Folks, if someone who is experienced with extension tubes could explain what I'm sure is obvious to the world excluding me, I would sure appreciate it.
The winds are blowing and I decided to do a more controlled experiment indoors with plastic flowers. You know, the cheap ones that you pick up at Michaels to brighten the corner of a dark room
Both of these images were shot with the D700, the 70-200mm lens @ 200mm, using all three Kenko extension tubes--36mm, 20mm, 12mm. The EV was -1. ISO 800. I used a tripod with MLU, waiting approximately 10 seconds for all to settle down
The first attached to this message was shot at 1/15s at f/4, and the second was shot at 1/6s at f/22.
In both cases, the tripod was approximately 18 to 24" away from the subject. Unfortunately I did change the angle of the flowers. Shame on me.
Obviously the DOF is very different. My personal preference is the f/22 shot, but in both cases, I think the bokeh is aesthetically pleasing.
Both images were cropped to eliminate the vignetting in the corners.
But what I don't understand (I do have to try to replicate it), is why yesterday I was using only the 36mm ext tube and I was all but brushing the live flower. Today with all three tubes I was a couple of feet away from the subject.
Carol, the most likely difference is that your lens was focused at infinity today and shorter than infinity yesterday. When you attach the extension tubes, you're changing the magnification, but changing the focal distance also changes magnification. Thus, for maximum magnification you want your lens at close focus and then add you extension tubes. The drawback of this route is that you'll get better performance (sharpness, contrast, etc.) with the lens focused at infinity. Another way to think about this is that the lens without extension focuses from some minimum distance to infinity. With the extension tubes, you've changed the region that you can bring into focus by shortening both the minimum and maximum focus distances. Hope this helps.
Mark, You're sending me back to the drawing board. I may have been using the focusing ring yesterday to bring the images into focus. Today I was not. I just repeated the experiment with only the 36mm ET. I was not able to replicate what I experienced yesterday. Today, with only the 36mm ET on the lens, I was approximately 2.5 feet from the subject. What I did notice was the first shots with all three ETs were sharper than just one ET.
And just for the heck of it, I attempted to do what you just suggested. Matters not. This set of extension tubes is supposed to be added to the camera; then the lens is added. Since they have auto focus, you can fasten the lens to the camera when the focus ring is in any position.
Carol, Mark nailed it . A Macro lens also has extension just that it is built into it and its not removable. Remove the extension and you have a normal lens (well almost). You are changing some variable, experiment to experiment - otherwise what you say is impossible - laws of optics and physics will not change . What this variable is, needs to be isolated.
And yes, all extension is attached to the body and the lens sits over that.
1. Put your lens on manual focus + body also in manual (lens alone should work anyway) - the M/A switch.
2. Set your focal length to 200mm - don't change it.
3. Put 36mm tube alone and move your tripod alone as little as possible everytime until focus is achieved and measure the distance to the subject from the front of the lens. Focus on the nearest point of your artificial flower. Lets say the distance is x inches.
4. Now add the 20mm and 12mm tubes to the 36mm ones. The only way you are now going to achieve focus at the same place (nearest point of your artificial flower) is by moving the tripod forward (and not back ward). If you had to move the tripod backward to achieve focus, then I will eat crow . Its not possible.
5. The magnification you get with 3 tubes stacked in this fashion is always higher than when only 36mm tube is used.
In this experiment, you should not touch the lens at all. This will also illustrate why many macro shooters use a Macro Rail as well.
And by the way, you will achieve higher magnification at 70mm end of your lens and not the 200mm end.
Mark and Ram, Thank you very much for your words of wisdom. I suspect we are all arriving at the same conclusions but simply saying it very differently. I just wrote to a friend and included the attached image along with the words... I can't believe I'm doing test shots on plastic flowers that look very much like little red lobsters!
Along with your words of advice, I continued to experiment. I suspect that the day I first attempted shooting with the ETs, I may well have been using a couple of the extension tubes which is why I found myself so close to the flower.
First, it appears that with this lens (70-200mm), this camera (D700), and these tubes (Kenko), the camera settings don't matter when you attach the tubes. All that matters is that the tubes are seated properly before the lens is placed in position. Second, I see why articles say you need ringlights for macro shooting. The flash onboard the camera is fairly useless.
