DVX Semi-Fisheye Lens project, $100
 

Greetings again DVX owners!

Although I am excedingly happy with the relatively wide angle lens that comes glued to this camera, there are many times when a wider angle lens is really necessary.

Indoors in cramped areas, of when you just want that super wide angle effect.

I haven't seen a 72mm .3X lens for this camera yet, and certainly not one under a gazillion dollars.

So I made one.

I used a Raynox .3X clip on as a base, and I have found my lens to do everything I wanted it to. Total cost is about $100, and its pretty darn easy to put together.

Enjoy the detailed instructions with photos here:

Thanks, and enjoy

http://www.neilslade.com/Papers/DVXlens.html

Neil: the photos on this page don't load for me, just like your LCD hood project. However your jib, GL-2 lens, boom pole and wind pal pages all display fine.

FIXED NOW
 

Fixed it--- I started using a new web page editor-- missed something. Thanks

neil, i would love to see some shots w/ this modified lens...thanks...

Will post
 

Will do-- give me a day or so, before Mon. for sure-- I'll put them up on the web page..

cool very cool.. !

got my cheap glass on order....how is the quality of the glass?? can you please post some shots from that lens setup like that?

Thanks for the post and site - excellent directions. But what about the glass quality?

DV is extemely vulnerable to contrast and sharpness loss at wide angles - do you have some high rez grabs to compare resolution with Century Optics models?

Photos posted
 

I added some comparitive photos on the web page now, look at the bottom of the page:

http://www.neilslade.com/Papers/DVXlens.html

There are a couple of things to keep in mind concerning this lens, but none of these should disuade anyone from using or making such a project.

1) We are using a single element Raynox llens as a base. This is not a multi-element lens, but it is also only going to cost you $100. I have not noticed any apparent practical quality problems arrising from this lens under normal use. I don't get flaring, false colors, or loss of sharpness. It looks very good to me. If you are using your footage on normal TVs, believe me, the amount of quality loss you experience is going to be a great deal more than you would ever see between this lens and any other lens anyway.

Additionally, This is a .3X wide angle lens, not a .5X wide angle lens like the commercially available DVX adapters, so you can't directly compare.

Know that a wide angle lens moves the images VIRTUALLY farther away from the camera's central focal point, and more so the further you go from the center of the picture. Naturally, objects will lose detail as the move away from the virtual camera image, so don't expect the same level of detail on edge objects using the lens, as you would get not using the lens. It's impossible because they are virtually farther away from the camera.


2) You CAN'T make high resolution still grabs with the DVX. It's not made for that purpose. You are limited to the pixel resolution of the CCD, unlike other consumer cameras that allow 1 and 2 megapixel still photos. The highest resolution still you can get from the DVX is a mere 327 X 240.

Although the still images look pretty meek, there is still not a camera under $30,000 that produces sharper and higher quality video that I've heard of.
Of course, this will change before you know it.....! Doesn't it always? The JVC HD camera has severe limitations in terms of color and sensitivity that the DVX does not.

Of course, this will change before you know it.....!

It's pricey, but Century Optics has added a .3x fisheye for the DVX100:

http://www.centuryoptics.com/product...ra_fisheye.htm

This gives a 130 degree FOV - what FOV does your kit offer?

Century Optics
 

The Century Optics lens is $800....!

Normally, I would say that this is like comparing apples and oranges.

However, my educated guess is that there little detectable difference, no where near as much difference in performance between these two lenses as you might find between a $100 camera and an $800 camera.

Sometimes, you get what you pay for, other times, the difference is very minimal.

Raynox has a good reputation, and all of my Raynox adapter lenses are satisfactory for me. And I am not blind, and have a rather discriminating eye.

When I use my lens in front of my Leica lens, I see no reduction in apparent quality. And that's the botom line.

Both are rated .3X so the focal length should be the same. The sample video on the Century Optics site looks just like the kind of widest video I get with my lens. Look at my web page pictures too.

