Another Wide-Angle Quezzie...

[PaulMontgomery]

If a sigma lens is a 'HSM' one it will autofocus on any modern body. As for the wideness its all down to percentages - the change from 18mm to ay 16mm is a little over 10% - quite significant...

[chris-p]

Originally Posted by ianpinion

Chris P would agree that the f/4 - f/5.6 is optically great enough not to warrant the extra expenditure of the faster lens in most cases.

Yes, I would!

Although the main reason for ignoring the f/3.5 is not the image quality "gain".

Consider that most landscapes will be shot either in relatively decent light or on a tripod. Few, if any, dedicated landscape photographers (or at least those prepared to shell out for a "landscape" lens) will try to hand hold in low light. So the extra light gathering capacity is redundant.

Then think that most landscapes are about large depth of field. So you don't really want the extra half a stop there either. Also remember that, as your focal length decreases, your depth of field increases anyway meaning it's night on impossible to get shallow DoF at these sorts of focal lengths.

Thats why I wouldn't spend the money on the f/3.5 version. I've never actually shot with my f/4-5.6 at anything wider than f/8!

Thoroughly reccomend the lens though. It's got some weird coatings on it which make it look like you've stuck a polariser on it as well, especially with skies. The effect is quite dramatic actually, especially when you compare it to other lenses at similar focal lengths...

Originally Posted by PaulMontgomery

If a sigma lens is a 'HSM' one it will autofocus on any modern body. As for the wideness its all down to percentages - the change from 18mm to ay 16mm is a little over 10% - quite significant...

Actually, its not percentages, it's trigonometry. The field and angle of view have an inverse tangential relationship to the focal length. In effect (and I've made these numbers up as I'm at work and can't be bothered to calculate actual ones) if the step between 18mm and 17mm is 5 degrees wider, the step between 17mm and 16mm is more than 5 degrees wider. In short, it's not a linear relationship.

[Orbster]

I have the Sigma on order, can't wait to try it out.

[silversnapper1]

You won't be disappointed.

Steve.

[Orbster]

It arrived today and with my job as a courier driver I get to see some lovely scenery, today it was the cliffs at New Milton.

I'm just amazed at how wide an angle it actually is.

It came with no filter and I'm wondering whether it would be advisable to get a circular polariser to go on it as opposed to a UV filter as I'll be primarily doing landscapes with it and I gather you can't stack filters on this for fear of vignetting.

[AndrewKulin]

That would be the way to go and is exactly the set-up I have for my 24 mm TSE lens (permanent polarizer only).

I was on a photo workshop last fall with a pro landscape photographer and he told me the only filter he puts on his lenses will be polarizers (on 99% of the time) and the occasional other specialized filter as required for the shot. Otherwise the lens is left "naked" so to speak.

Plus the polarizer then acts to protect your front element (if that is your philosophy) just as the UV would do. So you eliminate one additional (unrequired layer of glass by not buying the UV) and save yourself some money as well. And less chance of vignetting as you noted.

Depending how critical you are in what you want your image quality to be, and your budget, you may wish to consider investing in a higher quality filter (albeit more $$$), with the money saved from no UV filter.

[Orbster]

Originally Posted by AndrewKulin

Depending how critical you are in what you want your image quality to be, and your budget, you may wish to consider investing in a higher quality filter (albeit more $$$), with the money saved from no UV filter.

I've just bought one off eBay for £15 which is peanuts but it's a Hoya one so should be of sufficient quality I would have thought...we shall see I guess.

[Bluey71]

Thats the question I am thinking - which is the sharpest lens?

[jinky]

A polariing filter will be fine most of the time but you do get issues with the sky ultra wide sometimes where one part will be darker than the rest. Happened with me occaionally with Siggy 10-20 on my D80 but I was able to use control points in NX2 to balance it up. Still a worthwhile buy whatever you might read though.If you stack filters you might get vignetting at widest angle. This happens even if you use a cokin filter holder - although I found if I sawed the end holder piece off it worked fine as I never wanted 3 filters in there.

[kerchi]

Orbster, how's the Sigma 10-20mm? Have you had chance to try it out? I have the same camera as you and wondered if it has met or exceeded your expectations.