Another starting dummie here...

[soldevilla]

Hi, I visited your site for some time and I want to introduce myself. I will not be able to work a lot because my knowledge of English is very bad. I write from Spain. (thank you, Mr. Google).

For two years I have tried to get good macro minerals. I have obtained some interesting results but only to publish to the Internet, reducing the size of the image to 25%. I use a Canon 350D body, and I have a huge drawer full of accessories, bellows, extension rings, enlarger objectives, microscope objectives, microscope and telescope eyepieces ... and just I bought a StackShot unit ... My results are acceptable for fields of 5mm, but smaller fields (I want to get to fields of 1 mm, with quality) are difficult for me.

I've tried it with a body 350D + microscope objective, projection ocular + 350D body, afocal method with my G11 ...

I think my problem is the low quality of my microscope objectives, but I want to ask you before I spend money on expensive first-class objectives.

I'll see how I can add some of my pictures later ...

regards

[Craig Gerard]

Bienvenida soldevilla, (I hope that is the correct greeting)

Add some images when you are able. If you need help uploading images we will provide assistance.

Images will help us to determine possible solutions to your concerns.


Craig

[soldevilla]

near... Bienvenido, I´m a man ( I thing...)

Maybe these are my best shots. Eritrine and conicalcite. It measure less that 1mm.




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And this is a yesterday shot, a 4mm titanite. I need more quality...

[Mitch640]

Wait. Let me get this right. You want better quality than that?

These are already some of the best I have seen. Really nice.

[soldevilla]

Thanks, Mitch. But the pictures I show are reduced to 25%. Original size is really horrible. And I thought it was a limitation of optics until I saw pictures in this web. I'm looking for a resolution as that obtained by Eddy Clerk in his last post, for example.

http://www.photomacrography.net/forum/u ... _det_1.jpg

I know it probably is difficult (and expensive ... ) to achieve that level, but it is part of the game, right?

[rjlittlefield]

soldevilla, welcome aboard!

Your images look very good here at web size.

Can you post a crop at original size to show us what problems you see there?

Also, what optics were these images shot with?

By the way, these images are clearly good enough to be posted in the regular galleries, where they will be seen by more people. They are far better than what I expected when I read the title about "starting dummie".

--Rik

[lauriek]

These are very nice mineral shots, and to be honest very nice specimens too, I love the first one, would like that in my collection!

[soldevilla]

Thanks for the welcome, folks.

My latest images I take with the canon 350D, extension tubes and a microscope objective x4. It must be very cheap because I think it is only an achromatic lens. I think I learned the first lesson in this web: a objective designed to work with 160mm SHOULD work at 160mm!!. The image I just took I think is more definite that I have achieved in such conditions. Anyway, 100% still needs a lot of definition.

lauriek, I'm not sure I have some other piece of Cerro Minado. I look and if I have I tell you.

A tyrolite, 4mm wide



And a crop...

[rjlittlefield]

soldevilla, thank you for these new images.

This looks pretty good. A little blurred, but not as bad as I had feared.

It is always hard to tell what is causing the blur. So I have some more questions...

1. What kind of lighting are you using -- flash or continuous?
2. What shutter speed?
3. Can you show us a picture of your objective and any markings that are on it?

I notice that this example is 4mm wide, and you mentioned in your first post that "My results are acceptable for fields of 5mm, but smaller fields (I want to get to fields of 1 mm, with quality) are difficult for me."

Are you reasonably pleased with this 4 mm image? Can you show us an example of something that you are very displeased with?

I wonder, have you read about using "infinity" objectives on front of telephoto lenses, for example as shown HERE? The reason I ask is that the Nikon CFI Plan Achromat 10x NA 0.25 shown in that thread is very sharp and remarkably flexible. It can be pushed down to 6.75X or even to 5X by mounting on a 135 mm or 100 mm telephoto, and the image quality remains high over most or all of the frame of a small-sensor DSLR like you have. I think it would be the sharpest lens I own for shooting a 4 mm subject. Also nice is that it is not very expensive, typically around $120 including adapters to use it with telephoto lenses that you may already have.

--Rik

[soldevilla]

So I have some more questions...

Let´s go...

1. What kind of lighting are you using -- flash or continuous?

Continuous... I use a IKEA leds lights lamps. Placing a magnifying glass after the lamp I get a high intensity light spot of about 10mm.

