Muggins
Junk magnet
Or just not got the focus quite right? This is from a Zeiss Ikonta that I repaired the shutter on, and de-mushroomed the lens. The film that was in the camera when I was given it is sharp in the corners, whereas the film afterwards has very definite stretching of the image into the corners. I'm just wondering, at the same time as considering having a go at collimating the lens, whether I've managed to put the rear element back in backwards. Anyone else managed to do this who can confirm the effect?
22308_001-012 by gray1720, on Flickr
22308_001-012 by gray1720, on Flickr
JeffS7444
Well-known
While I don't have a direct answer to your question, I did find an optical diagram of the Novar.
https://sites.google.com/site/cameralensdiagramwml/
https://farm5.staticflickr.com/4113/5083728223_22fb452efb_b.jpg (larger view)
The closest thing that I've got to a Novar is an Agfa Apotar, which is a bit soft in the corners, but nothing like your photo, which looks like it's got some field curvature.
https://sites.google.com/site/cameralensdiagramwml/
https://farm5.staticflickr.com/4113/5083728223_22fb452efb_b.jpg (larger view)
The closest thing that I've got to a Novar is an Agfa Apotar, which is a bit soft in the corners, but nothing like your photo, which looks like it's got some field curvature.
Muggins
Junk magnet
Thanks, Jeff - that suggests my lens should have a convex rear element. Using the highly technical test of feeling my rear element it feels flat, whereas the Novar in my Nettar has a noticeably convex one. I bet I've turned the thing round at some point in the proceedings!
Darthfeeble
But you can call me Steve
I took apart a Canon 100 LTM and carefully laid out everthing in the order it came apart and then somehow got cross wired and put the whole bunch in backwards. Lenses will humble you.
Muggins
Junk magnet
And springs... I hate springs.... I must have retrieved the main spring from this one's shutter from about thirty different parts of the room before I finally got the tool to put it back right!
Pál_K
Cameras. I has it.
Looks reversed to me. Many years ago I bought a Zeiss Nettar 515/16 and my first images looked liked that in the corners - I reversed the rear element and all was fine.
TenEleven
Well-known
This definitely looks like the rendition you'd get with a reversed or otherwise mixed up element order.
Had a "patient" where that was the case on the viewing triplet. Since this was a TLR it also screwed up the focal length of the lens leading to focus mismatch.
I ended up referencing a generic online diagram for triplet lenses and then, like you, used my finger to feel out the surfaces (after which, of course, I cleaned the lenses thoroughly) and re-ordered them to be in line with what the diagram said. In my case the middle element was simply flipped. The other two were correct. It caused the same strange rendition you demonstrated above on the ground glass.
Now it looks and works flawlessly.
Good luck!
Had a "patient" where that was the case on the viewing triplet. Since this was a TLR it also screwed up the focal length of the lens leading to focus mismatch.
I ended up referencing a generic online diagram for triplet lenses and then, like you, used my finger to feel out the surfaces (after which, of course, I cleaned the lenses thoroughly) and re-ordered them to be in line with what the diagram said. In my case the middle element was simply flipped. The other two were correct. It caused the same strange rendition you demonstrated above on the ground glass.
Now it looks and works flawlessly.
Good luck!
Muggins
Junk magnet
Well, you are quite correct - I had indeed reversed the bloody thing. Now corrected, barring a dab of black paint on anything shiny it's ready to go again! Thank you all for confirming my suspicions.