Third, it's simply not possible to use the 36 coupled with the 20 with the 12 unless you set the focal length to be fairly long
Fourth, I'm sure it would be wonderful to have a focusing rail; however, money, only spends once, and the priority for a focusing rail is much lower than other wants and needs ;^)
My only comment on the direction you move the tripod, is that it depends where you start out; if you're very close to your subject, you may be moving backwards. But that's neither here nor there.
I also discovered that focusing can be accomplished using the manual focus collar (ring) or the zoom focus collar (ring).
I also found a comment from John Shaw that really came in handily...
[i]The total amount of extension you need in order to get to any given magnification depends on the focal length of the lens you are using. Notice that I say "total" extension; it does not matter how you gain the extension -- some could be added by using extension tubes, some could be in the focusing mount of the lens -- since the entire amount being used is what is important. A basic formula gives approximate magnification rates:
Total extension used / Focal length used = Magnification
If you want to photograph at 1/2x with a 50mm lens, you can see that you need 25mm of total extension. But on a 100mm lens, the same 25mm total extension yields only 1/4x, and on a 200mm lens it yields 1/8x. Any given amount of extension yields less magnification when used with a longer focal-length lens.[/]
I'm not unhappy with the attached shot taken at f/9, iso of 800, 1/60s, MLU, with matrix metering and using only the 36mm ET. Yes, it would have been better to take the image at a different angle; however, it was more convenient to stand upright.
Again, Ram and Mark, thanks for getting involved and sharing your wisdom.
Next experiment, attempting to use the 500mm lens with the ETs. Attempted it earlier today without much luck but with the insight I've gained today, perhaps I'll be able to make that work too.
If you want to photograph at 1/2x with a 50mm lens, you can see that you need 25mm of total extension. But on a 100mm lens, the same 25mm total extension yields only 1/4x, and on a 200mm lens it yields 1/8x.
Agree with that but with a small caveat. The formula is applicable only when the lens is focussed at infinity. In reality, < 50mm of extension on a 50mm normal lens will get you to 1:1.
Any given amount of extension yields less magnification when used with a longer focal-length lens
That is why I said with the extension you have, 70mm will give you more magnification than the 200mm end.
You can run your "Total extension used / Focal length used = Magnification " formula in reverse to determine the built in extension any lens has.
Suppose you have a 100 mm lens that close focusses to 1/3 life size for maximum magnification. Then you would have 33 mm / 100 mm = 1/3 of life size magnification.
So why would you need to know that? Well, what is the maximum magnification you can get out of that same lens if you put a 36 mm extension tube on it?
(33 (from the first calculation) + 36 (from the tube you just put on))/100 = 0.69, or about 2/3'rd of life size.
Sticking all of your extension tubes on :
(36 + 20 + 12 + 33 ) / 100 = 101/100 or basically life size (1:1, 1x).
(Okay, there is probably a couple of lens design technogeeks screaming NOOOOOoooooo!!!!, but it is close enough)
Thanks, Dan, I believe the expression is called, good enough for government work. I figured that one out right away. All I was after originally was a general idea of how extension tubes worked and I wondered why I appeared to be so close to a subject yesterday that I was almost touching it. Today I realized I must have had two tubes on the camera--the 36 and the 20.
And Ram, yes, ideally, one would have a focusing rail of some sort or handhold if the light is sufficient so that you can focus by moving the entire camera to or away from the subject.
If you are hand-holding or using a focusing rail or have wheels on your tripod, setting the lens to infinity would be perfection; however, you do not need to have the lens set to infinity to be able to focus. The focusing ring just changes the amount of extension, and changes the magnification slightly. With a two tubes (the 36 and the 20), if you use the focusing ring and the lens is set to 80mm, the amount of magnification isn't going to make a giant difference. I guess I'm an insufficient perfectionist
Ah, well, next on the horizon is seeing if I can make the extension tubes work with the 500mm lens.
Carol, Exactly. For my work, I don't care for magnification I get (well I do but what I mean is I don't worry about whether it should be exactly 1:1 or 0.8:1 etc etc) - I care for a magnification that gives me a photo that I desire.
However magnification becomes important for many photographers who are mainly into details and not necessarily a very artistic rendition. For them the focussing rail is key = they set the magnification they want on the lens (see the markings on the macro lens) and then move the rails to achieve focus and shoot at a pre-determined magnification.
