Is there a best f-stop for coin photography?

coolest · January 27, 2012 12:36PM

Thanks!

LanceNewmanOCC · January 27, 2012 12:52PM

.
i think M.G.'s book and others recommend 8
.
it is where i usually shoot but have gone higher/lower depending on situation
.

drwstr123 · January 27, 2012 12:57PM

Speriment.

Raufus · January 27, 2012 1:27PM

If using a macro lens it's generally f5.6 (for 60mm Nikkor Macro) to f8.

The sharpest focus for any lens is wide open + 2 stops. Of course, you have to consider depth of field, which is why most recommend f8 as a general rule.

blu62vette · January 27, 2012 1:31PM

I tend to be up more in the 10 range.

comma · January 27, 2012 2:35PM

Like was said, 8 is a good spot...but there is no "standard"...it all depends on your lighting, setup, and subject

morgandollar1878 · January 27, 2012 2:49PM

Generally I shoot around F-8 to f-11. It somtimes depends on the coin.

cameron12x · January 27, 2012 3:13PM

<< Like was said, 8 is a good spot...but there is no "standard"...it all depends on your lighting, setup, and subject >>

As was mentioned previously, usually the sharpest aperture is the widest + 2 stops. However, that may not produce enough depth-of-focus for your subject.

Conversely, f11 and higher will give you more depth-of-focus, at the expense of image sharpness (due to diffraction). Diffraction will vary by the lens, and also the image sensor form-factor.

Hence, the reason why f/8 is a good starting point.

Experiment. Digital film is cheap.

messydesk · January 27, 2012 3:15PM

<< I tend to be up more in the 10 range. >>

Mine goes to 11.

determined · January 27, 2012 3:23PM

<< Mine goes to 11. >>

Ah, you must have the Spinal Tap Lens.

rmpsrpms · January 27, 2012 6:19PM

There is no "best". The higher the f-stop, the more blurriness from diffraction. The lower the f-stop, the more blurriness from depth of field and lens aberrations. This is why the range of 5.6-8 is usually recommended. It's wide enough open to not be strongly diffraction-limited, but stopped-down enough that as long as the coin is flat you can get enough depth of field.

Take care though, since the "effective aperture" is dependent on magnification. If you are using an older manual lens, the aperture that is shown on the ring or in your display is for infinity focus. As you go to higher magnification, the same physical aperture opening results in a smaller effective aperture. The formula is f(eff)=f(inf)*(m+1). So if you are taking a picture of a Cent, with 0.8 magnification to fill the screen, and your aperture ring says f8, you are really at f14, which will be a bit fuzzier than you might like.

I make sure my coins are flat as possible vs the camera, and then push the infinity aperture down to f4-5.6 max for Cent photos. This results in effective f7-10 and is not strongly diffraction-limited. For a Morgan Dollar, at magnification of 0.4, f5.6-f8 will give you about the same effective aperture range (f8-f11 effective).

So I guess my simple answer would be: f5.6 for Cents, f8 for Dollars...Ray

sbeverly · January 27, 2012 7:04PM

Usually between f5.6 and f8. Lens manufacturers seem to have a slightly different sweet spot that their lens is
optimized for.

My Sigma 105 macro likes f8.

Agree with previous poster about testing.

LindeDad · January 27, 2012 9:00PM

<< 

<< I tend to be up more in the 10 range. >>

Mine goes to 11. >>

This is what I normally use with the Nicor 105MM but I have a lot of light availabe and a copy stand.

ambro51 · January 27, 2012 11:04PM

All lenses have an optimum sharpness. Years ago this was more important than nowadays, and usually f 5.6 was the best stop size.

today, with the digital cameras, it is basically the same but lens technology has advanced. A large opening will give you a short depth of field. A small opening will give you a greater depth of field.

If you work close in, with a small stop, you will see every mark on your slab. If you work further back, with a more open lens, you will have a focal plane that is on the coins surface and a lot of minor slab imperfections will not be visible.

