Lens Design?

[OldrockyGN]

Why aren't there lenses like a 500-800 with a reasonable, but not super-fast
aperture (say f11)?

For birding (and for all wildlife and a lot of sports photography too?) it seems to me that
lens design hasn't "kept up" with the realities of the recent cameras ... I'm finding that I
have lots of 'options' to shoot in low light with a 'slower' lens - because my R5m2 is so
good at getting very acceptable images at high ISO values. And let's not forget the IS.

On a recent trip to Ecuador we were often out of the lodge well before sunrise and "on the
birding ground" as well. AND shooting under the canopy. Several times when I turned
on the camera (which defaulted to 1/4000 or 1/3000) the viewfinder was -way- too
dark ... then I'd roll the shutter speed down to what seemed like crazy slow speeds
and the birds would become visible, shots would result in not just usable but good
exposures. Not "great" but way better than "just acceptable".

Canon's 600 prime is only f11. I rented one for a couple of weeks. Big, heavy, and
no real advantage over the 100-500 with a 1.4. I own the RF 200-800 - but am
seriously considering selling it because it is just too big to travel with ... and pretty
"soft" above 600mm. And that weakness with respect to the way it breaks ....

Wouldn't a 'fast enough, small zoom range, long telephoto, light weight' be possible?
And maybe it should even be an internal zoom?
- Jim

 

[neuroanatomist]

Considering a 500-800/11 zoom, it's not going to be any smaller than the current RF 800/11, rather it will be slightly larger than that...pretty much the same size as the 200-800. Compare those two lenses with the 800/5.6. Also keep in mind that the 800/11 needs to be extended to use it, even though it's not a zoom lens.

 

[AlanF]

Sorry, but I do feel I have to correct misinformation and myths, here about the RF 200-800mm at 800mm. I bought both the RF 100-500mm and 200-800mm on the first days they were released and use both regularly. @foda has been taking what are among the very best , sharp, bird photos posted here using the RF 200-800mm in several continents, and @Dragon great humming birds. @Nemorino , I and other regular posters in the bird thread are also getting sharp shots at 800mm. I've done extensive tests on it. And not many of us have had the lens break in two.

Thread 'Summary of my RF 200-800mm testing'

Jan 31, 2024

I have now taken a couple of thousand images with charts and birds in the wild to test the RF 200-800mm on the R5 and some on the R7. This was both from sheer interest and for me to decide whether to keep the lens and if so which lens to use in various circumstances. Much has been posted in two threads: https://www.canonrumors.com/forum/threads/rf-200-800mm-500mm-vs-800mm-etc-with-birds.43235/ and https://www.canonrumors.com/forum/t...-rf-100-500mm-vs-rf-800mm-on-r7-and-r5.43183/

After another 1000 shots in the past two days, comparing with the RF 800mm f/11...

• AlanF
• Replies: 134
• Forum: Canon Lenses

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Internal zoom telephotos are usually heavier and more expensive than extending ones. Canon's 600mm f/11 is hardly heavy and big compared with the RF 100-500mm. The prime weighs in at under 1kg compared with the 1.6kg of the zoom with its tripod foot and hood, is the same length retracted and shorter than when both extended.

 

[OldrockyGN]

Considering a 500-800/11 zoom, it's not going to be any smaller than the current RF 800/11, rather it will be slightly larger than that...pretty much the same size as the 200-800. Compare those two lenses with the 800/5.6. Also keep in mind that the 800/11 needs to be extended to use it, even though it's not a zoom lens.

View attachment 229279

 

[OldrockyGN]

Neuro,
I don't understand your response. I'm not a lens designer - just a simple(?) user. On the surface your response
seems to be based upon "the status quo" ... it doesn't seem, to me, to address my comments about how good
today's cameras are at high ISO values and IS. Maybe I used a 'bad example' but to me I am still wondering
why we don't have "new concepts of lens design" based upon accepted high(er) ISO values and current
image stabilization ... maybe what I'm asking for is a long focal length mirror lens? Just to be perfectly
clear on my motives ... I'm a birding photographer (not a videographer) who wants "more reach" in a
lens that is -very- capable of being hand held, and of being "the only lens I take with me when traveling
around the world to take pictures of birds". So I need a lens that is light and small enough to put in my
travel backpack - which the RF 100-500, mounted on the camera, does very well. I also take my 1.4 extender
and -one- "landscape lens" (the RF 24 -105).
- Jim in the PNW

 

[neuroanatomist]

I don't understand your response. I'm not a lens designer - just a simple(?) user. On the surface your response
seems to be based upon "the status quo" ... it doesn't seem, to me, to address my comments about how good
today's cameras are at high ISO values and IS.

Two points.

