# Anyone switched focusing screen on 5ds/r?



## Zeidora (Jun 20, 2015)

Has anybody actually swapped focusing screen on the 5ds or 5dsr, specifically to the Eg-S? Is it the same procedure as on 5d3? See
https://www.youtube.com/watch?v=H1xUyqQNlys


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## Eldar (Jun 20, 2015)

Be aware that the Eg-S is not a mechanical fit for the 5DIII and most likely not for the 5DS/R. I tried that and it worked well for awhile, but then I got a weird focus offset and I went back to the original. I then had an S-screen custom built for the 5DIII at www.focusingscreens.com (Taiwan), which fits perfectly and works well. Not as good as a Ec-S on a 1DX, but a lot better than the original.


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## Zeidora (Jun 20, 2015)

Thanks for the feedback on the 5d3. I ordered now both. Btw. the web address is www.focusingscreen.com (without the -s plural); the latter one land you on a domain name for sale page.


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## Eldar (Jun 21, 2015)

Zeidora said:


> Thanks for the feedback on the 5d3. I ordered now both. Btw. the web address is www.focusingscreen.com (without the -s plural); the latter one land you on a domain name for sale page.


Thanks for the correction (I´m on a cell phone). Their focusing screens are (naturally) a bit more expensive than from Canon, but they delivered as promised and it is a high quality product. 

If you decide to go for it, I´d be most interested in learning how it goes.


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## Zeidora (Jul 8, 2015)

Hi Eldar,

just got my 5dsr and the focusing screen for the 5d3 S type from focusingscreen.com. The screen does NOT fit the 5dsr out of the box. The big tab is too centrally located and too long. I shaved it down with a single edged razor blade so that the tab is shorter and extends less towards the center. Took about 5 minutes. Pretty straight forward if you have steady hands. Didn't even need a microscope to do it. However, please notice that I do prepare teeth of 0.5–1 mm snails for SEM, so possibly my manual dexterity and fine motor control is a bit above average.

I did a quick and dirty check with my Zeiss 100 mm MP at close focus and all open, and focus seems to be good. Certainly not miles off. Hope that helps.


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## Eldar (Jul 8, 2015)

Thanks. Please give an update when you have some more mileage.


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## Valvebounce (Jul 8, 2015)

Hi Zeidora. 
Please, for those of us who don't know, what are snails for SEM. You guys throw these things in just to leave us ??? It's not ;D
Enquiring minds need to know. :

Cheers, Graham. 



Zeidora said:


> Hi Eldar,
> 
> Snip..8<
> However, please notice that I do prepare teeth of 0.5–1 mm snails for SEM, so possibly my manual dexterity and fine motor control is a bit above average.
> Snip. 8<


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## 9VIII (Jul 8, 2015)

Valvebounce said:


> Hi Zeidora.
> Please, for those of us who don't know, what are snails for SEM. You guys throw these things in just to leave us ??? It's not ;D
> Enquiring minds need to know. :
> 
> ...



Probably a Scanning Electron Microscope, light stops working entirely at 200nm so you need to read surfaces with something else.

What I want to know is if the entire snail is 0.5mm long (after hatching maybe?) or if that's the size of its teeth.

And now I want to know what the size of a tooth on a baby snail is.


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## AcutancePhotography (Jul 8, 2015)

9VIII said:


> Probably a Scanning Electron Microscope, light stops working entirely at 200nm so you need to read surfaces with something else.



200 Nautical Miles? Now I am even more confused.  ;D


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## Zeidora (Jul 8, 2015)

9VIII said:


> Valvebounce said:
> 
> 
> > Hi Zeidora.
> ...



Snail = animal, creepy-crawly, slimy. SEM = Scanning electron microscopy. There are some snails that are fully mature 0.5 mm, i.e., some with terminal growth modification of lip. 0.5 mm is the shell. The animal is about half that (0.25 mm), the ribbon-like teeth = radula is about a third of the animal long (= 0.1 mm) and again half to a third the width (0.03-0.05 mm) and it tends to roll up along the long axis as well as across. So I have to unfurl the structure using tungsten needles (sharper points than steel) under a dissecting scope. It is free-hand manual work. That is what I mean with fine motor control. There only a handful of people in the world who do that sort of thing.

The finer structures on the teeth are on the 10-20 nm scale, so way beyond the theoretical Abbe limit for resolution limit of light of lamda/2 ~ 250 nm (nano meters = 1/1000 micro meter). Loads of fun.


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## Valvebounce (Jul 9, 2015)

Hi Zeidora. 
Well that clears that up nicely! I did wonder if you were making some sort of mechanical device similar to snail cams to move the subject by the small increments I imagine a scanning electron microscope might need. But real snails 0.5mm that's like a full stop. How can you tell it's a snail, half the time I can't see whether I just did a . or , ! ;D

Cheers, Graham. 



Zeidora said:


> 9VIII said:
> 
> 
> > Valvebounce said:
> ...


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## Zeidora (Jul 9, 2015)

Valvebounce said:


> Hi Zeidora.
> Well that clears that up nicely! I did wonder if you were making some sort of mechanical device similar to snail cams to move the subject by the small increments I imagine a scanning electron microscope might need. But real snails 0.5mm that's like a full stop. How can you tell it's a snail, half the time I can't see whether I just did a . or , ! ;D
> 
> Cheers, Graham.



Prep is all free-hand manual work; no coffee, and controlled breathing. For imaging, in photography I use a Cognysis StackShot motorized and computer controlled focusing rail for z-stacking. 100 images at 50 µm step-size is impossible to do accurately and consistently by hand. On the stereomicroscope, it has also a motorized focus (i.e., microscope moves up, lens is fix focal). On SEM the stage is 5 axis motorized and amount of movement is dependent upon magnification. At high mag, the stage is stationary and you move the electron beam. Depth of field is greater in SEM compared to LM, so I have not seen the need to do z-stacking on SEM, but I know of some people who have done it.

Re limits of optical resolution, you are right on. For the teeth, it can be difficult to tell if I have then right-side up, or upside down, even with kick-ass stereomicroscope optics (planapo 1.5x on Zeiss DV20). Curl direction can be a clue, as well as sparkly vs smooth-shiny surface appearance when in water. Just the prep is a whole science; wrote a 50 page paper on that.

Re collecting, I collect material from the habitat (sand samples, rock washings, algal shakings) and then sort & identify each particle under the microscope. Hours of fun!


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