Questions about extension tubes

I have never used Extension tube with any of my cameras and have a few questions I could not find a answer to.

The main one is do you lose far focusing with it? Can I still focus at infinity?

My Favorite wife likes to do close up of bugs and flowers so I would really like for her to have the capability with her 18-200. The 40mm I have is just to limiting. Also it would be nice on occasions to use on my D750.

Any answers? Anyone using these and really like or hate them?
 

Fred Kingston

Senior Member
No... and in fact, a extension tube has a very short focus range by itself, and is why folks use focus rails in conjunction with them to physically move the camera to achieve focus...
 

No... and in fact, a extension tube has a very short focus range by itself, and is why folks use focus rails in conjunction with them to physically move the camera to achieve focus...

That is what I thought but I have been wrong before. A LOT.

For the price though if might be worth it especially since there is no glass in them to mess with IQ.

Other than the short focus distance can anyone tell me why NOT to get a set for the favorite wife?
 

Marcel

Happily retired
Staff member
Super Mod
Extension tubes are a very good way to start doing macro without major investment. Some brand (Kenko just to name one) that have electric contacts to maintain auto-focus and aperture exif. I have a set and find them very practical and light to carry around on vacation.

The only culprit is that you loose light with them. Depending on the size of them from 1 to 3 stops.
 

hark

Administrator
Staff member
Super Mod
Contributor
Extension tubes are a very good way to start doing macro without major investment. Some brand (Kenko just to name one) that have electric contacts to maintain auto-focus and aperture exif. I have a set and find them very practical and light to carry around on vacation.

The only culprit is that you loose light with them. Depending on the size of them from 1 to 3 stops.

If you invest in one or in a set, be sure to get one that will communicate with your camera as Marcel mentioned.


The following quote comes from the link below:

...one other very important thing to understand about extension tubes is that some of them have electrical contacts that allow your camera to communicate with your lens, and some don’t....

https://photographylife.com/what-is-an-extension-tube
 

STM

Senior Member
Highly unlikely..........let me rephrase that........NO

Your extension tubes essentially increase the focal length of the lens you are using by moving the lens' focal point farther forward. They are in essence a fixed "bellows". Unlike close-up lenses, their use does not degrade the image nor alter the flatness of field. I have been mulling over in my mind getting a 105mm Micro Nikkor so I can have more working distance than my 55mm Micro Nikkor provides. But I tried something the other day and it has blown that idea out of the water. I have a slew of extension tubes; the first of which was my 27.5 mm PK-13 which I have for my 55mm which gets me to 1:1. I also have the three tube set, PK-11, PK-12 and PK-13. When I stack all of them together and use my 180mm f/2.8 I get a killer macro lens combination! The finder is fairly dark, which is to be expected but it certainly works and it has produced some pretty darn good images! I am sure the flatness of field is not all that great, but when you are photographing 3 dimensional objects it really is not a big deal.

I have been fortunate in the fact that my "favorite wife" is still my "only wife"...........34 years and counting!
 

STM

Senior Member
I have three.


Do you have three wives of just one with three personalities (her name is not Carrie is it?). Did you ever see that movie Multiplicity with Michael Keaton? If not you HAVE TO SEE IT. It is Michael Keaton at his best! Oh my Lord it is funny!
 
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480sparky

Senior Member
Highly unlikely..........let me rephrase that........NO

Your extension tubes essentially increase the focal length of the lens you are using......

Um, no it doesn't. If it is a 100mm lens without the tubes, it's still 100mm with them. Same thing when using bellows, or focusing any camera that uses bellows (folders, medium and large format cameras etc.)


..............by moving the lens' focal point farther forward.......

Again, technically an incorrect statement. Well, maybe not 'incorrect', but certainly not based on optical physics.

Extension tubes and bellows don't do anything to a lens' focal points. Any lens has an infinite number of possible focus points at both paths along the optical line in 'front' and 'behind' the glass elements. What extension tubes do is allow one to choose a focus plane in 'front' of the lens that is closer to the camera by physically moving the lens further from the focus plane where the film of sensor sets. But the lens still has the same infinite number of focus points. Most are registered in the image as out-of-focus. Yet the focal length is still unchanged.
 
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Highly unlikely..........let me rephrase that........NO

Your extension tubes essentially increase the focal length of the lens you are using by moving the lens' focal point farther forward. They are in essence a fixed "bellows". Unlike close-up lenses, their use does not degrade the image nor alter the flatness of field. I have been mulling over in my mind getting a 105mm Micro Nikkor so I can have more working distance than my 55mm Micro Nikkor provides. But I tried something the other day and it has blown that idea out of the water. I have a slew of extension tubes; the first of which was my 27.5 mm PK-13 which I have for my 55mm which gets me to 1:1. I also have the three tube set, PK-11, PK-12 and PK-13. When I stack all of them together and use my 180mm f/2.8 I get a killer macro lens combination! The finder is fairly dark, which is to be expected but it certainly works and it has produced some pretty darn good images! I am sure the flatness of field is not all that great, but when you are photographing 3 dimensional objects it really is not a big deal.

I have been fortunate in the fact that my "favorite wife" is still my "only wife"...........34 years and counting!

My favorite wife and I will celebrate 41 years next month


Sent from my iPhone using Tapatalk
 
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STM

Senior Member
My favorite wife and I will celebrate 41 years next month


Sent from my iPhone using Tapatalk

Congrats! Sadly there are very few of us who can claim that. For our parent's generation, that was the norm, for the latest generation if you make it past the 5 year mark you are lucky. For them, 5 years should silver and 10 years golden. My parents only made it to 22, but only because my father died in 1979. My inlaws have passed the 60 year mark
 
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STM

Senior Member
Um, no it doesn't. If it is a 100mm lens without the tubes, it's still 100mm with them. Same thing when using bellows, or focusing any camera that uses bellows (folders, medium and large format cameras etc.)




Again, technically an incorrect statement. Well, maybe not 'incorrect', but certainly not based on optical physics.

Extension tubes and bellows don't do anything to a lens' focal points. Any lens has an infinite number of possible focus points at both paths along the optical line in 'front' and 'behind' the glass elements. What extension tubes do is allow one to choose a focus plane in 'front' of the lens that is closer to the camera by physically moving the lens further from the focus plane where the film of sensor sets. But the lens still has the same infinite number of focus points. Most are registered in the image as out-of-focus. Yet the focal length is still unchanged.

Thanks professor, now post one of your macro images. Here is one of mine:

Housefly.jpg
 

Marcel

Happily retired
Staff member
Super Mod
[MENTION=6277]Don Kuykendall[/MENTION], I don't know if you did get the tubes for you better half, but I thought I'd give you some example shots done with the 20mm extension tube and my 125.00 $ Tamron 28-200 3.5-5.6 lens. The thing with ext. tubes and a zoom lens is that the shorter the focal length, the closer you can get. For example, for the ant picture in the flower, the lens was about 1/2" from the flower, and you get a bit more dof with a shorter lens.

Pics were done with my Fuji, but it's an APCS sensor so close to the 7100.

This one was done with the lens at 200mm
_DSF6500 - copie.jpg



This one at 28mm.
_DSF6545.jpg
 

GracieAllen

Senior Member
I'm not sure if you've purchased them yet or not, either, but be aware that even with the Kenko DG (?) tubes that have the contacts and such, you MAY lose the autofocus. The camera will try, but if it just sits there and jitters back and forth with the focus a small amount, you'll have to manually focus. If you have or buy the Kenko tubes, and they do this, I recommend calling Kenko USA (presuming you're in the USA), and talking to technical support... It may not help, but you never know.
 
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