(newbie) Need some help getting a ring flash to work

[chucklepie]

Hello,
I need a little guidance

My set is a D3300, a 105mm f2.8 G AF-S VR IF ED Micro Nikkor, along with a Kenro KFL201N ring flash.

I am completely new and bought it for, mainly, dental photography. I'm a complete beginner so only a few days into learning to use the camera but understand the basics.

The problem is no matter what I do when I use the flash everything is so over-exposed the images are white. Watching videos I can see using auto/macro with the flash on TTL it kind of 'just works'. I believe the flash is i-TTL compatible.

But the only way I have found an image that is barely usable is if I set the flash on manual, put it on its lowest setting of 1/128 and have iso down to 100. At these settings auto focus doesn't work and I have to manually focus for close up. I've tried all the various flash modes on the camera too.

I'm obviously doing something very wrong.

Happy to post photos (but they're mostly all white) and my settings from my various trials.

Thanks for any help.

 

[Needa]

Welcome!

How I would approach the problem is:
Make sure the camera is far enough back from the subject to auto focus reliably. I would use single point focus. Preferably tripod mounted.
Be sure no exposure or flash compensation are set. A reset from the menu might be worth a try.
Put the camera in manual mode with ISO set to 100 and the aperture set to F8 no flash, in a normally illuminated room this should result in a dark image.
At this point try the flash in manual mode and TTL to see results.

Setting the camera to manual and the flash to manual at the same working distance will allow repeatable results for different subjects.

Posting an image with EXIF is helpful when trouble shooting problems on the internet,

 

[Clovishound]

I do a lot of macro work. I use flash for the majority of it. I use a different setup, a normal shoe mounted flash with a macro diffuser, but the concepts are the same.

My guess from your description, is that you are using a large aperture. You will probably need to stop down to F/11 or F/16, since you are so close to your subject, and the teeth will reflect a lot of light.

I do almost all my flash macro work with both the camera and flash in manual mode. I set the shutter speed to 1/200 sec or slower to sync with the flash. I then set my aperture to F/16. I start out at 1/4 power with my flash setup, which will deliver a different amount of light than yours, and I am normally in the ballpark. I check my first exposure, and if it's too dark, I increase power. If it's too light, I decrease the power. I do this until I get an acceptable exposure. Once you get a good exposure setup you probably won't have to adjust much as the distance from the flash and reflectance of the subject likely won't change much.

A side benefit of a small aperture is that you will have greater depth of field, ie more of the subject will be in focus. Shooting closeup results in a rather narrow band in focus, so stopping down helps with that. There are other ways to increase depth of field, but those are best left for another day.

 

[BF Hammer]

I think I see 2 problems here. First is over-exposing, the other is the difficulty with making autofocus work. I don't believe they are related (entirely).

I am looking at the Kenro web site at that particular flash. It does say TTL, but that is not actually iTTL. Could be a misuse of the term in translation, but iTTL puts out a pre-flash before main exposure so the auto-exposure can measure the power needed. TTL mode just keeps the light on until exposure is judged correct and then it shuts off. The shutter stays open for the full 1/200 or 1/250 the entire time in either case (this is not a universal thing for all cameras). This is why old 1990s flash units don't work auto-mode on DSLR camera bodies, no pre-flash for iTTL.

I suspect it is really supposed to say iTTL on the flash specs, but I don't know. Assuming that it is, then you will have to dive into the manual for the flash. And I think you should do that anyhow for the next problem.

The reason you cannot autofocus is you are not using the modeling light. The D3300 has a built in LED light on the camera body that is used for autofocus assist in low light. It can be turned on or off in the setup menu, it should be A9 of the setup menu. But I only found the D3500 manual online, but I expect it will be there on the D3300. https://onlinemanual.nikonimglib.com/d3500/en/14_menu_02_07.html

However it looks like the ring flash is big enough to block that AF illuminator from the subject. For that reason there are LED modeling lights in the ring light (read that on the Kenro web page) which might not be working when you do your half-press of the shutter release to acquire focus. You will have to read the manual for the ring light to look why that is not happening. The modeling lights at macro distance would be perfectly bright enough for the autofocus sensor to operate.

Also to throw in the mix is the minimum focus distance spec. For that 105mm lens, you must be at least 12 inches away from the subject, and best to be a bit further back than that.