2. What shutter speed?

It vary... but 1/5 to 1/60 is usual. Too slow to stop vibration and too fast for the vibrations are no important. I know

3. Can you show us a picture of your objective and any markings that are on it?

I'm even a bit of shame ...



and in the other side...SELOPT KOREA
The best thing is that I'm sure that anything with which I to replace the lens will give me better quality.

I notice that this example is 4mm wide, and you mentioned in your first post that "My results are acceptable for fields of 5mm, but smaller fields (I want to get to fields of 1 mm, with quality) are difficult for me."

Are you reasonably pleased with this 4 mm image? Can you show us an example of something that you are very displeased with?

No, This last image is below my expectations. I'm looking to get the same quality that my camera gives me when I do travel photography. I can print 50x60cm. copies of my "normal" photos and that's my expected target ...

I wonder, have you read about using "infinity" objectives on front of telephoto lenses, for example as shown HERE? The reason I ask is that the Nikon CFI Plan Achromat 10x NA 0.25 shown in that thread is very sharp and remarkably flexible. It can be pushed down to 6.75X or even to 5X by mounting on a 135 mm or 100 mm telephoto, and the image quality remains high over most or all of the frame of a small-sensor DSLR like you have. I think it would be the sharpest lens I own for shooting a 4 mm subject. Also nice is that it is not very expensive, typically around $120 including adapters to use it with telephoto lenses that you may already have.

--Rik

Yes, set an objective "infinite" in front of a telephoto lens is one of the things I learned from reading this forum. It's another thing I have to try.

Thank you!

[rjlittlefield]

1/5 to 1/60 is usual. Too slow to stop vibration and too fast for the vibrations are no important. I know

I have several thoughts:

1. Try making your light less bright and using a much longer exposure time like 1-5 seconds. This allows some time for at least the fast vibrations to die out, so that most of the exposure is during quiet time.

2. Be sure you are using mirror lockup, if it is available on your camera. If it is not available, look to see if there is "hacked firmware" that will provide it. When I shot with Canon 300D, I found this very helpful.

3. Try some tests using flash, just to compare sharpness against continuous lighting. It would be nice to know for sure that your problems are in the optics and not the mechanics.

The best thing is that I'm sure that anything with which I to replace the lens will give me better quality.

Probably. But in the center of the field, there is surprisingly little difference in resolution between various objectives that have the same aperture. Better objectives mostly have more contrast, flatter fields, better color correction, and are sharper away from center. See for example the comparisons HERE, and look at center versus corner.

I'm looking to get the same quality that my camera gives me when I do travel photography. I can print 50x60cm. copies of my "normal" photos and that's my expected target.

That is an aggressive target. Due to diffraction, you will need a wide aperture objective to give a sharp image at actual pixels.

Working some numbers... Your camera has 3456x2304 pixels. A 1 mm field will require 20X magnification...

The calculator at http://www.microscopyu.com/tutorials/ja ... alculator/ shows that this many pixels is enough to capture all available detail at 20X even at NA 0.50.

What the calculator does not say, but is true anyway, is that the resulting image will still look pretty blurred at actual pixels. The two conditions go hand-in-hand: if the sensor is capturing all detail available in the optical image, then the image will look blurred at actual pixels. See HERE for some more discussion about that. Here is the relevant summary:

That's the Catch-22.

In order for our digital image to "look sharp", we have to shoot it or render it at a resolution that virtually guarantees some of the detail in the optical image will be lost. If you see some tiny hairs just barely separated at one place in the digital image, it's a safe bet that there are quite similar tiny hairs at other places that did not get separated, just because they happened to line up differently with the pixels.

Conversely, in order to guarantee that all the detail in the optical image gets captured in the digital image, we have to shoot and render at a resolution that completely guarantees the digital image won't look sharp.

So, there's "sharp" and there's "detailed" -- pick one or the other 'cuz you can't have both. What a bummer!

In other words, to get an image that looks sharp at actual pixels, you will need an objective that is even higher NA than what the calculator shows.

You can probably meet your goal at 4 mm by using the Nikon CFI Plan Achromat 10x NA 0.25 pushed down to lower magnification. It will still be working at NA 0.25, regardless of what final magnification is provided by choice of telephoto length.

At 1 mm, you may not be able to meet your goal without heroic effort.

--Rik

[soldevilla]

Thanks! I need some days to digest so much information.

This afternoon I made an interesting test. I photographed a aragonite using an enlarger lens Nikon and I compared the result of shooting at full aperture or f / 8. Very clearly the definition is better at full aperture, but the corners of the picture is far worse, of course ...