A bit more information on the upcoming RF 200-800mm f/6.3-9 IS
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Yes, the MFD was the top reason I preordered the zoom. I often use the 1.4 extender on the 800 f/11 just to get "closer" when, in fact, I am having to stand back to stay behind the MFD of the prime. I also have an EF 800 f/5.6L, but its MFD is the same as the RF f/11, so no gain for the application other than it is a little sharper, but a LOT heavier. I use an Olympus EE-1 red dot sight on the flash shoe for targeting, so the zoom is not a big deal for finding the subject, but the MFD is huge.
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Nice shots. Judging by the species, it looks like you spent some time in South America. We have between 50 and 100 Anna's Hummingbirds that live in our back yard almost year round. They stay all winter and then often a lot of them disappear for a month or so in the early spring, but they come back in full force for the summer and fall. During the summer, we also see quite a few Rufus, which are noted for being bossy, but they don't seem to get away with that behavior around our resident Anna's. In the middle of winter, they chow down about a gallon of sugar water a day. We are in the woods and there are lots of different kinds of spiders around, so I suspect that is another reason the Hummers like it here (beyond the ever-replenishing flowers
) since they eat a lot of small spiders for protein and also use spider egg-sack silk to line their nests. I used the EF 100-400 for several years on the 5DSR and a 70D and got a lot of nice shots, particularly on the feeders, but I like to shoot them on a natural perch and the optimum location is too far for good magnification with the 100-400, so I got first the EF 800 L and then the RF800 f/11, both of which work better for the desired area, but with the opposite problem that the MFD is too long. Now waiting for the new zoom, which seems just about perfect. At the other end of the reach equation, the below shot was with the EF 800L with a 1.4 extender strapped to an SL-2 (200D) at about 70 feet. The birds live in the Sequoias I planted in the back canyon about 30 years ago and 70 ft is about as close as I can get when they are there.
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A heavy lens is not much of a problem when you don't have to lug it around, especially when it's in your own backyard. Have you considered the EF 400mm f/2.8 II? It works very well with the 2xTC (unlike the III) and has an mfd of only 2.7m.
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Very true. Even if the f-number changes linearly with focal length, the readout would be in plateaus as the camera has 1/3rd of a stop in steps. A plot of f-number against the longer focal length at the end of each "plateau" is a straight line, and, apart from 200mm, the same is true for the beginning of each "plateau". As you say, the f-number is within 1/3rd of a stop at each point of the true value. At 500mm the f-number is 8. If the true f-number does increase linearly and not with jumps, the true value would f-number = 7.75, a 1/4 stop below the 100-500mm.
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I thought about that, but I already have a 10 lb 800mm lens and one almost as heavy with a shorter MFD thanks to being a 400mm with a 2x TC didn't excite me much. Also, I often use a 1.4 extender on my 800s and the only why to get there with a 400 is to stack the 1.4 II and the 2x II (which I have), and the resulting IQ is not that great. This new zoom looks to be just about perfect and the size and weight is quite manageable for fairly long sessions. If the IQ is consistent with the MTF chart, I will be a happy camper.
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It would be a dream to see a hummingbird, let alone photograph them!
Btw RF lenses allow 1/8 stop aperture increments in video mode (if you enable it in settings) so that could be a way of mapping the changes more finely, I wonder if anyone has done it?
Btw RF lenses allow 1/8 stop aperture increments in video mode (if you enable it in settings) so that could be a way of mapping the changes more finely, I wonder if anyone has done it?
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That is an interesting idea for mapping the aperture of a lens. You should suggest it to Brian at https://www.the-digital-picture.com/ . He might give it a try. Hummingbirds are fun. We have two kinds here, Anna's and Rufous. The Annas stay pretty much year round and the Rufous only show up in the summer. Here are a few samples
Firstly, an Anna's male shot with an R7 and the RF 800 f/11 barefoot (i.e. no TC)
Next an Annas' female shot with a Nikon P1000 at appox 2000mm eqivalent and ISO 1600.
Next, a Rufous male shot with an R5 and the RF 800 f/11 with 1.4x TC
Lastly, a Rufous female also shot with the R5 and the RF 800 f/11 with 1.4 TC.
Note that the Nikon P1000 has an amazing lens for a consumer superzoom with a tiny sensor.
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Whatever trickery Canon used to get the MFD so close at 800 mm makes it theoretically possible to make a new 800 mm prime without resorting to magnification elements like the RF 800 f/5.6 L.
Of course, it would be bigger and heavier.
Although, they could always make a DO version.
The big problem is that it would still probably cost so much more than the Nikon 800 PF.
The MFD on the 800 PF is terrible so maybe a better MFD, lighter weight, and smaller size would justify the extra cost.
People would still complain but that is how it always goes with Canon.
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A used EF 400 f/2.8 is so much more expensive than either a used EF 500 f/4 or EF 600 f/4.
I will end up with one eventually anyway.
