Posted by Basil Greber on July 10, 2006 at 4:46 PM
Hello all
I requested suggestions on macro lenses a while ago, and some people suggested extension tubes. Before jumping into it and buying a set, a few questions are left to be answered...
1) I have seen that many use a 300 mm lens with something like 30 mm of extension. What kind of magnification are you able to achieve with this combination when focused close (at infinity, it should be something like 1/10, right?)? The only tables I've found so far are for 50 mm lenses.
2) How much space can you cover with focus adjustments (from the 50 mm tables, it looks like the difference between the resulting min. and max. focusing distances with tube attached is only a few inches, or even less!)?
3) How much do you need to stop down to get some DOF, for example to include a dragonfly all-sharp in the picture (when it's aligned with the sensor, not perpendicular, of course )?
Anyway, I'm interested in which setup you use, and if you're happy with it!
Thanks for any suggestions! I appreciate it a lot.
Extension tubes don't result in any "magnification," rather they allow you to focus more closely than the normal limits of a lens. I use them on everything from my macro lenses to long telephotos (when I want to get closer, more frame-filling shots of small birds for example). I can't predict the amount of magnification, but can tell you that with 12mm of extension I can move into around 9" with my 105mm macro, which normally focused down to about a foot. With my 500 and 25mm of extension, my minimum focus distance shifts from around 13 feet to about 10 feet, with the subjects appearing correspondingly larger in the frame.
With all extension tubes remember that you lose your distant focusing capabilities.
I haven't calculated how much extra I have to step down. Rather, I simply use DOF preview to determine when I have enough, but not too much.
Posted by Basil Greber on July 10, 2006 at 5:15 PM
Thanks Hank.
Of course, you're right, I should have said reproduction ratio (which increases when you can get closer to the subject), not magnification, to be more precise.
I know that you lose distant focus capabilities - but to which extent? For example, with your 500 and 25 mm of extension, what's the *farthest* distance that you can focus on? 12 feet, 20 feet, 50 feet?
I have never measured max with the 500 and haven't used it with tubes recently, but if memory serves max is something like 30 or 40 feet. I could be off by twice that, but it's no where near a 100 yard shooter with extension tube in place. I can't focus much past three or four feet with 12mm of extension on my 105 micro. For convenience I carry the 105 with the tube in place, but usually take it off along with the lens cap when I use the lens, reinstalling it if I feel the need.
I've used the 105 with as much as 50mm of extension, but things are getting pretty dark by then and I'm moved way close to the subject. Those were studio shots to show facets on some jewels, so I had plenty of light. I did end up building some tiny reflectors to help get around the lens and its shadow. All in all a successful project, but it's nothing I would repeat in the field. I had better luck with extreme closeups in the field using a lens reversing ring to achieve 4:1 repro ratios with the right lens, but have used it so little recently can't even tell you where it's stored at the moment.
Posted by Basil Greber on July 11, 2006 at 1:05 AM
A quick formula for reproduction ration is extension/focal length. So a 300mm and a 50mm tube would give you about a 1:6 reproduction ratio.
I've used a 50mm tube with my 300 many times. It's great for larger flowers where you really need to control the background. I don't really remember how close I could get, I just slapped it on and did what I could do with it.
You definitely will lose infinity focus. At a guess, I think I could probably focus out to maybe 8 or 10 feet with the above combination. I may be wrong about that since I never really cared about it since the whole point was to focus closer.
My suggestion is to get a set of Kenko tubes and go have some fun with them
First: Just to comment on what Rod stated above.
So a 300mm and a 50mm tube would give you about a 1:6 reproduction ratio.
He is correct in that statement but you also must consider the crop factor with most digital cameras. All Nikon DSLR camera have a 1.5x factor. Canons vary from full frame to 1.3x and 1.6x. That would reduce the 1:6 to 1:3 ratio for the 300mm with a 50mm tube. Since most photographers use the kenko tube set (68mm total) that brings the reproduction ratio slightly below 1:3. Add a 1.4x Teleconverter and you are very close to 1:1 ratio.
With the Nikon 300mm f/4d IF-ED AF-S lens mounted on my D100 I have a minimum focus of about 19" when measured from the subject to the "end" of the lens. Maximum focus would be somewhere around 4 feet from subject to "end" of the lens.
I shoot the majority of my close-up shots with the above setup with an aperture of f/8 or f/11.
DOF is plenty enough for most insects at those apertures. I will sometimes stop down to f/16 but rarely.
Ronnie Gaubert
Posted by Basil Greber on July 13, 2006 at 1:07 AM
Ronnie, I think you are not quite correct about the crop factor (or then I have not understood physics... ). 1/1 means that something has the same size on sensor and in reality. The crop factor doesn't change magnification - this only depends on focal length and distance to subject, and sensor size doesn't influence the two, it's just optical physics. The 1/1-magnified image will show a smaller part of the subject on an APS-C sensor, though (or in other words, to get the same image on a FF and an APS-C sensor, you can stay a bit farther away with the APS-C equipped camera, using a reproduction ratio that is actually less than that for the FF camera).
Thank you VERY much for the figures (apertures & distances), though, I'm now more and more convinced that the tubes are the right thing for me.
