F/1.8 Zoom lens!!

[arthurking83]

And it's about bloody time too!

Sigma 18-35mm f/1.8 for APS-C

One of the biggest issues with APS-C was that it promised smaller or faster lens designs.
Well at least someone has taken the initiative and provided one of those advantages.

Not sure why they started at this focal length tho .. I would have thought that something a bit longer, in the 24-50 range would have been more appropriate to begin with.

As I suspected they would .. the thirdparty manufacturers would innovate in this area, just like they seem to be doing with lens designs in general. The big two are rehashing old design types with very little or no innovative concepts.

Although it must be said that Olympus has had f/2 zoom lenses for a long time now .. technically they're not quite as innovative as they could have been! The 4/3rds system is even smaller than APS-C so an f/2 zoom lens on 4/3rds is not quite as challenging as an f/1.8 lens on APS-C.

I've finally migrated to the larger 35mm format, so it's come a bit too late for me, but I'm still hoping this one is a great design and produces some good empirical data.

[ameerat42]

Saw this on DPR yesterday, AK. It looked well-specificated, I thought. Now I just wonder how much it will be.
?m.

[Sar NOP]

It's MTF looks impressive :

[Rattus79]

Huh! This could be the start of something beautiful...

Hopefully it performs well too!

[ameerat42]

It's MTF looks impressive :

Blast! I wasn't going to ask you, Sar NOP, but I cannot find the MTF chart ANYwhere!!! (Esp. not on the Σ site.)
m.

[Lance B]

And it's about bloody time too!

Sigma 18-35mm f/1.8 for APS-C

One of the biggest issues with APS-C was that it promised smaller or faster lens designs.

Don't know how they were going to provide faster lens designs and they won't necessarily be smaller, either. Laws of physics dictate that whatever the focal length, the aperture is going to be the ratio of that focal length regardless of format. I know the initial thought was that APS C was going to hopefully give us smaller lenses but this was only realised at the longer focal lengths where, say a 200mm lens on FF is "equivalent" to a 135mm on APS C. However, if you want to get the same narrow DOF on APS C, you need to have the APS C lens one stop faster so, taking the example of the 200mm lens on FF and it was f4, then you require the 135mm lens to be f2.8 on APS negating the benefit of APS C somewhat.

At the wide angle end, the APS C lenses are generally at least as large as their FF counterparts basically because of the fact that they are using the same lens mount distance from the days of film and they have to have special lens designs which mean that wide angle APS C lenses do not end up being any smaller.

The fact is, this lens has a very small zoom range of only a 2 x zoom ratio and a 18-35 zoom range and it is still relatively large and heavy considering it's small zoom range when all is said and done so, this shows that to make it a larger zoom range would mean a lens that is very much larger and heavier and would introduce other compromises as well, like way more distortion, vignetting, aberrations and of course that large weight and size penalty. An APS C 18-35 f1.8 lens on FF would be "equivalent" to a 28-52 f2.5 on FF, hardly a stressing focal length range or a stressing wide open aperture either and therefore would be at least a similar size if not smaller than the APS C counterpart. Looking at previous Nikon lenses, there is a 28-50 f3.5 lens, unfortunately it is manual focus and only f3.5 so, not really a comparison, but it is tiny and light and does show that it is not a focal length that is used all that much for zooms as there are very few made in that range and certainly none at f2.5 due to this reason. One really wonders at the value of such a lens on APS C, especially considering that where you generally want wide apertures like f1.8 you generally are using it on potraits or other applications where you want a narrow DOF for isolation purposes and at 35mm on APS C, this is not really a portrat length.

As they say, there is no free lunch and for every perceived benefit of a system, there is an equal loss somewhere else.

Well at least someone has taken the initiative and provided one of those advantages.

Not sure why they started at this focal length tho .. I would have thought that something a bit longer, in the 24-50 range would have been more appropriate to begin with.

My thoughts as well. 50mm on APS C is closer to a portrait length and therefore where you would want narrow DOF or some other subjects requiring narrow DOF for isolation purposes.

As I suspected they would .. the thirdparty manufacturers would innovate in this area, just like they seem to be doing with lens designs in general. The big two are rehashing old design types with very little or no innovative concepts.

They rehash old designs because they cater more the professional areas and because they are the popular, most used and most useful focal lengths and zoom ranges. You even said youself that it you wonder why they used this zoom range and I have to ask the same thing.

