F-Stop pioneered the idea of removable camera inserts for outdoor photography backpacks. So much so that most photographers universally refer to these padded inserts using F-Stop’s product name – ICU (Internal Camera Units) – even when other brands offer similar products with different names.
The great thing about F-Stop ICUs and the F-Stop backpack system is that you can buy multiple to suit different days of photography. Some days you need to carry all your lenses and a couple of camera cameras. In contrast, other days, you need one camera, and a single camera tucked into a bag holding essential non-photographic gear. With the ICU system, you can configure your bag with one or more inserts and quickly switch them out as needed.
TIP: When the ICUs aren’t in your bag, many photographers, myself included, use them to organize their gear.
In this gear guide, I thought I would round up one of every size ICU currently available and document their size, specifications, possible payloads, and packing configurations in every F-Stop backpack. If you are about to buy an F-Stop pack and aren’t sure which ICUs to buy with it, you’ve come to the right place. Many people also use F-Stop ICUs in non-F-Stop bags, so these photos and specifications should also help with that decision. To show appreciation for the time, money, and effort I put into this guide, please consider using the links on this page to buy your F-Stop bags and ICUs. Thanks!
How to Use This Guide
There are two ways to approach this guide. You can use the detailed photos and specifications of each ICU to narrow the options to the ones that will fit your gear. You can also click through to the section about a specific F-Stop backpack to find out which ICUs or combinations of ICUs fit into that bag. Most people should probably use both sections to clearly understand what they should buy.
Table of Contents
Using Multiple ICUs In Combination
It’s common for photographers to buy multiple ICUs. For example, you might buy one that is the largest available ICU for your bag and a second smaller ICU that accommodates your “fast and light” setup – whatever that may be. This is the most common dual-ICU setup.
Another thing to consider is the simultaneous use of multiple ICUs. Two Small Pro ICUs are, for example, are the same size as a Large Pro ICU. These two ICUs can be stacked with openings facing the bag’s back panel, or “hatch-backed” (F-Stop’s term), where one of the two ICUs faces upwards with contents reachable from the bag’s top opening. You can choose to use both ICUs when you need to carry a lot of camera gear or just one when you need to prioritize pack space for outdoor gear.
The disadvantage with dual ICUs is you lack the single long volume capable of storing longer telephoto lenses. The advantage is that it is a slightly cheaper approach to owning two ICUs in some cases. In our example, two Small Pro ICUs are more affordable than buying a Large Pro and a Small Pro.
Some of the diagrams available from F-Stop show options for multiple ICUs, but be aware that they do not show all possible options. Frankly, there would be too many. Consider the internal dimensions of the bag you have, or the one you are about to purchase, and compare to the combined dimensions of the various available ICUs.
F-Stop ICU Specifications and Photos
In this section, I have photographed every currently available F-Stop ICU and created side-by-side images of common combinations and size choices. Hopefully, this helps you choose perfect combinations or choose between two sizes when you are on the fence. While it’s impossible to photograph every type of camera and lens in each ICU, I have photographed the same camera and lens combinations next to and within each ICU. This should give you a clear sense of each ICU’s size.
Fit Notes
In the specifications, I have noted the bags into which each size of ICU will fit. Below this, I have added a “Best Fit” note. This Best Fit note indicates the most popular combinations of backpack and ICU. For example, the Small Shallow ICU technically fits into the largest Shinn backpack, but it would be swimming in there with no easy way to secure it. Thus, it is not a common combination.
Conversely, the XL ICU technically does fit into the Ajna Duradiamond, but the fit is very tight, and the zippers are hard to close. I wouldn’t go so far as to say they are incompatible because you might have a reason to use that combination, but it would not be my first recommendation for a bag+ICU combination.
Differing Interior Colours?
Eagle-eyed readers might spot that the interior colour of the ICUs appears to have some variation. Examining the labels, it turns out that some ICUs have been made in China, some have been made in Thailand, and some have been made in Vietnam. While the exterior fabric is identical to all three factories, the interior fabric colours vary slightly. This collection of ICUs has been acquired over many years, so the manufacturing location has likely been moved over time. I cannot say with any certainty which is the current manufacturing location or colour, nor does it matter. Aside from the interior colour shift, these are all identical, so this is a minor point.