Per vignetting, The Optics ad says "vignetting occurs". My lens has a direct 72mm screw mount which puts the back part of the lens right next to the DVX square cut out inner lens shade. This is as close as ANY lens can get without removing the inner shade.

If you look carefully at the sample video on the Century description page, you see a little vignetting in each corner. I've avoided this in three corners of mine even at the widest setting when viewed on a TV.

Also not, Century OPtics says, "No zooming".

2/3 of my zoom ability is retained with my lens- no refocussing necessary. 4.5-17 setting on my camera lens markings.

The Century Optics lens is 2 Element, and the front diameter is 112mm, whereas the Raynox is single Element and only about 72mm front diameter. Yes, I would imagine the Century lens is a fine lens, and optically- on paper and under the microscope- a better lens.

But I am excedingly happy with the DIY one, and I haven't noted any problems in any circumstance. Go get one, make mine, and let us know the differences ;-)

I've done a lot of work with wide-angle converters on DV cams, and you might like to go here:
http://www.fortvir.net/index.php
and have a look at tom's photo album. I show the Bolex Aspheron on the VX2k and the one magnificient overriding beauty of this lens is the complete lack of barrel distortion.

I've used wide-angle lenses made by Century, Raynox, Kenko, Cavision, Canon, Panasonic and Schneider, but none comes close to this Aspheron. I just got sick of having door frames bend and bow outwards as I went through them.

tom.

Re: Photos posted
 

<<<-- Originally posted by Neil Slade : The highest resolution still you can get from the DVX is a mere 327 X 240. -->>>

That's a curious statement. When in progressive mode, every frame the DVX shoots is a 720 x 480 still. Your capture software should allow you to extract one of those frames. You definitely can get 720x480 stills, although they'll be at DV aspect ratio, you'll probably want to re-size 'em in PhotoShop to be 640x480.

Various
 

1) Barry, Oh yes yes-- I goofed, when I made my grabs from my DVX progressive stills I had my Vegas Video project settings incorrect, set for 29fps interlaced. . Fixed, now and I reposted the pictures twice as big, and a much better representation. The lens seems to actually perform better the wider you zoom out.
http://www.neilslade.com/Papers/DVXlens.html



2) I looked at the Aspheron lens and a couple of things of notice- It is a .5X lens, and I do note the lack of barrel distortion (pretty darn cool)- but this lens, other than used examples, can't be found on the web. It looks like it was manufactured for 16mm film cameras.

Once you get into semi-fisheye and fisheye lens (.3X and greater) barrel distortion is just part of the equation. It's normal optics.

The Aspheron seems to be made very small diameter lenses and unadaptable for large diameter cameras like the 72mm DVX or anything even close to this. I'm only guessing, but the absense of barrel distortion may be a combination of the.5X strength and the very wide ratio of front lens diameter to rear lens diameter, i.e. to require this kind of performance on a 52mm or larger lens would require a lens a foot across. (like I said, only guessing here)-- and that's why you don't see them made by anyone. I would love to hear from a real technical lens expert on this-- something I am not.

Please note, even the normal Leica lens on the DVX starts to show barrel distortion at the widest setting.


Thanks

You're absolutely correct Neil - the Bolex Aspheron was made for the 16mm Switar zooms and is only available new from Bolex in Switzeralnd - at frightening cost. You say:
''barrel distortion is just part of the equation. It's normal optics.''
but it's only ''normal optics' if you talk of spherical lenses. Aspherical lenses (like the Aspheron) can be made any power you like, and barrel distortion will be controlled.

Interesting point you make about the DVX100 as the Aspheron works beautifully on that camera. So no - you don't need a lens a foot across. And my guess is that (like on my VX2k) it removes the inherrent barrel distortion that comes supplied as free with the original zoom. The lens actually has a small amount of pincushion distortion to correct such faults.

tom.