Aspheron lens, how to attach?

[Richard Corfield]

I've just aquired an Aspheron 6.5mm wide angle converter. It was made for a Bolex. The pictures look great when I hold the converter in front of the FX1 lens - hardly any barrel distortion - but short of glueing a 72mm thread ring on to the back, I've no idea how to attach it. Any ideas?

[Tom Hardwick]

Richard, you have mail from the Aspheron Guru. Don't even think about glue - that lens is heavy and expensive.

[Chris Wilkerson]

Does anyone in the US have one of these adapters. I acquired one about a year ago, but I still haven't managed to attach it to my XL2. I've talked to Tom and he sent me the plans to make an adapter ring for it, but I haven't been able to find anyone states-side that can make it.

If anyone in the US has found someone who can make the required adapter, please let me know.

[Tom Hardwick]

Chris - Richard (first poster here) has had a bayonet adapter made up for his FX1 by an Australian engineer, who copied the lens hood with a steel rule and a pair of calipers. I asked if he'd make me one too, but no go. I continue to screw mine on and delight in the wide-angle images.

tom.

[Nick Hope]

OK so I've finally got my Z1, my Aspheron, and a sacrificial spare Z1 hood ready to be chopped up in order to use it's bayonet mounting. With the amount of material and the construction of the hood I'd say it's looking promising to make a nice bayonet mounting solution.

I'll do some tests shortly but how far forward should this lens be mounted? Should it be right back as far as possible or further forward, perhaps even allowing room for a slim UV or polarizing filter behind it?

Tom Hardwick kindly sent me the attached sketch of the threaded adaptor he had made up (with an extra adaptor to fit a 58mm lens as well), showing that his is set forward a bit (I hope you don't mind me posting it Tom). But how critical is this distance?

[Tom Hardwick]

No-no Nick - the Aspheron needs to be used as close as possible to the Z1/FX1's front element, and if you look again at my quick sketch you'll see that the red adapter you'll have made up presses hard against the Aspheron and the Sony's filter thread. When this happens you get the tiniest amout (maybe 3 oixels) of vignetting at full wide on the Z1. The green one is another adapter allowing the use of this lens on the PD170, say.

I don't mind at all you posting it if it'll help people use the best wide-angle converter in the world. Remember the Z1 starts out with a 4.5 mm wide focal length, whereas the PD is 6 mm, so the combo is a lot less wide on the PD. The latter also has the VAP OIS spacing the Aspheron from the zoom's front element, but still there's no vignetting.

Nick, when you've made your bayonmet mount, be sure to let me have the plans, ok?

tom.

[Nick Hope]

Well Tom, as I'm not making a screw-thread adaptor I should be able to get it a little further back than your sketch and eliminate the vignetting, providing that doesn't entail cutting away too much of the hood's bayonet bits.

Just to clarify before I start cutting, if I was to physically hold the Aspheron right back into the front of the camera, with no adaptors in between... then that would be it's optimum position?

[Tom Hardwick]

Yes. The closer the better.

[Bob Hart]

Nick.

In Australia at least, there is a product which lends itself well to hanging things off the front of several camcorder types.

It is a sewer pipe cap, but not the heavy thick cap used for sealing permanent, but a thinner walled version which is referred to as a dust cap.

The end wall thickness is exactly the thickness of the channel the lugs of the lens hood mount goes into when it is turned. The downside is you cannot remake the screw lock arrangement without difficulty.

The product is "Ausplastics 100mm Dust Cap 31.100" Barcode is "9 323745 005552". There is likely a similar hardare item closer to you.

If you find it, check that there are no casting marks or rough die finishing on the inside surface. Some other cap products are much less precise on the inner face surface and thickness varies.

Iplex caps are stronger and thicker and require cutting or milling down.

There is another smaller cap in the ballpark of about 65mm but is too small for the FX1/Z1 bayonet mount. If you are going to do some hacking and drilling, I would be inclined to go this route first before wasting two Sony hoods getting it right.

The caps can be cut by a hot soldering iron, or with a Dremel with a small drillbit and trailing the side of the drillbit along the cut at an angle of about 50 degrees.

Go too slow and the plastic tends to melt instead of chipping. Go too fast and put too much pressure on and the plastic melts as well. There is a happy middle ground.

[Nick Hope]

Thanks for the advice Bob but I lived dangerously and went for it. I'm relieved to say it's been very successful. I have uploaded some annotated pictures here:

http://www.flickr.com/photos/1698776...7594342654330/

See the symbol for viewing the large sizes.

Destructions:

1. Completely disassemble the lens hood except for the little thumbscrew that locks the bayonet. Only the largest outer part of the hood assembly is used, the rest goes in the cupboard as spares for your other hood.

