[liveman2k]

Hello guys,

New to the forum, big time Pentax camera fan and user.

I recently got into macro shooting, close-up crystal/glass work that my wife makes on her free time, and dental/intra-oral shooting for my own practice. Here's my equipment: K20D + Pentax 100mm Macro WR f2.8/Tamron 90mm Macro + Yongnuo YN-14EX ring flash. Normally I have my setting at M/f22/1/125 ~ 1/160, and ring flash at ETTL or M. My biggest problem is that I'm getting a pretty bad over exposure (or under) with the same setting, under different angle or environment. Say when I'm taking a close up front teeth (when the teeth are closed), the photo will come out fine but then when I use a metallic mirror to take intra-oral pictures, most of the time I will get a very dark result, as if the flash didn't flash at all or wasn't syncing correctly with the camera.

After tweaking the setting for half a month I'm still not able to get the right light, right exposure for my work. One of my colleague uses Canon eos 400D + Sigma 105mm + Sigma EM 140DG ring flash and he's getting the right exposure like a piece of cake, just point, focus, shoot, boom, perfect photo. Now I'm stuck with switching the setting manually every time when I shoot from a different angle, it's frustrating and time consuming, and I have to take off/put on gloves and pause my work in between because I didn't want to put my assistant through the hassle with this camera.

My research shows that the Yongnuo YN-14EX ring flash (China brand) is only good with Canon ETTL, but no luck with Pentax PTTL, and I have to manually set the flash intensity differently each time. So far I've found three ring flashes that supports PTTL and may be capable for my work: Metz 15MS, Pentax AF160FC and Sigma EM 160ED (for pentax), are there no any alternatives? Despite from the high pricing factor, it's quite difficult to find these flashes here in Shanghai (currently residing and working oversea).

Has anyone had experience working with the Yongnuo YN-14EX ring flash and can perhaps give me some advises on the setting? I'm very new to camera flashes, still doing ongoing research about it, and I want to keep using the K20D since that's my wedding gift. Thanks in advance, any advises, greatly appreciated!

Jeff

[WPRESTO]

Beware of flashback reflections from your metallic mirror, as these would cause severe underexposure of the desired subject. A ring flash is coming at the mirror from many directions, and if any angle reflects back into the camera, this will throw off the desired exposure. Also, if part of a person's lips are in the image, these could throw off the exposure for the more distant molars. Try using the spot meter or perhaps center-bias averaging rather than matrix metering before you give up on the Yongnuo. Experiment with the mirror and a random small object, or maybe the interior of a cardboard tube.

I have no experience with the Yongnuo unit, but have used (and returned) both a Metz 15MS and Pentax AF160FC. The reason for returning: many of my macro lenses are older MF units, and no Pentax body will provide PTTL flash exposure with these. So, if you do opt to purchase a different ring light I would recommend the Pentax AF160FC used with the Pentax 100mm macro as the Tammy may not function properly for PTTL flash.

[Not a Number]

The main problem is the Yongnuo is made for Canon E-TTL and does not support Pentax TTL or P-TTL. So basically you are shooting in Manual mode. And, basically, you'll have to make charts of the f-stop and power settings that work best for each type of exposure. When using the mirror you have to open up the aperture, increase the flash power or change the ISO 1-3 f-stops.

Changing the aperture may not be desirable as it will change the Depth-of-Field too.

Ring flashes are not the best light source when shooting objects with highly reflective surfaces as much of the light gets reflected straight back into the lens. Remember the angle of reflection is equal to the angle of incidence.

Diffusion will help and the Yongnuo looks well diffused.

See Thomas Shahan's video(s) on macro lighting to see what effect diffusion and lighting angle has on subjects. Note his DIY rigs probably won't cut it in a professional setting like a dental practice

You Tube

You Tube

[liveman2k]

Beware of flashback reflections from your metallic mirror, as these would cause severe underexposure of the desired subject. A ring flash is coming at the mirror from many directions, and if any angle reflects back into the camera, this will throw off the desired exposure. Also, if part of a person's lips are in the image, these could throw off the exposure for the more distant molars. Try using the spot meter or perhaps center-bias averaging rather than matrix metering before you give up on the Yongnuo. Experiment with the mirror and a random small object, or maybe the interior of a cardboard tube.

