro lenses, and my 300f4 or 70-200 f4 also. They really are the best use of getting closer to a subject without and extra glass. Once you get used to them you will know what is the best focal area to work in. Easy decision to make whenever i do macro. My favorite is the 300 or 500 mm with the 12mm for birding up to about 18 ft. Have gotten my MOneys worth many times over.

Maybe the light fall off affects the sharpness when using more than 25 mm of tubes. Alot of factors there depending on dof and close backgrounds.



Mar 28, 2013 at 06:07 AM
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p.1 #10 · Extension tubes and (different) lenses - effects or not?


It's kinda hard to describe the change I see, it's kinda like the bokeh you get with a DO lens.


Mar 28, 2013 at 06:41 AM
Monito
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p.1 #11 · Extension tubes and (different) lenses - effects or not?


Access wrote:
it's kinda hard to describe the change I see


When inquiring about a vague observation, do a carefully controlled test to reduce waffling and hand-waving and beating around the bush.

I would suggest setting up a macro scene of an object located at a few inches beyond the minimum focusing distance of the lens in question. Shoot with the lens and then with the extension tube at the same distance (the lens refocused of course). Put some "busy" material or objects behind the target object at a couple of distances, say 20% farther and 50% farther. Make some shots at wide open, two stops down, and four stop down. Compare.



Mar 28, 2013 at 10:10 AM
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p.1 #12 · Extension tubes and (different) lenses - effects or not?


Sheldon N wrote:
My 85 f/1.2 looks pretty crazy when you throw a 12mm extension tube on it, especially wide open. It's the internal focusing + tube combo that really changes things. Makes the 85L into a glowy/wild soft focus lens.

This shot of my daughter was the 85L + 12mm tube at f/1.8

http://img.photobucket.com/albums/v483/sheldonnalos/_32O0515-1_zps576b66f1.jpg


What a wonderful shot and a perfect memory to have.

My experience with extension tubes is fairly limited but I have certainly found some lenses lend themselves to be used as macros much more than others.

The simpler, less complex ones like the 50mm 1.4 and 50mm 1.8 (and in a past life the Hass 80mm planar and Mamiya 127mm) seem to me to produce much better results than either zooms or lenses like the 135L.

Just a personal observation.



Mar 28, 2013 at 10:19 AM
Monito
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p.1 #13 · Extension tubes and (different) lenses - effects or not?


Another trick sometimes used in the days of aperture rings is to reverse mount the lens, especially 50 mm lenses.

To accomplish this with electronic aperture control, I am told you can depress the Depth of Field Preview button and hold it down while unmounting the lens.

Should work for simple non-automated extension tubes too, which is the context I read about it.



Mar 28, 2013 at 11:00 AM
Access
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p.1 #14 · Extension tubes and (different) lenses - effects or not?


Monito wrote:
I would suggest setting up a macro scene of an object located at a few inches beyond the minimum focusing distance of the lens in question. Shoot with the lens and then with the extension tube at the same distance (the lens refocused

I did some quick testing this morning. This probably isn't the best job, was rushed. This is an internal focus lens, neither the front element or the rear element move when focussing.

In all cases, the photos were taken at 135mm, f/4 (wide open the lens is f/2).
Since the camera is longer, I took each shot based on the front of the lens hood, trying to frame them as similar as possible, brightness matched as closely as possible, etc.

2nd, 3rd photos shot with an extension tube, 1st, 4th without.









It is very subtle but I think there is a little bit of difference in the bokeh. It's just the way it falls off, hard to describe.



Mar 28, 2013 at 04:18 PM
Monito
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p.1 #15 · Extension tubes and (different) lenses - effects or not?


Thanks for providing an example, Access. As you say, subtle. I think I prefer #1 over #2, but can't tell #3 and #4 apart reliably.


Mar 28, 2013 at 05:29 PM
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p.1 #16 · Extension tubes and (different) lenses - effects or not?


I don't know how many people here have used the 70-300 f/4-f5.6 DO lens (known mostly for its compactness). But the Bokeh with the extension tube has a bit of the same character.

In technical terms the best way I can describe it is this:

The 'spatial falloff' of an out-of-focus object, or the decrease in weight as you move farther from the point of the (actual) object -- is more gradual, and then abrupt. Without the extension tube, the decrease in weight is more linear. Bokeh is subjective, but the latter is preferred by most.

One other note is that for this lens with the 25mm tube, the overlap in focus distance was almost nonexistant. With the tube I was at nearly infinity focus, without the tube the lens was at its closest focus (0.9m).



Mar 28, 2013 at 05:56 PM





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