Aside from the depth of field changes, f stop is not all that important with modern lenses used on a supported camera.

derryb · January 27, 2012 11:19PM

A camera "takes" a picture by very briefly allowing light (a reflection of your image) to pass through the lens to be captured on either film or a digital storage device. Two settings on the camera determine the quality of your image, or your exposure. The aperature setting (f stop) determines how much light gets through the lens by changing the diameter of the opening inside the lens (the aperature). The shutter speed setting determines how long the aperature lets light through the lens. Think of the light coming through the lens as your actual picture.

The lower the f stop number the bigger the opening that lets light in. The higher the shutter speed number the quicker the aperature opens and closes. A perfect combination of the two results in a perfect picture, or exposure (time and amount of light passing through the lens). In modern digital cameras the photographer normally chooses one of the two and the camera automatically adusts the other. By choosing a lower f stop (smaller aperature opening that allows less light through the lens) you are telling the camera to automatically increase the amount of time (shutter speed) that light is allowed to pass through the lens.

f stop controls "depth of field." When you focus on a spot, depth of field is in front of and behind the spot of focus that will also be in focus. The higher the f stop number (the smaller the aperature opening) the greater the depth of field. When focusing on a coin from directly overhead, needed depth of field is at a minimum. When focusing on a coin from an angle, needed depth of field increases in order to also be in focus on areas beyond the point of focus.

Amount of time a lens is open (shutter speed) is critical in hand held applications because of camera movement during the exposure. Camera movement during the exposure results in a blurry image. A lower f stop results in a faster shutter speed which reduces blurring from camera movement while the lens was open. This is why the tripod was developed. For fixed camera applications (tripod) camera movement is greatly reduced allowing one to keep the lens open longer by choosing a higher f stop (smaller aperature opening). The choice of the higher f stop tells the camera to keep the lens open longer for that perfect exposure.

Note that many digital cameras will let you choose either the f stop or the shutter speed and will set the other for you automatically. They also will, in full auto mode set both to match for a perfect exposure. As an example, let's say you are taking a shot of a race car on the Daytona track. Shutter speed becomes most important because you want s sharp picture of the car traveling very fast past you. How long the lens lets light (the image of the passing car) through the lens will determine if your image is sharp or blurry. In a case like this you would want control over the shutter speed and allow the camera to automatically adjust the f stop for the perfect combination.

My suggestion would be to start in the middle of your aperature range and take shots increasing and decreasing it a few f stops. Normally each f stop doubles or cuts in half the amount of light passing through the lens which in turn tells the camera to automatically increase or decrease the shutter speed to maintain that perfect exposure. A perfect exposure can be the result of a number of different aperature/shutter speed combinations as long as one of them is correctly compensating for the other. A good digital photographer must know which of the two he wants control over for a particular shot and will let the camera select the other to match his choice. Your lens and your lighting conditions will really determine which setting works best for you and can be best determined with trial shots at different f stops.

Many digital cameras also have settings for things such as close-up that often give coin photographers great results.

cameron12x · January 28, 2012 12:00AM

<< f stop controls "depth of field." When you focus on a spot, depth of field is everything beyond that spot that will also be in focus. The higher the f stop number (the smaller the aperature opening) the greater the depth of field that will also be in focus. When focusing on a coin from directly overhead, needed depth of field is at a minimum. When focusing on a coin from an angle, needed depth of field increases in order to also be in focus on areas beyond the point of focus. >>

Very well said. Depth of field/focus (DOF) is a VERY relevant concept with coin (macro) photography, as shutter speed is usually not a factor (unless you're shooting in the dark or with poor light). As previously mentioned, however, shutter speed may be important if you are shooting hand-held (you don't want motion blur, due to hand-shake).

That all being said, an VERY important axiom with regard to depth-of-field (or sometimes referred to as "depth-of-focus") is that when you focus, DOF includes everything in focus both BEFORE and BEHIND the focusing "spot." The focusing "spot" is referred to as the "hyperfocal distance" in technical terms. In the past, a general rule of thumb was that 1/3 of the DOF occurred BEFORE the hyperfocal distance ("focus point or spot") and 2/3 of the DOF occured BEHIND the focus point. This is a very handy rule to remember but, again, like most concepts in photography, is variant among different lenses.

