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09-28-2010, 08:18 AM   #16
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QuoteOriginally posted by Basler30 Quote
Thank so much Ole

I think i have two choices in my head right now .....

1--- K7 + D FA 100mm f/2.8 + Pentax AF160FC or

2----K7 + Tamron 90mm macro F/2.8 + Sigma Flash Macro Ring EM-140 DG

...Let s go back to reading through this forum .. I love this place......
Either option is excellent. If the photography is inter-oral it will be very difficult to rely on any TTL flash exposure control. If you are filling the frame with a tooth the reflection off that tooth is going to trick the flash into underexposing. The solution here is to use plus flash exposure compensation. If you are exposing another part of the mouth that is less reflective, darker and farther inside the mouth (shooting the back side of number 31 for instance) will cause overexposure.

I have set this up for a number of dentists in my area using a variety of brands of camera, lens and ring flash. The constant I have found is that dentists want the least amount of adjusting of the camera when taking the inter-oral shots. I have found the following set-up to consistently provide the results the dentist is looking for whether the photos are for basic documentation or for color matching:

Shutter speed: 1/180 sec. This will help prevent the influence of the work light color putting a false tint on the tooth.

ISO: 100 to 200

Aperture: f/8 to f/16 to provide enough depth of field given the somewhat longish focal length and very close working distance.

Flash: If you are filling your viewfinder with a tooth use +1 flash exposure compensation. If you are shooting into the mouth FEC will likely be unnecessary, or you may need some negative exposure compensation so that the closer and brighter parts of the mouth don't get so overexposed.

White balance: It will be very important to set the white balance to Flash for the most accurate color.

Granted if you are shooting RAW files, whoever processes the image has a great deal of latitude in getting the exposure and color perfect at the computer. However the dentists that I have set up have all preferred to not spend time at the computer getting it right, and they don't want to have to take 10 pictures trying to get the exposure they were looking for. Limiting your variables to simply adjusting exposure compensation will greatly streamline the process and maximize the profit from whatever procedure requires the photos.

Best of luck on your choosing, and remember to practice on your office-mates before you start taking patient photos.

09-28-2010, 08:18 AM   #17
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I have the Tamron 90, and it is a very good lens. However in your case I'd consider Pentax's D FA 100 and Pentax's ring flash. The reason I suggest the D FA as opposed to Tamron is because of Pentax's Quick Shift focusing. It's bothers me to have to flip the AF switch on the camera to MF, then push/pull the lens focus ring to switch focus modes. On Pentax's DA lenses all you have to do is turn the focus ring and you can fine tune/manually focus.

With you photographing dental work, I think you'd find this very beneficial.
09-28-2010, 08:05 PM   #18
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Ok I think i m set now ....
Pentax D FA 100 and Pentax's ring flash...

Anyone selling those two?lol

Thank you everyone for the help ,lot of stuff are much more clear in my head now,thank you again.
09-28-2010, 08:13 PM   #19
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I think this would be cheapest option for D FA 100/???

Pentax SMC DFA 100mm f/2.8 Macro Lens NEW - eBay (item 170534986540 end time Oct-01-10 09:00:11 PDT)

09-29-2010, 08:06 AM   #20
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Price looks reasonable!
10-01-2010, 08:30 PM   #21
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I hate to say it but the Nikon macro lens is much better for this kind of work. It has great resolution at f22 and f32. Pentax macro lenses have problems with diffraction at f16. I've used my dentist's camera and can't get anything like the same depth of field with my FA 100 macro.
10-02-2010, 10:53 AM   #22
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Does your dentist have a full frame camera? If you look at the Nikon 105mm macro compared to the Pentax 100mm FA macro you see really similar performance, with resolution really falling off after f16. I think this has more to do with the crop sensor and diffraction, then the lenses themselves. If you were shooting on full frame, you could easily get to f22 without problems. Anyway, I don't think there is a whole lot difference in these lenses if shot with the same size sensor.
10-11-2010, 10:52 AM   #23
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Basler, how is your setup working for you? I am a pre-doc student but already have a K-7 and am thinking of getting a macro lens and flash. It looks like you went with the DFA 100mm macro and a pentax ring flash -- how are you liking it so far for dentistry? Any advice?

10-12-2010, 01:59 PM   #24
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Hi Pedro
I just received the macro lens couple of hours ago and I will give it a couple of days to get familiar with.
Coming from point and shot camera to K7 isn t easy it will take me some time for sure,I will post my impressions in couple of days after I spend some time .I love the K7 amazing camera I like the flash beside the fact I still don t know how to get constantly good exposure most of the time my pictures are way too exposed but like I sais I ll give it some time to test everything.
10-12-2010, 02:54 PM   #25
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Do you Have the Pentax Ring flash yet? I think you'll find that the K7, DFA100, AF160FC combo works quite nicely.

Not teeth but..



http://farm5.static.flickr.com/4125/4992402662_2d7ee60cc4_o.jpg

Flowers are about the size of a US Quarter when fully bloomed out. These are half wilted (to give you an idea of scale). They are focused at 1:1 and I think the fstop was f32. I wouldn't rely too heavily on Auto Focus however. Stop the lens down and use Manual focus. I find that *I* get best results that way.

10-12-2010, 04:53 PM   #26
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Nice! I am excited for your new setup, hopefully you like it. That lens and ringflash have been on my radar for a while. It just seems like the perfect dental setup since the K-7 is solid like a hammer and their WR lenses are built so great too. Also the onboard crop feature of the K-7 could be nice too, to cut out the retractors, etc, and save some time in post-processing. And don't be discouraged about the complexity of the K-7 or the inconsistecy of shots for now. It was my first SLR and I was confused at first but the controls get easier each time you use it and the shots soon start looking the way you want them to. Let me know how your new setup goes and if you would recommend it. Thanks, Doctor!

QuoteOriginally posted by Basler30 Quote
Hi Pedro
I just received the macro lens couple of hours ago and I will give it a couple of days to get familiar with.
Coming from point and shot camera to K7 isn t easy it will take me some time for sure,I will post my impressions in couple of days after I spend some time .I love the K7 amazing camera I like the flash beside the fact I still don t know how to get constantly good exposure most of the time my pictures are way too exposed but like I sais I ll give it some time to test everything.
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