Pentax with O-Flash & macro set-up
Feb 29, 2012 14:54:32 #
Because my old macro lens maxes out at 1:2 (1/2 life-size), I added an extension tube (61.86mm) in these photos.
Feb 29, 2012 15:28:41 #
cgchief wrote:
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.Because my old macro lens maxes out at 1:2 (1/2 life-size), I added an extension tube (61.86mm) in these photos.
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.
Feb 29, 2012 15:34:14 #
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.
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.
Feb 29, 2012 18:47:46 #
Nikonian72 wrote:
I am going to blame my confusion of magnification on my quote=cgchief Because my old macro lens maxes out... (show quote)
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.
Feb 29, 2012 18:57:50 #
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
Feb 29, 2012 18:59:05 #
Nikonian72 wrote:
I made that grip, I enjoy working in my shop.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.
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.
Top of the O-Flash in that picture is secured by string. Did you note the metal strip and tie securing the bottom?
Feb 29, 2012 23:31:40 #
cgchief wrote:
Davies formula is based on a 35-mm negative or slide, which is 24-mm high x 36-mm wide.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
Please explain how you derived 61.86-mm extension length? What are lengths of individual tubes? Different lengths will result in different magnifications.
Feb 29, 2012 23:40:15 #
cgchief wrote:
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.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?
Top of the O-Flash in that picture is secured by string. Did you note the metal strip and tie securing the bottom?
Mar 1, 2012 19:39:28 #
Nikonian72 wrote:
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.
Mar 1, 2012 20:41:56 #
cgchief wrote:
That brace would make any engineer proud. Well done!I have to get to the dollar store for ponytail bands.
Here a photo of under side showing metal strip that supports ring.
Here a photo of under side showing metal strip that supports ring.
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.
Mar 1, 2012 21:02:14 #
Nikonian72 wrote:
I measured each section of the extension tube and here are the results (maybe the caliper wasn't zeroed the last time).Please explain how you derived 61.86-mm extension length? What are lengths of individual tubes? Different lengths will result in different magnifications.
Mar 1, 2012 21:06:42 #
cgchief wrote:
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.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).
Mar 1, 2012 21:27:31 #
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.
Mar 1, 2012 21:40:53 #
cgchief wrote:
We wish you well, and look forward to seeing new images as seen through your new eyes.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.
Mar 1, 2012 21:48:25 #
hangman45 wrote:
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.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.
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