A great way to check the magnification is to shoot a scale - lets assume you are using a 36mm sensor camera which has a sensor of 36x24mm. If you are shooting in landscape orientation, and you are working at 1:1 then you should be able to fit in about 36mm on the scale into the viewfinder. If you can fit in more than that then you are working at less than 1:1 magnification. If you can see only 18mm in your viewfinder then you are working at 2:1 (2 times life size) magnification and so on.
Ram. I suspect that we both care about magnification only because it might enhance the subject we are shooting. I think back to last year sometime when I attempted to shoot Baby's Breath. One or more extension tubes might well have come in handily. The Canon d500 CU diopter didn't cut it.
I also imagine that if we had an assignment to shoot products or jewelry, we might very well be concerned about the actual ratio we're shooting.
I like your way to check magnification. Since I think in inches, if I can fit approximate (not accurately ;^) 1 1/2" in my viewfinder, then I know I'm working at 1:1. Very cool. Of course, we'll complicate things because most of us don't see 100% in our viewfinder Ah, well ...
Carol: You have just discovered why I HATE using tubes on a zoom My tubes only see the light of day on my prime lenses. Glad you have the patience to keep experimenting. >=))>
Discussion
11 repliesThe winds are blowing and I decided to do a more controlled experiment indoors with plastic flowers. You know, the cheap ones that you pick up at Michaels to brighten the corner of a dark room
Both of these images were shot with the D700, the 70-200mm lens @ 200mm, using all three Kenko extension tubes--36mm, 20mm, 12mm. The EV was -1. ISO 800. I used a tripod with MLU, waiting approximately 10 seconds for all to settle down
The first attached to this message was shot at 1/15s at f/4, and the second was shot at 1/6s at f/22.
In both cases, the tripod was approximately 18 to 24" away from the subject. Unfortunately I did change the angle of the flowers. Shame on me.
Obviously the DOF is very different. My personal preference is the f/22 shot, but in both cases, I think the bokeh is aesthetically pleasing.
Both images were cropped to eliminate the vignetting in the corners.
But what I don't understand (I do have to try to replicate it), is why yesterday I was using only the 36mm ext tube and I was all but brushing the live flower. Today with all three tubes I was a couple of feet away from the subject.
Doesn't make sense to me.
With that, here's the one shot at f/4.
Thanks, all, for you words of wisdom.
Carol
And just for the heck of it, I attempted to do what you just suggested. Matters not. This set of extension tubes is supposed to be added to the camera; then the lens is added. Since they have auto focus, you can fasten the lens to the camera when the focus ring is in any position.
I'm confused.
But thanks,
Carol
And yes, all extension is attached to the body and the lens sits over that.
1. Put your lens on manual focus + body also in manual (lens alone should work anyway) - the M/A switch.
2. Set your focal length to 200mm - don't change it.
3. Put 36mm tube alone and move your tripod alone as little as possible everytime until focus is achieved and measure the distance to the subject from the front of the lens. Focus on the nearest point of your artificial flower. Lets say the distance is x inches.
4. Now add the 20mm and 12mm tubes to the 36mm ones. The only way you are now going to achieve focus at the same place (nearest point of your artificial flower) is by moving the tripod forward (and not back ward). If you had to move the tripod backward to achieve focus, then I will eat crow
5. The magnification you get with 3 tubes stacked in this fashion is always higher than when only 36mm tube is used.
In this experiment, you should not touch the lens at all. This will also illustrate why many macro shooters use a Macro Rail as well.
And by the way, you will achieve higher magnification at 70mm end of your lens and not the 200mm end.
Along with your words of advice, I continued to experiment. I suspect that the day I first attempted shooting with the ETs, I may well have been using a couple of the extension tubes which is why I found myself so close to the flower.
First, it appears that with this lens (70-200mm), this camera (D700), and these tubes (Kenko), the camera settings don't matter when you attach the tubes. All that matters is that the tubes are seated properly before the lens is placed in position. Second, I see why articles say you need ringlights for macro shooting. The flash onboard the camera is fairly useless.
