Because my old macro lens maxes out at 1:2 (1/2 life-size), I added an extension tube (61.86mm) in these photos.
cgchief wrote:
Because my old macro lens maxes out at 1:2 (1/2 life-size), I added an extension tube (61.86mm) in these photos.
According to
http://www.dpreview.com/reviews/pentaxk10d/page2.asp , your Pentax K10 camera contains a 23.5-mm x 15.7-mm CCD sensor.
Your photo shows 20.5-mm wide image.
23.5/20.5 = 1.15/1 = 1.15:1 = 1.15x magnification = just a bit larger than life-size with tube.
Why such a strange tube length: 61.86-mm?
Usually tube sets are 12-mm, 20-mm, & 36-mm. You can stack two or three. Maximum is usually 68-mm.
One more question, and one comment:
Where did you get that grip? Don't see many around. Mine is 35-years old, and over the years, I have used it on six different cameras.
I use black "ponytail scrunchies" elastic bands, instead of rubberbands, to hold top of O-Flash tight to Speedlight, and to hold bottom of ring from tilting when I shoot straight down.
Nikonian72 wrote:
cgchief wrote:
Because my old macro lens maxes out at 1:2 (1/2 life-size), I added an extension tube (61.86mm) in these photos.
According to
http://www.dpreview.com/reviews/pentaxk10d/page2.asp , your Pentax K10 camera contains a 23.5-mm x 15.7-mm CCD sensor.
Your photo shows 20.5-mm wide image.
23.5/20.5 = 1.15/1 = 1.15:1 = 1.15x magnification = just a bit larger than life-size with tube.
Why such a strange tube length: 61.86-mm?
Usually tube sets are 12-mm, 20-mm, & 36-mm. You can stack two or three. Maximum is usually 68-mm.
quote=cgchief Because my old macro lens maxes out... (
show quote)
I am going to blame my confusion of magnification on my
reference text 'nature photography close up' by Paul Harcourt Davies. Most of the book covers the use of the 35mm Nikon; but he also covers the use of digital cameras with 'x 1.5 body factor'. Then on page 155 he gives formula for magnification as 36/22; no mention of the body factor. Poor excuse, but better than none.
The extension tube is a cheap, but well made aluminum, item. Made up of 3 sections, a body mount end, and a lens
mount end; total length 61.86mm. My other hobby is my
basement machine shop; every photographer should have a South Bend lathe, or two, to maintain his equipment.
I have that same lens to get 1:1 you only need 50mm of tube they made a 50mm single tube that was made to go on this lens but have not run across one yet only seen it in a old catalog
Nikonian72 wrote:
One more question, and one comment:
Where did you get that grip? Don't see many around. Mine is 35-years old, and over the years, I have used it on six different cameras.
I made that grip, I enjoy working in my shop.
Top of the O-Flash in that picture is secured by string. Did you note the metal strip and tie securing the bottom?
cgchief wrote:
I am going to blame my confusion of magnification on my reference text 'nature photography close up' by Paul Harcourt Davies. Most of the book covers the use of the 35mm Nikon; but he also covers the use of digital cameras with 'x 1.5 body factor'. Then on page 155 he gives formula for magnification as 36/22
Davies formula is based on a 35-mm negative or slide, which is 24-mm high x 36-mm wide.
Please explain how you derived 61.86-mm extension length? What are lengths of individual tubes? Different lengths will result in different magnifications.
cgchief wrote:
I made that grip, I enjoy working in my shop.
Top of the O-Flash in that picture is secured by string. Did you note the metal strip and tie securing the bottom?
Look at the black ponytail elastic bands on my second photo. I bought 20 for 99-cents at discount store. I see the zip-tie on bottom of your ring, but not how the ring is attached to grip. One black elastic band goes around bottom of my ring, linked to another black band that attaches to thread-in mount, bottom of grip.
Nikonian72 wrote:
cgchief wrote:
I made that grip, I enjoy working in my shop.
Top of the O-Flash in that picture is secured by string. Did you note the metal strip and tie securing the bottom?
Look at the black ponytail elastic bands on my second photo. I bought 20 for 99-cents at discount store. I see the zip-tie on bottom of your ring, but not how the ring is attached to grip. One black elastic band goes around bottom of my ring, linked to another black band that attaches to thread-in mount, bottom of grip.
quote=cgchief I made that grip, I enjoy working i... (
show quote)
I have to get to the dollar store for ponytail bands.
Here a photo of under side showing metal strip that supports ring.
cgchief wrote:
I have to get to the dollar store for ponytail bands.
Here a photo of under side showing metal strip that supports ring.
That brace would make any engineer proud. Well done!
I will have to post a photo of my lower support band.
For all interested parties: Coast Guard Chief's brace and my elastic band keep the ring from cantilevering when shooting straight down.
Nikonian72 wrote:
Please explain how you derived 61.86-mm extension length? What are lengths of individual tubes? Different lengths will result in different magnifications.
I measured each section of the extension tube and here are the results (maybe the caliper wasn't zeroed the last time).
cgchief wrote:
Nikonian72 wrote:
Please explain how you derived 61.86-mm extension length? What are lengths of individual tubes? Different lengths will result in different magnifications.
I measured each section of the extension tube and here are the results (maybe the caliper wasn't zeroed the last time).
I have that same set of cheap tubes but I got a better set when I bought my M100F4 that have the aperture lever so I can use the green button to meter.
Most of my old lenses are manual focus and I hope be better at it in a few weeks. Cataract surgery scheduled: March 6-left, March 13-right.
cgchief wrote:
Most of my old lenses are manual focus and I hope be better at it in a few weeks. Cataract surgery scheduled: March 6-left, March 13-right.
We wish you well, and look forward to seeing new images as seen through your new eyes.
hangman45 wrote:
I have that same set of cheap tubes but I got a better set when I bought my M100F4 that have the aperture lever so I can use the green button to meter.
I own a set of Kenko "auto-focus" tubes, which allow electronic communication between my camera and my lens. A standard set is comprised of a 12-mm tube, a 20-mm tube, and a 36-mm tube. They can be used individually, paired, or all combined to equal 68-mm of extension.
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