How much is too much?

[Mayo]

I was board yesterday and was rummaging thru my shed looking for something to tinker with. That's when I found a shop vac tube extension. Hmmm! What can I do with this. :scratch: Then it hit me. I have some manual macro tubes I don't use anymore. The vac tube was just the right size and thickness to be able to cut threads into it. So after some measuring, I put the vac tube on my lathe and started cutting. It fits perfectly. I was very eager to try it out and to my surprise it worked great. But since it is smooth and reflective in it, I'm getting unwanted light bouncing around. So I took it apart and painted the inside black matte. I haven't tried it yet since its been painted due to work but I will tonight. Now my question is, how long is to long? It measures 508mm and that is just the tube with no lens on it.

here it is beside a 55-200 kit lens

 

[sscarmack]

Interestingggggg. I have no idea but would love to see the results.

 

[pgriz]

Assuming the plane of focus is outside the lens, that plane will be very, very close to the lens, I suspect. In effect, you will have created a microscope. And that means you need LOTS and LOTS of light to get any kind of meaningful exposure. Heck, even to see the subject and achieve focus, you'll need a very bright light shining on the subject. Of course, this also means that focusing is done with a focusing rail, and with the type of magnification you'll be getting, the whole thing will need to be rock solid to avoid motion blur.

 

[Mayo]

Assuming the plane of focus is outside the lens, that plane will be very, very close to the lens, I suspect. In effect, you will have created a microscope. And that means you need LOTS and LOTS of light to get any kind of meaningful exposure. Heck, even to see the subject and achieve focus, you'll need a very bright light shining on the subject. Of course, this also means that focusing is done with a focusing rail, and with the type of magnification you'll be getting, the whole thing will need to be rock solid to avoid motion blur.

Using the 55-200mm, the focus plane to my surprise was about 1ft from the glass.????... And yes it needs a lot of light. Ill post some pics tonight when I get back home and play around with it.

 

[tirediron]

Interesting - looking forward to the images.

 

[Mayo]

Ok.. As promised here are two pics using the tube. I used my 18-55mm and the subject was nearly on the glass. Tomorrow ill go back to the 55-200mm and get some more test shots. It needs a lot of work to make it useful. But with a good stable mount and a better lighting source I'm sure I could get good results. The light I used for the flower was a 10watt LED flashlight.

yes! It was very hard focusing it and was very sensitive to movement. But I was able to get a recognizable picture of pollen.

My subjects where a flower and a lit LED.

Sorry if the uploads are not right. I'm still learning to export from lightroom.