Third, it's simply not possible to use the 36 coupled with the 20 with the 12 unless you set the focal length to be fairly long
Fourth, I'm sure it would be wonderful to have a focusing rail; however, money, only spends once, and the priority for a focusing rail is much lower than other wants and needs ;^)
My only comment on the direction you move the tripod, is that it depends where you start out; if you're very close to your subject, you may be moving backwards.
I also discovered that focusing can be accomplished using the manual focus collar (ring) or the zoom focus collar (ring).
I also found a comment from John Shaw that really came in handily...
[i]The total amount of extension you need in order to get to any given magnification depends on the focal length of the lens you are using. Notice that I say "total" extension; it does not matter how you gain the extension -- some could be added by using extension tubes, some could be in the focusing mount of the lens -- since the entire amount being used is what is important. A basic formula gives approximate magnification rates:
Total extension used / Focal length used = Magnification
If you want to photograph at 1/2x with a 50mm lens, you can see that you need 25mm of total extension. But on a 100mm lens, the same 25mm total extension yields only 1/4x, and on a 200mm lens it yields 1/8x. Any given amount of extension yields less magnification when used with a longer focal-length lens.[/]
I found a series of discussions that some of you might find useful.
http://photography-on-the.net/forum/showthread.php?t=19350
http://www.slrphotographyguide.com/camera/lens/extensiontube.shtml
I'm not unhappy with the attached shot taken at f/9, iso of 800, 1/60s, MLU, with matrix metering and using only the 36mm ET. Yes, it would have been better to take the image at a different angle; however, it was more convenient to stand upright.
Again, Ram and Mark, thanks for getting involved and sharing your wisdom.
Next experiment, attempting to use the 500mm lens with the ETs. Attempted it earlier today without much luck but with the insight I've gained today, perhaps I'll be able to make that work too.
Carol
Agree with that
That is why I said with the extension you have, 70mm will give you more magnification than the 200mm end.
You can run your "Total extension used / Focal length used = Magnification " formula in reverse to determine the built in extension any lens has.
Suppose you have a 100 mm lens that close focusses to 1/3 life size for maximum magnification. Then you would have 33 mm / 100 mm = 1/3 of life size magnification.
So why would you need to know that? Well, what is the maximum magnification you can get out of that same lens if you put a 36 mm extension tube on it?
(33 (from the first calculation) + 36 (from the tube you just put on))/100 = 0.69, or about 2/3'rd of life size.
Sticking all of your extension tubes on :
(36 + 20 + 12 + 33 ) / 100 = 101/100 or basically life size (1:1, 1x).
(Okay, there is probably a couple of lens design technogeeks screaming NOOOOOoooooo!!!!, but it is close enough)
Have fun!
And Ram, yes, ideally, one would have a focusing rail of some sort or handhold if the light is sufficient so that you can focus by moving the entire camera to or away from the subject.
If you are hand-holding or using a focusing rail or have wheels on your tripod, setting the lens to infinity would be perfection; however, you do not need to have the lens set to infinity to be able to focus. The focusing ring just changes the amount of extension, and changes the magnification slightly. With a two tubes (the 36 and the 20), if you use the focusing ring and the lens is set to 80mm, the amount of magnification isn't going to make a giant difference. I guess I'm an insufficient perfectionist
Ah, well, next on the horizon is seeing if I can make the extension tubes work with the 500mm lens.
Thanks guys,
Carol
However magnification becomes important for many photographers who are mainly into details and not necessarily a very artistic rendition. For them the focussing rail is key = they set the magnification they want on the lens (see the markings on the macro lens) and then move the rails to achieve focus and shoot at a pre-determined magnification.
A great way to check the magnification is to shoot a scale - lets assume you are using a 36mm sensor camera which has a sensor of 36x24mm. If you are shooting in landscape orientation, and you are working at 1:1 then you should be able to fit in about 36mm on the scale into the viewfinder. If you can fit in more than that then you are working at less than 1:1 magnification. If you can see only 18mm in your viewfinder then you are working at 2:1 (2 times life size) magnification and so on.
I also imagine that if we had an assignment to shoot products or jewelry, we might very well be concerned about the actual ratio we're shooting.
I like your way to check magnification. Since I think in inches, if I can fit approximate (not accurately ;^) 1 1/2" in my viewfinder, then I know I'm working at 1:1. Very cool. Of course, we'll complicate things because most of us don't see 100% in our viewfinder
Onward to macro shooting.
Carol