Although it must be said that Olympus has had f/2 zoom lenses for a long time now .. technically they're not quite as innovative as they could have been! The 4/3rds system is even smaller than APS-C so an f/2 zoom lens on 4/3rds is not quite as challenging as an f/1.8 lens on APS-C.

I've finally migrated to the larger 35mm format, so it's come a bit too late for me, but I'm still hoping this one is a great design and produces some good empirical data.

[ameerat42]

I think the main point of this lens is its speed - f/1.8 - and the fact that it is constant over the zoom range.
That means it would have to be looking through a wide piece of glass ALL the time (at max. aperture, that is).
And then it has to be retro-focus to project that wide-ish view into (even the APS-C) innards... So, size and weight.

As for its max. reproduction ratio - 1:4.3 - well, modest, but for the rest of what it can do I suppose it's OK.

I just hope it's price is "right".
Am.

[WhoDo]

Confuses the heck outa me! Here is a quote from Petapixel on the subject:

The lens, officially called the Sigma 18-35mm f/1.8 DC HSM, is geared toward APS-C format cameras. On a 1.5x crop sensor it’ll be the equivalent of a 27-52.5mm f/1.8 lens.


Read more at http://petapixel.com/2013/04/18/sigm...eqeQgDtrwAA.99

Now that reads to me like it's a lens for FF or why bother to talk about the crop factor in these terms? I would have thought that if it was designed for APS-C then it would be 18-35mm on APS-C and not suitable for FF. Have I misunderstood (I do that a lot these days)?

[MattNQ]

Sigma is on fire of late- the new 35/1.4 from last year is reportedly very nice and this one looks to be a cracker of a lens to be sure.

I'm thinking we'll see some more interesting lenses from them before the year is out.

[ameerat42]

Confuses the heck outa me! Here is a quote from Petapixel on the subject:
Now that reads to me like it's a lens for FF or why bother to talk about the crop factor in these terms? I would have thought that if it was designed for APS-C then it would be 18-35mm on APS-C and not suitable for FF. Have I misunderstood (I do that a lot these days)?

?Makes then sound knowledgeable to the un-knowledged? A red herring? Space filler? Nothing better to say?... etc? etc?

[WhoDo]

?Makes then sound knowledgeable to the un-knowledged? A red herring? Space filler? Nothing better to say?... etc? etc?

[Lance B]

Confuses the heck outa me! Here is a quote from Petapixel on the subject:
Now that reads to me like it's a lens for FF or why bother to talk about the crop factor in these terms? I would have thought that if it was designed for APS-C then it would be 18-35mm on APS-C and not suitable for FF. Have I misunderstood (I do that a lot these days)?

No, it's an APS C lens, not a FF lens. It is saying that if it were to be the equivalent of a FF lens, then it would be a 27mm-52.5mm.

- - - Updated - - -

Sigma is on fire of late- the new 35/1.4 from last year is reportedly very nice and this one looks to be a cracker of a lens to be sure.

I'm thinking we'll see some more interesting lenses from them before the year is out.

The Sigma 35mm f1.4 is a real gem, one of the sharpest lenses I own, almost as sharp as the 85mm f1.4g or my 300 f2.8 VRII. It is a superb walk around general purpose prime with superb IQ, one of my favourite leses!

D800+ 35mm f1.4








See the tiny little frog



Here it is in crop

[MattNQ]

Some wonderful shots Lance - That lens is indeed superb on your D800.

[Lance B]

Some wonderful shots Lance - That lens is indeed superb on your D800.

Thank you for your nice comments, Matt!

[WhoDo]

No, it's an APS C lens, not a FF lens. It is saying that if it were to be the equivalent of a FF lens, then it would be a 27mm-52.5mm.

Understood, but what I don't get is why bother to do the comparison on a DX-only lens? Sure, give the equivalent FoV if the lens can be swapped from one to the other, but why bother when it's never going to be other than 18-35mm and APS-C only? How many FF photographers would even bother to buy or use a DX body-lens combo and also need to understand the equivalent FoV they'd be getting?

[arthurking83]

Don't know how they were going to provide faster lens designs and they won't necessarily be smaller, either. Laws of physics dictate that whatever the focal length, the aperture is going to be the ratio of that focal length regardless of format. .......

In this instance the laws of physics have nothing to do with the minaturization of lens designs.

The idea that APS-C format cameras require smaller lenses is simply because of the smaller format. ... In a way, it's a similar notion to lens design for mirrorless(ie. rangefinder) cameras.

That is, especially at the shorter focal lengths, the faster aperture wider angle lenses require less extreme optics, and hence smaller designs.