First, I think Canon has done just that with the RF 600/11 and 800/11 and the RF 200-800, which is f/9 at the long end. With such narrow apertures and a need for a fast shutter for moving subjects, high ISOs are often necessary. The fact that those lenses are much slower than the f/5.6 (and f/6.3 from other manufacturers) and thus much smaller/lighter/cheaper is quite consistent with designs taking the high ISO capabilities of modern cameras into account (and also their ability to AF with narrow apertures).

Second, you referred to a hypothetical 500-800mm f/11 zoom lens because the existing 200-800 is too large for travel, and my point about the other lenses is that your hypothetical lens won't be any smaller than the existing 200-800, which is only 2/3-stop slower than the prime at the long end (and making it a constant f/11 zoom won't help with size or weight).

 

[scyrene]

I think Canon has done just that with the RF 600/11 and 800/11 and the RF 200-800

Precisely this! We couldn't have dreamed of lenses like this in the EF days.

 

[Dragon]

Neuro,
I don't understand your response. I'm not a lens designer - just a simple(?) user. On the surface your response
seems to be based upon "the status quo" ... it doesn't seem, to me, to address my comments about how good
today's cameras are at high ISO values and IS. Maybe I used a 'bad example' but to me I am still wondering
why we don't have "new concepts of lens design" based upon accepted high(er) ISO values and current
image stabilization ... maybe what I'm asking for is a long focal length mirror lens? Just to be perfectly
clear on my motives ... I'm a birding photographer (not a videographer) who wants "more reach" in a
lens that is -very- capable of being hand held, and of being "the only lens I take with me when traveling
around the world to take pictures of birds". So I need a lens that is light and small enough to put in my
travel backpack - which the RF 100-500, mounted on the camera, does very well. I also take my 1.4 extender
and -one- "landscape lens" (the RF 24 -105).
- Jim in the PNW

A mirror lens is the only way you will get to a materially smaller size than the 200-800. Canon did file some mirror lens patents a year or two ago, but so far nothing has come of them. Historically, there has been only one AF mirror lens, a 500mm f/8, first released by Minolta and then rereleased by Sony (both in A-mount). I have a large collection of mirror lenses, including some of the best, and although they are fun to play with, aside from the doughnut bokeh issue, they all exhibit a substantially narrower DOF than an equivalent refractor lens. I believe this is due to the central obstruction in the catadioptric design flattening the airy disc, so the near-in-focus area has less definition than on a similar refractor. The only other known possibility would be to design a lens using the ping-pong mirror approach that is commonly used in spotting scopes. This approach would not suffer from the loss of DOF, but I suspect it would be hard to achieve good contrast, given that the light bounces off the same mirror more than once, but at different angles. Probably the best performance with front surface mirrors, but then lifetime becomes an issue.

 

[AlanF]

Neuro,
I don't understand your response. I'm not a lens designer - just a simple(?) user. On the surface your response
seems to be based upon "the status quo" ... it doesn't seem, to me, to address my comments about how good
today's cameras are at high ISO values and IS. Maybe I used a 'bad example' but to me I am still wondering
why we don't have "new concepts of lens design" based upon accepted high(er) ISO values and current
image stabilization ... maybe what I'm asking for is a long focal length mirror lens? Just to be perfectly
clear on my motives ... I'm a birding photographer (not a videographer) who wants "more reach" in a
lens that is -very- capable of being hand held, and of being "the only lens I take with me when traveling
around the world to take pictures of birds". So I need a lens that is light and small enough to put in my
travel backpack - which the RF 100-500, mounted on the camera, does very well. I also take my 1.4 extender
and -one- "landscape lens" (the RF 24 -105).
- Jim in the PNW

You have your lightweight travel lens, the RF 100-500mm. I use it with the 2xTC, which gives good images at 1000mm, and give a miss to my 1.4xTC. If you want something really light, the RF 100-400mm is really the best bang-for-the buck telephoto out there. I've recently posted several shots where it on the R7 is pretty close to the RF 100-500mm on the R5ii for static shots and not bad for BIF. I would like to have a lightweight prime like the Nikon Zs but if you are travelling or hiking with just one telephoto lens, a zoom wins out every time for me.