Micro Tiny ICU
- External Dimensions (in): 4 Depth x 6 Width x 8 Height
- External Dimensions (cm): 10.2 Depth x 15.2 Width x 20.3 Height
- Internal Dimensions (in): 3.25 Depth x 5 Width x 7 Height
- Internal Dimensions (cm): 8.3 Depth x 12.7 Width x 17.8 Height
- Weight: .18 kgs (0.4lbs)
- Fits: Any F-Stop Mountain Series or Ultra-Light Series backpack
The Micro Tiny is the smallest in the ICU family. As demonstrated in the photos, it is precisely half the size of a Small Shallow ICU. This is an excellent size for a mirrorless camera with a single short zoom lens or a wide-aperture prime, plus a couple of spare batteries and an SD card holder. The Micro Tiny ICU is also a perfect size for a single flash with cables, batteries and radio triggers, or a GoPro kit with all the necessary mounts accessories. Although just half the width of any F-Stop pack, it still includes the hook and loop tab to secure it to the inside and prevent it rattling around when your bag isn’t full.
Small Shallow ICU
- External Dimensions (in): 5 Depth x 11.5 Width x 8 Height
- External Dimensions (cm): 12.7 Depth x 29.2 Width x 20.3 Height
- Internal Dimensions (in): 4.5 Depth x 10.5 Width x 7 Height
- Internal Dimensions (cm): 11.4 Depth x 26.7 Width x 17.8 Height
- Weight: .32 kgs (0.71lbs)
- Fits: Any F-Stop Mountain Series or Ultra-Light Series backpack
Small Pro ICU
- External Dimensions (in): 7 Depth x 11.5 Width x 8 Height
- External Dimensions (cm): 17.8 Depth x 29.2 Width x 20.3 Height
- Internal Dimensions (in): 6.5 Depth x 10.5 Width x 7 Height
- Internal Dimensions (cm): 16.5 Depth x 26.7 Width x 17.8 Height
- Weight: 0.42 kgs (0.93lbs)
- Fits: Any F-Stop Mountain Series or Ultra-Light Series backpack
Medium Shallow ICU
- External Dimensions (in): 5 Depth x 11.5 Width x 11 Height
- External Dimensions (cm): 12.7 Depth x 29.2 Width x 27.9 Height
- Internal Dimensions (in): 4.5 Depth x 10.5 Width x 10 Height
- Internal Dimensions (cm): 11.4 Depth x 26.7 Width x 25.4 Height
- Weight: .43 kgs (0.95lbs)
- Fits: Any F-Stop Mountain Series or Ultra-Light Series backpack
- Best Fit: Guru, Kashmir, Loka, Lotus
Medium Slope ICU
- External Dimensions (in): (Top: 5 Depth x 11.5 Width), (Bottom: 7 Depth x 11.5 Width) x 11 Height
- External Dimensions (cm): (Top: 12.7 Depth x 29.2 Width), (Bottom: 17.8 Depth x 29.2 Width) x 27.9 Height
- Internal Dimensions (in): (Top: 4.5 Depth x 10.5 Width), (Bottom: 6.5 Depth x 10.5 Width) x 10 Height
- Internal Dimensions (cm): (Top: 11.4 Depth x 26.7 Width), (Bottom: 16.5 Depth x 26.7 Width) x 25.4 Height
- Weight: .54 kgs (1.2lbs)
- Fits: Any F-Stop Mountain Series or Ultra-Light Series backpack
- Best Fit: Guru, Kashmir, Loka, Lotus, Ajna, Tilopa
Large Pro ICU
- External Dimensions (in): 7 Depth x 11.5 Width x 15 Height
- External Dimensions (cm): 17.8 Depth x 29.2 Width x 38.1 Height
- Internal Dimensions (in): 6.5 Depth x 10.5 Width x 14 Height
- Internal Dimensions (cm): 16.5 Depth x 26.7 Width x 35.6 Height
- Weight: .76 kgs (1.71lbs)
- Fits: Kashmir, Loka, Lotus, Ajna, Tilopa, Sukha, Shinn
- Best Fit: Loka, Lotus, Ajna, Tilopa
The Large Pro ICU can hold two camera bodies with 6-10 additional lenses depending on their size. With its Pro depth, this ICU can hold pro-sized camera bodies or gripped mirrorless or DSLRs. In the example photos, I have two cameras, a Sony 200-600mm, a Sony 70-200mm and three more prime lenses, with one slot remaining for my 1.4x teleconverter.