2. Snap off the little spindly upstands inside the hood. I think there were 4 of them.

3. Cut the two large slots in the top and bottom of the hood. Leave a tongue on one of them (like I didn't). Both don't need to be full rectangular slots to hook the Aspheron in. Note that in a perfect world I got my slots the wrong way around. I think the slit for assembly (under the gaffer tape in my pic) would have been better on the bottom, not top, of the hood. Actually I thought that's where I was putting it because I was thinking of my VX2000's thumbscrew which I think is on the bottom, not the top of the hood (?).

4. Cut the crescent-shaped upstands in the hood fairly near to the bottom. Judging how much to leave is the most difficult part of the whole job to get right. There's hardly any plastic left above the thumbscrew afterwards but just enough to keep it working and strong enough. I'm afraid there is no pic of the insides because I'm nervous about disassembling everything again and cracking the hood.

5. Cut the plastic back inside around where the lever was to operate the hinged shutters.

6. Insert the Aspheron. You will need to do this many times until the fit is right as you remove a bit of plastic at a time. Be careful because it would be easy to crack the hood when the Aspheron is snapped in.

7. Cut back the corners and sides of the hood until they don't appear in shot. There is no vignetting from the Aspheron itself but the corners and sides of the hood appear on full wide. Go menu > others > assign button and set up allscan mode so you can see the whole picture during testing.

The initial machining is best done on a milling machine, but I don't have access to one so I used a dremel and hand files.

I removed the rubber grip ring on the Aspheron during testing and fitting but replaced it at the end.

I also made a little brow for the top out of a DVD box, but it doesn't give much shade. I should have made it a bit wider.

Seem to me it would be quite straightforward to cut a slot in the hood to allow 4" x 5.5" filters in without the edges being in shot. That applies to the standard hood too. What do you think?

No idea yet what I'm going to do about lens caps for the Aspheron as neither the front nor back one fit now. Any ideas? I might just keep the whole thing in one of these for quick access and try to keep it spotlessly clean inside:

http://www.lowepro.com/Products/Belt...rion_Mini.aspx

Nick

[Tom Hardwick]

A most excellent job you've done Nick, and your stills and notes make the modification look pretty straightforward. What's a dremel? I flunked metalwork at school. Good to hear what you'd do on your Mk II version as well.

As to filtration up front I'd be very wary. We're dealing with a focal length of 2.3 mm and as the Aspheron is at it's best focused at 1.5 metres (actual, not on the Z1's scale) the dof can easily encompass the front surface of the Aspheron - as you'll immediately find out if you shoot into the light with a lens that isn't ER spotless.

So your thoughts on lens caps are timely. When I remove my Aspheron the front cap goes on first, then I unscrew it and screw on the rear cap, then it slots into my 'ammo belt' around my waist. This has a velcro flap and holds the Z1's hood and Aspheron caps when the Aspheron's on camera.

tom.

[Martin Mayer]

Originally Posted by Tom Hardwick

........... What's a dremel? .........

Available in B&Q (in UK!), etc.... :)

[Tom Hardwick]

To put the Bolex Aspheron into perspective it is a 0.52x wide-angle converter that costs £420 and converts the Z1 / FX1 into a non-distorting 2.34 mm to 15.2 mm zoom (17 mm equivalent) going from f/1.6 to f/2.2.

Canon sell a wide-angle zoom for their XL-H1 (HDV). This is a 3.4 to 20.4
mm zoom going from f/1.6 to f/2.6. So it's a lot less wide (21 mm equiv), has less zoom, is slower and costs a whopping £2291.25

Makes the Aspheron look like some sort of bargain, but then again I'd expect the Canon lens to have much better control over chromatic aberation, it has a better hood and is designed for the HDV format.

Just a thought.

tom.

[Nick Hope]

I will try and post some shots with and without the Aspheron, when I've got some appropriate footage.

Actually the tool I'm using is not a Dremel. It's a similar Taiwanese tool called a Talon. Good quality and cheaper a Dremel. It's a bit like an electric screwdriver but has variable speed and takes all sort of little tools for cutting, grinding and polishing. The tool I used for most of this job was like a mini milling cutter. I rested the dremel on an appropriately thick book and then slid the hood around to keep the slots straight. Worked well.

I take your point about the filter Tom. Might be an idea for the standard lens though? Could save the cost of a matte box if one's on a tight budget although it would have barely any shade.

[Tom Hardwick]

For all the same reasons I'm not keen on filtering the standard lens either. There are times when you must (polarisor, dust, salty spay, sticky-fingered kids parties) but otherwise no.