A Long Telephoto Lens for Fellow Peasants

[RobbieKB]

So I saw a lens at a boot sale. A Sigma 400mm AF f/5.6 prime:



Immaculate condition optically and only a few cosmetics scuffs. It came with lens hood, both lens caps, tripod attachment, some sort of buckle for if I want to fashion it as a belt accessory and a Jessops 72mm filter - probably UV or circular.

I bought it off the chap for £20 and thought if I can do anything with it, that'll be nice. Turns out, it didn't even need an adapter to fit my 5D II (as I suspected from merely looking at it.) Even more surprising - as this is clearly an old lens presumably for film Canons - its auto-focus works! And for the final cherry on this peasants cake: it works with my 1.4x teleconverter.

It's not the sharpest lens by some stretch and it isn't going to create anything portfolio worthy I don't doubt . However, I don't have a spare £1000+ for 400 or more millimetres of Canon L deliciousness. Example images:

400mm:



560mm:



Not bad for £20. I'm sure I can turn its shots all B&W and artsy to take focus off the softness.

The only issue with it, which isn't a problem, is it can only interact with my camera body at the minimum (5.6 or 8) apertures. Maybe someone more learned than myself can clear that mystery up for me.

[Mr Will]

RobbieKB said:

The only issue with it, which isn't a problem, is it can only interact with my camera body at the minimum (5.6 or 8) apertures. Maybe someone more learned than myself can clear that mystery up for me.

That's likely half the reason it's so soft, stopping down should improve things significantly.

Unfortunately old Sigma lenses have a compatibility issue with modern Canon cameras (anything post-2002) where the protocols changed leaving the lenses unable to stop down at all. Will likely work perfectly on an older body.

Sigma did offer a re-chip service for a time to get around this problem but most of the supplies of replacement chips have been used up by now. Still worth a call to them though, they were extremely helpful when I had exactly this problem recently with an old 28-70.

[RobbieKB]

Mr Will said:

RobbieKB said:

The only issue with it, which isn't a problem, is it can only interact with my camera body at the minimum (5.6 or 8) apertures. Maybe someone more learned than myself can clear that mystery up for me.

That's likely half the reason it's so soft, stopping down should improve things significantly.

Unfortunately old Sigma lenses have a compatibility issue with modern Canon cameras (anything post-2002) where the protocols changed leaving the lenses unable to stop down at all. Will likely work perfectly on an older body.

Sigma did offer a re-chip service for a time to get around this problem but most of the supplies of replacement chips have been used up by now. Still worth a call to them though, they were extremely helpful when I had exactly this problem recently with an old 28-70.

Yes that's a good point actually - thanks. I've heard nothing but good things about Sigma customer service.

Will the image be softer at widest aperture even if that value is raised? For example, the widest aperture is f/5.6 which will produce quite soft images. When I put the 1.4x teleconverter on, the widest aperture obviously raises with the focal length and I get a widest aperture of f/8.0. Now, f/8.0 is the sweet spot in terms of sharpness for a lot of lenses, so would it be sharper than without the teleconverter because the aperture has stopped up automatically or is the widest and narrowest apertures of a lens always the softest regardless of what the value is?

I think that made sense.

[Mr Will]

RobbieKB said:

Yes that's a good point actually - thanks. I've heard nothing but good things about Sigma customer service.

Will the image be softer at widest aperture even if that value is raised? For example, the widest aperture is f/5.6 which will produce quite soft images. When I put the 1.4x teleconverter on, the widest aperture obviously raises with the focal length and I get a widest aperture of f/8.0. Now, f/8.0 is the sweet spot in terms of sharpness for a lot of lenses, so would it be sharper than without the teleconverter because the aperture has stopped up automatically or is the widest and narrowest apertures of a lens always the softest regardless of what the value is?

I think that made sense.

It's only the effective aperture that is changing, not the actual one. You are still using all the lens and so it will still be just as soft (in fact softer due to the TC).

I'd expect the sweet spot on this lens to be a lot lower than f8 as well. Bear in mind it was designed for film which doesn't suffer half as badly from diffraction softness as digital.

[DibblyDobbler]

Not bad for £20 Rob! You could try using the dof preview button to set the aperture - along the lines of this :

http://www.dpreview.com/forums/thread/3238172

Not sure if it would work but worth a try

[...Mole...]

RobbieKB said:

400mm:



560mm:

I quite like the softness in those images actually, creates a really nice look.

[flat-planedCrank]

Well considering you cant buy a decent filter for £20 getting a 400m f5.6 lens seems like a bargain


I'd contact Sigma as well, see if you have options on getting control of the aperture

[budfox]

That looks painfully soft to me, and I have to say I wouldn't bother with it. I know it's more money, but for well under £70 you have the choice of loads of 70-300 Sigma lenses on eBay that will be hugely sharper. I grant you they don't reach 400mm, but a bit of cropping will sort that.