Sigma's New Constant Aperture Zoom: Just got this newsletter from Sigma about their new 18-35mm f1.8 constant aperture zoom lens.

DebAnn Loc: Toronto

Just got this newsletter from Sigma about their new 18-35mm f1.8 constant aperture zoom lens.

http://blog.sigmaphoto.com/2013/sigma-18-35mm-f1-8-dc-hsm-art-first-impressions/

I read the text but I'm a bit puzzled. I'm assuming the lens can only shoot at f1.8, whatever zoom point you choose. I'm wondering how useful this would be. Any input?

MT Shooter Loc: Montana

No, that is its MAXIMUM aperture at all zoom lengths, a major feat in a lens like this at F1.8. The minimum aperture is F22, and you can select any aperture in-between for your shooting.

speters Loc: Grangeville/Idaho

No, you can close it down, but it allows you to use 1.8 through its entire range (if you so choose)!

DebAnn Loc: Toronto

Thanks you two for clarifying that. Now I understand why it's touted as a great lens. I thought it was interesting that the test photographer was using a Canon T3i which is what I generally use.

speters wrote:

No, you can close it down, but it allows you to use 1.8 through its entire range (if you so choose)!

SharpShooter Loc: NorCal

DebAnn wrote:

Thanks you two for clarifying that. Now I understand why it's touted as a great lens. I thought it was interesting that the test photographer was using a Canon T3i which is what I generally use.

Deb, 1.8 is VERY fast for a zoom. That's great for crop users.
But I believe it drops to 2.8 on a full frame. Get one. SS

mwsilvers Loc: Central New Jersey

DebAnn wrote:

Just got this newsletter from Sigma about their new 18-35mm f1.8 constant aperture zoom lens.

http://blog.sigmaphoto.com/2013/sigma-18-35mm-f1-8-dc-hsm-art-first-impressions/

I read the text but I'm a bit puzzled. I'm assuming the lens can only shoot at f1.8, whatever zoom point you choose. I'm wondering how useful this would be. Any input?

All lenses specify their maximum aperture. For example a 24-70 f/2.8. or for a variable aperture lens it might be something like 18-135 f/3.5-5.6. Generally lens can be stopped down from their maximum opening to somewhere between f/16 and f/22 depending on the lens. Wider aperture lenses tend to stop down less than variable aperture lenses. If the Sigma works well it will be a real breakthrough. It will be the first general purpose zoom with a fixed aperture of f/1.8. Of course the main limitation is that this lens is designed for crop sensors only. It is fairly large and heavy at 29oz and fairly expensive for a crop lens at $899. If they had attempted to build a similar lens to work on a full frame camera the size and weight would have been much much greater and the cost sky high. The real key of course is how effective is the design. If this lens is really good it is destined to be very popular. In that event I would certainly consider getting it.

mwsilvers Loc: Central New Jersey

SharpShooter wrote:

Deb, 1.8 is VERY fast for a zoom. That's great for crop users.
But I believe it drops to 2.8 on a full frame. Get one. SS

It is not intended to work on a FF and with its limited image circle would probably vignette badly.

MT Shooter Loc: Montana

SharpShooter wrote:

Deb, 1.8 is VERY fast for a zoom. That's great for crop users.
But I believe it drops to 2.8 on a full frame. Get one. SS

Exactly why would you think that?

mwsilvers Loc: Central New Jersey

MT Shooter wrote:

Exactly why would you think that?

I've seen that suggested before elsewhere. As far as I'm aware, f/1.8 is f/1.8 regardless of the body. The aperture size doesn't change.

MT Shooter Loc: Montana

mwsilvers wrote:

I've seen that suggested before elsewhere. As far as I'm aware, f/1.8 is f/1.8 regardless of the body. The aperture size doesn't change.

Absolutely NOTHING changes on a lens when switching between crop sensor and full frame bodies. Only the Field of View of the cameras sensor changes, that's it.
There is a WEALTH of mis-information on the internet concerning crop sensors and associated lenses. A lens is a lens is a lens, regardless of what body its mounted on. The body's sensor sees different portions of the image projected by that lens is all, hence the "perception" of a different lens, even though it is not.

mwsilvers Loc: Central New Jersey

MT Shooter wrote:

Absolutely NOTHING changes on a lens when switching between crop sensor and full frame bodies. Only the Field of View of the cameras sensor changes, that's it.
There is a WEALTH of mis-information on the internet concerning crop sensors and associated lenses. A lens is a lens is a lens, regardless of what body its mounted on. The body's sensor sees different portions of the image projected by that lens is all, hence the "perception" of a different lens, even though it is not.

Absolutely agree. I am aware of this and even though you were responding to my post I presume that info was not meant for for me. Perhaps I should have said "as far as I'm concerned" instead of "as far as I'm aware".

GoofyNewfie Loc: Kansas City

mwsilvers wrote:

I've seen that suggested before elsewhere. As far as I'm aware, f/1.8 is f/1.8 regardless of the body. The aperture size doesn't change.

And neither does the focal length.
I'm bummed they don't make a full-frame "Art"series yet.
I've been impressed with what Sigma is doing these days.
My first Sigma lens (a long time ago) was a piece of crap.
I have two APS-C lenses and they are very, very good.
Not investing in APS-C lenses anymore now that I have a D800.

mwsilvers Loc: Central New Jersey

GoofyNewfie wrote:

And neither does the focal length.
I'm bummed they don't make a full-frame "Art"series yet.
I've been impressed with what Sigma is doing these days.
My first Sigma lens (a long time ago) was a piece of crap.
I have two APS-C lenses and they are very, very good.
Not investing in APS-C lenses anymore now that I have a D800.

They do. The Sigma 35mm f/1.4 at $899 is a full frame lens in the ART series.

GoofyNewfie Loc: Kansas City

mwsilvers wrote:

They do. The Sigma 35mm f/1.4 at $899 is a full frame lens in the ART series.

Uh oh...
Must...resist...hand... on ...wallet.

Thanks- I missed that and what a great focal length that is.

mwsilvers Loc: Central New Jersey

GoofyNewfie wrote:

Uh oh...
Must...resist...hand... on ...wallet.

Thanks- I missed that and what a great focal length that is.

Its been available for a few months. Generally very well reviewed so far. The build is excellent and performance, according to many, is first rate.