Extra Large Pro ICU
- External Dimensions (in): 7 Depth x 11.5 Width x 19 Height
- External Dimensions (cm): 17.8 Depth x 29.2 Width x 48.3 Height
- Internal Dimensions (in): 6.5 Depth x 10.5 Width x 18 Height
- Internal Dimensions (cm): 16.5 Depth x 26.7 Width x 45.7 Height
- Weight: .93 kgs (2.06lbs)
- Fits: Loka, Ajna, Tilopa, Sukha, Shinn
- Best Fit: Tilopa, Sukha
Master Cine ICU
- External Dimensions (in): 8.25 Depth x 14 Width x 25.5 Height
- External Dimensions (cm): 20.95 Depth x 35.56 Width x 64.77 Height
- Weight: 2.24 kgs (5 lbs)
- Fits: Shinn
- Best fit: Shinn
The Master Cine ICU is the largest of them all. It is 1.25″ deeper than the XL Pro ICU, 3.5″ wider, and a whopping 6.5″ taller. The added size makes it possible to carry fully rigged cine cameras and multiple super-telephoto prime lenses. The Master Cine ICU can also be opened from the top, allowing you to pull a camera mounted to a long lens from the top of the Shinn backpack. Unsurprisingly, due the enormous size of this ICU, it only fits in the F-Stop Shinn backpack.
Which ICU For Which F-Stop Bag?
Ultra-Light Series
Jump to section using these links.
Guru
F-Stop’s smallest Ultra-Light backpack, the Guru UL, can accommodate the Micro, Small and Medium-sized ICUs in any depth. The photos above give a clear view of the remaining space in the top of the bag when using any of the Small or Medium ICUs. The small size of the zippered back panel opening, and the curvature of the zipper, do slightly limit access to gear when the Medium Slope or Medium Shallow ICUs are used. This can be seen in the third photo, where some of the items in the bag are slightly hidden.
Kashmir
The Kashmir UL is 5L larger in volume than the Guru UL. It has a much larger back panel opening than the Guru (15.7″ vs 11″), this time allowing utterly unobstructed access to the gear inside a Medium Shallow or Medium Slope ICU for the perfect pairing. Of course, if you don’t need to carry that amount of equipment, you can safely use either of the Small ICUs.
Loka
The F-Stop Loka is similar in size to the Ajna pack from the Mountain Series. The recommended ICUs for the Loka are the Small, Medium and Large ICUs. The photos above give you a clear indication of how much additional space there is in the top of the bag with these three ICU sizes. Another great setup is hatch-backing a Medium Slope ICU with a Large Pro ICU, as seen in the photo below.
Mountain Series
Jump to section using these links.
Lotus 4 Core
The Lotus 4 Core is the 4th generation of the F-Stop Lotus pack. Updated to use the latest Duradiamond materials, the Lotus 4 Core is also slightly smaller than the previous Lotus model, now coming in at 28L compared to 32L. For now, F-Stop is continuing to sell the older Lotus (32L), calling it the Lotus Classic.
F-Stop Lotus
The 32L F-Stop Lotus is essentially a shorter version of the Ajna, designed as an option for people with a shorter torso. This shorter height also keeps the bag’s weight well centred on your back, making it an excellent choice for very active pursuits with a camera on your back, such as Mountain Biking.
