Is time to restart

soldevilla · Post by **soldevilla** » Sat Aug 08, 2015 12:59 am

After a long time testing lens, lighting, optical paths (and no very happy with the results

) maybe the time of start again is arrived.

Before all, a question... I assume that the speed of flash is enough to stop any vibration, but seen the results, I no sure about it when I go to high magnifications. ¿someone has made tests in this way?

Let´s go. Anglesite with the simpliest optical path: only my JML lens, bellow and camera. 2,5mm FOV. At this magnification, the final image is good for me. But all the comment will be apreciated!

rjlittlefield · Post by **rjlittlefield** » Mon Aug 10, 2015 10:01 am

soldevilla wrote:Before all, a question... I assume that the speed of flash is enough to stop any vibration, but seen the results, I no sure about it when I go to high magnifications. ¿someone has made tests in this way?

I'm not aware of any calibrated tests on this issue.

As general discussion... Illuminating by consumer flash at low power, say 1/16, the effective exposure time will be in the range of 1/5000 second. Clearly no finite time can completely prevent motion blur, so the question is whether the blur has been reduced to a small enough fraction of a pixel that you can't see it.

In my own work, I have gotten good results with flash in situations even where the live view image was bouncing around so badly that I could not see it clearly when zoomed in. But I cannot say that "good" meant "no visible blur at all", because I didn't run a head-to-head test with and without the vibration.

So, let me put it this way. If your live view image is stable enough to look clear even when zoomed in, and you shoot with flash at low power in a darkened room with mirror lockup and second curtain sync with a 2 second shutter time, then I think you can be quite confident that any blur is due to optics and not motion. To check that, you can also compare two images that were shot at different power levels, and thus at different exposure times (flash pulse length). If the images look the same, then probably both cases were fast enough to freeze out motion.

all the comment will be apreciated!

The image shown here looks great. I'm assuming that "JML lens" refers to the JML 21mm f/3.5. I've tested one sample of that lens and found it to be remarkably free of false colors, but not nearly as sharp as other lenses that might be used at high magnification. See the comparisons at http://www.photomacrography.net/forum/v ... 8051#58051 and http://www.photomacrography.net/forum/v ... hp?t=15876. At the second link, look especially at the camera-resolution images for the JML 21 versus the Nikon CFI 10X NA 0.25 microscope objective pushed down to 5X, HERE versus HERE. Those are slightly different magnifications, and a bigger subject than you have, but I think you'll get the idea.

For a subject of this size and color, the best lens I know would be the Mitutoyo M PLan Apo 10X NA 0.28, used with a tube lens of suitable focal length to fill your sensor.

--Rik

soldevilla · Post by **soldevilla** » Wed Aug 12, 2015 10:33 am

Thanks, Rik. Nope, my JML is the 26 f4. I not have the 21 (I´m loosing an important lens??). But for fields near 3mm (I´m using a 1100D canon) the JML is enough.

These two last days i made tests with a mimetite, very nice seeing it in the binocular, because the contrast of colors, yellow over black. But take an image was a nightmare! I have tried the Nikon x10, 160mm distance to chip. Horrible... all highlights are a big flare around, and the sharpness is

. Well, maybe the projection eyepiece can save the image... new tests, and the ouput image is very far that I looking for. The lighting is not the same in each test.

Today, finally I tested a "I don´t know" Minolta. Because I have mechanized the barrel for to fit it in my rig, I can´t say anything about it. I bought it many years ago in Surpluss Shed. Some earlier tests indicate that this lens give good quality

http://www.photomacrography.net/forum/v ... highlight=

but with a FOV of 1,6mm clearly it is not the best lens

The last test I can do (just now, after writing this) is to forgot the 160mm. between lens and chip, to mount a x20 objective and decrease distance. And to hope that the geometric aberrations are no too much big.

rjlittlefield · Post by **rjlittlefield** » Wed Aug 12, 2015 10:37 am

soldevilla wrote:I have tried the Nikon x10, 160mm distance to chip. Horrible... all highlights are a big flare around, and the sharpness is .

Can you show us some actual-pixel crops so that we can see what evil sharpness you're talking about?

--Rik

soldevilla · Post by **soldevilla** » Wed Aug 12, 2015 2:30 pm

Okay, Rik. Is there an award for worst picture of the month? I win three at a time ...

The JMI 20x with less than 160mm seems to be something better. But far from what I want ...

soldevilla · Post by **soldevilla** » Wed Aug 12, 2015 2:39 pm

After a lot of work... the image final with the JMIx20 +eyepiece. Is feel that some colors have a bigger difficult, perhaps colors near the primary or secondary colors, but I´m not sure, and now is not the moment for planning more tests.

Thanks for your help.

rjlittlefield · Post by **rjlittlefield** » Thu Aug 13, 2015 12:25 am

I'm very confused about your optics. In the first post, you mentioned JML+bellows+camera. That setup I think I understand. But what are these "+ eyepiece" setups? And when you say "NIKON x10", exactly what objective is that?

--Rik

soldevilla · Post by **soldevilla** » Thu Aug 13, 2015 11:54 am

Well, my language lacks, again...

