OT: Explain Wideangle 0.45x vs. 0.7x, etc. for HV20 at DVinfo.net

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Old August 17th, 2007, 12:39 PM   #1
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OT: Explain Wideangle 0.45x vs. 0.7x, etc. for HV20

Okay, as most know I have the Merkury Wideangle lens for my HV20 which is 0.45x. (it's a wider picture), but I've searched for an answer and still come up empty. If I want to capture an even wider image, pushing more towards fisheye (but not really looking too fisheye), then what would the lens be? I don't understand how the numbers work. Would a 0.7x be an even wider image? I'm wanting to experiment with capturing home interiors from a 360 degree rotating stand that the HV20 is sitting upon and the 0.45x Merkury is still not wide enough in my opinion - I want to go wider and capture even more of the room in the video.
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Old August 17th, 2007, 01:11 PM   #2
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Those numbers like .45x refer to how much magnification the adaptor lens adds to the builtin lens. So a 1.00x lens would have no effect - it would be 100% of the normal image size. Numbers smaller than 1.00x give a wide angle effect. As the numbers get smaller your field of view gets wider, so a .70x adaptor is not as wide as a .45x. OTOH, a 1.50x lens would magnify the image by 150% and give you a telephoto effect.

.45x is relatively extreme for a wide angle adaptor and they typically introduce significant barrel distortion (the horizon line turns into a curve for example). Although I'm not familiar with accessories for the HV20, the adaptor lenses I've seen for other cameras are indeed usually fisheyes when you get into the .30x sort of range.
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Old August 17th, 2007, 01:24 PM   #3
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Originally Posted by Boyd Ostroff View Post
Although I'm not familiar with accessories for the HV20, the adaptor lenses I've seen for other cameras are indeed usually fisheyes when you get into the .30x sort of range.
Thanks for your answer. That's the odd thing about using the Merkury lens on the HV20, it doesn't look very curved at all. But...I bought a lens adapter tube for my Canon A630 digital camera that allows me to attach this Merkury lens to it and the still images are definitely more curved looking on the digital camera than they are on the HV20. Besides, this Merkury lens is probably actually designed for a digital still camera and not a video camera. But you answered my question - smaller numbers mean wider images.
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Old August 17th, 2007, 07:33 PM   #4
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Originally Posted by Nathan Shane View Post
Thanks for your answer. That's the odd thing about using the Merkury lens on the HV20, it doesn't look very curved at all. But...I bought a lens adapter tube for my Canon A630 digital camera that allows me to attach this Merkury lens to it and the still images are definitely more curved looking on the digital camera than they are on the HV20. Besides, this Merkury lens is probably actually designed for a digital still camera and not a video camera. But you answered my question - smaller numbers mean wider images.
Nathan - your Merkury isn't .45x - it's roughly .75x, even less wide than the Canon WD-H43. That's b/c of the macro lens that sits behind it. Take off (unscrew it) and you have a .45x semi-fisheye (hence the ".45x wide angle"). Problem is, there's no way to mount it on your HV20 without the macro lens. Best I can tell the rear thread is 53.5mm. So you'd essentially need a 52mm (or whatever you're using to step up from 43mm) to 53.5mm step up ring. I couldn't find any.
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Old August 18th, 2007, 01:18 AM   #5
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Nathan - your Merkury isn't .45x - it's roughly .75x, even less wide than the Canon WD-H43. That's b/c of the macro lens that sits behind it. Take off (unscrew it) and you have a .45x semi-fisheye (hence the ".45x wide angle"). Problem is, there's no way to mount it on your HV20 without the macro lens. Best I can tell the rear thread is 53.5mm. So you'd essentially need a 52mm (or whatever you're using to step up from 43mm) to 53.5mm step up ring. I couldn't find any.
Ahhhh...thanks for bringing this to my attention, now I know why I'm not getting enough wideangle. So I guess now I'll need to go find another widescreen lens (like the Canon one) to use in addition to this Merkury. Like you, I was thinking the wideangle lens itself was a 53 or 53.5mm and looked for a step up ring - and I couldn't find any either. So are you saying that the Canon WD-H43 doesn't use a macro lens, it's just a single wideangle lens by itself? Is this how most wideangle lenses are - just a lens only, no macro with them?

I just did an experiment, looking through the Merkury lens with my bare eye (no camera) and I now understand that as I look through just the wideangle lens itself, it's a very fisheye look with an image that's much smaller and further away looking, and then when I attach the macro, the macro brings the image closer back to it's original size (but much wider).
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Old August 18th, 2007, 01:31 PM   #6
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I may be mistaken but I believe all wide angle lens would have to use a macro in the mix. Think about it...as the images get wider and wider on the outer lens it would have to get smaller and smaller for it to fit in the len's view... therefore the needed macro lens would have to get stronger and stronger in order to bring it all back into view.

I don't have one myself but this seems to make sense to me. Someone correct me if I'm wrong.
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Old August 20th, 2007, 11:36 AM   #7
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Originally Posted by Ian G. Thompson View Post
I may be mistaken but I believe all wide angle lens would have to use a macro in the mix. Think about it...as the images get wider and wider on the outer lens it would have to get smaller and smaller for it to fit in the len's view... therefore the needed macro lens would have to get stronger and stronger in order to bring it all back into view.

I don't have one myself but this seems to make sense to me. Someone correct me if I'm wrong.
The Canon may or may not incorporate macro elements in it's mix - but it is only one piece of glass. There are not two separate/ separable elements. The cheap 3rd party wide angles seem to share the same removable macro setup - which is fine, but they should provide an adapter ring so you can use the fisheye portion on it's own.

Nathan - as far as the conversion goes, the Canon WD-H43 is .7x. My guess is the Merkury 52mm/67mm (silver) is closer to .8x . Not a huge difference but noticeable when you compare them head to head. The Merkury 52mm/62mm (black) on the other hand, appears identical to the Canon (.7x) at full wide.
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Old February 24th, 2008, 01:56 PM   #8
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Find anything?

Nathan,

I too have that Merkury and find it's not wide enough. Did you ever find something wider in the same low cost range? How about and adapter allowing you to unscrew it?
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