Setup of Ploum

ploum · Post by **ploum** » Thu Oct 30, 2014 10:31 am

Administrator's note [Rik]: This thread is a continuation of the discussion started HERE, in Photo of Ploum.

Ok rik i post here an image.

ploum · Post by **ploum** » Thu Oct 30, 2014 10:44 am

In front positioning system. It's not impossible to stack with but i don't use for that. With that i place specimen or i can make panoramic photo or what i want : No obligation to built like that.

and the last stage with manfrotto.... Work is fast, easy and if motorisation is possible for the moment i don't use.

Manfrotto work fine around a balance position. I prefer work with a standard distance but you can, as a bellow, change this distance if you want... In this case you can increase until x1.5 magnification.

repositionning system is usefull for stay around balance position and allows all overcrawding. No limitation and very economic.

Light camera is better...

FOV with a 10x is 1.5 mm but until 1 mm for example.

rjlittlefield · Post by **rjlittlefield** » Thu Oct 30, 2014 11:11 am

Excellent -- thanks for the picture! This makes the setup much more clear.

And be assured, your setup fits right in here at photomacrography.net . We have no problems with breadboards, clamps, counterweights, and springs.

I wonder, would you object if I split this thread to move the discussion of your setup into the Technical Discussions forum? It may seem out of place here in the images gallery, and surely it will distract people from the images of your specimens.

--Rik

ploum · Post by **ploum** » Thu Oct 30, 2014 11:16 am

Rik if you want i let you done that

. After i can explain a little more with my "English" globish ....

rjlittlefield · Post by **rjlittlefield** » Thu Oct 30, 2014 11:36 am

Excellent. I have split the thread and cross-linked the two parts.

Explain more, at your convenience!

--Rik

Chris S. · Post by **Chris S.** » Thu Oct 30, 2014 2:24 pm

Frédéric,

Thanks for posting the image and explanations of your setup--ingenious! I hope you will share additional pictures of specific details, such as how you have arranged your relay lens. As you've shown, there are benefits to this approach. And even though I have a motorized microscope focus block, I've considered using a relay lens in addition, for some purposes.

Like you, my macro setup has been mocked (gently) in a French forum. We share the honor.

By the way, your mineral images, in your other thread, are exquisite!

ploum · Post by **ploum** » Thu Oct 30, 2014 4:24 pm

Chris S. wrote:Frédéric,

Thanks for posting the image and explanations of your setup--ingenious! I hope you will share additional pictures of specific details, such as how you have arranged your relay lens. As you've shown, there are benefits to this approach. And even though I have a motorized microscope focus block, I've considered using a relay lens in addition, for some purposes.

Like you, my macro setup has been mocked (gently) in a French forum. We share the honor.

By the way, your mineral images, in your other thread, are exquisite!

I done that in next month

. A little busy

Chris. My lens is a nikon (sysem Nikon cfi) 200 mm Inside the principal pipe (58 mm). I have insert this in a small pipe (astronomic system on eBay) with a 42 mm mount. All is 42 mm at the head.

Length of my system is important (before i use a bridge with a dcr 250 to catch primary image = 125 mm + 200 mm). I use a DCR 150 to project a correct size on my captor (micro 4/3). Without magnification is x1.5 (as a crop of the image).

We see that in next month

FRed

abpho · Post by **abpho** » Sun Nov 02, 2014 7:13 am

Good for you Ploum. Your images speak for you. The means that you took to get there are meaningless.

The last page of images are spectacular.

canonian · Post by **canonian** » Mon Nov 03, 2014 2:00 am

I like the cleanliness and perfection of the Bradcam, but I also like how you manage to make excellent photos's with a setup like this.
I have absolutely no critique on your rig but are those tubes glued together? What's that you use as XYZ Stand/focus block? What's its origin?

soldevilla · Post by **soldevilla** » Wed Dec 17, 2014 3:06 pm

Maybe my poor english, maybe my poor knowledge of optical laws, but I can´t imagine how is mounted this optical setup. ¿is a short focal length objective in front of a 200mm. tele lens; and these lens project the image to an objective + Raynox lens fitted in the camera?