Measure the front element of your 35/1.4 .. I bet you that the front lens element is going to be a lot larger than 25mm in diameter!!
It's probably more like 50 or more mm which technically indicates that the lens is actually capable of being a 35mm f/0.75 lens as a minimum focal length/front lens diameter.
While the front lens element is not necessarily the entrance pupil in every lens design known, it's a close enough approximation.

The reason the front element needs to be so so large on faster aperture lenses is ensure that as many rays of light are used in the formation of the image at the entrance pupil .. which then transpires that these rays of light on the formed image then create an image of higher quality at the sensor.
(well that's the basic theory).

So to put it into perspective ... your 35mm f/1.4 lens should have a front diameter of only 25mm .. and hence only require a 25mm front filter thread size, but the reality is very much different.
If actual lens designs approached theoretical lens designs requirements of manufacture, then there would be no allowances for APS-C lenses to become smaller either.

[Lance B]

In this instance the laws of physics have nothing to do with the minaturization of lens designs.

The idea that APS-C format cameras require smaller lenses is simply because of the smaller format. ... In a way, it's a similar notion to lens design for mirrorless(ie. rangefinder) cameras.

That is, especially at the shorter focal lengths, the faster aperture wider angle lenses require less extreme optics, and hence smaller designs.

Measure the front element of your 35/1.4 .. I bet you that the front lens element is going to be a lot larger than 25mm in diameter!!
It's probably more like 50 or more mm which technically indicates that the lens is actually capable of being a 35mm f/0.75 lens as a minimum focal length/front lens diameter.
While the front lens element is not necessarily the entrance pupil in every lens design known, it's a close enough approximation.

The reason the front element needs to be so so large on faster aperture lenses is ensure that as many rays of light are used in the formation of the image at the entrance pupil .. which then transpires that these rays of light on the formed image then create an image of higher quality at the sensor.
(well that's the basic theory).

So to put it into perspective ... your 35mm f/1.4 lens should have a front diameter of only 25mm .. and hence only require a 25mm front filter thread size, but the reality is very much different.
If actual lens designs approached theoretical lens designs requirements of manufacture, then there would be no allowances for APS-C lenses to become smaller either.

My comment about aperture to focal length ratio wasn't specifically directed at 18-35, I was remarking on your thoughts that people believed that APS C lenses would be smaller. I am completely aware that wide angle lenses are a different kettle of fish due to their wide nature and require large front elements in order to encompass a wide view, maybe a bit of point scoring are being had by you? I mean, I do own the 14-24 f2.8 lens which has a bulbous front element probably 100mm wide and obviously has nothing to do with focal length to aperture ratio, please don't insult my intelligence. The fact is, wide angle lenses for APS C are not really smaller and I alluded to this when talking about the lens mount distance which was a leftover from the film days which meant that they have to have special lens designs so as to cause less vignetting and other factors. This generally makes them large than they need to be. Olympus was one of the few that redesigned their entire format when they went 4/3rds and thus could have a lens mount distance that was suited to the 4/3rds format and could, thoerically, make their wide angle lenses smaller than their FF counterparts. However, the other thing to consider again is that to be a true equivalent, they need to have an aperture which is two stops faster than their FF counterparts and for APS C, this needs to be 1 stop faster than their FF counterparts to be a true equivalent.

[zollo]

Faster lens are said to help the af sensors do their thing especially as light dims. I could see a use for a wide-ish lens with f/1.8

[I @ M]

Image samples look pretty good, Sigma are on a bit of a roll lately.

How many FF photographers would even bother to buy or use a DX body-lens combo and also need to understand the equivalent FoV they'd be getting?

I stick my hand up as one, I don't believe that the APSC format is anywhere near dead yet and seeing as we own a couple of capable DX bodies to work with relatively cheap dedicated APSC lenses they make good sense as travel cameras.

[swifty]

I for one welcome this lens spec although its not particularly useful to me as I no longer have any investment in the APS-C format.
Sure its a little large but the usefulness of a constant f1.8 zoom cannot be underestimated.
For a street photographer, the zoom range is incredibly useful. How many threads are there debating 28mm vs 35mm vs 50mm (FF equivalent) as the best street focal length. You get all three and everything in between at f1.8 with this lens.

I hope companies like Olympus and Panasonic sit up and take notice. A similar equivalent FL lens for m43 would sell like hot cakes. Make it constant f1.4 and the internet's gonna go beserk!!