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Small jewellery - reversed lens trial
Lens: Reversed FA 43 ltd Camera: K-x Photo Location: Toowoomba, Queensland, Australia ISO: 3200 Shutter Speed: 1/20s Aperture: F8 
Posted By: Ash, 01-20-2011, 04:38 AM

Just curious to know how a reversed 43 would go... pretty decent and would be even better if my skills were up to scratch. All handheld without flash:







Anyone have an idea whether the focus ring on a reversed lens bears any significance to the resultant focusing of the image? I haven't seen any effect from my few little experiments.
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01-20-2011, 05:47 AM   #2
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These look outstanding to me, Ash.

Jer
01-20-2011, 06:54 AM   #3
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"Anyone have an idea whether the focus ring on a reversed lens bears any significance to the resultant focusing of the image? I haven't seen any effect from my few little experiments."

No with a simple lens....in that case the focusing ring simply moves the lens away from the sensor...but when the lens is reversed it stays a fixed distance from the sensor and the focusing ring just pushes the lens barrel out into the air "in front of" the reversed lens.

Reversed Internal Focus lenses will change macro characteristics when the focusing ring is moved; that's because changing the focusing ring changes the focal length of the lens. I think the usual case is the focal length decreases as the focus is moved closer than infinity...this will increase the magnification.

Say a 100mm lens is focused at infinity: it is 100mm from the image plane. Now shorten its focal length to 50mm while keeping it 100mm from the image plane. The equation connecting image distance, focal length and magnification is:

ImageDistance = FocalLength(1+m) or 100=50(1+m)

m = 1x

So decreasing focal length while keeping the distance to the image plane constant increases magnification. In general, cutting focal length in half gives a magnification of 1x.

Dave

Last edited by newarts; 01-20-2011 at 08:16 AM.
01-20-2011, 03:20 PM   #4
Ash
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Thanks Jer.

Great explanation Dave. Much appreciated.

01-20-2011, 06:31 PM   #5
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great shots, I am still not clear on why a person would reverse, I guess the magnification, but why not use a macro lens. I have so much to learn, so little time. thanks Bob
01-20-2011, 09:17 PM   #6
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Bob, reversing an old 28mm lens or something of that vintage gives a photographer an effective means to capture macro images without the need for a dedicated macro lens, which is considerably more expensive.

I definitely have a preference for my FA 100/2.8 macro if closeups are what I'm after, but these reversed lenses can give you even more than 1:1 magnification - all dependent on whether or not you attach extension tubes to the lens, and what length of extension tubes you attach. Then you can get into the realms of extreme macro that dedicated macro lenses cannot get to.
01-20-2011, 11:00 PM   #7
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QuoteOriginally posted by Ash Quote
Bob, reversing an old 28mm lens or something of that vintage gives a photographer an effective means to capture macro images without the need for a dedicated macro lens, which is considerably more expensive.

I definitely have a preference for my FA 100/2.8 macro if closeups are what I'm after, but these reversed lenses can give you even more than 1:1 magnification - all dependent on whether or not you attach extension tubes to the lens, and what length of extension tubes you attach. Then you can get into the realms of extreme macro that dedicated macro lenses cannot get to.
thanks so much for the explaination, now I understand the what and why. I have always wondered how some of the images are obtained. I guess I am not too old to learn. Bob
01-21-2011, 03:01 AM   #8
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Always worth a try too with a couple of bucks for a reversing adapter with your bump & scratch 28mm prime...

All you have to know is the filter thread size and get the necessary step-down/up filter (if needed) to hitch it up. And you have a decent macro setup, just like this guy shows us: Flickr: Thomas Shahan's Photostream - see his video here:

[yt]http://www.youtube.com/watch?v=wqRn3at0H60[/yt]

01-23-2011, 05:57 PM   #9
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QuoteOriginally posted by Ash Quote
see his video here:
Thanks for the link.
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