Speccing out a jewelry photography setup

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Scarodactyl
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Speccing out a jewelry photography setup

Post by Scarodactyl »

Hi everyone. I have been thinking about putting together a setup for photographing jewelry. I am currently using an all-in-one setup which works pretty well, but it's also old and has a 1mp camera.
Problem is, I know what I need in a lens but I really only know anything about macro/micro stuff, nd this is more closeup/normal macro.

What I need is a parfocal zoom setup which works from about 0.2x-1x on aps-c.

I was thinking about the rayfact 80mm but after reading a bit more it's not parfocal (which is too bad since otherwise it's a slam dunk). In theory I could probably use a modular industrial zoom lens--I currently have a navitar 6000, a couple optem fusion zoom bodies and a monozoom 7 on hand--but they're really more meant for small sensors and higher mags, so I'm not sure it makes sense to push them to the edge of their specs in two directions if there's something better, though it doesn't have to be toppest wuality either. My other thought was duelling lenses with a zoom lens focused to infinity taking, which might work? The closest I have come to that are brief tests putting stereo objectives in front of a kit zoom lens but that's it. It seems like it might get a bit bulky too, which isn't a dealbreaker but not ideal either.

Anyone have any ideas? It's not exactly a near-term project but I figured it would make sense to deal with the optics before I figure out the mechanical positioning and lighting.

physicsmajor
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Re: Speccing out a jewelry photography setup

Post by physicsmajor »

Parfocality is going to be your main limiting factor, most of the usual suspects either aren't zooms, don't perform anywhere close to worth considering, or aren't parfocal. You have a few usual suspects in terms of industrial inspection zooms at hand it sounds like. Other fancy industrial line-scan zooms are out there (Macro varon, a Rayfact, and a Mejiro some of which Robert has tested) but I don't have experience with them and suspect most aren't parfocal.

The only addition I have which comes close is the rather esoteric and discontinued (but readily available on used market) Nikon Zoom-Micro-Nikkor 70-180mm. This is a Nikon F-mount lens and it is parfocal. Lens focuses to infinity but at minimum distance the reproduction ratio is essentially 0.27-0.7x with focus plane held. Nikon then made a No. 6T close-up lens which is an achromatic doublet that directly mounts to this zoom macro and basically turns it into a 0.39x-1x lens (this is, also, discontinued and pricier used now than it was new). The need to move the camera on the short end and add a close-up lens for high mag might be a deal breaker, or it might be fine; depends on your use cases.

I have all of the above and enjoy using this lens for mineral photography, the versatility is great.. But it should be noted that the performance is not as good as a dedicated prime. To minimize chromatic aberration I usually work at f/8 instead of f/5.6, but the results are quite good overall.

If you want me to run any particular tests or other questions I'd be happy to oblige; could toss a ring on black velvet or something.

Scarodactyl
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Re: Speccing out a jewelry photography setup

Post by Scarodactyl »

Thanks! That does sound intriguing, but looking at the used price I think I'll try getting a 0.25x objective for the navitar first and seeing how it does, and failing that see if I can find one for the monozoom 7 (seems to be a rarer objective though). I can shell out more if need be but might as well check the cheaper options first.

Duke
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Re: Speccing out a jewelry photography setup

Post by Duke »

I thought about low mag setup before and tried different approaches too.

So I've started with abbe-typ (cmo) stereomicroscope, and eventually, through trial and error, came back to it, making this full circle of continuous disappointment. Now I have SMZ-10 with 0.53x and 2.0x lenses, seem to work best of what I've tried.
Leica (actually baush&lomb = optem) monozoom 7 was one of such disappointments. There's two main problems with it.
First being low optical resolution of the zoom system, the aperture of the system is very low, exit pupil is actually much lower than what we have on stereomicroscope (I've expected it to be higher, since macroscopes usually suppose to deliver better detail, otherwise, what is the point).

Second being the fact MZ7 is a finite system, and most finite objectives are trash. Even when I've found some good finite projection objectives - there was no real advantage in the resolution, since the zoom-system sets the limit really low, about F/10 or so. Stock objectives 0.5x and 1x, being single achromatic lenses, work even better most of the time.

The one thing could work, but I've not tried yet in pairing good Zoom foto lens, focused at infinity with LOMO Korrektar F=150mm f/5.6. Korrektar is an amazing plasmat-type lens, works best at infinity back focus plane, it's designed to be flat field at 0.3x on full-frame, or 0.2x on aps-c. I've also have some Microplanars (F=100mm f/4.5, F=65mm f/4.5) but they are not as good by far in terms of resolution.

There's a problem though - as I do not know any good Zoom lenses. I'm thinking of taking a shot buying Tamron or Sigma 18-250mm lenses, cause they are relatively cheap, but not sure, they might be completely useless for this purpose, as I've heard, they might zoom not parfocally, bring vignetting and aberrations.
“Thoroughly conscious ignorance is the prelude to every real advance in science.” - JCM

Pau
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Re: Speccing out a jewelry photography setup

Post by Pau »

Just a very wild guess:
Because 0.2-1x range is well covered with high quality by many non zoom camera macro lenses and (at least at the higher limit) you'd need to do focus stacking, I can imagine a system with two stepper motors:
- one motor moves the camera + lens or subject stage for focusing with a rail like in most stacking setups
- the second motor* rotates the lens focus ring to set the magnification, there are many cine accessories to do it
-- both motors movements are controlled by a computer or two channel electronic controller coordinated in order to maintain focus at any magnification or at some prefixed steps once experimentally determined.

