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Lobby
Pillar Of The Community
United States
522 Posts
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Just trying to find something a bit better than what I posted in the "Beginners..." thread I started.
Where I am now:
- Olympus E-420 digital SLR
- Olympus Digital Zuiko lens 14-42 mm, 1:3.5-5.6
I bought this camera for a couple of reasons: not too expensive, plus it's small, making it easy to carry on motorcycle trips.
I currently use enlarging filters for coin photography (described elsewhere)
One of those filters is 4x, the other is 10x magnification.
Just screw them into the front of the lens, and easy coin photography (with led lights and a tripod). While the pics are decent, they're not great.
4x filter
10x filter
Those pics are not cropped.
I've been wanting to get clearer pics. Plus the option for more closeup detail. So I purchased an Olympus EX-25 digital extension tube. I figured this would allow me to get the magnification and close focusing capability I desired, but with sharper pics than the magnifying filters.
So, how does it work? Not well at all.
I had to get really close to the coin to be able to focus. And I was so fed up, I didn't really try that hard to get a good pic, as I couldn't get the LED lights in close enough.
So I got close to a decent pic, then disconnected everything.
The focal length of my stock lens is just too short, causing the EX-25 to shorting the focusing distance too much.
I've got several options to follow, but prior to chasing them, I thought I'd ask for ya'll advice.
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Pillar Of The Community
United States
1044 Posts |
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
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Pillar Of The Community
United States
522 Posts |
It seems to me that going the bellows route will also require a longer lens, though.
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Pillar Of The Community
United States
522 Posts |
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.  |
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Valued Member
United States
223 Posts |
Making great progress I'd say. I should comment that the smallest apeture (f#) of a lense is not related to the lens ability to resolve images (sharpness). It is a measure of how large the apeture ring inside the lens will open to admit light. The lower the number the more light, and the less depth of field you will end up with. The bellows suggestion is a good one as it will allow a greater range of magnification. I chose to stay with macro type of lens. I use two, a 60mm and a 100mm for smaller subjects. Here is a pic of a 19mm Civil War Token taken with my 100mm lens.  |
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Pillar Of The Community
United States
1044 Posts |
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
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Pillar Of The Community
United States
522 Posts |
Quote:
I should comment that the smallest apeture (f#) of a lense is not related to the lens ability to resolve images (sharpness). It is a measure of how large the apeture ring inside the lens will open to admit light. The lower the number the more light, and the less depth of field you will end up with.
Yeah, I understood that. I was just making the general observation that lenses with lower fstops are higher quality than the cheaper, high min fstop lenses. Thanks for the kind words. Oh, and your pics are wonderful. Quote:
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 Yes, I've got more room for lights. But this has actually caused a problem for me. I'm getting more flash / glare on the coins than before. I'm not sure what to attribute this to, the sharper lens, or the different light position. By placing tissue paper over the led's, I've reduced the sparkle a bit. Re the bellows route, part of the reason I've not chosen it is because of the strange 4/3 format. I figured I had to purchase a 135mm or 150mm lens, compared to the 75mm that ya'll have settled on. I didn't feel like experimenting on lenses; and finding the correct bellows seemed a bit daunting. Although I suspect that's the next challenge.
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Pillar Of The Community
United States
1044 Posts |
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
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Valued Member
United States
342 Posts |
Lobby, I was browsing Google search returns, and came across this one. I thought it was relevant and quite helpful with some of the information it was offering for the 4/3 format. http://www.wrotniak.net/photo/43/ma...bellows.htmlIn addition, Ray has never pointed me in the wrong direction, and he's keen at finding really good deals on eBay, so when you're ready to move to a bellows system, he's your guy! |
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Moderator
United States
12559 Posts |
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. The best thing about a bicycle is that it uses no gasoline, therefore the chance of fiery death is greatly reduced.
First Catman, then Gary Burke and now Bigg Fredd - there's one heck of a coin club in Heaven.
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Pillar Of The Community
United States
1044 Posts |
Of course SuperDave is right and is steering you in the right direction. As long as you can do at least a 2x integer downsizing from the original size and come out with between 650-900px image you will be in good shape for resolution and sharpness. The larger working distance you get with the longer lens will give you plenty of lighting options, so no worries there. So let's see some more photos with this setup!
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Pillar Of The Community
United States
522 Posts |
Quote:
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?
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.  Quote: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. 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.
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Pillar Of The Community
United States
522 Posts |
Quote:
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 Thanks, Ray. What I'm more interested right now is in some sort of camera rail / adjustable stand. So I can quit messing with the tripod. I haven't found anything cheap yet.
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Pillar Of The Community
United States
522 Posts |
Quote:Lobby, I was browsing Google search returns, and came across this one. I thought it was relevant and quite helpful with some of the information it was offering for the 4/3 format. http://www.wrotniak.net/photo/43/ma...bellows.html Thanks!
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Pillar Of The Community
United States
1044 Posts |
Lobby...Don't worry so much about magnification, or distances. Instead, concentrate on how many vertical pixels the coin fills up on the sensor. What you want is for smaller coins to fill between 1300 and 1600 pixels in order to allow downsizing the image by a factor of 2 and get the final image at 650-800 pixels for publishing. This is between a bit less than 1/2 of the sensor to a bit more than 1/2, so filling half the sensor is probably about optimum for small coins like the farthing. The 2x reduction will significantly reduce any issues you might have with lens sharpness, camera shake, etc. For larger coins like the Peace dollar, you might shoot for filling about 1950-2400 vertical pixels. Then downsize by a factor of 3 to get the same 650-800 pixel final image size. This means filling approx 75% of the sensor with the coin. The 3x reduction gives even more reduction in any image problems. So you pretty much have two "ranges" to target: fill the sensor 50% with the coin and downsize 2x, or fill the sensor 75% with the coin and downsize 3x. Note the integer reduction factors give a better resulting sharpness to the image due to the way the jpg resizing algorithms work. Edited by rmpsrpms
01/24/2012 11:33 pm
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Pillar Of The Community
United States
522 Posts |
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.
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Posted 01/11/2012 11:23 pm
