extension tube help

jocose · Feb 28, 2006

JonK said:
and it only took 29 posts hehe (Y)

erm...yea...not really...I was just talking about your racking joke...I still don't get the extension tubes :lol:

Seriously, though, for a second...without the tubes, the lower the F number (so higher the stop, right?) the shallower (more out of focus) the DOF. That is, (again, without the tubes), my 50mm at f/1.8 will make the background very blurry, while at f/22 everything will be sharp (relatively speaking of course)...right? So, does this still hold true with the tubes on? that is why you said to use my smallest appreture, right?

OK, I think I got, I really got...the rain in spain.... Oh, sorry....

JonK · Feb 28, 2006

jocose said:
erm...yea...not really...I was just talking about your racking joke...I still don't get the extension tubes

Seriously, though, for a second...without the tubes, the lower the F number (so higher the stop, right?) the shallower (more out of focus) the DOF. That is, (again, without the tubes), my 50mm at f/1.8 will make the background very blurry, while at f/22 everything will be sharp (relatively speaking of course)...right? So, does this still hold true with the tubes on? that is why you said to use my smallest appreture, right?

OK, I think I got, I really got...the rain in spain.... Oh, sorry....

yeah you got it.
when you add the tubes the DOF jus gets shallower thruout ...so for example if it was 10mm of in focus area at 50mm and f1.8 without the tubes; add a tube or two or three and it becomes even less...like 8mm or 5mm or 3mm of in focus area (these are jus play numbers; not good enough at math to give you the real thing)
comprende?

zedin · Feb 28, 2006

woodsac said:
I have yet to get a bug to sit still long enough to use that combo

One trick you can do (works mainly with setup shots) is to get some dry ice and water. A steady stream of CO2 vapor cools the bug and stops them moving long enough to get a shot without hurting the critter. I used this to take some pictures of ticks we have in lab and it keeps them from running all over the place.

woodsac · Feb 28, 2006

zedin said:
One trick you can do (works mainly with setup shots) is to get some dry ice and water. A steady stream of CO2 vapor cools the bug and stops them moving long enough to get a shot without hurting the critter. I used this to take some pictures of ticks we have in lab and it keeps them from running all over the place.

Very cool tip...thanks!

jocose · Feb 28, 2006

woodsac said:
Very cool tip...thanks!

that's pretty punny there Woody!

jocose · Feb 28, 2006

JonK said:
yeah you got it.
when you add the tubes the DOF jus gets shallower thruout ...so for example if it was 10mm of in focus area at 50mm and f1.8 without the tubes; add a tube or two or three and it becomes even less...like 8mm or 5mm or 3mm of in focus area (these are jus play numbers; not good enough at math to give you the real thing)
comprende?

I'm even worse at math cuz I believed you :lol:

I get it though now...methinks.

woodsac · Feb 28, 2006

Jo, these shots were done with different combinations of tubes and the 50mm. All were at f/22...I think

http://www.thephotoforum.com/forum/showthread.php?t=43613

JonK · Feb 28, 2006

nice shots jake ...especially the last. as you can see the closer jake got in the shallower the DOF became.

here's one I shot with my 200mm...think I used one tube on this:

http://photobucket.com/albums/a206/JonKilimnik/MacroandCloseup/?action=view&current=swallowtail2.jpg

Dweller · Feb 28, 2006

Thanks for the timely thread guys! I can lurk and learn while Jocose throws out all the questions hehe

I was just looking at some extension tubes for the D70s I recently got but suffered some sticker shock when a set of 3 Nikon branded was going to run $300 or better from a local store.

I currently just have the kit lens but am thinking a 50mm 1.8 (which I miss from my film setup) and some tubes are in my future.

woodsac · Feb 28, 2006

I can't compare, only tell you what I've heard, Dweller. But I've read from several different articles, both on the net and paper, that the Kenko tubes are 100% as good as the Nikon or Canon brand.
I've also heard that Adorama.com sells a set of tubes (can't recall the brand) that are just as good for $85. I looked into them when I ordered my Kenko set, but they were on backorder. So I dished out the extra $$$ for the Kenko's.

Dweller · Feb 28, 2006

yeah I am not loyal to Nikon on things like this... there is no glass involved so as long as the lens can communicate fully with the camera then thats all I should need right?

I had not shopped at all for these things until last night when I stopped in to a camera shop I had not been to before and started talking with one of the sales people. One thought led to another and I realized that I was not set for any kind of close in stuff so I started discussing filters vs. tubes.

I really expected tubes to be less expensive than filters. What a suprise hehe.

After getting home and talking to some people in chat the Kenko brand came up and I saw much nicer pricing.

Torus34 · Feb 28, 2006

First, the numbers refer to the length of the tubes in mm.

Next, as you go to longer tubes, or combinations of tubes, you will have to increase your exposure [assuming a film camera, not digital.]

Last, you will be using the tubes with the lens well stopped down. Depth of field at wide open, using tubes, is minimal, to say the least.

Finally, when using combinations of tubes, your lens will work best with a reversing ring.

PS: Auto exposure is for simple shots in simple lighting.

jocose · Feb 28, 2006

Torus34 said:
First, the numbers refer to the length of the tubes in mm.

Next, as you go to longer tubes, or combinations of tubes, you will have to increase your exposure [assuming a film camera, not digital.]

Last, you will be using the tubes with the lens well stopped down. Depth of field at wide open, using tubes, is minimal, to say the least.

Finally, when using combinations of tubes, your lens will work best with a reversing ring.

PS: Auto exposure is for simple shots in simple lighting.

Erm...thanks for the info, but I really don't understand a whole lot of this...by increase exposure you mean slower shutter speed? What does well stopped down mean...lower fnumbers or higher? what's a reversing ring?

Torus34 · Feb 28, 2006

Looks like you've taken a giant step in equipment while thus far you've only taken baby steps in knowledge. Not a put-down, by the way. Just an observation.

So . . . , let's take it one by one. We're talking about macro [close-up] photography using extension tubes on a 35mm film camera.

Your camera must be kept steady by a tripod. You'll use a cable release to trip the shutter.

You'll determine the exposure with an exposure meter or use the exposure indicated in the film information [check the inside of the film box -- the information is sometimes printed there.] The correct exposure will be a combination of a shutter speed [say, 1/125 sec] and a lens stop [say, f8.]

You increase the exposure by slowing the shutter one or more 'numbers' from the exposure indicated by your exposure meter, say from 1/125 to /60 sec. This increases the light reaching the film.

You focus on the subject with the lens wide open [set to the smallest f number] and then 'stop down' to the correct f number. Then, if possible, go to the next larger f number and also slow the shutter by an additional number. Continue this f number & shutter speed adjustment until you run out of larger f numbers for your particular lens. At that point, your lens is fully stopped down -- usually at a f number of 16 or 22. At this setting the lens will produce the greatest 'depth' of focus.

When using long extension tubes, your lens will give a better image if you reverse it. A reversing ring allows you to screw the lens onto the front of the extention tube(s) in a reverse position.

Suggestion: Hit the local library and get hold of some good books on basic photography -- something with a title such as 'The Complete Guide . . .'

jocose · Mar 1, 2006

yea, so I hooked the rings up to the 70-300mm...WOW. I could zero in on the crap on my shelf from 1/2 a room away...the only problem was that my apartment is like cave-dark. there's no light...so I will need to figure out how to move lamps around...but it was still awesome!

yeah!!!