hello
Could someone confirm me that any longer symmars or plasmat tipe lenses convert into longer lenses by removing the front element out of the shutter?
Thanks
Rui Lourosa
hello
Could someone confirm me that any longer symmars or plasmat tipe lenses convert into longer lenses by removing the front element out of the shutter?
Thanks
Rui Lourosa
well, they do of course, but are there any data in what focal distances will they convert, i´m specially interested in lenses over 400mm,
thanks again
rui
Rodenstock's instructions for the Sironar was to remove the rear element to convert it. This also, of course, help protect the shutter and aperture blades from damage.
Well there are lenses that work both way´s, but what i was looking for is some kind of data sheet that shows what are the focal distances for each cell... i´m looking for a long decent lens
thnks
Rui
A converted Symmar or Sironar is not a decent lens when converted. They also need a lot of bellows extension.Originally Posted by ruilourosa
I don't know if anyone has gathered all manufacturer data together in one place. For convertible lenses (that were meant to be convertible), you could check on the specific lens brand, i.e. Schneider or Rodenstock, or etc. The Schneider website has data for "Vintage" Schneider lenses for example. If you look at convertible lenses for sale on ebay, a front shot of the lens shows the different focal lengths.
bob... my standards are quite low... i´m doing direct positives and i would apreciate a fair amount of aberrations...
thanks for the answers
cheers
rui
It's been years since I researched convertible lenses, but I have many and love them more than any other.
My first suggestion would be an old Turner Reich. Triple convertible with the 12/19/25" being very common. If you get a decent one, they perform very-very well, even with a bit of balsam separation around the edges.
The old Daggors are also convertible but for some odd reason they go for much more than they're really worth...
Next would be a Symmar. The old convertible ones used to be common and work extremely well standard and pretty good converted. You'll find all Symmar convertibles as f/5.6. Back when I found that the Symmar-s (f/5.6) lenses are the same AND convertible. They just stopped advertising them as such which saved them (and made them) a lot of money.
There is a simple formula for combining the two cells focal length to find the combined focal length. I don't remember it but have it laying around somewhere.
I have never seen a compiled list of convertibles and their cells. Goof luck with that. If you find one, let me know!
For me, I would grab an old Turner-Reich and be happy with it. Oh, wait... I did
I wanted to add:
If you buy a lens that is not marked on the shutter with the converted lengths and f stops, you can figure it all out yourself. You can actually measure the effective llens stop through the lens with a controlled light source (nighttime lighted white wall for instance) and measuring off the GG. You can also directly measure the size of the stop and use the formula against the length of the lens.
Finding the length of the lens is as simple as focusing at infinity and measure the distance from the lens to the film...
I did an f-stop ring for one of my lenses years ago by measuring off the GG and it worked just fine. Paper label and pencil was all that was needed for the shutter.
Remember though that if you use the rear cell (removing the front), you can add a good 3 inches to the bellows draw for the focal length!
Mmm, I guess I need to try this on some lenses. I do have the bellows for almost anything...
Anybody try a Cooke or Artar, converted?
Seems aberrations are hip.
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