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10mm Angenieux and Close-up lenses?


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#1 Sir Alvin Ekarma

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Posted 08 August 2014 - 02:21 PM

I'm doing some lens tests soon and I have a question: can close-up lenses be used to increase the DOF of the angenieux at a wide aperture? According to some threads here, five feet away is as close as you can get with the lens wide open and I wanted to see if throwing something on would negate that. I know the lens thread on the angenieux is barely there so I'd have to tape it all together, but has anybody tried this?


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#2 Stuart Brereton

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Posted 08 August 2014 - 06:03 PM

A close-up lens, or Diopter reduces the minimum focus distance of a lens. It has no effect on Depth of Field.


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#3 Brother Power

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Posted 08 August 2014 - 06:35 PM

Nuts. So diopters do zero for fixed focus lenses?


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#4 Jean-Louis Seguin

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Posted 08 August 2014 - 06:54 PM

Are you shooting film or digital?
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#5 Sir Alvin Ekarma

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Posted 08 August 2014 - 08:11 PM

Film. 


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#6 Jean-Louis Seguin

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Posted 08 August 2014 - 08:16 PM

You can always focus closer by loosening the three setscrews around the base of the lens but with the 10mm but judging exactly where you're focused at is not easy with most viewfinders which is why Angenieux chose to lock the focus ring at the hyperfocal distance in the first place.
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#7 Sir Alvin Ekarma

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Posted 08 August 2014 - 08:24 PM

Oh well. I do have a Cinegon I can use in a jam. I have a turret-style beaulieu now and the cinegon doesn't give clearance to my arri-s style matte box, thus the Angeneiux. I can figure out what works best after I shake it down. Thanx for the info :)


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#8 Gregory Irwin

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Posted 08 August 2014 - 08:24 PM

You can always focus closer by loosening the three setscrews around the base of the lens but with the 10mm but judging exactly where you're focused at is not easy with most viewfinders which is why Angenieux chose to lock the focus ring at the hyperfocal distance in the first place.


Loosening screws on a wide angle lens?? Risky!! That sounds like a depth of FOCUS disaster in the making. I would go with diopters.

By the way, how many names do you post under Sir Power? So... Complicated.

G
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#9 Sir Alvin Ekarma

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Posted 08 August 2014 - 08:28 PM

@G. Irwin  I'm a complicated man that nobody understands but my woman.


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#10 Jean-Louis Seguin

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Posted 08 August 2014 - 08:34 PM

Risky? Not if you know what you're doing.
But then again I am a lens technician.
Diopters degrade image quality substantially when the iris is wide open.

Jean-Louis
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#11 Gregory Irwin

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Posted 09 August 2014 - 12:20 AM

With all do respect Jean-Louis, there are not many out there on set with your qualifications. Thus, the disaster. I have a physical optics background and I would be reluctant to do that - in the field and with time constraints. I agree with you about diopters degrading an image but I would argue that any lens wide open is a degraded image in many ways. If it's a trade off of a degraded image when compared to an out of focus image, I would choose the former. Especially when referring to such a wide angle.

G
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#12 Dom Jaeger

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Posted 09 August 2014 - 05:10 AM

I'm doing some lens tests soon and I have a question: can close-up lenses be used to increase the DOF of the angenieux at a wide aperture? According to some threads here, five feet away is as close as you can get with the lens wide open and I wanted to see if throwing something on would negate that. I know the lens thread on the angenieux is barely there so I'd have to tape it all together, but has anybody tried this?

 

 

The only real way to increase the depth of field is to stop the lens down. To make a fixed-focus lens like the 10mm Angenieux focus closer you need to move it away from the film plane a bit. Re-setting the lens back-focus as Jean-Louis suggested is easy enough for a lens technician, but another solution that doesn't interfere with the hyperfocal factory setting is to cut a washer-shaped shim out of some thin plastic sheet to a size that just fits over the lens mount threads and fit it before screwing the lens on. The thicker the shim the closer the lens will focus (and the more out-of-focus infinity will become). One or two tenths of a mm are enough to shift the fixed plane of focus substantially closer on a lens of this focal length. By simply removing the shim the lens returns to normal.

 

For fixed-focus wide angles like this shimming the lens out (or adjusting the back-focus by other means) is a better solution than using close focus diopters.


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#13 Jean-Louis Seguin

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Posted 09 August 2014 - 06:41 AM

Yes, Dom is right. Shimming is the preferred way to go. I just came back from a friend's funeral and my head is not thinking straight right now.

JL
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#14 Bengt Freden

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Posted 09 August 2014 - 06:42 AM

Ingenious, Dom!

I have a (rare black) Angénieux 1.8/10mm lens, that I bought recently off eBay from Germany. I will certainly try the 'shim' option, which sounds really nice and very easy and cheap to do. It could even be cut from black cardboard (yes, I am a card modeler, too).

That would then function as a very thin 'extension tube', which is always a better solution optically than a diopter or close-up lens.
If you use a diopter, you have to stop down the lens at least two stops (sometimes three) if focus at the edges of the frame is critical. And when filming that is not always so easy, for example on Vison3 50D stock.

Best regards,
Bengt in Stockholm


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#15 Gregory Irwin

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Posted 09 August 2014 - 07:24 AM

I guess that I'm looking at these solutions as a temporary, on set fix for a specific shot. Then I would want to restore the the intended use of the lens right then and there. Shimming is a great solution. Again, I wouldn't want to do this in the field under time constraints. I must say, we used Schnieder diopters regularly on Christopher Nolan's INTERSTELLAR in order to get closer in the IMAX format. The 65mm images are beautiful at a T2.

G
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#16 Brother Power

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Posted 14 August 2014 - 08:43 AM

Update: so I also dropped this question to Bernie at Super16 since he's a stand-up guy and will be doing my U16 conversion. Anyway, he said it would work so I got some close-up lenses, and per the usual, he was right on the money. I did an eyeball test indoors while looking through my 10mm angenieux, wide open at 1.8, and the image was soft, but add one +4 close-up lens and pow! It snapped into focus. I still need to know how close I can get and to do some film tests so I'll post again once that's done.


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#17 Sir Alvin Ekarma

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Posted 08 September 2014 - 11:37 AM

So I got my camera tests back and the 10mm Angenieux plus diopter didn't do so hot. I didn't do a comparison with/ without (and I should have, my bad-- I had a lot lenses to test and I'm a budget) but with the diopter on the lens and at all the f-stops I tried (16, 5.6, 2.8), it was soft and since it's a fixed focus there's not much you can do with it. As I said, eyeballing it, it looked fine in the viewfinder, but it totally didn't resolve on film, plus the 10mm cinegon I tried it against totally destroyed it. I have one more set of tests to do and I'll give it another whirl without the diopter, but I'll probably put it up on the Ebay pretty soon. 


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#18 Mark Dunn

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Posted 08 September 2014 - 11:47 AM

OP, are you actually entitled to the honorific 'Sir'?


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#19 Sir Alvin Ekarma

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Posted 08 September 2014 - 12:17 PM

OP, are you actually entitled to the honorific 'Sir'?

You bet.  I got the hat and everything from Burger King. I got it for messin' up the Hamburglar in the Sandwich Wars of '75.


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#20 Mark Dunn

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Posted 08 September 2014 - 01:04 PM

Reported.


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