# First post, questions about my equipment



## jonesdds (Apr 11, 2013)

Hello,

I'm a dentist and have purchased my last two cameras for both intra/extra oral photography and my other passion automobiles.  My first camera was a Rebel Xti from a dental photography company.  Included was a macro lens, a ring flash and various mirrors/etc. to facilitate intraoral photography.  Worked pretty well but got sick of the old larger storage chip after a pin bent early internally plus wanted to use a wifi chip for my working photography and an adapter I tried fried the wifi chip.  So, relegated the old camera to automobile and other photo duties(without chip removal downloads!) and i purchased a 4ti and a wifi chip.  Using the same ring flash as before and the macro lens.

There are specific settings that were recommended by my dental photography company for use with my old rebel Xti for close up intraoral photos.  They are:

Exposure mode AV
Shutter speed 1/200
F-stop F22
ISO 100
Flash Exposure Compensation indicator +1
white balance setting set to daylight


The flash exposure is the only setting recommended for change.  Can be altered to change darkness/lightness

Seemed to work well with Xti but not with 4ti.  Much lighter with the 4ti.  Any thoughts as to why?

Also, the other strange thing is that with my Xti the picture appeared almost instantaneously.  With the 4ti there is a large delay, sometimes 8-10 seconds.  It sounds as though the shutter is taking that long to open and close, but many times I get a good photo.  I've had some success with the brightness of the photos changing F-stop but that's not supposed to be changed.

Any help would be appreciated.  I'm a real newby with photography.


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## Derrel (Apr 12, 2013)

I 'think' the 4ti has Canon's new, color-aware light metering, and therefore is doing a better job of metering the light, whereas the Xti was "color-blind", and needed the +1 exposure value flash exposure compensation to make teeth basically "white", as opposed to a mid-tone.

Is the shutter taking 8-10 seconds??? At f/22 and ISO 100, indoors that would be a fairly normal exposure time in a dental scenario, I would expect. In Av mode, the Aperture Value is what the user selects: that would be the f/22 part of the exposure. The USER CAN NOT *select *the shutter speed in *Av* mode!!!! THE CAMERA's meter would do that...with a flash turned on, the camera would take a flash exposure and then the shutter of a camera aimed inside of a person's mouth would probably take 8 to 10 seconds to make the "ambient light exposure"...so, yes, your shutter probably IS being held open 8 to 10 sec. if you are using Av mode and are selecting a tiny aperture like f/22.

So...your settings are, how can I say it...messed up. You should try M mode. Manual. Set the lens to f/22 for good depth of field. Set the shutter to 1/160, which is a good flash sync speed and one I assume the T4i can handle. Then shoot with the flash. If the shots are fine, you're good to go. If they need to be "whiter", then add the +.3 or +.7 or +1.0 EV, whatever is needed to work.


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## JClishe (Apr 12, 2013)

I was at the dentist 2 days ago and the Dr was using a Rebel with onboard flash to take pictures of my teeth. I kept thinking, at the close distance he was shooting at, seemed like the lens would have created a shadow from the flash. Seems like a ring flash would be better for closeup oral work.


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## tirediron (Apr 12, 2013)

Without meaning to derail the thread, what is the purpose of photographing someone's teeth (assuming that is, that there isn't something wildly unusual about them that you can write a paper on)?


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## Dao (Apr 12, 2013)

tirediron said:


> Without meaning to derail the thread, what is the purpose of photographing someone's teeth (assuming that is, that there isn't something wildly unusual about them that you can write a paper on)?



Maybe for Teeth Braces.   Before and after?  Just guessing.


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## JClishe (Apr 12, 2013)

My dentist does consults before he works on your teeth and uses pictures to point out what he's going to do, then shows you an "after" picture when he's done.


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## TCampbell (Apr 12, 2013)

jonesdds said:


> Hello,
> 
> I'm a dentist and have purchased my last two cameras for both intra/extra oral photography and my other passion automobiles.  My first camera was a Rebel Xti from a dental photography company.  Included was a macro lens, a ring flash and various mirrors/etc. to facilitate intraoral photography.  Worked pretty well but got sick of the old larger storage chip after a pin bent early internally plus wanted to use a wifi chip for my working photography and an adapter I tried fried the wifi chip.  So, relegated the old camera to automobile and other photo duties(without chip removal downloads!) and i purchased a 4ti and a wifi chip.  Using the same ring flash as before and the macro lens.
> 
> ...



If you set the exposure mode to "Av" (Aperture value mode) it means you set the aperture (f-stop) -- in your case f/22 for maximum depth-of-field (greatest range of distances in focus) -- and the camera will set the shutter speed automatically.  The shutter speed should not exceed 1/200th because it takes about half that long for the shutter to completely slide open, allow the flash to fire (with a fully exposed sensor) and then slide shut again.  

The flash-exposure compensation works in conjunction with the camera's metering mode.  When a Canon flash is using E-TTL (or E-TTL II) you actually get two bursts of the flash, but they happen so quickly most people don't realize it.  The first burst of the flash occurs when the camera shutter is still closed.  The camera meters the light, fires the flash at a default of 1/32nd power (you can change the default, but that's what it is if you haven't changed it) and then the computer analyzes the difference between no flash and the 1/32nd power flash to determine how much _actual_ power should be used when the shutter is opened.  Having calculated that, the shutter opens, and the flash fires a 2nd time... using the pre-determined power level.

When you set the flash exposure compensation to +1, you're telling the camera that you'd like brighter flash power... +1 means 1 "stop" (a stop "doubles" or "halves" the amount of light (+1 doubles... -1 halves it.)  +2 would double it again (for a total of 4 times brighter.)  You can adjust in 1/3rd stop increments.  

