This topic has been one of my most requested; I think the idea of shooting film with flash can be a bit intimidating, but let's break down a few simple tricks that I love to use.
Direct Flash
Direct flash can be incredibly useful for two reasons: it allows you to shoot film at much higher f-stops at lower light and it's relatively easy and consistent to get the hang of. Let's look at a few ways that I use direct flash in my film work:
With the Holga
This is one of the most common ways that I shoot film with flash (and one of the easiest). The key is to ensure that your flash is giving off enough light to keep up with the F/8 or F/11 aperture. I highly recommend getting this speed lite for your Holga, and ensuring that you're shooting at full power (or almost full power) at night. Grab a Holga here.
* Want to learn more about how I use the Holga in my work? Grab my Holga Guide here.
The image above was shot with the Holga, Portra 400 film, and this flash.
With My 35mm Camera
In a similar way, I shoot my Leica at night (or in darker spaces) with direct flash. I typically keep my shutter speed at 1/30th or 1/60th (remember, you can rely on the flash to freeze your subject in frame), then I shoot my aperture around F/8-F/11 (similar to how the Holga shoots).
Depending on what 35mm camera you use, the exact speed lite or flash you can use may change. I personally use my Contax G2 flash on either my Contax G2 or my Leica camera (works with both well). I prefer to shoot TriX 400 mostly when shooting at night with direct flash.
The image above with shot with my Leica camera, TriX film, and this flash.
Constant Lighting
If you're reluctant to try a speed lite at first, I highly recommend trying to use video/constant lights for your film work. It's a bit less intimidating as you can see exactly what the lighting looks like as it's happening. If you're looking for a small, budget-friendly light to start with, I highly recommend getting this light.
And if you're looking to add 1 or more off camera constant lights to your receptions, I can't recommend this light enough. This light offers multiple color temps, extremely adjustable power (the lowest setting is very low, brightest is extremely bright), and can be used with a battery, rather than an outlet.
Image of bride above shot with Contax 645, Kodak Portra 400, and this video light.
Metering with Your Video Light
Don't be intimidated by metering when you're working with a video light. You'll want to act as-if your video light is just another sun/source of light. I typically meter bulb in and not pointed directly back into the light (somewhere in-between shadows and highlights of my subject). Once you get a reading, you can typically use that reading over and over again until the light changes or moves drastically.
Complimented with My Digital Work
I love to find ways to compliment my direct flash film work with my digital work. One of my favorite ways is to shoot my digital camera as if it's my Holga. I set my aperture to around F/8 or higher, then pop on a flash and shoot directly towards my subject. If you're unhappy with the look this is giving you, try messing around with Manual flash (flash strength and flash zoom).
If you want to play further, try getting one of these flash modifiers: MagMod Snoot, MagMod MagGrid, or the Gary Fong Diffuser (I typically shoot this directly up, without the top on).
Pro Tip: Try dragging your shutter just a bit with your flash to let in those ambient lights.
Image above shot with the Canon R5, MagMod Snoot, and the Canon 600 speed lite.
Contax 645 Flash
Consider grabbing a Contax flash for your Contax 645. I have only recently began shooting my Contax 645 with bounced or direct flash, but I'm already loving it. Pro Tip: Don't use other, more modern flashes on your Contax645, as it's not built to hold them and may cause damage to your camera.
Image above shot with Contax645 and Contax645 Flash, along with TriX film.
What to Read Next: How I Shot That (Holga at Night)