How to achieve 5:1 magnification ?

falconeye · 05-18-2010, 05:19 PM

Originally posted by newarts

The combination of a 300mm lens reversed in front of a 300mm lens will have a magnification of 1:1 and a working distance equal to the registration distance.

I stand corrected. You're right.

**pentaxman** · 05-18-2010, 08:42 PM

I think I am understanding what you are asking now. Since the original photo was 4672 pixels wide and covered 2.5mm, the pixel size was 0.53 um. When I uploaded the original file to flickr, the site resized the photo and did not keep a copy of the original size. I am sorry to say that I don't have the original.

Tom

Originally posted by falconeye

I wondered if you would understand what I mean.

A pixel with a K20D/K-7 displays 5µm at 1:1 and 0.5µm at 10:1.

However, if you're downscaling to 1024 for the web, this becomes 23µm and 2.3µm resp.

You may still call it 10:1 but it is meaningless. A 3x2px photo at 10:1 would have 0.8mm wide pixels and stll you would call it 10:1 ...

Marc Sabatella · 05-18-2010, 10:05 PM

Originally posted by glasbak

It is still a wide angle, with the same focal length, but normally it projects the huge world onto a small sensor, exchange world and sensor, then it projects a sensor sized part of the world onto a huge image circle.

I think at this point we're quibbling over what it means for it to be a wide angle lens. Something that takes creates an image with a small FOV is pretty much by definition not wide angle as far as I'm concerned.

Klaus · 05-19-2010, 12:23 PM

I think best an easyest is combining rings with TCs.

If you have 50mm macro, 50mm of rings plus a 2x TC gives you scale 4:1. With a 90mm macro it has to be 90mm of extension plus the TC…

The rings have to go between lens and TC.

I have used this sort of combination and the results are good. You will need an adecuate flash system. I am using 2 360 fgz mounted above and below, to a side, with home-made bar, using wireless sync of K10D.

Cheers - Klaus

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05-18-2010, 05:19 PM	#76
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871	Originally posted by newarts The combination of a 300mm lens reversed in front of a 300mm lens will have a magnification of 1:1 and a working distance equal to the registration distance. I stand corrected. You're right.

05-18-2010, 08:42 PM	#77
pentaxman Site Supporter Join Date: Oct 2007 Location: Washington Photos: Gallery Posts: 250	I think I am understanding what you are asking now. Since the original photo was 4672 pixels wide and covered 2.5mm, the pixel size was 0.53 um. When I uploaded the original file to flickr, the site resized the photo and did not keep a copy of the original size. I am sorry to say that I don't have the original. Tom Originally posted by falconeye I wondered if you would understand what I mean. A pixel with a K20D/K-7 displays 5µm at 1:1 and 0.5µm at 10:1. However, if you're downscaling to 1024 for the web, this becomes 23µm and 2.3µm resp. You may still call it 10:1 but it is meaningless. A 3x2px photo at 10:1 would have 0.8mm wide pixels and stll you would call it 10:1 ...

05-18-2010, 10:05 PM	#78
Marc Sabatella Veteran Member Join Date: Sep 2006 Location: Denver, CO Photos: Gallery Posts: 10,685	Originally posted by glasbak It is still a wide angle, with the same focal length, but normally it projects the huge world onto a small sensor, exchange world and sensor, then it projects a sensor sized part of the world onto a huge image circle. I think at this point we're quibbling over what it means for it to be a wide angle lens. Something that takes creates an image with a small FOV is pretty much by definition not wide angle as far as I'm concerned.

05-19-2010, 12:23 PM	#79
Klaus Senior Member Join Date: Jan 2010 Location: Murcia, Spain Photos: Gallery Posts: 100	I think best an easyest is combining rings with TCs. If you have 50mm macro, 50mm of rings plus a 2x TC gives you scale 4:1. With a 90mm macro it has to be 90mm of extension plus the TC… The rings have to go between lens and TC. I have used this sort of combination and the results are good. You will need an adecuate flash system. I am using 2 360 fgz mounted above and below, to a side, with home-made bar, using wireless sync of K10D. Cheers - Klaus

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