Does The Profoto Frost Dome Make A Difference At All?

For years photographers and YouTube commenters have been telling us that in order to get the most out of our Profoto B1 and D1 lights, we need to add the Profoto Frosted Glass Dome to our strobes. Today I test this add-on to see if it makes a difference at all, and the results are surprising.

What does the Profoto Frosted Glass Dome do exactly? When Profoto released their portable all-in-one D1 mono lights, some photographers were surprised that the flash tube was recessed deep within the D1's housing. Photographers who were used to Profoto's Acute and Pro heads argued that by removing the protruding flash tube and glass enclosure, the new D and B series mono lights fail to illuminate many of Profoto's light modifiers evenly. The most cited light modifiers that suffer from this lack of light dispersion are the Profoto Beauty Dish and the larger Profoto Softboxes and Octaboxes. 

I wanted to test this theory for myself so I ordered a frosted dome from B&H Photo and tested it in both our beauty dish as well as our Profoto 3' Octabox. I called up former Miss South Carolina Teen Erica Wilson to stand in for a few test shots, and we created some simple images to compare side by side.

The first test was using the Profoto Beauty Dish. The beauty dish we own is the standard white dish, and because of its design, I was skeptical it would show any difference in light quality with or without the frosted dome. The reason I questioned if the glass dome would make a difference is because all of the light coming out of a beauty dish is either bounced directly into the side bowl, or double reflected after hitting the plate in front of the flash head itself. There are some photographers who like to use the tiny little gap in between the bowl and the plate but for this test I wanted to just place the beauty dish in the more traditional location: about 24-36 inches away from the subject's face. Below are the resulting images. 

As you can clearly see, there is a pretty significant difference in color cast caused by the two glass diffusers. The glass plate was definitely more cool in color when the camera was set to a white balance of 5000k, and the frosted dome looked more warm and natural in color. However, these color differences could easily be adjusted in Lightroom, especially if they are your only light source. There may be a slight increase in exposure in the glass dome image but it appears to be less than a 1/3 of a stop in light. When you compare the shadows — which is where the biggest difference should appear — they look almost identical to my eyes. There might be a slightly softer light with the frosted dome as seen in some of the skin texture, but for an image like this, both photos would probably go through extensive retouching before being published. Other features like the catch light shape, light falloff, and specularity all look similar enough that I would not be upset shooting either one of these setups. 

I'm curious to know what you guys think though. Feel free to vote in the poll below if you agree or disagree with my assessment on this set of beauty dish photos.

Next up was the 3' Octabox. I was most interested in this test because it would seem more likely that the recessed flash tube and flat glass plate combination would probably cause a more defined hot spot in the middle of a large softbox than the Profoto B1 strobe outfitted with the frosted glass dome. Since Profoto has discontinued making their huge 7' octabox, we decided to use the 3' Octabox because, well, we don't own the 5' Octabox they make. The big question with this test was "will the frosted dome help illuminate the octabox more evenly, and therefore create a more balanced photograph?" Let's look at the resulting images below.

This test does show some slight differences in image quality but it was definitely not as big of a difference as I would have thought. You can clearly see that the glass plate has a slightly hotter exposure on Erica's face compared to the frosted dome. As we will see in the photos below, this is because there is a slightly larger hot spot in the middle of the octabox which will contribute to more light output in the middle of the modifier. How much of a difference is this? To my eyes it looks about 1/3 to 2/3s of a stop of light. It is definitely measurable and noticeable but I think I might prefer the slight increase in exposure when comparing the two images. 

Strangely, the shadows in the frosted dome image appear to be filled in ever so slightly especially around Erica's nose. It's subtle and it may be splitting hairs, but you can definitely see it when the images are stacked in Photoshop. However, much like the beauty dish example, many of the other nuances like light falloff, overall scene exposure, specular highlights, catch lights, and shadow to highlight transitions are pretty similar at least to me. 

To help illustrate the differences in exposure across the face of the octabox, I also took a photo showing the front of each light modifier. For these exposures, I wanted the smallest hint of blown highlights so that we could see exactly where the flash was firing the most amount of light. As you can see in the images below, the glass plate does have a significantly larger blown highlight distribution in the middle of the octabox when compared to the glass dome. What's interesting to me though is that even with the recessed flash tube, the B1 straight out of the box is still able to produce some blown highlights around the edge of the light modifier. This is probably caused by the internal baffles in the octabox, but it does prove that some of the same light intensity found in the middle of the octabox is able to reach the outer most edge of the octabox. It's safe to say that anything directly in front of this hot spot will get a slightly brighter exposure, but once you move out towards the edge of the softbox, the effect is negligible in my opinion. 

What do you think about these two images? Can you say one of these examples is definitely better than the other?

Conclusion

So at the end of the day, this wasn't the most scientific test, but for me it represented a real world situation well enough that I can say — without a shadow of a doubt — that I personally do not see enough of a difference to justify buying and installing the frosted glass domes on my B1 and D1 mono lights. Installing these domes is kind of a pain and I have no doubt with a lot of use I would most definitely break a few of these throughout the year. It would be great to simply install these frosted domes and keep them on my lights permanently but they don't work with Profoto's grid system and they also take up much more space when packing in your grip cases and camera bags. Also, did I mention, they are $183 a pop?!

There might be some very specific situations where the frosted glass dome makes a big difference, and if so, I'd love to hear your experiences in the comments below. As much as I love Profoto, and they are by far my favorite photography lighting system, I tend to believe this specific light shaping tool might be more like snake oil than something that completely changes the quality of light coming out of your strobe heads. This was a test I have wanted to do for a long time and I'm glad I finally set some time aside to see if all the snarky YouTube commenters were right. That being said, the final thing I will leave you with is a link to all the positive comments on the frosted glass dome sales page on BH. I am clearly in the minority when it comes to improvement this light modifier makes to your strobes.