I have no experience with the Yongnuo unit, but have used (and returned) both a Metz 15MS and Pentax AF160FC. The reason for returning: many of my macro lenses are older MF units, and no Pentax body will provide PTTL flash exposure with these. So, if you do opt to purchase a different ring light I would recommend the Pentax AF160FC used with the Pentax 100mm macro as the Tammy may not function properly for PTTL flash.

Thank you so much for the suggestion, I think the biggest problem with me manually tweaking the M setting is that I waste too much time for me and my customers. The best solution is probably going to get one of the above ring flash, might save all of us from a lot of trouble. As for the Yongnuo ring flash, I think I will keep it as a collection, after all for $70 bucks I think this ring flash is outstanding in many aspects, and produces amazing result on M setting. I did found an AF160FC on their "ebay equivalent" website (Taobao), but the seller rating is terrible, still digging through... Thanks!

The main problem is the Yongnuo is made for Canon E-TTL and does not support Pentax TTL or P-TTL. So basically you are shooting in Manual mode. And, basically, you'll have to make charts of the f-stop and power settings that work best for each type of exposure. When using the mirror you have to open up the aperture, increase the flash power or change the ISO 1-3 f-stops.

Changing the aperture may not be desirable as it will change the Depth-of-Field too.

Ring flashes are not the best light source when shooting objects with highly reflective surfaces as much of the light gets reflected straight back into the lens. Remember the angle of reflection is equal to the angle of incidence.

Diffusion will help and the Yongnuo looks well diffused.

See Thomas Shahan's video(s) on macro lighting to see what effect diffusion and lighting angle has on subjects. Note his DIY rigs probably won't cut it in a professional setting like a dental practice
Lighting for Macro Photography and Review of the Venus KX-800 Twin Flash - YouTube

Thank you for clearing up my question! The reason why I got the Yongnuo ring flash was that the seller told me it works fine on Pentax as well. Well, it is working perfectly on K20D, just only on M setting. It got me thinking that I was doing something wrong, now that's out of the way I can go ahead and move on! The DIY rigs is amazing! The "bug antenna" flash sticking out might be something cool for my clinic, maybe I can make it into an octopus or cartoon bug figure so the kids will like it. (or hate it, and traumatized).

[Not a Number]

Thank you for clearing up my question! The reason why I got the Yongnuo ring flash was that the seller told me it works fine on Pentax as well. Well, it is working perfectly on K20D, just only on M setting. It got me thinking that I was doing something wrong, now that's out of the way I can go ahead and move on! The DIY rigs is amazing! The "bug antenna" flash sticking out might be something cool for my clinic, maybe I can make it into an octopus or cartoon bug figure so the kids will like it. (or hate it, and traumatized).

The only problem with "antenna" flash is that it's a bit fiddly and might take some time to adjust the light position - not good for patient anxiety - plus they make creaking sounds when you move them. A ladybug motif might work - kids are taught ladybugs are good and they are used to seeing them in "cute" contexts.

You want pretty much a "point and shoot" solution.

A possibility would be the small Pentax AF201FG flash, O or C ring flash bracket and an off-camera cable. The AF201FG is water/dust resistant which is perfect for a dental office. You should be able to find a small diffusion box or sock for the flash or you may not need one for dental applications - there aren't many flat surfaces in the mouth.

I'm not endorsing any of the products below but just using them as examples.
Pentax AF201FG P-TTL Auto Flash 30458
Polaroid O-Ring Dual Flash Bracket PLBRO B&H Photo Video
Vello Off-Camera TTL Flash Cord for Pentax Cameras (3') OCS-P3

It looks like you can take the O bracket apart and use only one half but you can find C-ring brackets too.

Search the forum for reviews on the AF201FG. Unfortunately the flash unit has very limited manual power settings.

Lester Dine in Florida will sell you a complete Nikon or Canon system for dental offices. They used to have Pentax based systems too but dropped Pentax in the digital era. A pity.

Lester A. Dine Product Line | Dinecorp.com

[TER-OR]

The only problems I've had with the 201 is it is pretty slow to recharge. Perhaps in manual mode with reduced output it won't be so bad. You can add a homemade light director to focus the output to you focus zone, which may help.