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Steve Spencer wrote:
What is clear is that you don't understand my preferences and why I want a smaller kit for landscapes. My preferences are not driven by how picky I am. They are driven by my shooting now being primarily day hikes and how much I can carry for such hikes. If I decided to be more picky that wouldn't change what gear I bought or what I use to shoot landscapes. That you bring up that my decision depends on how picky I am is saying that if I was more picky I would make different decisions.That is what depends on means. I am not misreading what you wrote. You are simply wrong about my preferences and you are mischaracterizing them in a way I find rude,
Now in choosing between gear that I can carry for the types of hikes I do, quality does matter to me and I don't think that the Tamron 50-300 f/4.5-6.3 is anywhere near the quality of the Fuji 70-300 f/4-5.6. I may be wrong, but your arguments are hardly convincing that somehow the Tamron would give me better images especially when it too would have to be cropped for much of its range.
Further although it is true that I you can of course visualize a 1.5X crop in the viewfinder on Sony cameras, and I find that works well on my A7r V, part of the reason I don't have an A7Cr as you recommend is that I rather hate the tiny viewfinder in the A7C cameras. What I was trying to say is not that you can't visualize the crop with the gear that you recommended, but the for me the visualization of the crop is inferior with the system your recommended and I know that using that viewfinder is something that I don't want to do. It is the same reason that I don't choose the Fuji X-E5 and one of the primary reasons I chose a Sony A7r V over the A7Cr in the first place.
Now let's talk about magnification and diffraction, and the relation between them that you do not seem to fully understand. Dan did a good job of trying to explain it to you as well, so I won't go into depth here, but the first thing you need to know is that thinking that there is some f/number when diffraction matters and it doesn't matter if you are below that f/number, what you seem to call diffraction limited, is not right. Diffraction begins to affect our images from the moment we stop down a lens. For almost all lenses, however, the reduction of aberrations improves the image as we stop down much more than diffraction limits the image. That changes as we stop down, however, as gains in aberration reduction diminish. The question isn't whether diffraction affects the image at all. It does, but typically the effect is so small at wider aperture that we can't perceive it at all. The question is when does diffraction become noticeable and that is a function of both how small the aperture is and how much we magnify the image. Cropping the image either in post-processing or by using a smaller part of the sensor magnifies the image and makes diffraction more noticeable at a wider aperture.
Now how do these basic facts about diffraction apply to the decision between the Fuji 70-300 f/4-5.6 and the Tamron 50-300 f/4.5-6.3? I agree that on full frame I don't find diffraction noticeable at f/6.3. I do find diffraction just noticeable, but not objectionable on an APS-C sized sensor or part of the sensor at f/6.3. I start to find diffraction to be a little problematic only at f/11 on full frame and f/8 on an APS-C sensor or part of the sensor. What this means is that the Tamron lens can hardly be stopped down at all if you are cropping the images and taking a zoom with that large of a focal length range and expecting to use the long end without even really being able to stop it down a stop is in my estimation asking for frustration. Frankly, what I worry most about with the Fuji 70-300 is exactly this same issue. Will I be able to stop it down enough at the long end (from 312 to 450 FF equivalent)? It seems from the experience of people here on FM that with this particular lens that isn't necessary on the long end, which is rare for a zoom. I have serious doubts that the same would be true about the Tamron 50-300.
Finally you ask where I get the f/9.5 number from? That is easy it is a function of the entrance pupil of the lens which by the way is what is directly related to diffraction. The size of the entrance pupil is the focal length of the lens divided by the f/number. So when we say a 300mm lens has an effective focal length of 450mm, we are multiplying the the focal length by 1.5. If you do the algebra, then you will find that the actual size of the entrance pupil of a 300mm lens at f/6.3 is the same as a 450mm lens at f/9.5. And we know that when the 300 f/6.3 lens is used on an APS-C sensor or and APS-C size portion of a sensor, it will look just like a 450mm f/9.5 lens on FF in field of view, depth of field, and diffraction. It has the same depth of field and diffraction as such a lens because it has the same sized entrance pupil. If you don't want to do all the math just know that you can multiply the f/number by the crop factor and that will tell you about the depth of field and diffraction in FF terms. So, f/6.3 time 1.5 is f/9.5. ...Show more →
Steve Spencer wrote:
You don't understand my preferences and why I want a smaller kit for landscapes
I understood that part, which is why I proposed an even smaller kit for landscapes.
