Macro question
Dec 22, 2019 10:21:00 #
I have started testing various ways to magnify with various lens configurations.
My T2I has a sensor 22.3mm sensor width.
I shoot an old wooden metric ruler and divide that by width in mm of the ruler reading. Am I correct that if I see 5mm that I am at 4.5x or so?
A photo taken with a reversed 28mm lens on 72mm of extension.
Thanks in advance for your help.
Only a few yes or no needed, thank you.
Bill
My T2I has a sensor 22.3mm sensor width.
I shoot an old wooden metric ruler and divide that by width in mm of the ruler reading. Am I correct that if I see 5mm that I am at 4.5x or so?
A photo taken with a reversed 28mm lens on 72mm of extension.
Thanks in advance for your help.
Only a few yes or no needed, thank you.
Bill
Dec 22, 2019 10:29:45 #
Dec 22, 2019 10:32:52 #
Dec 22, 2019 10:56:01 #
Dec 22, 2019 11:49:13 #
It makes sense to me. If it were 1x it would reveal 22 mm. I know with extension tubes one divides the extension by the focal length and adds any native magnification.
Not sure how the math works reversed. Here is a cut and paste from the article linked below.
The formula for reversed lenses is 1/S1 + 1/S2 = 1/F All in mm, S1 is distance from object to the lens' optical centre, S2 is distance from the lens' optical centre to the camera sensor, and F is focal length. To find the sensor distance, there is usually a stripe marked on top of your DSLR which shows where the sensor plane is. Read more at http://extreme-macro.co.uk/single-reverse-lens/#ixzz4c5n0ZHnx
http://extreme-macro.co.uk/single-reverse-lens/
Not sure how the math works reversed. Here is a cut and paste from the article linked below.
The formula for reversed lenses is 1/S1 + 1/S2 = 1/F All in mm, S1 is distance from object to the lens' optical centre, S2 is distance from the lens' optical centre to the camera sensor, and F is focal length. To find the sensor distance, there is usually a stripe marked on top of your DSLR which shows where the sensor plane is. Read more at http://extreme-macro.co.uk/single-reverse-lens/#ixzz4c5n0ZHnx
http://extreme-macro.co.uk/single-reverse-lens/
Dec 23, 2019 10:31:47 #
The math is simpler if you do what the OP did, which is to take a picture of a metric ruler. Divide the known width of the sensor by the width of the field of view. 22.3mm/5mm.
Dec 23, 2019 10:35:18 #
That looks about right to me Bill. As you say, your sensor is 22.3 x 14.9 mm and, I am being pedantic here, it is considered correct to take the first measurement as being the long side and called length and not width which you said. It does seem logical however to call it width and height but it is not done that way. Happy Christmas Bill, I look forward to your pics with this set up, it looks interesting, I like to see experimentation.
Dec 23, 2019 10:45:58 #
Dec 23, 2019 10:48:19 #
newtoyou wrote:
I have started testing various ways to magnify with various lens configurations.
My T2I has a sensor 22.3mm sensor width.
I shoot an old wooden metric ruler and divide that by width in mm of the ruler reading. Am I correct that if I see 5mm that I am at 4.5x or so?
A photo taken with a reversed 28mm lens on 72mm of extension.
Thanks in advance for your help.
Only a few yes or no needed, thank you.
Bill
My T2I has a sensor 22.3mm sensor width.
I shoot an old wooden metric ruler and divide that by width in mm of the ruler reading. Am I correct that if I see 5mm that I am at 4.5x or so?
A photo taken with a reversed 28mm lens on 72mm of extension.
Thanks in advance for your help.
Only a few yes or no needed, thank you.
Bill
Yes!
Dec 23, 2019 11:23:33 #
Dec 23, 2019 13:01:06 #
EnglishBrenda wrote:
That looks about right to me Bill. As you say, your sensor is 22.3 x 14.9 mm and, I am being pedantic here, it is considered correct to take the first measurement as being the long side and called length and not width which you said. It does seem logical however to call it width and height but it is not done that way. Happy Christmas Bill, I look forward to your pics with this set up, it looks interesting, I like to see experimentation.
And I was a carpenter.
Thanks to all responders.
Brenda, look at photo gallery.
A visit from Queen Elizabeth to Annapolis.
Bill
Dec 23, 2019 15:09:57 #
[quote=newtoyou
Brenda, look at photo gallery.
A visit from Queen Elizabeth to Annapolis.
Bill[/quote]
I have looked and commented Bill, thanks.
Brenda, look at photo gallery.
A visit from Queen Elizabeth to Annapolis.
Bill[/quote]
I have looked and commented Bill, thanks.
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