F-Stop Ajna
The Ajna 37L is F-Stop’s second-best seller after the Tilopa. Although the bag’s overall volume is around 10L less than the Tilopa, much of that difference comes down to the smaller front pocket on the Ajna. This means that the bag’s main compartment is nearly the same size as the Tilopa’s, and as a result, ICUs fit similarly in both of them. Comparing the dimensions provided by F-Stop, both Ajna and Tilopa have an internal height of 20″ and a zippered back panel opening that is 18″.
Dimensions only tell part of the story, though. These bags are not perfectly cubic, and the Ajna’s tighter taper makes the XL ICU a much tighter fit in this bag than it is in the Tilopa. As you can see from my photos, it does fit, but the zippered closure is tighter, and there is zero room left on the top of the bag. As a result, my preferred ICUs for the Ajna are the Medium Slope and the Large Pro.
F-Stop Tilopa
The 50L size of the F-Stop Tilopa is a real sweet spot in the lineup. It is little surprise that this is the most popular bag in the F-Stop lineup, and 15 years after its original launch, this bag has been tweaked to perfection with the newest Duradiamond version.
In my opinion, the two best ICU options for the Tilopa are the Large Pro ICU and the XL Pro ICU if you are carrying a lot of camera gear. Use the smaller ICUs if you have a lot of non-photographic equipment to carry. F-Stop primarily recommends the Large Pro, and this is the one available with the bag if you buy the “essential bundle” package. The 18″ back panel opening of the TIlopa gives you unobstructed access to the contents of a Large Pro ICU.
Those that want to carry 400mm, 600mm and 800mm super-telephoto lenses will need to use the XL Pro ICU. As you can see from my photos, the XL Pro ICU does extend slightly beyond the zippered back panel opening. If you are tucking the end of a large telephoto lens up into that section, this overlap has zero effect on efficiency and usability.
F-Stop Sukha
When the Sukha was initially launched, it came with the Master Tele ICU. This has been discontinued, and the XL Pro ICU is now the recommended pairing. Another great combination is the Large Pro ICU, with a hatch-backed Small Shallow ICU on top for storing a drone or simply as a protected place to keep your lunch.
F-Stop Shinn
Most F-Stop backpacks have an internal width of 11.5″; thus, all Small, Medium, Large and XL ICUs are 11.5″ wide. However, the F-Stop Shinn backpack is 14″ wide, and for this reason, it needed a dedicated ICU called the Master Cine (or Cine Master, depending on which part of the F-Stop website you read).
My recommendation is to use the Master Cine ICU with this bag. Using any of the 11.5″ wide ICUs leaves gaps around the ICU where your other gear gets trapped. If you are going for the colossal capacity of the 80L Shinn pack, you should probably go the whole hog and pair it with the Master Cine ICU. As the name suggests, this is a combination that is perfect for large Cine rigs such as REDs, Sony Cine Alta, and Canon Cinema EOS cameras.
The exception will be explicitly using the Shinn for overnight camping with camera gear. The size of the Shinn makes it one of the few camera bags on the market capable of carrying a tent, sleeping bag and other overnight essentials, alongside a still-substantial amount of camera gear. In this case, choose whichever smaller ICU you need, and pay attention to how you pack gear around it to make sure it is well secured.
Discontinued ICU Models
As far as I know, the ICUs listed below have been discontinued. When writing this guide, I was able to source some of them on third-party websites through Google searches, but it’s anyone’s guess how long that stock will last.
Mico Nano ICU
- External Dimensions (in): 4 Depth x 6 Width x 4 Height
- External Dimensions (cm): 10.2 Depth x 15.2 Width x 10.2 Height
- Fits: Any F-Stop camera bag
Designed for GoPros and point and shoot cameras, the Micro Nano ICU is the smallest model in the ICU lineup. It could easily be argued that these days, the padded F-Stop accessory pouches are a much better solution for protecting that kind of gear.
