Just a bit of fun here but I thought it might be of interest to others. I'm a "lapsed" macro photographer (active here years ago) but still dabble with different macro set ups sometimes and I'm currently experimenting with vintage and antique cameras.
Here's what happens if you reverse mount an antiques lens from an antique bellows camera on a DSLR. This lens was obsolete by 1924 and the camera body type dates from 1917 onwards, so it's probably from the period around 1920. I've no idea why the lens needed to be 2/3 of a meter away from the sensor, so any ideas welcome!
As mentioned in the post here on my blog, I didn't take the time and effort to do proper testing under good lighting etc. so the results certainly don't reflect what's possible with this kind of set up, but quite encouraging anyway.
Iain
https://fouragesofsand.blogspot.com/201 ... kodak.html
Strangest Macro set up? 1920 lens reverse mounted on DSLR
Moderators: rjlittlefield, ChrisR, Chris S., Pau
-
rjlittlefield
- Site Admin
- Posts: 23626
- Joined: Tue Aug 01, 2006 8:34 am
- Location: Richland, Washington State, USA
- Contact:
Iain, welcome back!
To get magnification m, the lens has to be positioned so that its rear principal plane is located a distance (m+1)*FL away from the camera sensor. (Because you've reversed the lens, the rear plane mentioned here would be the lens's front principal plane as mounted normally on the camera.)
http://camerapedia.wikia.com/wiki/Kodak ... ic_Brownie says that the lens was 122 mm focal length.
Then 122*(2.5+1) = 427 mm = 0.427 m.
Depending on the lens design, the principal planes may be located somewhat outside the physical body of the lens, for example as with telephoto or retrofocus designs.
Whatever difference there is between 0.427 m in the calculation, versus the 2/3 of a meter that you mention, must be due to either differences in the numbers or location of the principal plane of the lens.
If you really care about more closely matching calculations to observations, then I could tell you how to measure the actual focal length and principal plane locations.
But unless you're maniacal about that sort of matching (as I sometimes am), the effort won't be worth the trouble.
--Rik
The short answer is that it's because you're using a long focal length to get high magnification.I've no idea why the lens needed to be 2/3 of a meter away from the sensor, so any ideas welcome!
To get magnification m, the lens has to be positioned so that its rear principal plane is located a distance (m+1)*FL away from the camera sensor. (Because you've reversed the lens, the rear plane mentioned here would be the lens's front principal plane as mounted normally on the camera.)
http://camerapedia.wikia.com/wiki/Kodak ... ic_Brownie says that the lens was 122 mm focal length.
Then 122*(2.5+1) = 427 mm = 0.427 m.
Depending on the lens design, the principal planes may be located somewhat outside the physical body of the lens, for example as with telephoto or retrofocus designs.
Whatever difference there is between 0.427 m in the calculation, versus the 2/3 of a meter that you mention, must be due to either differences in the numbers or location of the principal plane of the lens.
If you really care about more closely matching calculations to observations, then I could tell you how to measure the actual focal length and principal plane locations.
But unless you're maniacal about that sort of matching (as I sometimes am), the effort won't be worth the trouble.
--Rik