darlot lever stop hemispherical

[jnantz]

hi

i just dug up a lens i bought years ago ..
which i believe to be a 10 1/2 " darlot rapid hemispherical.
has anyone else gotten their hands on one of these ?
will it cover 8x10?
and has anyone removed the rear element and used it as a single ?
i stuck it on a big camera without the rear element and it had a HUGE image circle ...

any ideas what i should expect image wise?
i've shot with it on a speed graphic and loved what it did, but never
without the front or back, and never on a camera bigger than 4x5 ...

i'd LOVE to remove the throat that closes down the fstop "wide open"
better yet, maybe i'll just put the elements on a board without the barrel


thanks!

john

[Toyon]

These are wide-angle rectilinear designs. Their "rapid" lens did not have the lever stops because it only allowed 4 f-stops. Yours, if I remember correctly is designed to cover at least 11x14, possibly larger. The 8 1/4" is for 10x12. It is not designed as a convertible. There is a good reason for the small stop (f16), unless you are looking for distortions. These lenses can be astoundingly sharp (particularly in the center 20 degrees). They are also useful for their perfectly round stops. Darlot wide-angles are one of the best lenses ever and very undervalued IMO. It would be a mistake to damage it.

[goamules]

I have one of these, and it's a favorite. I've had a lot of Darlot lenses, but I think these are their nicest, and I keep this one. Their very earliest ones were actual hemispherical designs, but then they went to the easier to manufacture rectilinear design, but kept the name. Here is a period ad that shows their coverage.

I think any rectilinear can be soft if you use half of it. But you can look for one of the pillbox darlots (or other) achromat meniscus types, which already have one group, and without a stop are soft.

[jnantz]

toyon and goamules

thank you very much for the information about my lens.
i guess it is a wide angle hemispheric then i was kind of joking about
removing the throat, and i am looking forward to using it on a 8x10 when i get the chance.
the lens i bought for my 8x10 ( wollensak 1a triple ) is being used on a different camera
and i kind of like the idea of having a dedicated lens for my camera. it makes
things easier than too many lenses ( too easy to get carried away with lenses ).

thanks for posting the advert.
it is nice to see my lens cost more than a month's pay when it was new

john

[jnantz]

i just noticed mine has "040" engraved next to one of the levers ( the largest one "7" )
does that mean it is a #4 ( size ) "8 inches" according to the attachment ...
i will have to figure out the focal length again because the last time it seems that i might
have been way off ..

thanks again!
john

[jnantz]

i realized i misread the serial number,
it was obscured under the lens shade ...
5040 ...
i'll be sticking it on an 8x10 to see how it covers ..

thanks again!
john

[goamules]

Unfortunately, there are no (known) serial number to date references. My 5" covers whole plate easily. A 10" or even 8" will cover 8x10 no problem. It'd probably cover double that.

[Eric Lohse]

Hi all,
I acquired one of the wide angle hemispherical Darlots with a whole plate camera from Maine (R.O.C) I was curious about the numbers on the lens stop levers, 3, 5, 7. A few years back, my cousin in Germany gave me a reprint copy of "Atelier und Apparat des Photographen" ( Studio and Equipment of the Photographer)by Otto Buehler, copyright 1869, Weimar.
Reading through the section on lenses, he indicates the #'s represent the # of times the exposure must be increased from full aperture. i.e. 3x, 5x, and 7x for the smallest aperture. He also comments that the apertures are generally between 1/16th and 1/72nd of the focal length.The reason for the math is beyond me. Thought it might be of interest
Eric Lohse

[Eric Lohse]

A change to my previous post. Apertures were between 1/36nd and 1/72nd of the focal length. FWIW.
eric

[David Aimone]

I just picked up one of these on e**y. Does anyone here have more information on it? Or photos taken by it? The information I have on it is pretty sketchy (exact sizes, focal length and apertures). I'll be able to get a better idea once it arrives.