For certain types of coin photography, in a practical sense, DOF may not be relevant. For example, if you only want the fields of the coin to be in focus, you're typically not interested in what is in focus BEFORE or BEHIND the "spot." However, if you focus on the raised coin devices, which are closer to the camera than the fields, you will want to have enough DOF BEHIND the focus spot so that the fields are also in focus. In that case (particularly with raw coins). what is in focus BEFORE the "spot" may or may not be relevant. For raw coins, it's mostly irrelevant (thin air does not need to be in focus, for example).

For slabbed coins, however, DOF can be very relevant. If you want scratches on the slab to show in your photo, ensure that you have enough DOF BEFORE the focus "spot." If you want scratches to be blurred (or not even visible in some cases), you will want to ensure that your DOF is narrow enough, or that your focusing spot is far enough BEHIND them.

One can calculate DOF mathmatically but, in a practical sense, simple experimentation with different f-stops is probably the easiest and best approach, since digital "film" is cheap (free). The important takeaway to remember, though, is that there is a "focus area" (DOF) both BEFORE and AFTER the hyperfocal distance (the focusing "spot"). I hope this VERY important concept (DOF) makes sense, as it relates to ALL photography, not just coins.

derryb · January 28, 2012 12:05AM

correct, depth of field includes areas in front of and beyond the actual point of focus and will increase with higher f stops. My original explanation has been corrected.

cameron12x · January 28, 2012 12:25AM

<< correct, depth of field includes areas in front of and beyond the actual point of focus and will increase with higher f stops. My original explanation has been corrected. >>

Cool... thanks!

To me, DOF is one of the most important concepts to understand in ALL of photography...

derryb · January 28, 2012 12:30AM

<< 

<< correct, depth of field includes areas in front of and beyond the actual point of focus and will increase with higher f stops. My original explanation has been corrected. >>

Cool... thanks!

To me, DOF is one of the most important concepts to understand in ALL of photography... >>

Agree. A good understanding of what happens inside the lens when you push the "button" and how you control what happens is equally impotant.

renomedphys · January 28, 2012 12:44AM

I think anywhere between 4 and 11, with 4 being a bit shallow, and 11 being dep enough to show lines from the holder. Using tilt will usually force you into a higher number to stay sharp, but shooting a little wider open is a usual sweet spot for sharpness, and will allow a little more light to dance on your coin's surface.

blu62vette · January 28, 2012 12:45AM

I got up to 15 with no issues as far as holder.

comma · January 28, 2012 12:58AM

<< 

<< correct, depth of field includes areas in front of and beyond the actual point of focus and will increase with higher f stops. My original explanation has been corrected. >>

Cool... thanks!

To me, DOF is one of the most important concepts to understand in ALL of photography... >>

Lighting is the other.

ambro51 · January 28, 2012 1:05AM

Many of my large format cameras I build use huge lenses that work at f 3.6 with a 16 inch fl. Depth of field at portrait distance (8 feet) is the eyeball to the ear

rmpsrpms · January 28, 2012 1:26AM

<< 

<< 

<< correct, depth of field includes areas in front of and beyond the actual point of focus and will increase with higher f stops. My original explanation has been corrected. >>

Cool... thanks!

To me, DOF is one of the most important concepts to understand in ALL of photography... >>

Lighting is the other. >>

For coin photography, lighting is by far #1. Since coins are relatively flat, DOF is less important than in general photography.

ambro51 · January 28, 2012 1:31AM

Depth of field matters quite a bit when you are shooting on an angle to capture toning or avoid a bad reflection

derryb · January 28, 2012 2:02AM

The technical aspects of photography (f stops/shutter speeds) determine correct exposure no matter what lighting is used. Automatic modern cameras make this easy. Lighting determines the visual appeal and actual "likeness" of your correct exposure. Lighting is something that the photographer learns to adjust once he understands how the camera makes its adjustments. More light through a lens requires a faster automatic shutter speed and a smaller automatic aperature opening (a higher f stop number). While the camera can make these changes automatically, it is important to understand them so that the photographer can determine one of them himself to control things such as blur/sharpness and/or depth of field.