I´m happy with my rig, but some days ago I read that a microscope is a telecentric system by definition, and I´m looking for how test it and to compare it with my setup, and I don´t know if the Poum´s system is in this way. Excellent results, by the way.

rjlittlefield · Post by **rjlittlefield** » Thu Dec 18, 2014 1:36 pm

soldevilla wrote:Maybe my poor english, maybe my poor knowledge of optical laws, but I can´t imagine how is mounted this optical setup. ¿is a short focal length objective in front of a 200mm. tele lens; and these lens project the image to an objective + Raynox lens fitted in the camera?

I don't know exactly what lenses ploum is using, but I do understand the basic setup. Perhaps I can explain.

Start by imagining a system with lens, bellows, and camera, focused by changing the rear extension of the bellows. The front lens and the subject stay in exactly the same place. Focus stepping is accomplished by moving the position of the image plane on the back side of the bellows.

A system like this has the advantage that moving the focus plane at the rear of the bellows by a distance of 1, moves the focus plane at the subject by a distance of only 1/(magnification*magnification). So, at 10X, a focus step of 0.5 mm at the rear of the bellows gives a focus step of 0.005 mm at the subject. At 20X, a focus step of 0.5 mm at the rear of the bellows gives a focus step of only 0.00125 mm at the subject!

Now, to get ploum's system, you will remove the camera from the bellows, insert a relay lens, and move the camera + relay lens far enough back that it focuses at the same place where the camera sensor would have been when the camera was mounted directly on the bellows. When using the relay lens, you have even more options for how to focus. But ploum is using the simple one, just moving the camera and relay lens on a macro focusing rail.

I´m happy with my rig, but some days ago I read that a microscope is a telecentric system by definition

A microscope is definitely not a telecentric system "by definition". Some objectives are almost telecentric; many are not. However, at high magnification such as 10X and above, the very shallow depth of field allows a microscope to be treated as if it were telecentric, even though it isn't really. This works better when the magnification is constant. Ploum's method of focusing has a drawback here, because in his system magnification is not constant. The farther back you move the focus plane, the larger the magnification gets.

--Rik

soldevilla · Post by **soldevilla** » Fri Dec 19, 2014 5:38 am

Uf!

If I understand, you are talking about to create a telescope. The objective is focusing to infinity, and the distance between both lenses is the sum of their focal distances. But with a telescope, the object is really in the infinity, and the image that exit from the eyepiece in focused in the infinite again, as our eye need, working in afocal

I will try what happens when I use a small telescope as microscope. The theoretical part is too hard for me.

Back to Poum´s rig, I like very much how small is the defocused area around several planes., And I think that it can be produced because the increased distance between object and objective. Minus defocused areas and more distance for lighting, sound very well.

soldevilla · Post by **soldevilla** » Fri Dec 19, 2014 8:18 am

Well. Yes, it works. I have tested a telescope finder and if I invert their position in order that the eyepiece are pointing to the sample and the chip is in the point focal of the objective, I obtain a focused image in my camera. Of course, the quality is horrible, but a finder is for to watch stars, not small minerals

Small steps...

rjlittlefield · Post by **rjlittlefield** » Fri Dec 19, 2014 9:15 am

soldevilla wrote:The theoretical part is too hard for me.

So try this simpler model... Ploum has built a large horizontal microscope. He steps focus by moving the eyepiece.

--Rik

soldevilla · Post by **soldevilla** » Mon Dec 22, 2014 1:11 pm

I will try to explain my doubts. In this first diagram I drew a simple telescope like the one I used for testing.

In this second scheme I'm using the same telescope, with the same distance between lenses, but I've rotated and have placed the focal plane coincident with the focal length of the objective of the telescope.

Here I get image. I think if the telescope provides 8x, I am getting an 8x microscope. Poor quality, I said it before, but I'm not talking about quality but of optical design.

Now I think about quality, and use good optics. I can put a 200mm telephoto in the camera body as a substitute microscope objective, and a short focal lens (enlarger, microscope) replacing the eyepiece.

But I don´t know the distances between the two objectives, because as the telephoto lens is a compound lens system I do not know where the resulting lens is. I used telephoto as telescopes, it is very easy: just replace the camera body by an eyepiece. But if this is a telescope, then to turn this into a microscope the telephoto must be inverted in the camera body.

I'm a little lost in my thoughts.