Home

Please support mflenses.com if you need any graphic related work order it from us, click on above banner to order!
SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

The reality of scaled images
Post new topic   Reply to topic
Home   Manual Focus Lenses
View previous topic :: View next topic  


PostPosted: Mon Mar 16, 2009 3:53 am    Post subject: The reality of scaled images Reply with quote
Here we have two sets of crops from a photo taken with Macro-Elmarit 2.8/60 on 350D, crops from the original and a copy after applying some Gaussian blur:









When the images are scaled down to the size which I'm using on my web site (slightly larger then often is the case on most forums), we get a version for the original, sharp image:



and a version for the blurred image:



The scaled down copies haven't been sharpened for display. An A-B comparison indicates a slightly higher contrast for the original, but tells little of the quite vast difference in resolution. This image size is good for comparisons perhaps at something like 10 lp/mm for lenses mounted on the 350D and 6 lp/mm on 5D, smaller images pro rata.

Veijo


PostPosted: Mon Mar 16, 2009 4:47 am    Post subject: Re: The reality of scaled images Reply with quote
vilva wrote:

The scaled down copies haven't been sharpened for display. An A-B comparison indicates a slightly higher contrast for the original, but tells little of the quite vast difference in resolution. This image size is good for comparisons perhaps at something like 10 lp/mm for lenses mounted on the 350D and 6 lp/mm on 5D, smaller images pro rata.

Veijo


True, and for most prints (up to 20x30cm?) as well. Which is why flare resistance, colors and contrast are equally important attributes as sharpness for a good lens.


PostPosted: Mon Mar 16, 2009 7:07 am    Post subject: Reply with quote
Yes, it is unfortunate, but most photos intended to show how great a lens is actually show nothing at all. Only 72dpi 100% crops actually convey real information. It's really rather funny (and sad) to see the "wow, great lens" comments made about thumbnail-size photos.


PostPosted: Mon Mar 16, 2009 7:11 am    Post subject: Reply with quote
nice tutorial
and with extra sharpening, the difference in contrast will probably be even smaller


PostPosted: Mon Mar 16, 2009 11:30 am    Post subject: Reply with quote
PaulC wrote:
Yes, it is unfortunate, but most photos intended to show how great a lens is actually show nothing at all. Only 72dpi 100% crops actually convey real information.

I think that is only true about sharpness. A lot of qualities can be seen (like "out-of-focus rendering") in scaled down pictures. And those qualities maybe make a picture even more pleasing to the eye than pure sharpness.


PostPosted: Mon Mar 16, 2009 2:29 pm    Post subject: Reply with quote
Are opposite the concepts of massive image and quality image?

All the pics that we see internet via, are better than the pics 6 x 4 in paper, but aren't better than a good 30 x 40 cm.

The Vilva's post responds to the question about Internet: is the right way to evaluate the possibilities of lenses or tends to equal lenses that not be so equals?

Perhaps not so, but some reason Vilva has.

Rino.


PostPosted: Mon Mar 16, 2009 2:59 pm    Post subject: Reply with quote
eeyore_nl wrote:
PaulC wrote:
Yes, it is unfortunate, but most photos intended to show how great a lens is actually show nothing at all. Only 72dpi 100% crops actually convey real information.

I think that is only true about sharpness. A lot of qualities can be seen (like "out-of-focus rendering") in scaled down pictures. And those qualities maybe make a picture even more pleasing to the eye than pure sharpness.


Fair enough, large-scale detail is still visible, but the information about sharpness, chromatic aberration and detailed bokeh is all lost. You're left with the overall look, contrast and colour rendition (as long as those haven't been messed about with). I really don't think that is enough to judge a lens on.


PostPosted: Mon Mar 16, 2009 3:41 pm    Post subject: Reply with quote
estudleon wrote:

The Vilva's post responds to the question about Internet: is the right way to evaluate the possibilities of lenses or tends to equal lenses that not be so equals?

Perhaps not so, but some reason Vilva has.

Rino.


Ok, in that case I agree: Internet (scaled and sharpened) pictures are not a good measure of lens performance. Even more because you don't know what post processing was done.
But a lot of discussions about lenses focus on sharpness mostly (MTF-values), while other characteristics are just as important for a pleasing picture.
PaulC wrote:

Fair enough, large-scale detail is still visible, but the information about sharpness, chromatic aberration and detailed bokeh is all lost. You're left with the overall look, contrast and colour rendition (as long as those haven't been messed about with). I really don't think that is enough to judge a lens on.


Yes, agreed, CA is often invisible on resized pictures, and is an important quality of lenses.
Post new topic   Reply to topic
Home   Manual Focus Lenses
Page 1 of 1