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

Aspherical lens elements — always good?
Post new topic   Reply to topic
Home   Manual Focus Lenses
View previous topic :: View next topic  


PostPosted: Fri Feb 12, 2010 5:09 pm    Post subject: Reply with quote
Thank you! BTW, absolutely no pp to the images at all.


PostPosted: Fri Feb 12, 2010 5:16 pm    Post subject: Reply with quote
I think Yashica's the second image.


PostPosted: Fri Feb 12, 2010 9:10 pm    Post subject: Reply with quote
Orio is correct.

I like this view for comparing lenses because there are a lot of discrete objects at different distances from the camera. It's interesting to see which lenses create the most cohesive image — one that makes it clear how far away each object is. The more unified the image the more the 3-dimensional effect. A lens that has this quality lets me feel like I could walk right up to any spot in the scene and be there.


PostPosted: Sat Feb 13, 2010 11:37 am    Post subject: Reply with quote
as far as I know, planar construction does generally more 3d-ish look, aspherical is known to be good for less CA, but my 24-70L has a lot of it and it has asph element.


PostPosted: Sat Feb 13, 2010 11:43 am    Post subject: Reply with quote
I think asph elements are used to correct distorsion, astigmatism and spherical aberration... not for sharpness or CA corrections.


PostPosted: Sat Feb 13, 2010 2:01 pm    Post subject: Reply with quote
no-X wrote:
I think asph elements are used to correct distorsion, astigmatism and spherical aberration... not for sharpness or CA corrections.


yes.
Resolvance is more a matter of the quality of the optical glass (high refraction index glass) and of the precision of the building.
CA is also related to glass quality (low dispersion glass), although perhaps spherical aberration might increase visually the presence of CA


PostPosted: Sat Feb 13, 2010 2:03 pm    Post subject: Reply with quote
Today, most aspherical elements (except those found in very expensive lenses) are hybrid elements, which means they are made from a spherical glass element with a thick plastic coating molded around the spherical element to give it an aspherical profile. I suspect that the use of plastic in the optical path might have a detrimental effect on image quality.

Also, the very large number of elements in modern lenses (some zooms have more than 30 elements !) is certainly not a good thing, even though the coatings have made tremendous progress during the last 50 years.

Cheers!

Abbazz


PostPosted: Sat Feb 13, 2010 2:17 pm    Post subject: Reply with quote
Abbazz wrote:
Today, most aspherical elements (except those found in very expensive lenses) are hybrid elements, which means they are made from a spherical glass element with a thick plastic coating molded around the spherical element to give it an aspherical profile. I suspect that the use of plastic in the optical path might have a detrimental effect on image quality.


Yes, I thought of this also, esp. with regards to Canon EF lenses which seem to make abundant use of the plasticky trick, and whose lenses produce results that to me, look flat and with unpleasing colours.

Quote:
Also, the very large number of elements in modern lenses (some zooms have more than 30 elements !) is certainly not a good thing


Yes, for image clarity, contrast, microcontrast especially, I doubt that a ray of light that passes throught 30 different glasses can maintain the same "presence" of lenses that use 4, 6, 10 glass elements.
Post new topic   Reply to topic
Home   Manual Focus Lenses
Goto page Previous  1, 2
Page 2 of 2