Here some lens I use. Left to right, the JML 26, NIKON x10 LWD, machined MINOLTA, Componar 75, Tominon, Olympus 32 and JMLx20

The optical group... Canon 1100D, two extension tube (I need them for to have a image circle enough for the camera chip), estension tube with the eyepiece projector inside, bellows, and in this case, the JMI x20

......................

And some images of my rig:

Homemade XYZ stage

Homemade suport for flash units

And a general vision, including the TV monitor for the Live View

soldevilla · Post by **soldevilla** » Fri Aug 14, 2015 12:13 am

For Carmen:
I have read your PM yesterday, but now I can´t open it, (SQL error...¿?). My column is not a copy stand, very expensive, but a column of a old Meopta enlarging. It is not the best device, because the axis are no normal to the work surface, but as I have my homemade XYZ, it is not a great trouble.

rjlittlefield · Post by **rjlittlefield** » Sat Aug 15, 2015 2:53 am

soldevilla wrote:Okay, Rik. Is there an award for worst picture of the month? I win three at a time ...

Sorry, no award for worst picture. We might consider something for the most improved. So, in search of that...

Most of your setups have glass that is being used differently from how it was designed to be used. This is always a potential problem. I am especially concerned about the use of a relay lens, what you are calling an "eyepiece projector". It takes a very special lens to do that job well, and I have no idea what you are using there.

But in any case...

The image you show from the 10X objective looks pretty sharp.

https://lh6.googleusercontent.com/-tney ... ikon10.jpg

But it suffers from some sorts of "echos" :

These look to me like what happens when a wide aperture lens is used with shiny crystals and the illumination is not diffuse enough.

I suggest to use your 10X optics, and set up some diffused lighting like shown by Ploum at http://www.photomacrography.net/forum/v ... 005#175005. It is much better when the subject is bathed with light from many angles, instead of coming from just one or two flashtubes.

very nice seeing it in the binocular, because the contrast of colors, yellow over black.

Sure, but when you use the binocular you get to "cheat" -- focusing the microscope on exactly the bits that you want to look at, and ignoring everything else. In addition your binocular scope does not resolve very fine details, because it is made to use small aperture, to give more DOF at the expense of detail. It is harder to make an image that is sharper, and is sharp everywhere, especially when there is bright foreground and dark background. See HERE for an explanation of that problem.

Revisiting the question you asked earlier...

I assume that the speed of flash is enough to stop any vibration, but seen the results, I no sure about it when I go to high magnifications. ¿someone has made tests in this way?

The results reported by other people, including myself, have been using consumer flashes that make shorter pulses at low power levels. But I think those flash bulbs that you're using always run at full power, so they always make light pulses around 1/1000 second, maybe longer. Those will not be as effective at freezing motion. I do not think that this motion is your problem, but I just wanted to mention this in case it is an issue.

Summary: try again, using your 10X setup, but with a lighting setup that is more diffuse like Ploum's.

--Rik

soldevilla · Post by **soldevilla** » Sat Aug 15, 2015 9:18 am

step to step... Let´s go to start by the flash speed.

Mi Hi-tech tests.

First, a sincronous motor.

And I don´t know the english name of this device, black painted, with a white spot.

images at 1/15; 1/20 and 1/40. The motor seem to have a regular speed (as sicronous motor must have...)

Now, an image with the flash only as all lighting.

And let´s go to find a speed in the camera with the same aspect.

at 1/1000. It seem less fixed that the flash image.

At 1/2000. Very similar. Then, the speed of the flash pulse is around 1/2000 or a bit more...

Seem it correct?

soldevilla · Post by **soldevilla** » Sat Aug 15, 2015 9:24 am

Eyepiece projector... Searching in Google, the english name is Photoeyepiece. I buy the mine at Brunel Microscopes many years ago.

rjlittlefield · Post by **rjlittlefield** » Sat Aug 15, 2015 10:14 am

The flash and the mechanical shutter behave differently.

For practical purposes, the mechanical shutter blocks either all or none of the light at each spot on the sensor. Both sides of your white spot get captured equally well.

But the flash gets bright quickly and then takes a long time to fade. As a result, the flash catches one side of your white spot as a sharp edge, but the other side is very blurred.

Compare the images:

To my eye, the blurred side of the white dot with flash looks much more blurred than the 1/1000 second shutter, maybe more like 1/500 second.

If you do have motion problems, then any bright highlights will behave like the white spot, with a long blur on one side.

--Rik

rjlittlefield · Post by **rjlittlefield** » Sat Aug 15, 2015 10:33 am

soldevilla wrote:Eyepiece projector... Searching in Google, the english name is Photoeyepiece. I buy the mine at Brunel Microscopes many years ago.

Good, that is the right type of lens.

But one caution: projection eyepieces only work well when they are used at the correct magnification, which depends on how far they are mounted from the camera.

Do you know what magnification the eyepiece is rated for, and what magnification you are using it?

--Rik

rjlittlefield · Post by **rjlittlefield** » Sat Aug 15, 2015 10:36 am

By the way, I just noticed that this thread is currently in Nature Photography, clearly not the right place.

It should go in Technical & Studio, or even better in Technique and Technical Discussions.

I will move it.

--Rik

Is time to restart

Is time to restart

Re: Is time to restart