[Ailuropoda]

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It could still use some work, but sensor dust was getting annoying. Macros seem to really make any dirt stand out so clearly. Gotta settle on and get a cleaning device sooner or later.
Taken using a m28/2.8 reversed on a formula 5 80-200mm f4.5 lens. Those old prime lenses fit in the built in lens hood so nicely. The ME Super I picked up at the pawn shop along with my old lenses came with a cable release and I still have zoom range left, and enough image circle. Trying this on film could be interesting.

[yeatzee]

Head-on shot of the hoverfly

[Damian]

So my wife had her engagement ring worked on recently as it had lost a few of it's itty bitty diamonds that surround the sapphire in the middle. While discussing the service work, the jeweler told her that the sapphire in the ring looked more like a Tanzanite then a Sapphire due to a large amount of scratching and other damage on the stone. He suggested she get it analyzed in a spectrometer to know for sure. When she came home and told me this I of course was less then happy because the ring was sold to me as a Sapphire. Before anyone says "that's what you get you cheap bastard" she picked it out from this place that carried antique jewelry online and I bought it without her knowledge to surprise her when I proposed a few years back. After she told me the news I performed all the known do-it-yourself tests on the stone to see if I could determine if it was a Sapphire or not. The tests were inconclusive. So I decided to investigate these scratches and gouges myself. Not having a microscope, reversed lens stacking is my only means of seeing into the sub-macro world. Here's what I found.
Just for everyone's knowledge, all the pictures below were subject to minimal post processing. Auto Levels, contrast adjust, re-size and finally minimal sharpening.

Here's a the ring at close to 1:1 for comparison. I used a Tamron Adaptall-2 90mm 2.8 macro at f11.


Roughly 1.80:1. This was the first stack using both my macro lenses stacked. I was actually the least pleased with the results from this combination. Tamron AD2 90mm 2.8 with Sigma 50mm 2.8 reversed. Both lenses were set to f4 for this shot. I tried only setting the aperture of the Sigma to f5.6, but the vegnetting was very pronounced, so I compromised by setting both lenses to f4.


Roughly 3.75:1. This ones is using the same Tamron 90mm but wide open this time with a Miranda (Cosina, Vivitar) 24mm f2.8 reversed and set to f5.6.


Roughly 5.63:1. This was taken using a Pentax-A 135mm f2.8 wide open with the same Miranda 24mm reversed and set to f8.


Roughly 8.33:1. Now we start getting really close. Taken using an old M42 Auto Mamiya Sekor 200mm f3.5 wide open with the same Miranda 24mm reversed and set to f8. The flare spot you see is probably a result of the older singles coated optics of the Mamiya Sekor. Regardless, resolution held up nicely.


Roughly 16.67:1. This was by far the hardest shot to take and is the only keeper out of about 20 shots. It probably could have been sharper, but it's hard to get sharp results at that magnification when there are two little boys chasing each other around the house sending vibrations through the floor system. Taken using a Tokina SD 400mm f5.6 with the same Miranda 24mm reversed and set to f5.6.


I'm still not sure if it's a Sapphire or a Tanzanite. Assuming this really is an antique stone and setting, it's possible the the sapphire was damaged when purchased and we just haven't noticed until told. I guess I'm just going to have to get it spectrally analyzed to know for sure.

[Chaos_Realm]

Not being an expert on gemstones I warn I could be wrong in saying this. But I tend to agree with your jeweler. Tanzanite (Heat treated zoisite) is rather soft 6.5-7 on the mohs hardness scale the same as the likes of a steel file. Compared to a 9 for Sapphire or ruby (colour variations of the same mineral) which, behind diamond, the second hardest mineral known to man apparently.
So assuming it was sapphire if there is scratches they would have been caused by either diamond or the same gem. I can see a couple of scratches that appear to be out of alignment with the direction of the "cutting" marks but it could still have been caused in the cutting process. But in all likely hood it is a key indicator it's Tanzanite. =(
Your photos seem to focus more on the fractures or "chipped" edges, which is not the same as scratches but still an indicator as sapphire is more durable than tanzanite.

My understanding of this comes from my studies to be an engineer, where there was a whole subject devoted to material properties, and another looking at minerals. So although not directly related it there is some overlap.

[crewl1]

I can't comment on the precious stone issue and hope for the best outcome for you, but I must say that the magnification achieved in your investigation work is outstanding.

[Damian]

So assuming it was sapphire if there is scratches they would have been caused by either diamond or the same gem. I can see a couple of scratches that appear to be out of alignment with the direction of the "cutting" marks but it could still have been caused in the cutting process. But in all likely hood it is a key indicator it's Tanzanite. =(

Wow, I honestly didn't expect any comments regarding the stone. But you are probably right, I'm thinking it is a Tanzanite as well. I've done a lot of research on both Tanzanite and Sapphire because of this little issue. It is possible though for a Sapphire to become scratched or chipped during normal wear. But it is unlikely. All around us, in everyday materials there are microscopic particles of diamond and other precious stones. They are too small to see or gather. So even a sapphire or a diamond can become scratched in everyday use. I've also seen hard stones damaged by impact with materials softer then themselves, yet still hard, such as granite, concrete, quartz, and steel. So basically, though it is most likely a Tanzanite, the only way to know for sure is to have it analyzed. If it is a Tanzanite, it's not the end of the world. To have a high quality sapphire of the same size set would only cost about $250-$350, which isn't bad considering what I paid for the ring to begin with. Yes, I'm a cheap bastard, but so is my wife, so it's all good. She actually said she would prefer to keep it for now. Regardless of what it is, she likes the look of it.

