Extension Tubes: How much light loss?

[Mike K]

I'm thinking of adding an extension tube to my kit, particularly for my 100-400 lens. Not sure if I'd bother if I'll lose more than 1 stop of light. Any info, stories, recommendations?

 

[Overread19 7]

Well how much light you lose depends on the amount of extension tube you add to the setup. That said what are you hoping to gain with adding the extension tubes?

 

[cgipson1]

^yes.. curious to hear why you want to put extension tubes on a 100-400?

 

[mjhoward]

hope you weren't planning on 1:1 with a 100-400! You'll end up with a slinky

 

[SCraig]

An extension tube (as in for macro photography) or a teleconverter (as in to increase focal length)? A 2x TC costs 2 stops. A 1.4x costs 1 stop.

 

[mjhoward]

Well how much light you lose depends on the amount of extension tube you add to the setup. That said what are you hoping to gain with adding the extension tubes?

And at what focal length the zoom is set at

 

[Buckster]

I've used tubes on my 100-400, and it worked out fine for me.

Situation was a hike in Bombay Hook National Wildlife Preserve during migrating season, which is a great place to get photos of a lot of different species of birds. That said, I took the longest lens I had at the time, a 100-400. I didn't really want to carry much else, but wasn't sure what else I might run into, so I also stuffed a set of Kenko tubes in my pocket. As it turned out, they allowed me to get shots of very skittish mud fiddler crabs from a vantage point that I couldn't attain with the that lens without the tubes, so it worked out well for me.

1.

2.

On the way back to my vehicle, I used the combo again to shoot a monarch butterfly:

Here's a set of test images I did with the combo years ago to see what I might be able to use it for:

 

[Mike K]

Well how much light you lose depends on the amount of extension tube you add to the setup. That said what are you hoping to gain with adding the extension tubes?

Closer focus capability. Right now I'm at just under 6 feet.

 

[Mike K]

Thanks Buckster. Great demo and EXACTLY the kind of results I was hoping for. Any idea of the amount of light lost at maximum extension? I assume the change is linear along the way?

 

[Buckster]

Thanks Buckster. Great demo and EXACTLY the kind of results I was hoping for. Any idea of the amount of light lost at maximum extension? I assume the change is linear along the way?

Honestly, I didn't even think to check into the light loss. It certainly wasn't enough to put a damper on what I was doing with it.

Yeah, it's got to change along the way, based on the formula for calculating it, which I don't personally know off the top of my head. Certainly someone around here knows it or can look it up, and maybe they'll chime in to help with that.

For giggles though, I just tested it maxed out for you. Lens maxed at 400mm on a 7D, shutter priority on a tripod aimed at just a white piece of paper that fills the viewfinder. Results:

Without the tubes: f/11
With all three tubes (68mm): f/6.3
Difference: 1-2/3 stops (1.6 stops)

Those that I posted earlier were all shot with a Canon 20D, btw, just fyi, so it's not like I had a lot of ISO reach to compensate with at the time, if I'd needed to. On today's more ISO-capable bodies, it REALLY shouldn't be much of an issue at all.

 

[Derrel]

I have used tubes on the Nikkor 80-400 VR, which does NOT focus very close! A 12mm and a 20mm proved to be the two most-useful tube lengths. Kenko AF tubes for Nikon; if you shoot Canon, the Canon 12mm or 25mm Canon-brand tubes are VERY solid. ROCK-solid tubes. But do make sure to support the LENS from underneath!

Here is a 6MP shot I made nine years ago, using the 80-400 and a tube.

These are rosebuds from my climbing rose,which is now as tall as the house is. It blooms but once a year, with hundreds of fragrant pink blossoms. I was trying out the 80-400 VR lens with a 20mm Kenko extension tube, and to my delight, this tube preserves the Vibration Reduction feature of the lens,and for some reason,I had just assumed it would not!
This little spider web marks the spot where I suspect the very first roses will bloom! Since the 80-400 only focuses down to about eight feet, an extension tube is a real boon for doing very close-up shots,at up to 400mm focal lengths,which on a 1.5x body,is like having a 600mm lens that focuses down to well under eight feet....pretty much unheard of. Now that I realize the Kenko AF extension tubes preserve VR with this lens, I think I'll start looking for more opprtunities to use the 80-400 as a closeup lens! At 80mm setting,the lens focuses down to a measured 22 inches with the 20mm tube. At 135mm it focuses to about 38 inches,and spans left to right an area about 4 and a quarter inches with the camera in horizontal mode. To answer Lisa's question, this was hand held and no tripod was with me.

FujiFilm FinePix S2 Pro ,80-400 VR Nikkor +20mm extension
ISO 400 STD-ORG-OFF 12MP FINE 299mm f/9.5 @1/125th 80-400 VR + Kenko 20mm AF Extension tube with VR enabled

 

[Mike K]

Thanks Buckster. Great demo and EXACTLY the kind of results I was hoping for. Any idea of the amount of light lost at maximum extension? I assume the change is linear along the way?

Honestly, I didn't even think to check into the light loss. It certainly wasn't enough to put a damper on what I was doing with it.

Yeah, it's got to change along the way, based on the formula for calculating it, which I don't personally know off the top of my head. Certainly someone around here knows it or can look it up, and maybe they'll chime in to help with that.

