Bert - It appears that you have a filter of some type in front of the WA converter - did you try things with this off to see if the sharpness/CA in the corners improves?

- John

I've never known a filter to reduce sharpness (unless it was smeared with vaselene for that express purpose) but I have seen them vignette the image corners and I have seen them add considerably to the lens flare.

tom.

I always use high grade filters with my lenses, in this case a low profile B+W filter, and never had a problem. In any case, I took a couple of shots with the filter removed, and it made no difference: The center region, roughly 60%, is sharp but the rest of the image is blurred. Could someone post some samples shot with a Canon wide angle adapter?

http://img464.imageshack.us/img464/8...filter1lf9.jpg

http://img464.imageshack.us/img464/1...filter2xa6.jpg

Bert - I've just had a thought. Are you using the camera /widie combo in the auto-focus mode? I'll take a guess and say yes, because I see the same 'whoosh' edge effects with some of my converter lenses.

Might be worth trying this. Place your camcorder/widie combo in the auto-focus mode about 3 feet from something contrasty and then lock the focus at that distance. At all apertures and at wide-angle you may well find the image quality improves noticeably, the DoF covering everything from element front to infinity

If you zoom in things will deterioriate of course, but then I've always maintained a wide-converter is for wide shots, and anything else should be done by your unaided zoom.

tom.

Oh-oh. I've had another think. Your second shot is just that right? A 3 foot close-up of the get-fit notice, yet the edges are quite poor. And the barrel distortion is nothing short of horrible. Doesn't look like a good combo to me.

Do you think it's just a bad/defective WA converter or would ALL of these models perform poorly? The Century optics web site specifically lists the HV10 for this converter (but perhaps only because it shares a 37mm filter thread) and some other threads have indicated that Century optics are typically best in their class (mayber they are in the low class though).

- John

There is another older post in the FX1 section with sample pics of the Century non zoom through. It was either a .5x or .6x, I don't remember. But I do remember the pic. Big time barrel distortion.

http://www.dvinfo.net/conf/showpost....8&postcount=10

From what I've seen online, barrel distortion may be a common problem with wide angle adapters: Pana DVX100 with Century Optics WA adapter, how about this sample with the 0.55x Century Optics adapter. Edge sharpness seems to be a common problem too, although the poster of this sample of a Tiffen 0.56x WA converter says that he finds no edge sharpness issues with the lens, the loss of resolution at the edges looks pretty obvious to me.

Barrel distortion is indeed a common problem with wide-angle converters. In fact most camcorder zoom lenses barrel distort pretty horribly down the wide end on their own, and a converter lens only adds to this.

Simple test. Stand a few feet from your flat-screen TV, zoom your camcorder to full wide and move so that the TV frame (either 16:9 or 4:3) fills your v'finder. See the curvy edges? It's your cheap camcorder lens doing that.

The only way to combat this barrelling is to abandon all thoughts of zoom through converter lenses and fit a single element aspheric.

tom.

Tom - Do you have any suggestions for a single element aspheric? Is this what you mean: http://www.schneideroptics.com/ecomm...=1069&IID=1754

- John

That looks to be a very interesting lens John, especially so if their claim that it is ''without noticeable distortion''. Trouble is they don't mention anywhere that it has an aspherical surface, and that makes me suspicious of their claim. Very suspicious. Aspherical elements are very much more expensive to grind and every single sperical element I've used has increased my barrel distortion - regardless of the camera I've used.

Still, I'm not one to make claims without having made tests, so all I can say is that someone (you?) should. But I'd want a water-tight returns policy in case it did just happen to add barrel distortion.

These people make proper aspherics:

http://www.lenswvl.com/
http://cinematechnic.com/products/ze...6mm_Zeiss.html
http://www.wittner-kinotechnik.de/ka...a/b_optike.php
http://www.wittner-kinotechnik.de/ka...a/b_optike.php

I have the Bolex Aspheron. It's big, powerful (0.52x) beautifully T* coated and takes my Z1 down to a non distorted 17 mm (35 mm equiv). Now that's a focal length to make Krubrick sit up and take notice.

tom.

John - I see on that Schneider site there's an 'ask a question' box. So I've asked:

Your .55x wide adapter 37mm.

1) Is it glass?
2) Does it have an aspherical surface?
3) Is it available in other thread sizes?
4) Is it multi-coated?

Kind regards,

tom.

Tom -

Thanks for asking Schneider those questions. On a related note to one of my other threads - is there an advantage to using a WA adapter that is larger than you need so that you aren't using "all" the glass? I've read a few posts where people have reportedly used, for instance, a 49mm WA adapter when all they needed was a 37mm and claimed improved corner sharpness.

- John

BTW John - my 'is it glass?' question comes about because aspherical surfaces lend themselves to plastic high pressure injection moulding techniques, and Schneider they call their 0.55x a 'lightweight'.

I can't see any reason whatsoever to use the 'centre of the element', unless of course the edge is scratched, not coated, unpolished or dirty. My guess is these people are seeing better definition because they think they should, and because they're shooting at better apertures and focused distances.

When you've got a wide-angle on it's imperative you avoid small apertures as diffraction losses are far more obvious at short focal lengths.

tom.

This is one of the lenses that I found a posted sample image. Its barrel distortion is certainly nothing to get excited about...

http://www.camcorderinfo.com/bbs/att...ntid=917&stc=1