Tamron developing 150-600mm VC USD lens

John Sheehy wrote in post #16681340
A full-res image from an 18MP camera would be 9x the area of HD monitor; 22MP, 11x the area.

My point has been that no lens that wouldn't be laughed out the marketplace would fail to allow sharp, downsampled images. That is not in question. If one understands this, they will not be surprised that any lens that isn't an outright toy could have a sharp 0.5 to 2MP image made from it. The question is how it stands up to much closer inspection; that is where the variation between lenses mostly lies. If the lens were not able to make sharp 0.5 to 2MP images, every serious person who already had one would have told you that "it is junk; don't buy it", and even the web images would have to be sharpened enough to create extra noise.

I see. Thanks for the explanation. So if the original image is from 18mp and why not crop it to .05 or 2mp and if it is sharp in that size it means that the whole 18mp is for sure sharp? I am trying to understand this myself, And I am glad you are taking time for it. I appreciate it. I don't mind if people laugh at me in this thread I'd rather ask then pretend I know what is going on. Thanks John.

Peter2516 wrote in post #16681410
I see. Thanks for the explanation. So if the original image is from 18mp and why not crop it to .05 or 2mp and if it is sharp in that size it means that the whole 18mp is for sure sharp?

Yes, that would mean that the lens was at least that sharp with those pixels (size and AA filter strength). Even if a 100% crop is oversharpened, it is usually pretty obvious because of the artifacts that sharpening a dull image at the pixel level brings.

I would never laugh at someone who can fly, has excellent eyesight, sharp talons, and a sharp, hooked beak.

John Sheehy wrote in post #16681431
Yes, that would mean that the lens was at least that sharp with those pixels (size and AA filter strength). Even if a 100% crop is oversharpened, it is usually pretty obvious because of the artifacts that sharpening a dull image at the pixel level brings.

I would never laugh at someone who can fly, has excellent eyesight, sharp talons, and a sharp, hooked beak.

Now I got it. Thank you very much John.

You just described my Avatar. He he he I like that.

Just picked up mine today. We got the wife's last week. Now if the weather would only improve.

It could also be there some copies that just aren't sharp. There sure are copies of Canon lenses that fall into this category thats for sure.
What exactly is the return policy If you think a lens isn't sharp anyways ?

MCAsan wrote in post #16681521
Just picked up mine today. We got the wife's last week. Now if the weather would only improve.

You have 2? one each? his and her. Awesome. Congrats. Just tried mine in the marina near the office during my lunch break and I am impressed how quick is the AF even in overcast condition. I think I just need to be aware of the AF limiter switch of this lens when to apply full or 15m to infinity.

Peter2516 wrote in post #16680823
Awesome field test review I am glad that the reviewer admitted that he is not into lab test or pixel peeper and I feel the same way not that I don't like the lab tests and I am thankful there are people doing it. It's a good tool or guide for consumers. But I'd rather have a field test reviews and some pictures along with it. So for me this is an awesome review and thank you for sharing. This is just my opinion.

like the review, don't like the nickname "Bigron"...just doesn't have the panache of Bigma.. Tamonster would be better imho

Peter2516 wrote in post #16681410
I see. Thanks for the explanation. So if the original image is from 18mp and why not crop it to .05 or 2mp and if it is sharp in that size it means that the whole 18mp is for sure sharp? I am trying to understand this myself, And I am glad you are taking time for it. I appreciate it. I don't mind if people laugh at me in this thread I'd rather ask then pretend I know what is going on. Thanks John.

He's not talking about cropping, but rather about resizing (down sampling). If you look at a small crop (what you describe above) and it is sharp, then you KNOW it's good. If you RESIZE your image to that size, it will probably look fairly sharp no matter what, unless the original is just horrendous.

archer1960 wrote in post #16681705
He's not talking about cropping, but rather about resizing (down sampling). If you look at a small crop (what you describe above) and it is sharp, then you KNOW it's good. If you RESIZE your image to that size, it will probably look fairly sharp no matter what, unless the original is just horrendous.

Thanks for the correction I meant resize not crop when I was replying to his post. I am so used of the word crop .

Peter2516 wrote in post #16681410
I see. Thanks for the explanation. So if the original image is from 18mp and why not crop it to .05 or 2mp and if it is sharp in that size it means that the whole 18mp is for sure sharp? I am trying to understand this myself, And I am glad you are taking time for it. I appreciate it. I don't mind if people laugh at me in this thread I'd rather ask then pretend I know what is going on. Thanks John.

here, give this a quick read...i'm actually getting close to linking it in my signature
http://www.juzaphoto.c​om/article.php?l=en&ar​ticle=10

lescrane wrote in post #16681669
like the review, don't like the nickname "Bigron"...just doesn't have the panache of Bigma.. Tamonster would be better imho

See this

rndman wrote in post #16682222
See this

Yeah. I added my two non-cents.

DreDaze wrote in post #16682203
here, give this a quick read...i'm actually getting close to linking it in my signature
http://www.juzaphoto.c​om/article.php?l=en&ar​ticle=10

While I don't, completely, disagree with the concept, that's a pretty flawed comparison. The crops being used to compare the two shots are not even taken from the same portion of the frames; the "soft" one is taken at the extreme back of the photo where things are going to be outside of the DoF if the shot isn't taken well and the "sharp" one is taken from much closer to the center of the frame where things are going to be sharp anyway.

Snydremark wrote in post #16682506
While I don't, completely, disagree with the concept, that's a pretty flawed comparison. The crops being used to compare the two shots are not even taken from the same portion of the frames; the "soft" one is taken at the extreme back of the photo where things are going to be outside of the DoF if the shot isn't taken well and the "sharp" one is taken from much closer to the center of the frame where things are going to be sharp anyway.

That's a fair point.

I think one of the easiest ways to explain it to any photographer that's shot more than a few images in their time: have you ever taken a photo, reviewed it quickly on the LCD and thought "yea!", then been disappointed when you've downloaded it to a computer and realised you'd missed focus by just enough that the subject was unacceptably soft?

It's basically the same issue - a downsampled version of an image will always hide some degree of softness in the full sized image.

For anyone who hasn't experienced this - set up your camera on a tripod, manual focus, and take a shot, then take another shot where you defocus just enough for you to normally reject the image as being too soft. Bring both into Photoshop (or equivalent) and resize down to, say, 800 pixels on the longest side. There's a very good chance that both images will look very similar (and certainly not different enough to realise that one was actually unusable).

The guys saying "don't base a decision on web sized images" aren't trying to be difficult; we're just making the point that small resampled images can hide a lot of problems, so don't really tell you if a lens is capable of producing sharp shots.

Andrushka wrote in post #16681390
Haha - so a sharp image is not an indicator of potential, but neither is a soft image? Thanks for that illusion-shattering reality

Truly! It seems that we are fools for trying to make judgments based on anything we see online. This will save me a lot of time, not having to look at images from this (or any) lens any more.

The points about resampled images are accurate, of course, but the real question for me is whether, with normal post-processing (which I would do with any image that I actually planned to use for any purpose), the results are acceptable. The images I have seen from this lens suggest that this will seldom be a problem.