To the coin shooter amount of light is not as critical as the placement of the light source(s). Different placement of light sources provides many different results when the position of the camera and the coin remains unchanged. How light reflects from the coin (the angle of the lighting) to the lens is the most critical aspect of lighting when trying to achieve that "in hand" look with coins or any flat, reflective surface.

comma · January 28, 2012 2:10AM

<< The technical aspects of photography (f stops/shutter speeds) determine correct exposure no matter what lighting is used. Lighting determines the visual appeal and actual "likeness" of your correct exposure. Lighting is something that the photographer learns to adjust once he understands how the camera makes its adjustments. More light through a lens creates a faster automatic shutter speed and a smaller automatic aperature opening ( a higher f stop number). To the coin shooter amount of light is not as critical as the placement of the light source(s). Different placement of light sources provides many different looks of a coin when the position of the camera and the coin remains unchanged. How light reflects from the coin (angle) to the lens is the most critical aspect of lighting when used with coins or any flat, reflective surface. >>

It is definitely good to know the ins and outs of your camera (no matter what), but without correct lighting, no matter how good the camera and how good the photographer you'll never get the result you want.
With coin photography you can't compensate for lack of light with a small fstop, so correct lighting is everything.

derryb · January 28, 2012 2:13AM

<< It is definitely good to know the ins and outs of your camera (no matter what), but without correct lighting, no matter how good the camera and how good the photographer you'll never get the result you want.
With coin photography you can't compensate for lack of light with a small fstop, so correct lighting is everything. >>

An automatic camera will give you a proper exposure when taking a picture of the moon. It may require the lens to stay open for full seconds and may require the camera to choose a wide aperature opening (low f stop number).

Correct lighting involves much more than amount of light from its source. In close up photography, more critical are type of light and number of light sources and where they are placed when trying to achieve that "in hand" look. My point is that an automatic camera adjusts for amount of light when determining proper exposure. Proper exposure does not guarantee perfect picture or the "in hand" look.

astrorat · January 28, 2012 2:19AM

<< 

<< I tend to be up more in the 10 range. >>

Mine goes to 11. >>

cameron12x · January 28, 2012 2:30AM

<< 

<< It is definitely good to know the ins and outs of your camera (no matter what), but without correct lighting, no matter how good the camera and how good the photographer you'll never get the result you want.
With coin photography you can't compensate for lack of light with a small fstop, so correct lighting is everything. >>

An automatic camera will give you a proper exposure when taking a picture of the moon. It may require the lens to stay open for full seconds and may require the camera to choose a wide aperature opening (low f stop number).

Correct lighting involves much more than amount of light from its source. In close up photography, more critical are type of light and number of light sources and where they are placed when trying to achieve that "in hand" look. My point is that an automatic camera adjusts for amount of light when determining proper exposure. Proper exposure does not guarantee perfect picture or the "in hand" look. >>

I couldn't agree more.

The bottom line is that any one of a number of factors can ruin the potential for a great photograph or a great coin photograph.

In the end, ALL of the technical AND aesthetic considerations need to be brought together to achieve the desired resuilts.

mgoodm3 · January 28, 2012 2:32AM

For sharpness: Most macro lenses will be sharpest from about f/4 to f/8 (shorter focal length will tend to have larger sharper apertures, such as f/4 for a nikon 55 micro, around f/8 for a 105/4 micro). The kicker is that Nikon will show you the "effective" aperture with their newer lenses (the ones that you choose an aperture in the camera and not on an aperture ring on the lens). That means that as you go higher in mag, you will need to select a "smaller" aperture. When shooting at 1:1 (the highest mag for most modern macro lenses), you will actually need to select an aperture 2x that you would choose otherwise. When shooting with this type of lens I choose an aperture around f/13 (equiv to f/6.5). If you are at lower mag, you can choose a somewhat larger aperture.