 

[OldrockyGN]

Neuro/all,
OK, I accept your answers. I guess. I'm not saying you are wrong. I'm saying there is a lot
about lens design that I don't understand. I do understand that the diameter of the lens is
directly related to its "light gathering" (maximum f stop). From the responses so far I
guess there is also a relationship between the length of the lens and the focal length - or
maybe that affects the image quality/usefulness ... I'm saying you -could- make a lens
that is both high focal length and physically short - but you might not like the resulting
image quality? And based upon your reply to my speculation about a mythical 500-800 I
guess I don't understand the relationship of the lower end of the focal length for a zoom -
because I have always thought that the amount of zoom was directly related to the
overall physical length of the lens.
I am not unhappy with my RF 100-500, FAR from it. My 'happiness' with the RF 200-800 is
significantly less (but that's me) due to it is too big to travel with and, again for me, is not
anywhere near as easy to hand hold and get equivalent results. Nor is it as easy to
carry (as in when I'm birding) as the 100-500. I realize these are MY perceptions.
On my most recent trip I had, but didn't even use, the 1.4 with the 100-500 ... and found
that I was getting useful/satisfactory results from simply cropping tighter for those shots
where the bird was a small part of the frame. One of the biggest reasons why I didn't
use the 1.4 was because we were almost always "under the canopy" and that extra stop
was better (necessary?).
- Jim in the PNW

 

[Dragon]

Neuro/all,
OK, I accept your answers. I guess. I'm not saying you are wrong. I'm saying there is a lot
about lens design that I don't understand. I do understand that the diameter of the lens is
directly related to its "light gathering" (maximum f stop). From the responses so far I
guess there is also a relationship between the length of the lens and the focal length - or
maybe that affects the image quality/usefulness ... I'm saying you -could- make a lens
that is both high focal length and physically short - but you might not like the resulting
image quality? And based upon your reply to my speculation about a mythical 500-800 I
guess I don't understand the relationship of the lower end of the focal length for a zoom -
because I have always thought that the amount of zoom was directly related to the
overall physical length of the lens.
I am not unhappy with my RF 100-500, FAR from it. My 'happiness' with the RF 200-800 is
significantly less (but that's me) due to it is too big to travel with and, again for me, is not
anywhere near as easy to hand hold and get equivalent results. Nor is it as easy to
carry (as in when I'm birding) as the 100-500. I realize these are MY perceptions.
On my most recent trip I had, but didn't even use, the 1.4 with the 100-500 ... and found
that I was getting useful/satisfactory results from simply cropping tighter for those shots
where the bird was a small part of the frame. One of the biggest reasons why I didn't
use the 1.4 was because we were almost always "under the canopy" and that extra stop
was better (necessary?).
- Jim in the PNW

Just a note on whether to choose the extender or not. The number of photons from the bird is going to be essentially the same with or without the extender, but with the extender, you will have more pixels on the bird. If you are working in the linear portion of the DR curve, then the question is whether "smart" software will recover more detail with fewer quieter pixels or more noisier pixels. That is something you have to test empirically with the software you use. If you are in the non-linear portion of the DR curve (e.g. with your R5 II, if you were shooting at ISO 400 with the base lens and ISO 800 with the extender), then you would likely see some advantage with the extender independent of "smart" software. It is important to understand the behavior of the sensor in your specific camera and Photonstophotos.net will give you that information.

 

[AlanF]

On my most recent trip I had, but didn't even use, the 1.4 with the 100-500 ... and found
that I was getting useful/satisfactory results from simply cropping tighter for those shots
where the bird was a small part of the frame. One of the biggest reasons why I didn't
use the 1.4 was because we were almost always "under the canopy" and that extra stop
was better (necessary?).
- Jim in the PNW

One important point about signal to noise and extenders that is not widely known is that if you increase the iso to compensate for the loss of the stop you don't decrease the signal to noise in a cropped image. Supposing you take a picture of a duck, then the S/N in the image of the duck depends on the number of photons hitting the image of the duck, not on the iso number. If you use the same f-number and shutter speed with a 1.4xTC but double the iso to compensate for the loss of brightness, the image of the duck is no noisier. That is because although the number of photons per unit area of the duck is halved by the TC, the area of the duck is doubled, which fully compensates for it. If you don't like maths arguments, think of it in another way. If you don't use the extender, the image is smaller and you have to enlarge it more, which wipes out using a lower iso. By the same reasoning, an f/9 800mm lens puts as many photons on the duck as does an f/4.5 400mm lens. So, the take home message is don't worry about the loss of a stop when using a 1.4x extender as you can just double the iso. I posted a thread on this years ago but can't find it.

 

[AlanF]

@Dragon our posts crossed in the ether! In low light, you are usually in the linear region of the photonstophotos plots. One further point to note, you don't lose DR by increasing the iso by two on using the 1.4x TC although it looks like you would do at first sight. This is because the DR is measured by viewing at a specific enlarged image size, and the larger image is enlarged less to reach it, which compensates its iso being lower down on the chart.

 

[AlanF]

Found the thread about iso and extenders

Thread 'Extenders and high iso with the R5'

Jun 27, 2021

Concerns are frequently expressed about lenses like the RF 100-500mm with f/7.1 being narrow and so the images must surely be noisy because high isos are necessary in dim light? Some claim the 400mm f/5.6 is superior in low light because it is 2/3 of a stop faster (or a 1/3rd faster than the 100-500mm at 400mm f/6.3). I've pointed out that the 100-500mm has the same size front element of the 400mm f/5.6 that although you need to crank up up the iso by 2/3 of a stop to maintain the shutter speed, the extra magnification of the longer lens compensates for any extra noise. Others are...