Your photos seem to focus more on the fractures or "chipped" edges, which is not the same as scratches but still an indicator as sapphire is more durable than tanzanite.

I'm thinking I may have to try again, but focus on the flat face of the stone to see if I can get a better look at the scratches.

I can't comment on the precious stone issue and hope for the best outcome for you, but I must say that the magnification achieved in your investigation work is outstanding.

That's why I posted these. I was actually happy enough with the results from the stack of the 135mm with the 24mm, but I already had everything set up so I decided to see how deep I could go. I'm fairly pleased with the results, but I think it's about time to invest in a good linear stage if I'm ever going to try this again. My cheapo macro rails just aren't precise enough and are very frustrating to use.

[crewl1]

Plus wait till the boys go to bed

[Chaos_Realm]

Yes, I'm a cheap bastard, but so is my wife, so it's all good. She actually said she would prefer to keep it for now. Regardless of what it is, she likes the look of it.

Well being "a cheap bastard" probably is the wrong approach to your purchase. I would look at it from the perspective of your getting the same looking stone, with the same beauty, and the only sacrifice is the long term durability of the stone. but the savings far out weighed the loss of durability, I mean the ring in which it has been cast (although repairable) is more likely to break or wear out.

I'm thinking I may have to try again, but focus on the flat face of the stone to see if I can get a better look at the scratches.

sorry I got a little encapsulated by the ring and a little off topic, considering what you have in the way of equipment (and kids running round) I think you did very nicely.

[savcom]

Some of the shots here - and the engineering behind them - are simply superb. I've only just joined this club having played with a reversed 50mm F1.7 in the garden. Nevertheless, these are two of my first attempts taken early morning while it was still calm....





My problem was getting the focus right on these shots as all I had was the camera on the tripod. Perhaps I need a sliding base for the camera - or a different head on the tripod. Ah well - the colder darker evenings means I will have the time to spend in my basement workshop. Such a shame.

Just a thought - has anyone tried 3D macro shots? Anaglyphs or similar?

Great stuff!

Martin

[newarts]

Perhaps I need a sliding base for the camera

See: Macro Focusing Rail Slider for DSLR (Fast Ship from US) | eBay

It will do what you want for $48. If you are willing to wait longer you can get the same thing shipped from china for around 1/2 as much. Focusing rails are quite helpful for macro work.

[savcom]

See: Macro Focusing Rail Slider for DSLR (Fast Ship from US) | eBay

Yeah, thanks for that. Was looking at getting something similar made up of two two-way units so I can play with other configurations - such as 3D anaglyphs and remote flash mounts - carefully selecting the 'best' supplier for perhaps a fotomate LP-01. I have an old Velbon tripod head that will provide a stable platform for this too.

Thanks

Martin

[newarts]

Yeah, thanks for that. Was looking at getting something similar made up of two two-way units so I can play with other configurations - such as 3D anaglyphs and remote flash mounts - carefully selecting the 'best' supplier for perhaps a fotomate LP-01. I have an old Velbon tripod head that will provide a stable platform for this too.

Thanks

Martin

Two of the units I (and you) referred to could be cobbled together & would give you 4D control. They can be separated into individual sliders as well.

[LightMeter]

I can join this club now. I made an adapter that allows me to use Nikon lenses on my 645. It will not focus to infinity, but is for macro only-the 645 lenses I have don't focus close enough. A Pentax body cap and Nikon lens cap were drilled and glued together with JB Weld. Then I drilled small holes and used screws to hold them together to guarantee that it would not come apart. I was going to make an adapter that would use the 645 lenses, like an extension tube. But they will not allow you to stop down the aperture when the lens is not on the camera like the Nikons.




My 50 1.8 lens has a good reproduction ratio, but almost no working distance. The 75-150 zoom offers decent RR and working distance.



This is an Arsat 80mm 2.8 lens with a Pentacon 6-Nikon tilt adapter. So I have tilt capability. Just wish it would focus to infinity. When I shoot some pics and get developed, I'll post here.

[yeatzee]

^ cool stuff, and way to be creative

[Nass]

Lightmeter, can you show us some macro tilt pics? I'm interested in whether or not tilt is relevant for macro, how many degrees you use up to? (as opposed to shift which I was always told was the handier of the two wrt macr). When I tried tilt I found that I had to really tilt the lens massively -- too massively -- it meant I had to start using the worse periphery of the lens.