Master Tele ICU
- External Dimensions (cm): 20.95 Depth x 29.21 Width x 66.04 Height
- External Dimensions (in): 8.25 Depth x 11.5 Width x 26 Height
- Weight: 2.33kg (5lbs)
- Fits: Sukha and Shinn
- Recommended Use: Sukha
Originally developed and launched alongside the first version of the Sukha backpack, the Master Tele ICU can hold up to an 800mm lens with a pro-sized camera body attached. The Master Tele ICU has a zippered front opening and a zippered top panel, which allows you to pull a super-telephoto lens vertically out of the top of the backpack. With the discontinuation of this ICU model, the only ICU with a zippered top panel for vertical extraction is the Master Cine ICU which will not fit in the Sukha. The recommended ICU for the Sukha is now the XL Pro ICU.
I think it’s a shame that this ICU was discontinued. For wildlife photography with big super-telephoto lenses, it’s nice to have the option to draw the lens from the top of the bag. You can still do that if you opt to use the Shinn and the Master Cine ICU, but the Shinn is an overall far bigger pack than most people need. The perfect combination for wildlife photographers with a big 400mm or 600mm lens was the Sukha with the Master Tele ICU.
Medium Pro ICU
The Medium Pro ICU has been discontinued in name only. It has simply become the Medium Slope ICU. I had to think about this one and find some old photos taken over a decade ago to jog my memory. You can see the slope in the design of what was, back then, called the Medium Pro ICU.
Large Slope ICU
- External Dimensions: Top: 127 x 292 x 381mm Bottom: 165 x 292 x 381mm
- Internal Dimensions: Top: 114 x 267 x 356mm Bottom: 165 x 267 x 356mm
- Weight: 0.73KG
An old blog post I wrote tells me that the Large Slope ICU was introduced way back in March 2013. I’m not sure when this model was discontinued, but I don’t think it lasted long in the lineup, with most people preferring to use the Large Pro ICU.
Shimoda Core Units as an Alternative
Shimoda Designs make a similar selection of padded camera inserts for their adventure photography backpacks. The size of their Core Unit camera cubes closely mirrors the F-Stop ICU sizing, and I have known people to mix and match between these brands. If you’d like to find out more about these options, look at my guide to Shimoda Core units.
FAQ
What’s the difference between the Medium Shallow ICU and the Medium Slope ICU?
The main difference between the Medium Shallow and Medium Slope ICUs is that the Slope version can accommodate a pro-sized or gripped camera body, while the Shallow ICU cannot. The Medium Slope ICU is deeper at one end (7’’/17.8cm). The Medium Shallow ICU has a depth of 5’’/12.7 cm across the whole insert.
This is very useful. Thanks.
I agree that it’s a shame that F-Stop dropped the Tele Master. It’s one of the very few cases that will take my Sony 400 2.8 with TC and body attached as well as sunhood extended.
Thanks! And yeah, I actually just managed to get one from a store in Australia and had it shipped to Canada. I got a great deal as it was the last one in stock. As far as I can see, it was the last one available on any web photo store.
Lol. Digidirect?
I’m an Aussie. That’s where I got mine.
Yes, that’s where I found it.
Hi!
I wonder if a Nikon Z 800mm f/6,3 with the lens hood backwards and the “dust cap” on with a Z9 mounted will fit in the Pro XL?
Thanks for a great site and reviews!
I own this combination, so I was able to test it. I can confirm that a Z 800mm+Z9 does fit in the XL ICU. Just.
Thanks for testing! You don’t happen to own the 24-70/2.8 and the 100-400/4,5-5,6 or similar size lenses and can see if they would fit in the ICU at the same time as well?
Thanks again!
I have the 100-400 and the 24-120, so that was a good approximation. Yes, I can get all of that in there with no issues.
Hi Dan, thanks for the reviews. At this point, with the lenses, would one more non-grip body go in as well? You should make a “what’s in my bag” packing video with this stuff!
That’s good to hear, so a 600mm (unattached to body) should be fine too?
Assuming the newer Z 600mm TC? That lens is 17.2″ long, and the ICU is 18″, so yes, that should be fine. I don’t have that lens (at the moment) but I do have a Sony 600mm f/4 and that fits.