• AlanF
• Replies: 20
• Forum: EOS R

• 

 

[Dragon]

@Dragon our posts crossed in the ether! In low light, you are usually in the linear region of the photonstophotos plots. One further point to note, you don't lose DR by increasing the iso by two on using the 1.4x TC although it looks like you would do at first sight. This is because the DR is measured by viewing at a specific enlarged image size, and the larger image is enlarged less to reach it, which compensates its iso being lower down on the chart.

Hi Alan. Yes, I understand your point. Hopefully the combination of your comments and mine will help the OP to better understand when it makes sense to use the extender. The alternative is to use a sensor with denser pixels, e.g. R7 on base lens vs R5 with 1.4x extender offers equivalent pixels on the bird and in my experience, the R7 approach (specifically with the 200-800) typically gives slightly better results. Of course, much depends on AF performance and R5 II with extender may well outperform the R7 with bare lens (but I haven't, at least yet, sprung for an R5 II). But then, there will be an R7 II . My real preference would be for an R5s that would provide the wider field of view AND the higher pixel density. 101 MP would be perfect (and you could capture a frame of 12k open gate video for full resolution) .

 

[AlanF]

Hi Alan. Yes, I understand your point. Hopefully the combination of your comments and mine will help the OP to better understand when it makes sense to use the extender. The alternative is to use a sensor with denser pixels, e.g. R7 on base lens vs R5 with 1.4x extender offers equivalent pixels on the bird and in my experience, the R7 approach (specifically with the 200-800) typically gives slightly better results. Of course, much depends on AF performance and R5 II with extender may well outperform the R7 with bare lens (but I haven't, at least yet, sprung for an R5 II). But then, there will be an R7 II . My real preference would be for an R5s that would provide the wider field of view AND the higher pixel density. 101 MP would be perfect (and you could capture a frame of 12k open gate video for full resolution) .

Absolutely about the R5s, I preferred the 5DSR over the 7Dii and the Nikon D850 over the D500 APS-C, both pairs having similar pixel density. The 7D R7 with the 100-500mm is pretty close to the R5ii/R5 with the RF 200-800 as the better IQ of the 500 compensates for the theoretical higher resolution of the 800mm, which is not quite as as sharp. I really want a good R7ii.

 

[OldrockyGN]

I suspect that many of the posts have not been made with full understanding of my preference for
HandHeld. Using a lens on a tripod + gimbal (I have both) is simply "not for me". I carry my camera
and whatever lens (without or with an extender) I'm using for the session. I'm walking around, up
and down small hills for at least an hour without ever going back to where ever my 'kit' is - so no
changes ... just aim, frame, focus, shoot. I've tried several different carry methods and now choose
a shoulder sling style with a wide pad. I'm no spring chicken - I'm over 80 - so some methods and/or
places aren't going to happen (no back country on foot, no steep cliffsides, no lying on the ground
or crouching in the mud, etc.) ... but I'm getting some good, sometimes even great, images and
still improving. I still have my R7 + 100-400 but it sits waiting for the call since I got the R5m2
with the 100-500. Birds only (pretty much), and stills only (haven't even experimented with video).
Thanks to ALL of you for bringing me back to the reality that is - instead of wishing for some sort of
equipment change that will make a difference. I'm off to take some pictures of birds. - Jim

 

[Dragon]

The 7D with the 100-500mm is pretty close to the R5ii/R5 with the RF 200-800 as the better IQ of the 500 compensates for the theoretical higher resolution of the 800mm, which is not quite as as sharp. I really want a good R7ii.

I think you meant R7 and not 7D in that sentence.

 

[neuroanatomist]

I suspect that many of the posts have not been made with full understanding of my preference for
HandHeld.

Not sure why you would think so, but I really doubt that’s the case. The concepts of signal to noise and lens design don’t depend on whether you are handholding or using a tripod. One of the points about shooting with a long lens in “low light“ is that often happens at light levels that would not normally be considered limiting, but when one needs a 1/2000 s shutter speed for a bird in flight, the amount of light reaching the sensor is low, even though to your eyes there is plenty of light.

Personally, I shoot a variety of subjects, some of which require tripod shooting (e.g., blue hour and astro, because handholding for a 30 s exposure is not really feasible). But most of my bird shooting is handheld, including most of my shooting with the EF 600/4L II (which I typically use with a 1.4x extender, currently the RF 1.4x). The exception to that is winter raptors, where I will sometimes set up in a spot for an hour or two waiting for a snowy owl to take off, and in that case I use a tripod and side-mount gimbal for the 600/4.