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Given that there are no full length (i.e. without magnification) super telephoto primes around with close MFDs, I suspect there is a reason in optical physics that makes shortening the MFD impossible. Variable aperture zooms clearly use some magnification at the long end or they wouldn't need to have variable aperture. The old mirror lenses that were able to close focus also had a considerable amount of magnification. Bottom line, I don't think you are looking at trickery, but rather just the nature of a variable aperture zoom. If you have a half-length prime with a (perfect) 2x TC, then the native sharpness has to be twice as good as a full length prime to achieve the same result. The RF 800 f/5.6L is an example. It is a good lens, but not as good as the EF 800 from 15 years ago and it certainly does not support additional magnification (i.e. external TCs) as well. AFAIK, the only way to make a lens shorter without magnification is to fold the optical path. Catadioptric lenses are one example. Binoculars and spotting scopes are two others. It is notable that Canon filed for a patent not too long ago that used multi-bounce mirror optics very similar to a spotting scope. The price to be paid for mirrors seems to always show up in loss of contrast, so no free lunch. As a final note, you can shorten the MFD by adding an extension tube, but that is also a form of magnification in that you are illuminating a larger area than needed and thus also have an effective loss of aperture. This is true of all macro lenses.
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When the lens is long, the DOF is short. In the case of the P1000 image, the actual focal length is 369mm at f/6.3. That combo does not have a large DOF when close focused, no matter what size the sensor. In fact, the the useful DOF is less with the tiny pixels on the small sensor because the slightest loss of focus is noticeable. Also, in all the images, the birds are in nearby bushes and the background is some distance away. With the RF 800 f/11, I don't have a lot of spare DOF beyond the bird itself. I suspect the 200-800 with a closer MFD and f/9 will be right on the edge to keep the whole bird in focus. I have to stop down the EF 800 f/5.6 L at MFD or I only get half a bird
. The P1000 has a number of issues, but the quality of the optics is not one of them. The stabilizer is spotty, so I shoot bursts of 3or 4 images and most of the time one or two will be sharp.. It is a huge camera (1.4 kg) for a consumer super zoom, but it is still much smaller than packing around an 800mm lens with an extender so fun to take on a walk if the day is reasonably bright (anything beyond ISO 1600 is hard to recover).
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There are the same numbers of photons per duck with or without an extension tube - in your case photons per humming bird - and the S/N viewed at the same size is not affected.
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That is also true with a teleconverter. The result with an R7 without a TC and an R5 with a 1.4x TC is essentially the same minus the degradation introduced by actual losses in the TC which are relatively small. The R7 sees 1 stop brighter illumination on the same number of pixels that are half the area, so the result is a push (i.e. same number of photons per hummingbird) with the R7 winning by nose because the TC is less than perfect. The shorter MFD offered by the 200-800 zoom will behave much like an extension tube in that to achieve the close focus it is very likely that the actual f stop will be impacted in the close focus region, whether or not the camera actually reports it (much like a macro lens which doesn't change the reported aperture for close focus), but the overall design is much more convenient than constantly adding and removing extension tubes. I have an old Minolta MD bellows macro lens and it has the effective f stop (for an open aperture) labeled on the bellows track. The lens is f/4 at infinity and f/32 at closest focus. The bellows design is an extreme case of progressively adding extension tubes to stay in focus. All Macro lenses exhibit that behavio(u)r to some degree as do variable zoom lenses that have close focus capability, but cameras pretty reliably do not report the change in effective aperture even though they correct the exposure for the loss of light.
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Because of serious focus breathing, the focal length of the telephoto zooms significantly decreases at the mfd, which should maker the f-stop wider!
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For those that breathe significantly, I think you are correct. Some breathe a lot more than others, so it is probably a case by case situation. The available data on the 200-800 MFD and magnification https://cweb.canon.jp/eos/rf/lineup/rf200-800-f63-9/spec.html when compared to the RF 800 f/ll and the EF f/5.6 L (which are specified identically) https://www.the-digital-picture.com/Reviews/Lens-Specifications.aspx?Lens=1513&LensComp=459 suggests that at MFD, the 200-800 will be about 630mm if I am doing the math correctly, so a fair bit of breathing, but not as much as some lenses. If it is actually that short, I may resort to a 1.4 TC, but am not going to lose sleep until I have it in hand. 0.2 magnification is still a big jump from 0.14. Seeing is believing.
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A man after my own heart who also calculates focal lengths from mfds! I think I posted this somewhere, but my calculations are different from yours. I calculate for a magnification of 0.2 at an mfd of 3300mm at 800m (remember they calculate mfd distance from the sensor) that the apparent centre of lens to object is 2750mm, the image 550mm to give an effective focal length of 458mm.
For comparison, the RF 100-400mm is 212mm at 1050mm mfd, RF 100-500mm is 224mm at 1194mm. I thought that maybe the decrease in focal length would result in a change in f-number as you got closer so that the iso would go down or the shutter speed gets faster. So, I did a quick experiment, and nothing much changed. Either the movement of the lenses on focus breathing somehow alters the apparent diameter of the lens or the iris automatically stops down. You could check with the fixed aperture f/11, I suppose, but it's raining at present and I would need to do it outside. But, the f drops only to 646mm at its mfd of 6000mm and I don't think I could reliably detect a 20% change.
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Your calculation is more elaborate than mine. I simply did a ratio calculation from the primes. Either way, there is clearly some breathing, but if it really gives me .2 magnification at 11 ft, I think I will be happy. As soon as Bryan over at TDP gets his hands on one, we will have the full detail.
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