For giggles though, I just tested it maxed out for you. Lens maxed at 400mm on a 7D, shutter priority on a tripod aimed at just a white piece of paper that fills the viewfinder. Results:

Without the tubes: f/11
With all three tubes (68mm): f/6.3
Difference: 1-2/3 stops (1.6 stops)

Those that I posted earlier were all shot with a Canon 20D, btw, just fyi, so it's not like I had a lot of ISO reach to compensate with at the time, if I'd needed to. On today's more ISO-capable bodies, it REALLY shouldn't be much of an issue at all.

Thanks. Great information so now I'm completely stoked to get the set of Kenkos. On the Bombay Hook shots, were those handheld? ISO? F stop (I'll download and check the data if it's there). I'm having trouble getting that much DOF on close shots handheld. Guess I'll have to surrender and use my tripod.

 

[Mike K]

I have used tubes on the Nikkor 80-400 VR, which does NOT focus very close! A 12mm and a 20mm proved to be the two most-useful tube lengths. Kenko AF tubes for Nikon; if you shoot Canon, the Canon 12mm or 25mm Canon-brand tubes are VERY solid. ROCK-solid tubes. But do make sure to support the LENS from underneath!

Here is a 6MP shot I made nine years ago, using the 80-400 and a tube.

These are rosebuds from my climbing rose,which is now as tall as the house is. It blooms but once a year, with hundreds of fragrant pink blossoms. I was trying out the 80-400 VR lens with a 20mm Kenko extension tube, and to my delight, this tube preserves the Vibration Reduction feature of the lens,and for some reason,I had just assumed it would not!
This little spider web marks the spot where I suspect the very first roses will bloom! Since the 80-400 only focuses down to about eight feet, an extension tube is a real boon for doing very close-up shots,at up to 400mm focal lengths,which on a 1.5x body,is like having a 600mm lens that focuses down to well under eight feet....pretty much unheard of. Now that I realize the Kenko AF extension tubes preserve VR with this lens, I think I'll start looking for more opprtunities to use the 80-400 as a closeup lens! At 80mm setting,the lens focuses down to a measured 22 inches with the 20mm tube. At 135mm it focuses to about 38 inches,and spans left to right an area about 4 and a quarter inches with the camera in horizontal mode. To answer Lisa's question, this was hand held and no tripod was with me.

FujiFilm FinePix S2 Pro ,80-400 VR Nikkor +20mm extension
ISO 400 STD-ORG-OFF 12MP FINE 299mm f/9.5 @1/125th 80-400 VR + Kenko 20mm AF Extension tube with VR enabled

Beautiful shot! Thanks for posting.

 

[Buckster]

Thanks Buckster. Great demo and EXACTLY the kind of results I was hoping for. Any idea of the amount of light lost at maximum extension? I assume the change is linear along the way?

Honestly, I didn't even think to check into the light loss. It certainly wasn't enough to put a damper on what I was doing with it.

Yeah, it's got to change along the way, based on the formula for calculating it, which I don't personally know off the top of my head. Certainly someone around here knows it or can look it up, and maybe they'll chime in to help with that.

For giggles though, I just tested it maxed out for you. Lens maxed at 400mm on a 7D, shutter priority on a tripod aimed at just a white piece of paper that fills the viewfinder. Results:

Without the tubes: f/11
With all three tubes (68mm): f/6.3
Difference: 1-2/3 stops (1.6 stops)

Those that I posted earlier were all shot with a Canon 20D, btw, just fyi, so it's not like I had a lot of ISO reach to compensate with at the time, if I'd needed to. On today's more ISO-capable bodies, it REALLY shouldn't be much of an issue at all.

Thanks. Great information so now I'm completely stoked to get the set of Kenkos. On the Bombay Hook shots, were those handheld?

Yes. The crab shots were taken lying down, so although they were hand-held, I was well-braced.

ISO?

Likely 100. I rarely strayed from ISO 100 on the 20D.

F stop (I'll download and check the data if it's there).

I doubt it's there. I used to strip all EXIF to make the files just a little leaner. Now in the age of fatter bandwidth, I don't bother to do that anymore. In any case, chances are that I had it wide open. Extended to 400mm, that means f/5.6.

The originals from many years ago are tucked away on DVDs and hard drives that I'm not interested in searching right now to find, or I'd get you the specific answers. I just don't think it matters enough to do that much research into it.

Bottom line: Get the tubes, and enjoy.

I'm having trouble getting that much DOF on close shots handheld. Guess I'll have to surrender and use my tripod.

"Handheld" vs. tripod has nothing to do with how much DOF you get from a particular lens on a particular body at a particular distance to subject.

Review the following: Online Depth of Field Calculator

 

[Patrice]

Hope somebody more knowledgeable jumps in to correct this post if it contains a glaring error.

We know that light intensity decreases with the square of the distance, so if the distance from the rear element to the sensor increases the intensity of the light will decrease by the square of the increase in the relative distance. So, doubling the distance would result in a 4x reduction in light, ie 2 stops. Increase the distance by a factor of 1.4 and the light will decrease by a factor of two, ie 1 stop. And so it goes.