topic Thoughts on RF 100-400mm F5.6-8 IS USM? in Gear Guide

Thoughts on RF 100-400mm F5.6-8 IS USM?

justadude — Tue, 06 Jan 2026 23:17:51 GMT

Hey guys, this question goes out to anyone that owns, or has used the RF 100-400mm f/5.6-8 IS USM lens.

For the first time in my roughly 50 years of photography, I am playing around with a bit of wildlife photography. Currently using the EF 70-200mm f/2.8, which is ok for unclose, but I'd like a bit more reach. At the same time, I'm not sure how much I will like doing this after six months, so I want to go for inexpensive for now. I don't think it's a boredom passing fad thing for me, but who knows.

What I would like to know is just opinions from actual users of this lens on the image quality. I'm fine with the aperture, and know I need plenty of light, and higher ISO - so IQ is my only concern. While I don't expect the IQ to be up there with the RF 100-500mm f/4.5-7.1 L, on the other hand I'm hoping it's not down there with cheap EF era kit lenses.

So what can you tell me?

Re: Thoughts on RF 100-400mm F5.6-8 IS USM?

March411 — Wed, 07 Jan 2026 00:37:26 GMT

Gary, I can say that some will disagree but I use my RF100-400 frequently for wildlife and overall I'm real pleased with the results. It does struggle with low light but when that becomes a challenge I mount it on my R6 MkII. The focus is fast and the hit rate high unless you are in very low light @400mm, f8 can be a kick in the butt.

This lens is an easily an all day carry; small and light weight, great for hiking. I'm waiting for the R7 MkII to hit the shelves and once I have one the RF100-400mm has probably found a long term home. For the price it can't be beat.

All that being said, it will at times make you angry because it doesn't have the range, especially for birds in flight. You may have seen these before but they are worth posting again. Some are SOOC and others have a crop and some denoise but overall worth the price.

Re: Thoughts on RF 100-400mm F5.6-8 IS USM?

justadude — Wed, 07 Jan 2026 03:12:55 GMT

That is pretty impressive image quality at this price point! This is what I was hoping to see.

I have shot with longer lenses (many years back) so I am aware that 400mm isn’t often enough of a focal length for wildlife, but since I’m not really sure if I will continue with this type of photography, I thought it would be a good focal length (and price) to start. Besides, a majority of my work is between 15mm to 50mm (other than sports with my 70-200mm), so using a lens between 100-400mm is going to be an adjustment where I will often feel too close.

Thank you for the feedback, Marc.

Re: Thoughts on RF 100-400mm F5.6-8 IS USM?

SignifDigits — Wed, 07 Jan 2026 21:53:14 GMT

I will second what Marc said. I bought mine in January 2022, and owned it until this year. I liked it and think it's a great value. And it's only gone up $100 over the past 4 years.

When I could afford it I switched to the Canon RF 200-800mm f/6.3-9 IS USM and like it a lot, but it's over double the price even refurbished (as I got mine). I think the image quality and reach are a bargain at that price, though.

I do not recommend pairing the 100-400mm, as I tried, with a 2x extender. I hear people have better results with the 1.4x extender, but I cannot speak to that. Perhaps others here have had a good experience with that, but I would personally only use it without an extender. I'm mentioning that in case a 2x extender might be something you are considering.

I think Marc could use a pinhole camera and get great photos because he has great photography skills.

Re: Thoughts on RF 100-400mm F5.6-8 IS USM?

Cantrell — Wed, 07 Jan 2026 22:19:09 GMT

justadude,

When I bought my R10 the first lens I purchase was the RF100-400mm. I have used for taking pictures of birds flying and it did find. Also, took pictures of eagles in Alaska.

I sold my R10 and purchased a R6M2 in July 25. Used the RF 100-400mm with that camera. It has done well. Used this lens with the 1.4 extender and I was happy with the result.

Reese

Re: Thoughts on RF 100-400mm F5.6-8 IS USM?

justadude — Wed, 07 Jan 2026 23:24:04 GMT

Thank you for the feedback! I did look at a few of the better lenses (RF 200-800mm, RF 100-500mm, and the excellent Sigma 150-600mm) but before I lay down that much cash I want to give it a year with something a bit more budget friendly... so it's good hearing about your experience with it.

As for the extenders, I've never been impressed with any extender over the past five decades, and after all this time, I don't see that changing.

Marc does some very nice photography!

Re: Thoughts on RF 100-400mm F5.6-8 IS USM?

justadude — Wed, 07 Jan 2026 23:26:14 GMT

Thank you Reese! It's nice hearing more positive opinions from people who have owned this lens.

That's what I like about this forum. Honest replies, and none of the BS that we see in the Facebook Canon groups where too many people spout off often false advice about gear they never used.

Re: Thoughts on RF 100-400mm F5.6-8 IS USM?

