petrochemist Loc: UK

I have several very long lenses that are fixed aperture. They are generally slower than I'd like so I'm not concerned about not being able to close them down further. They are a long way from the quality of the best lenses of similar focal length, but they didn't cost more than my car. Results they produce can still be good.

I also have some more normal focal length lenses without an iris, such as my 50mm/1.2, an 18mm/2.8 & a tiny 24mm/2.8. All of these have given qute a few decent images, but the lack of aperture control can be more of a hinderance. With the 50/1.2 I ended up adding a few homemade paper apertures to hold on the front to enable it to be used during the day (1/8000s at minium ISO was heavily over exposed).

Not all of the apertureless lenses I've tried have been worthwhile, they've all been relatively cheap (several were free) and often offer capabilities I simply couldn't afford in a normal variable aperture lens. The total cost of all of them has easily been worth it for just a few of the more impressive ones. Still in general I prefer to have lenses with control of the aperture.

I suppose digiscoping & shooting thropugh a microscope could also be classed as fixed aperture lenses. Some of the results from such systems can be very impessive but I've never tried one of the budget telescopes that are sold converted to ultra telephoto lenses. I'll stick to systems that are honest about what they are.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

A hint is to get close to your subject and have the background far away. That way you can get separation from the background using an f11 lens.
here is the link to B&H on that lens, you can read the reviews for yourself and look at some of the images that users have posted, many have out of focus backgrounds.
Life is full of tradeoffs, it's how you deal with them that makes the difference. F11 lens, not so expensive, f4 lens, expensive. It's how you use the lens that will make the difference. Good luck and keep on shooting until the end.
https://www.bhphotovideo.com/c/product/1573779-REG/canon_rf_800mm_f_11_is.html/reviews?sts=pi&pim=Y

tjkraemer1 Loc: Maryland

This photo was taken with the 800mm F11 on my R5. I believe this should answer your question as to weather or not you can get acceptable photos with a fixed aperture lens. I have been exceptionally pleased with the results from this combo.

(Download)

genocolo Loc: Vail and Gasparilla Island

Wow!

tjkraemer1 Loc: Maryland

Here a a couple more with the same combo,

(Download)

agillot

the fix F stop would not scare me .i use a old nikkor 800 mm that start at f8 , so i only use f8 or 11 for birds .never been higher than f11 .i use speed and iso .i try not to go much past 500 iso if i can .the D300 is not that great at 2000 iso .i have a cheap vivitar 500 / 1000 with fixed F11 that is ok .you have to think depth of field , it is narrow on a 800 .so a higher f stop will help .

jbmauser Loc: Roanoke, VA

You have asked two questions. I know nothing about the lens in questions but to your first question about fixed aperture lenses. I would test the new camera to see how high your ISO can be set before you find the grain unacceptable. Long telephotos and wildlife require higher shutter speeds so you camera will need to rely on higher ISO performance if you have a fixed f11 lens of any manufacture. Some cameras can produce acceptable images at crazy high ISO. Your sensor performance will tell you what your options are.

Jimmy T Loc: Virginia

JRiepe Loc: Southern Illinois

I learned something today. Didn't know there were lenes with only one aperture setting.

tcthome Loc: NJ

tcthome Loc: NJ

Probably get usable photos at 20.000 ISO with the R5 &R6 cameras.

imagemeister Loc: mid east Florida

I share your concerns and skepticism ! ......I would really have to say you should rent one and see if it meets your needs.......

Most reviews are really positive - but their parameters may be different from mine and yours ....
.

CHG_CANON Loc: the Windy City

The RF 600mm and 800mm fixed aperture lenses will change how we think about mirrorless, how we think about photography, how we think about life.

tjkraemer1 Loc: Maryland

I love your whit and humor Paul.

CHG_CANON Loc: the Windy City

That eagle and fish is wonderful! Like most things in life, a picture always beats a thousand cluckings around the henhouse.

Life changing, probably. Perfect, probably not. The horizonal orientation of these two lenses and their mounts is an interesting approach Canon has taken. The collapsible design is another. Thank you for adding a usage example to the discussion.