For depth of field: Macro DOF differs from normal photography in that the DOF behind the focus plane is about the same as that in front of the focus plane. just because something is inside the DOF does not mean that it will be sharp. It will be acceptably sharp at a standard reproduction size viewed at a standard distance. The only truly sharp place to be is at the focus plane. If you zoom the image up to full size, things will tend to get fuzzier in those areas. As the mag rises, the magnification DOF goes down. So, if you want to make a 2 ft. x 2 ft. print of a gold dollar, parts of it may look out of focus at the usual f/8 when zoomed up that large. If you resize that same image to 6 in x 6 in, everything may be sharp again. DOF is not a fixed process.

derryb · January 28, 2012 2:43AM

the good news is that modern, automatic cameras make the technical adjustments to ensure a proper exposure. To turn that proper exposure into a great picture requires an understanding of how to control things such as depth of field and choice of lighting and its placement. No better way to gain that understanding than to experiment by changing the things you have control over.

My experince as a combat photojournalist was back in the Hassleblad days when the operator had to decide what today's cameras will decide for you, if you want them to. I'm still a student of digital photography. That's why I bought, learned from and enjoyed Mark's book.

Back to the OP, there is a best f stop for every shutter speed. For coin photograhy whith an automatic camera, choosing an f stop somewhere mid range (of what the lens allows) works best for me as long as my camera is fixed on a tripod and shutter speed becomes unimportant. Experimenting from the mid range f stop setting is something I would suggest you do. Often times a camera's "close up" feature gives great results.

cameron12x · January 28, 2012 2:43AM

<< For depth of field: Macro DOF differs from normal photography in that the DOF behind the focus plane is about the same as that in front of the focus plane. just because something is inside the DOF does not mean that it will be sharp. It will be acceptably sharp at a standard reproduction size viewed at a standard distance. The only truly sharp place to be is at the focus plane. If you zoom the image up to full size, things will tend to get fuzzier in those areas. As the mag rises, the magnification DOF goes down. So, if you want to make a 2 ft. x 2 ft. print of a gold dollar, parts of it may look out of focus at the usual f/8 when zoomed up that large. If you resize that same image to 6 in x 6 in, everything may be sharp again. DOF is not a fixed process. >>

Agreed and well said...

The whole concept of "circles of confusion" is relevant here, but introducing it might also "confuse" some of the readers (just Google it). DOF markers on lenses are represented using certain arbitrary CoC values.

The bottom line is that even within DOF, there are varying degrees of "sharpness." At the hyperfocal distance ("focus point") the sharpness (or resolution) will be the highest. As you move away from the focus point, the subject becomes less sharp (lower resolution).

That has an impact on how large of a print you want to make or how large you can display the image on a given viewing medium (e.g. computer monitor).

So, the "target" output medium (and type) needs to be considered here, too, along with the anticipated viewing distance, for the final image.

This thread is rapidly evolving into a tutorial on photography.

UtahCoin · January 28, 2012 4:23AM

I try to stay around F11. That's using a Canon 100mm macro lens.

Kove · January 28, 2012 5:02AM

<< the good news is that modern, automatic cameras make the technical adjustments to ensure a proper exposure. To turn that proper exposure into a great picture requires an understanding of how to control things such as depth of field and choice of lighting and its placement. No better way to gain that understanding than to experiment by changing the things you have control over. >>

One key technical adjustment to include here regards light metering.

Yes, digital cameras can automatically set the shutter speed once you choose an aperture. However, that shutter speed will be set based on where in the frame you tell the camera to measure the light. Many digital cameras have several metering settings like full-frame light averaging, center-weighted, or point-metering (where you can choose one of many points in the frame). Light metering can be very different between raw coins, opaque PCGS slabs, and bright white NGC slabs. Metering will also be different if the coin is bright silver, dull gold, or dark copper. For the proper exposure, the digital photographer needs to tell the camera whether to measure the light from a point on the slab, an area of the coin, or a combination of both. Exposure can be less than perfect if the photographer just uses an "average metering" over the full frame.

I've seen many photos where the user sets a decent f-stop, but the coin turns out over-exposed or under-exposed because they chose the wrong place in the frame for the camera's sensor to base the light metering. The slab might be properly exposed, while the coin looks terrible, or vice-versa.

Based on photos I see, I suspect many folks try to fiddle mostly with their lighting and aperture, when proper metering would make a big difference.

Is there a best f-stop for coin photography?

Comments

Leave a Comment