Steve Spencer wrote:
quality does matter to me
Ok, then we do agree on something.
Steve Spencer wrote:
I don't think that the Tamron 50-300 f/4.5-6.3 is anywhere near the quality of the Fuji 70-300 f/4-5.6
I cant comment on the quality of this Fuji lens, but I wont expect either to approach the level of a 70-200GMii
However, typically FF will produce higher real resolution unless the FF lens is really abysmal. For example if a lens produces 60 lp/mm then we will get 60 * 15.6 = 936 lp/mm on APSC, but on a FF sensor we will get 60 * 24 = 1440 lp/ph.
This advantage will drop off as we approach 450mm equivalent, but I would expect the FF system to produce more real resolution at 50-300mm, (and even above 300mm if you crop in POST) even if the Fuji lens is somewhat better.
Steve Spencer wrote:
although it is true that I you can of course visualize a 1.5X crop in the viewfinder on Sony cameras, and I find that works well on my A7r V, part of the reason I don't have an A7Cr as you recommend is that I rather hate the tiny viewfinder in the A7C cameras.
Lets drop the A7CR then, we both like nice viewfinders, and the A7RV has far and away the best one.
You don't like PZ lenses so lets drop that too
These are some examples of FF setups similar in weight to the X-T5 setup proposed.
Fuji X-T5 - 557g
Sigma 10-18 f/2.8 - 250g
Tamron 17-70 f/2.8 VC - 530g
Fuji 70-300 f/4-5.6 OIS - 580g
total weight: 1,917g
Option 1
Sony A7r V - 730g
edit: Tamron 17-50/4 - 460g
Tamron 70-300mm F/4.5-6.3 - 545g
Total 1735g
Option 2
Sony A7r V - 730g
Sony 16-35GMii - 547g
Tamron 50-300mm F/4.5-6.3 - 665g
Total 1942g
Steve Spencer wrote:
Diffraction begins to affect our images from the moment we stop down a lens.
This is true in principle. Diffraction is always present at any finite aperture. The Airy pattern is there no matter what.
However it is also misleading. At wide apertures, the Airy disk is much smaller than the blur from lens aberrations, so diffraction has no practical effect on image resolution. The system is not diffraction-limited there it is aberration-limited. So, saying “diffraction always affects the image” is technically correct but functionally unhelpful, because its effect can be completely swamped by aberrations until you stop down.
Steve Spencer wrote:
There is no f/number where diffraction matters and doesn’t matter below that.
This misunderstands the conventional use of “diffraction-limited.” In optics, a system is “diffraction-limited” when its resolution is constrained only by diffraction, not by lens flaws. That does imply there is a practical f-number below which the lens is not diffraction-limited (because aberrations dominate), and above which diffraction sets the fundamental ceiling. So it’s incorrect to reject the idea that diffraction-limited apertures exist.
Steve Spencer wrote:
The question is when diffraction becomes noticeable … and that is a function of both aperture and magnification.
Cropping or magnifying an image does not alter diffraction itself, the size of the Airy disk is determined solely by wavelength and aperture. What cropping does is lower the effective line pairs per picture height (lp/ph), making the loss of resolution more apparent in the final output. We do not directly “see diffraction”. what we perceive is the reduction in lens resolution that diffraction, or other aberrations, produces. Whether this reduction becomes visible depends on how the effective image resolution compares to the eye’s angular resolving power at the chosen viewing distance. Once resolution drops below that threshold, the image appears soft, regardless of whether the limit is set by diffraction, aberrations, or both.
Steve Spencer wrote:
What this means is that the Tamron lens can hardly be stopped down at all if you are cropping the images and taking a zoom with that large of a focal length range and expecting to use the long end without even really being able to stop it down a stop is in my estimation asking for frustration. Frankly, what I worry most about with the Fuji 70-300 is exactly this same issue. Will I be able to stop it down enough at the long end (from 312 to 450 FF equivalent)? It seems from the experience of people here on FM that with this particular lens that isn't necessary on the long end, which is rare for a zoom. I have serious doubts that the same would be true about the Tamron 50-300.
...Show more →
What do you mean by "stop down enough"? Are you worried about insufficient depth of field?
Edited on Oct 02, 2025 at 09:11 AM · View previous versions
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