Experiments In Olympus 4/3 Photography For Coins

With such a short lens, your working distance is going to be poor, and since the lens is big it's going to be tough to get light in there.

At this point I can only suggest going the bellows route. But that's usually my suggestion anyway...Ray

Continuing with the 4/3 Edisonian (trial and error) experiments:

After some thinking (we should all try that sometime) it was pretty clear that the focal length of the stock lens was just too short for the extender I was using.

As I wanted (sort of) a zoom lens for my camera, I thought I'd try this route and see what I could come up with.

I purchased a 40-150MM F3.5 lens for the Olympus 4/3 system. Note: I sorta got the "wrong" lens. Olympus makes a 40-150 for their E-500 cameras. It fits mine, but according to the literature, it's not as clear as the 40-150MM F4 for the E-420.

Weird. Normally, lower f-stop capability means a sharper lens....

Anyway, here's the setup:

(note I had to raise the legs on the tripod by quite a bit)



The kit lens on the camera, plus the extender and zoom lens



With the extender and zoom lens installed:



Some pics:










Am I happy? Well, I believe my pics are sharper. I believe closeups are better.

But this setup on a tripod isn't a good deal. I have to use the zoom feature on the lens to focus. If I want to actually "zoom," that is, adjust the size of the coin on the viewfinder, I have to move the legs on the tripod up and down.

Rather a pain. I either need a focusing rail, or I move to a bellow system.

Regardless, I'm headed in the correct direction.

Looking pretty good Lobby. Is the bigger working distance giving you more room for lighting?

If you go the bellows route, you might want to pick a bellows that has a built-in focusing rail. The Vivitar has one available that is separate but bolts together seamlessly. The Pentax and Canon Auto Bellows have the rail integrated in their design. Some Nikons do, others don't. The rail can give you better focusing flexibility without having to buy a copy stand.

...Ray

Lobby...you worry too much! The 4/3 format is very popular, and adapters are available to mount most any lens (or bellows) on your camera. 4/3 to M42 or T-Mount adapters are plentiful and cheap on ebay. You will need to be careful to make sure the bellows and adapters you choose are not too long if you want to stick with 75mm. Best bet is to go with a smaller M42 bellows since the M42-M39 adapters don't add any length. When you get ready let me know and I'll make specific suggestions...Ray

So let's talk for a moment about the images you're getting right now. You'd mentioned early on that the pics you were posting were not cropped; I assume from that to mean you're physically downsizing them to post here. If I'm correct....

....just how large are these images to begin with? And how large are the coins themselves, cropped?

It's entirely possible that you're already achieving shots of ample size to be as good as you need, with a little judicious postprocessing. The second set - the Farthing and the Peace dollar - are already almost large enough. The 800x600 images posted here are an exact downsize from your camera's maximum 3648x2736 resolution. If what I see here is the full image, downsized, then the Farthing will measure almost 1400 pixels in diameter on the sensor.

That's plenty big enough to work with, leading me to believe that the optics you have are more than sufficient. Yes, it's a bit labor-intensive in use - the tradeoff for using equipment not optimized for macro photography will always be additional labor - but that labor level can be reduced by accepting one idea that we never talk about here:

You don't always have to fill the sensor with the coin, every time.

The ultimate goal is to post nice, gradable images here. 800px diameter is nice; 650px is normally acceptable if the focus is sharp (you're getting that), the lighting is good (you're getting that) and the color is right (you're getting that, too). If these are full-sensor images, there isn't a coin minted that you cannot post here at 800px diameter with this equipment.

It's my contention, if I'm right about what I'm thinking here, that it's time to stop adding equipment and consider what a little postprocessing can do to maximize what you've already got. Chances are you can reduce the constant fiddling with camera distance down to two or at most three "stock" distances - one to fit a Dollar-sized coin, and one to fit that Farthing - and those settings will give perfectly acceptable images of smaller coins.

This pic is about 4.5 mb on my computer disk. Uncropped.



I didn't crop it when I uploaded it to my pic hosting site. The Peace dollar is 38.5 mm in diameter.




The farthing, I unfortunately can't find on my laptop.








When ya'll talk about coin size vs sensor size vs 1:4 and 4:1, I get lost. I just don't think in the math of enlargement ratios.

Concerning settling on a few "stock" distances, I think that's a good idea. While I don't much want to mess with the tripod, getting the coin a bit closer to the lens (placing it on a book, for example) isn't difficult to do.

I don't understand what you mean by post processing, though.

Thanks!

Yeah, but how do I do that? How do I know "how many vertical pixels the con fills up on the sensor?"


That what I meant in my earlier post about not understand the math of magnification that ya'll always talk about.