You are probably correct in your physics assessment. From the technical side of equipment, I am not a guru by any stretch of the imagination. I based the 1:1 reproduction ratio, when using the 300mm, 68mm of ext. and a 1.4x TC mounted on my D100, from rough estimation. There is a very small damselfly species that is fairly common in my yard. They are about the width of my camera's sensor and when I shoot them with the above setup at minimum focus, the damselfly just about fills the frame.
Posted by Basil Greber on July 16, 2006 at 9:07 AM
I do really appreciate your responses - because in the end, it doesn't matter what physics says, but what works in the field. And an experienced photographer confirming that a setup works quite well is more than I was hoping for. So - thanks! I hope I'll be able to post a couple of extension tube-images sometimes next month.
Discussion
9 repliesI requested suggestions on macro lenses a while ago, and some people suggested extension tubes. Before jumping into it and buying a set, a few questions are left to be answered...
1) I have seen that many use a 300 mm lens with something like 30 mm of extension. What kind of magnification are you able to achieve with this combination when focused close (at infinity, it should be something like 1/10, right?)? The only tables I've found so far are for 50 mm lenses.
2) How much space can you cover with focus adjustments (from the 50 mm tables, it looks like the difference between the resulting min. and max. focusing distances with tube attached is only a few inches, or even less!)?
3) How much do you need to stop down to get some DOF, for example to include a dragonfly all-sharp in the picture (when it's aligned with the sensor, not perpendicular, of course
Anyway, I'm interested in which setup you use, and if you're happy with it!
Thanks for any suggestions! I appreciate it a lot.
Basil
Extension tubes don't result in any "magnification," rather they allow you to focus more closely than the normal limits of a lens. I use them on everything from my macro lenses to long telephotos (when I want to get closer, more frame-filling shots of small birds for example). I can't predict the amount of magnification, but can tell you that with 12mm of extension I can move into around 9" with my 105mm macro, which normally focused down to about a foot. With my 500 and 25mm of extension, my minimum focus distance shifts from around 13 feet to about 10 feet, with the subjects appearing correspondingly larger in the frame.
With all extension tubes remember that you lose your distant focusing capabilities.
I haven't calculated how much extra I have to step down. Rather, I simply use DOF preview to determine when I have enough, but not too much.
Of course, you're right, I should have said reproduction ratio (which increases when you can get closer to the subject), not magnification, to be more precise.
I know that you lose distant focus capabilities - but to which extent? For example, with your 500 and 25 mm of extension, what's the *farthest* distance that you can focus on? 12 feet, 20 feet, 50 feet?
Thanks a lot, and sorry for being so persistent!
Basil
I've used the 105 with as much as 50mm of extension, but things are getting pretty dark by then and I'm moved way close to the subject. Those were studio shots to show facets on some jewels, so I had plenty of light. I did end up building some tiny reflectors to help get around the lens and its shadow. All in all a successful project, but it's nothing I would repeat in the field. I had better luck with extreme closeups in the field using a lens reversing ring to achieve 4:1 repro ratios with the right lens, but have used it so little recently can't even tell you where it's stored at the moment.
Basil
I've used a 50mm tube with my 300 many times. It's great for larger flowers where you really need to control the background. I don't really remember how close I could get, I just slapped it on and did what I could do with it.
You definitely will lose infinity focus. At a guess, I think I could probably focus out to maybe 8 or 10 feet with the above combination. I may be wrong about that since I never really cared about it since the whole point was to focus closer.
My suggestion is to get a set of Kenko tubes and go have some fun with them
First: Just to comment on what Rod stated above.
So a 300mm and a 50mm tube would give you about a 1:6 reproduction ratio.
He is correct in that statement but you also must consider the crop factor with most digital cameras. All Nikon DSLR camera have a 1.5x factor. Canons vary from full frame to 1.3x and 1.6x. That would reduce the 1:6 to 1:3 ratio for the 300mm with a 50mm tube. Since most photographers use the kenko tube set (68mm total) that brings the reproduction ratio slightly below 1:3. Add a 1.4x Teleconverter and you are very close to 1:1 ratio.
With the Nikon 300mm f/4d IF-ED AF-S lens mounted on my D100 I have a minimum focus of about 19" when measured from the subject to the "end" of the lens. Maximum focus would be somewhere around 4 feet from subject to "end" of the lens.
I shoot the majority of my close-up shots with the above setup with an aperture of f/8 or f/11.
DOF is plenty enough for most insects at those apertures. I will sometimes stop down to f/16 but rarely.
Ronnie Gaubert
Thank you VERY much for the figures (apertures & distances), though, I'm now more and more convinced that the tubes are the right thing for me.
Thanks!
Basil
You are probably correct in your physics assessment. From the technical side of equipment, I am not a guru by any stretch of the imagination. I based the 1:1 reproduction ratio, when using the 300mm, 68mm of ext. and a 1.4x TC mounted on my D100, from rough estimation. There is a very small damselfly species that is fairly common in my yard. They are about the width of my camera's sensor and when I shoot them with the above setup at minimum focus, the damselfly just about fills the frame.
Basil