Cantrell — Thu, 08 Jan 2026 00:01:28 GMT

Justadude,

I had the RF100-500mm for a short period time. It is heavier than the RF100-400MM, but it has a much longer reach. I used for about 20 shots and did not feel that I had a need for that much reach and weight. If I need that much reach I will put the Canon 1.4 extender on with the RF100-400mm. Happy with that combo.

The money that I got for selling the RF100-500mm went to purchasing a used RF15-35mm and a 50mm lens. Gives two lenses that I can use more often.

Reese

Re: Thoughts on RF 100-400mm F5.6-8 IS USM?

justadude — Thu, 08 Jan 2026 15:08:55 GMT

If I do enjoy wildlife photography with the RF 100-400mm for roughly a year, I'm pretty certain that I will trade in the 100-400mm and move up to the RF 100-500mm. Sure, it's heavier, but it's actually lighter than my EF 70-200mm f/2.8 plus the adapter by about a half pound... and I am very used to hauling that EF lens around for sometimes 10 hours at some events. Then again, the RF 200-800mm looks tempting as well - lol.

Personally, I've never been a fan of extenders. I know many people love them, and that's fine. They are just not for me.

I do see your point for you selling the 100-500mm for the other two since you bought the 100-400mm. I'd be lost without lenses in those focal lengths. I use my 15mm, 35mm, 50mm, 17-40mm (favorite, and most used), and 24-105mm lenses far more often than my 70-200mm... but it's just recently that 200mm is not enough for what I'm trying to do.

Re: Thoughts on RF 100-400mm F5.6-8 IS USM?

Cantrell — Thu, 08 Jan 2026 16:02:19 GMT

Gary,

Which EF lenses do you own? Is the 70-200mm an EF? I have cousins that live in the Detroit area. Best wishes on your search.

Reese

Re: Thoughts on RF 100-400mm F5.6-8 IS USM?

justadude — Thu, 08 Jan 2026 20:16:20 GMT

It's the original version of the EF 70-200mm f/2.8 L from 1996 - the old heavy boat anchor version. I won't give this one up until it dies. Such a great lens!

I haven't been around Detroit in probably 10 years - and that was just in the downtown area (which I like). I tend to mostly stick to the west side of our state, or the upper peninsula if I'm traveling around on day or weekend trips. We are fortunate to have the beautiful area of the state.

Re: Thoughts on RF 100-400mm F5.6-8 IS USM?

justadude — Tue, 13 Jan 2026 16:00:34 GMT

Marc, it was mostly your feedback and sample images that helped me make the final decision. I purchased the lens from our local camera store on Saturday, went on a couple of hikes to do some initial testing, and I am very impressed with the image quality at this price point. The weight was pretty surprising as well. I mean, I knew it was light, but to walk around with this for five miles in the snow, it really felt feather light on the R6m2 at the end of the hike. I was concerned at first about the lack of a tripod foot, but this is balanced so nicely that I can see why it doesn't need one.

My only gripe is the lack of a lens hood (which I knew in advance). Just about every manufacturer out there gives you a lens hood with the purchase of the lens. I would be happier paying the added cost of the hood being in the box with the lens, instead of the inconvenience of buying one separately. The camera store had these on back order, so I had to order the hood from B&H, and now I wait a week.

Anyway, it wasn't a great place to shoot on either of these hikes, but I simply wanted fresh air and exercise, and take some quick test shots to see what the lens could do. Three random images attached.

Re: Thoughts on RF 100-400mm F5.6-8 IS USM?

March411 — Tue, 13 Jan 2026 16:22:57 GMT

Great frames Gary, all three have excellent color and sharpness but I really like the last one of the pods. Excellent composition and real nice bokeh with a lens some scoff at for wildlife.

On the R6MkII it's so nicely balanced and the IS/IBIS will allow you to hand hold at some incredibly slow shutter speeds.

The whole Canon lens hood is so odd, why they don't add one is so weird. I've bought a couple lenses from BH Photo and they come with a hood and case.

Really glad it worked out!

Re: Thoughts on RF 100-400mm F5.6-8 IS USM?

Cantrell — Tue, 13 Jan 2026 16:34:38 GMT

Gary,

Great shots.

Reese

Re: Thoughts on RF 100-400mm F5.6-8 IS USM?

justadude — Tue, 13 Jan 2026 19:43:23 GMT

Thanks, Marc!

I was pleasantly surprised at the bokeh on the last one considering it was at f/8. Actually, same with the Cardinal considering how close the other branches were. I think this lens will get a lot of use.

I think the only Canon lenses that I've ever bought that come with hoods are the L series lenses. With my Pentax gear, even the inexpensive lenses come with hoods. I've heard the same from my Sony and Nikon friends. I've also noticed the same for the third party lenses I buy for Canon cameras. It seems like such a little thing to keep customers happy.

Re: Thoughts on RF 100-400mm F5.6-8 IS USM?

justadude — Tue, 13 Jan 2026 19:43:45 GMT

Thank you, Reese!