HOWEVER... this is all based on the cameras metering mode.  I'm not sure how much of your typical images are intra-oral vs. the patient's face.  If the mouth region is only in the center and the camera is also exposing skin around the mouth then it may be attempting to avoid over-exposure of those areas at the expense of leaving the mouth too dark.

By default the camera will use "evaluative" metering.  This means it assess the light from an array of points all around your image to determine the best exposure (it also uses a database to see if it can't figure out what type of subject you are shooting, but that's not important here.)  There are two other metering modes... "spot" metering and "center weighted" metering.  Spot metering means the camera will only take the metering sample from a small area near the center of the image.  Center weighted metering means it will still meter the "whole" image, but it will give greatest weighting to the region of the image which is roughly near the center (a much larger area than "spot" metering).

You might try changing the metering mode to either "center weighted" or "spot" metering and see if that does not improve your exposures.  Basically you're telling the computer "this is the part of the image that I care about".

I'm a bit confused about what you mean by the "delay".   Are you saying that the camera wont take the photo for 8-10 seconds (there is a 10-second delay timer mode that you might have mistakenly enabled) or are you saying the camera takes the photo instantly, but it's 8-10 seconds before the image to be transferred via WiFi to your computer?

If the former (10 second delay to take the photo) check to make sure the self-timer is not enabled.  
If the latter (instantly takes shot... but 8-10 seconds before it arrives on computer) make sure you're shooting in JPEG mode and not "RAW" (RAW images are very large and they take a while to transfer).  Canon cameras that work with the EyeFi card are programmed to disable the radio while you're shooting in order to conserve power.  When the camera notices that a few seconds have elapsed without you doing anything with the camera, it will wake up the radio, connect to wifi and transmit the image.  This was a battery-saving condition as WiFi cards have a reputation for _really_ eating into the battery power on cameras.


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## 2WheelPhoto (Apr 12, 2013)

Welcome to the forum


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## Krawler (Apr 12, 2013)

tirediron said:


> Without meaning to derail the thread, what is the purpose of photographing someone's teeth (assuming that is, that there isn't something wildly unusual about them that you can write a paper on)?



I was hit in the face with a cable in December resulting in my jaw, nose , and pallet being split in half. Last time I was at the dentist they took picks of my remaining  teeth with a T3 right in my face using the onboard flash. I was wondering how they came out but I had more stuff on my mind then the photos.  I had never thought about this being done but he said that they do it in some cases so the lab can have something to look at and for documentation for the insurance companies. 

I wonder how often photos are made of teeth? Maybe the OP can feel us in.


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## jonesdds (Apr 12, 2013)

Krawler said:


> tirediron said:
> 
> 
> > Without meaning to derail the thread, what is the purpose of photographing someone's teeth (assuming that is, that there isn't something wildly unusual about them that you can write a paper on)?
> ...



I'm not doing them enough cause it takes time.  I need to train my staff to do them.  Documentation is one of the primary reasons but also for presentation of treatment-pictures really prove your case as to why the patient needs the treatment.  Plus, shade selection for my laboratory, before and after case shots that I can show others(with patient's permission) and proof of need of work to insurance companies.  These are most of the reasons.  If I had the time, I'd take full arch shots, side and frontal views and individual teeth as needed on everyone that has a complex tx plan.

As far as flash, I use a ring flash, the onboard flash is no good.  It's been suggest a two pod flash from the sides(not sure what it's called) is better but that's another $700 I'm not willing to spend yet.  

Reading through all the other posts still, you guys are great.  Little above my head some of it, once I do look all the responses over Ill post back.  thanks


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## jonesdds (Apr 30, 2013)

2WheelPhoto said:


> Welcome to the forum



Thanks, should have introduced myself first, sorry about that.  Obviously, I'm a dentist, so that's my most important photography subject.  I'm also an car lover, european cars mostly, and have a very large number of photos taken at various car shows including Pebble Beach.  Other interest is fly fishing, and picture taking doing that is also something I want to do, the guys and gals on the fly fishing forums love the reports with pictures.  The worry is that water and cameras don't mix, haven't quite figured out how to  take that problem out of the equation.


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## jonesdds (Apr 30, 2013)

Derrel said:


> I 'think' the 4ti has Canon's new, color-aware light metering, and therefore is doing a better job of metering the light, whereas the Xti was "color-blind", and needed the +1 exposure value flash exposure compensation to make teeth basically "white", as opposed to a mid-tone.
> 
> Is the shutter taking 8-10 seconds??? At f/22 and ISO 100, indoors that would be a fairly normal exposure time in a dental scenario, I would expect. In Av mode, the Aperture Value is what the user selects: that would be the f/22 part of the exposure. The USER CAN NOT *select *the shutter speed in *Av* mode!!!! THE CAMERA's meter would do that...with a flash turned on, the camera would take a flash exposure and then the shutter of a camera aimed inside of a person's mouth would probably take 8 to 10 seconds to make the "ambient light exposure"...so, yes, your shutter probably IS being held open 8 to 10 sec. if you are using Av mode and are selecting a tiny aperture like f/22.
> 
> So...your settings are, how can I say it...messed up. You should try M mode. Manual. Set the lens to f/22 for good depth of field. Set the shutter to 1/160, which is a good flash sync speed and one I assume the T4i can handle. Then shoot with the flash. If the shots are fine, you're good to go. If they need to be "whiter", then add the +.3 or +.7 or +1.0 EV, whatever is needed to work.



I'm going to be trying this manual mode setting and see how that works out.  Thanks for the help!

Jeff


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