I would not be able to design it with deeper detail but I'm sure than many forum members would be.

* maybe even the own focus motor in some autofocus lenses
Pau

lothman
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Re: Speccing out a jewelry photography setup

Post by lothman »

Scarodactyl wrote:
Mon Dec 07, 2020 12:03 pm
What I need is a parfocal zoom setup which works from about 0.2x-1x on aps-c.
I am not aware of such a parfocal optic, but may be for a smaller senser have you had a look at the newer Navitar lenses like their Resolv4K
https://www.thorlabs.com/newgrouppage9. ... p_id=13181

they offer higher resolution at larger sensors with bigger field of view at higher prices ;-)

Lou Jost
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Re: Speccing out a jewelry photography setup

Post by Lou Jost »

A reversed internal-focusing internal-zooming zoom lens on a tube lens would be parfocal, though perhaps not over the wide range of magnifications you need. [Edit: This really isn't possible with such low m, even if you used a medium format front lens. It might work with a large format front lens and a zoom tube lens.. But probably not.]

I don't know your reasons for wanting parfocality, but a simple macro lens on a manual focusing rail would allow you to cover a wide range of magnifications without moving the tripod.

Scarodactyl
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Re: Speccing out a jewelry photography setup

Post by Scarodactyl »

OK, I finally got something put together for this, and I figured it would be worth sharing.
My day job (such as it is) is making and selling jewelry online. We needed an easy to use system to take photos of a decent resolution quickly and easily. Our previous solution was an all-in-one type of deal, which worked surprisingly well but had a 1mp sensor--perfectly fine for online listings ten years ago, less so today. We tried a few newer ones with higher resolution cameras but they all had one sort of issue or other--bad interface, bad color, etc etc. It felt like an ideal solution would be to use my DSLR with a lens mounted in a fixed position and zoom across our most-used magnifications without having to rejigger everything each time we did.

I did pick up one of the Kubotek lenses just to see how it would work, but while mounting it is easy the magnification range and extreme lack of parfocality made it a poor choice for this, though I'm enjoying it for other stuff.

Long story short, after some more review of what magnifications we actually use I realized was aiming a bit too high--about .18-0.5 or so is fine. It's interesting how awkward it is to find a good solution for this--basically a few microscope features and a few macro features which are rarely combined. What I really wanted was essentially an extra low-mag macroscope, and I remembered the Leica Z6 manual notes that for lower magnifications you can use Leica surgical objectives on them rather than the normal apo ones. I didn't want to give up my Z6 for this project (and I sure can't afford to buy another one!), but really all I needed was another appropriate zooming tube lens. So I just ended up getting a Leica 400mm (~0.25x) surgical microscope objective and mounting it on a Tamron 70-200 f2.8. I got the Tamron with inexpensively because autofocus was broken and manually focused it to infinity. Since it's an internally zooming lens the length is constant as focal length changes, and it is parfocal enough that the subject stays in focus from low to high zoom with the objective mounted. One more 3D printed adapter and it sits in a standard 76mm microscope mount on a hefty Diagnostic Instruments boom stand (I've always wanted to get one of these, and I finally had an excuse!)
Image
Image quality is not just good, it's good enough!
Image
(this was just a test photo with a desk lamp, but we also have tons more working distance now for whatever lighting we want).
The ergonomics are good, and I'm overall really happy with it. I might also pick up one of the focusable 300mm objectives to try out slightly higher mag and not having to reach up to the focusing knob if I see one cheap.

dolmadis
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Re: Speccing out a jewelry photography setup

Post by dolmadis »

Hi, thanks for posting. Does the Leica 400 objective have a thread (type, size) that makes it compatible with the camera lens?

Thanks, John

Scarodactyl
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Re: Speccing out a jewelry photography setup

Post by Scarodactyl »

It's a Leica standard m65x1.5mmish thread. I 3d printed an adapter for it onto the m77x0.75mm filter threads.

dolmadis
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Re: Speccing out a jewelry photography setup

Post by dolmadis »

Thanks. I like the build you have achieved,

Br John

Scarodactyl
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Re: Speccing out a jewelry photography setup

Post by Scarodactyl »

Thanks!
Just in case anyone was curious (actually, just because I was) I took a few wafer pictures to see what kind of fine detail it can capture. Not very controlled, bad lighting etc, this is just to get a general idea in five minutes. Honestly it did much better than I expected. I did have to refocus a bit from center to corner (partially from nonplanarity, partially because the lens is a little tilted), but quality is pretty consistent at min mag, and corners still aren't awful at max mag.
Minimum mag:
Image

Image
center^
Image
corner^
Max mag:
Image

Image
center^

Image
corner^

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