topic Re: RF 28-70 F2 IS STM f-stop range question in EF & RF Lenses

RF 28-70 F2 IS STM f-stop range question

Cantrell — Wed, 26 Nov 2025 14:07:49 GMT

All,

Considering purchasing the above lens. Because there is not a range in F stops. The F2 is the F stop at 28mm as well as 70mm. Is that correct?

Thank you in advance for your response.

Re: EOS R6M2 with a RF 28-70 F2 IS STM

Anonymous — Wed, 26 Nov 2025 08:37:35 GMT

Correct, F-stop does not change while zooming, whether set at f/2 or f/22.

Re: EOS R6M2 with a RF 28-70 F2 IS STM

shadowsports — Wed, 26 Nov 2025 09:40:11 GMT

Greetings.

This is a constant aperture lens. meaning it can be set at f2 (wide open) throughout the entire focal range. It's a top performing lens but note it's big and heavy. It takes a 95 mm lens filter and is 103 mm overall. It weighs 3.15 lbs. It's definitely on the chunky side 🙂.

Re: EOS R6M2 with a RF 28-70 F2 IS STM

Cantrell — Wed, 26 Nov 2025 09:55:53 GMT

pcs1,

Thank you for your response. Happy Thanksgiving.

Reese

Re: EOS R6M2 with a RF 28-70 F2 IS STM

Cantrell — Wed, 26 Nov 2025 09:58:16 GMT

Rick,

Thank you for your response. Probably should have bought this lens instead of some others that I have purchased since buying the R6M2. Happy Thanksgiving.

Reese

Re: EOS R6M2 with a RF 28-70 F2 IS STM

shadowsports — Wed, 26 Nov 2025 12:47:02 GMT

When it comes to lenses, there's always one more. 😂

Happy holidays to you and your family also.

Re: RF 28-70 F2 IS STM f-stop range question

ebiggs1 — Wed, 26 Nov 2025 15:27:20 GMT

"Probably should have bought this lens instead of some others ....."

No, not at all. He who has the most lenses wins! At least that's my motto. 😁 And I have a brilliant start. Seriously, I always try to find and buy zooms that are constant aperture. The only lens that I have, I use regularly, that is not a constant aperture is my beloved Sigma 150-600mm f/5-6.3 DG DN OS Sports Lens. All my Canon big three are constant aperture zooms.

Re: EOS R6M2 with a RF 28-70 F2 IS STM

Cantrell — Wed, 26 Nov 2025 15:32:50 GMT

Rick,

Thank you for your holiday wishes.I will tell my wife that you told me that it was okay to buy that lens. LOL!

Reese

Re: RF 28-70 F2 IS STM f-stop range question

Cantrell — Wed, 26 Nov 2025 15:43:30 GMT

ebiggs1,

Thank you for your comments about the lenses with constant aperture. I have been paying more attention to the F stop value of the lens. When I first started buying lens for the R6M2 I just looked at the range of the zoom, but after posting questions on this board and getting responses which stressed the importance of the F stop I have changed my philosophy on purchasing lens. Now the first feature that I look at is the F stop.

Happy Thanksgiving.

Reese

Re: RF 28-70 F2 IS STM f-stop range question

ebiggs1 — Wed, 26 Nov 2025 16:22:24 GMT

"Now the first feature that I look at is the F stop."

It always seems to be the more costly models. 🙄

Re: EOS R6M2 with a RF 28-70 F2 IS STM

p4pictures — Wed, 26 Nov 2025 17:32:02 GMT

The photography rules apply here…

Q: How many lenses do you need?

A: N + 1

Where N is the number of lenses you already own 🙂

Re: EOS R6M2 with a RF 28-70 F2 IS STM

Cantrell — Wed, 26 Nov 2025 18:54:55 GMT

Brian,

Formula means that you can always use one more lens. I do not know if my wife would agree.

Reese

Re: RF 28-70 F2 IS STM f-stop range question

vantage — Thu, 27 Nov 2025 00:37:29 GMT

Fully extended with the hood it's 8.5" long and 3.60 lbs. but it's easy to balance. IQ is tremendous. Full review at

https://www.digitalcameraworld.com/reviews/canon-rf-28-70mm-f2l-usm-review

You can always buy used and save some $.

https://www.cpricewatch.com/product/06707/Canon-RF-28-70mm-F2-L-USM-price.html

Re: RF 28-70 F2 IS STM f-stop range question

Cantrell — Thu, 27 Nov 2025 02:14:47 GMT

vantage,

Thank you for your comments. Great suggestion on buying used. That is probably the only way that I would buy this lens. On Facebook Market there is a new one for sale in a town 120 miles from us. The owner is discounting this lens by $500.

Happy Thanksgiving.

Reese

Re: RF 28-70 F2 IS STM f-stop range question

ebiggs1 — Thu, 27 Nov 2025 15:13:14 GMT

"IQ is tremendous."

You own this lens? Or, do you just read about it?

Re: RF 28-70 F2 IS STM f-stop range question

vantage — Thu, 27 Nov 2025 16:38:52 GMT

I own it.

Why do you ask?

Re: RF 28-70 F2 IS STM f-stop range question

ebiggs1 — Fri, 28 Nov 2025 21:33:12 GMT

Because this forum and the ole inner web as well is full of "readers" who are not owners that actually use the gear they tout or bad mouth so freely. Glad you are able to give hands on experience.

Re: RF 28-70 F2 IS STM f-stop range question

Cantrell — Fri, 28 Nov 2025 23:57:56 GMT

ebiggs1,

Thank you for your comments. Looking in the used market for either the RF24-70mm F2.8 or RF28-70mm F2.8. Very few RF24-70s out there, but more of the RF28-70mms. Numerous EF lenses are out there. The only lenses that I bought new was the RF100-400mm which I bought with the R10 that I owned and the RF 24-240mm that I bought when I purchased my R6M2.

Reese

Re: RF 28-70 F2 IS STM f-stop range question

vantage — Sat, 29 Nov 2025 00:07:49 GMT

Another strategy is to rent first to see if the RF 28-70 F2 IS STM works for you. Better than having a $3000 US case of buyer's remorse.

If you buy the rental, some rental places will discount the purchase price because it's a used lens. They also deduct the rental fee from their purchase price.

Re: RF 28-70 F2 IS STM f-stop range question

Cantrell — Sat, 29 Nov 2025 00:36:50 GMT

Vantage,

Great suggestion. Thank you for mentioning. Buyers remorse is not good.

Reese