Sigma 150-600 C or RF 100-400

[amonmi2]

For background I have a r100 with a Ef 75-300 and am looking to upgrade to a r5 or r6mkii. Most likely a r5. I already have an adapter for rf to Ef but am wondering if the 150-600 or rf 100-400 is better for plane spotting. I use a lot of zoom which is a pull for the 600 mm. Focus is t a big thing as long as it’s pretty quick for what the camera can do. But my main thing is quality. Mainly in sharpness and low chromatic aberration.

[shadowsports]

Greetings,

The R100 is Canon's entry level mirrorless body.  As you may have discovered, it is extremely limited from a feature standpoint.  It was designed primarily for mobile device users who wanted interchangeable lens capability.

The EF75-300 is an entry-level optic and not one of Canon's best endeavors.  It's optical quality is okay, and it lacks IS.  

Either of the body's you are considering would be excellent.  May I ask what you do with your pictures after you take them?  Viewing on your computer, sharing on social media, making large prints?  While the R6 Mark II has the same resolution as your R100, you will notice an immediate difference in image quality if you're using higher quality lenses.  If you want the added resolution then the R5 is the answer.  

Of the two lenses you're considering, I own both.  The RF100-400 is a medium range zoom.  If you were right on the other side of the fence next to the runway, it would probably do fine.  At greater distance, or shooting planes airborne in the sky, It might feel limiting In some cases.  I purchased the RF100-400 to replace an EF70-300 USM II I used for travel, hiking and day trips.  It offers a great value in range, clarity and performance at its price point.

If you're going to buy an EF mount lens, I would only buy used.  Many people use the sigma 150-600c for wildlife and air shows. It's extremely popular.  It will perform well adapted on the R6mkII or R5.

Two other lenses you may want to consider depending on your budget.

The RF100-500, All I will say is it's one of my prized lenses, offering wow factor.

The RF200-800. I'm waiting for this to be delivered, but there are plenty of posts from others here showcasing the quality and performance of this lens.  It's less money than the 100-500 and will provide all of the reach you'll ever need.  

[Tintype_18]

Lots of choices and a range of budget prices. Consider refurbished to factory specs. Members can direct you to sources as Canon, B&H, etc.

FWIW, I have the Sigma 150-600 for my T7. Good lens but a bit heavy, requiring a monopod or tripod. Now...you have "committed" to some photos for the community.

[Tronhard]

Hi and welcome:

If you are going to do aircraft photography, I would suggest one of the following, but the decision will really depend on your working distance to the aircraft and the output you intend to create, as my respected colleague Rick has mentioned.  All super tele zooms are reasonably heavy, but depending on your physical condition you may be able to shoot hand-held with them or, if not, use a monopod.
Sigma 150-600c:   The range is good, and definitely you will appreciate the much greater reach on an R5 FF body.
Sigma 60-600s:   This is more expensive, but the focal range is massive and the results are excellent.

Both lenses will perform well on the R5 or R6II body and both have good image stabilization and excellent image performance.  As a general comment, chromatic aberration will be corrected in post in most software, but these lenses, as is not unusual for pure telephotos do not exhibit any significant CA.   You may be more used to that as an issue with the EF75-300, which is not a great lens in many respects.  The difference will be massive.

RF 100-500L:  This lens is a premium lens, and built for the likes of the R5 and R6 series.  It has dual nano USM motors that drive its focus incredibly fast and it produces tack sharp images.
RF 200-800:  While not an L lens, the optics are, nevertheless, absolutely excellent and the focal range is unmatched.

[ebiggs1]

If you are considering one of the super zooms get the Tamron SP 150-600mm f/5-6.3 Di VC USD G2.

The best one on the market today isn't either one of the Sigma offerings, S or the C, and if I was to buy today it would  be the Tamron SP 150-600mm f/5-6.3 Di VC USD G2. It's just a tad bit better than any other super zoom currently available. And if you are not going Canon you might as well get the best you can and that is the Tammy.  This includes the newest Sigma 60-600mm super zoom., too.

I agree with Rick, 400mm is probably going to be too short at times, most for the time, for aircraft. It is better to have extra FL and not need it than to not have FL and need it. Canon does have some inexpensive prime lenses in the 600mm and even 800mm FL but they are very slow and of course you can't zoom.

[Waddizzle]

Welcome to the Canon Community.

The upgrade from the R100 to the R5 Series or R6 Series is a huge leap in camera technology.  Do you have a budget?

Given the choices you have listed, I think the best bang for the buck is the R6ii with the RF 100-500mm.  I strongly advise against making a significant investment in a EF mount DSLR lens.  The DSLR lenses will perform at least as well on an R Series body as they would on a DSLR, if not noticeably better.  The L-Series RF lenses are cut above that standard.

[ebiggs1]

" I strongly advise against making a significant investment in a EF mount DSLR lens. "

I tend to agree but only to a point. These lenses especially the Tamron G2 series provide f antastic results even on R series cameras. There is no reason they will not do so for a long time. It's best to get the lens that does the job for you and not worry about whether it is EF or RF. The EF to RF adapter, although I don't like adapters, seems to be innocuous and works very well.