Perkin Elmer Lens Focal Length 4.5” @ T1.0 (F ~ 0.95) - High Resolution

Description

Perkin Elmer Lens Focal Length 4.5” @ T1.0 (F ~ 0.9-0.95)
Serial Number: 0053
(Note: Picture show S/N 1021- #053 looks identical)
10 deg. Field of View *
*The lens is marked 10 deg. FoV, but when viewed on an optical bench the image covers
~60mm (15 deg. FoV). Quality seems excellent out to at least 40mm, so would cover full-frame format.
Extremely high resolution = 101 lp/mm averaged over field of view
(see last picture)
This lens has no diaphragm, nor focus mechanism. It is used fully open.
Typically focus
is achieved by screwing the complete lens in an out via the large external thread.
Front Lens Diameter:             5.1"
Rear Lens Diameter:             1.7"
Specified Image Diameter:    40 mm
Length:                                  7.2"
Mounting Thread:                  5.0” x 32 Threads/inch
Back Focal Distance:          approx. 8mm (Important! Take note! See below)
Shipping Weight:                   approx. 15lb
Clean optics and coatings.
Just a few internal dust spots
Slight browning of a rear element.
Note 1:
Most of these aerial lenses and ultra-fast lenses were produced (at considerable expense) for the Military in the 1960-1970s, so are now 40-50 years old. Consequently it is rare (but not impossible) to find them in mint condition; there is often some deterioration of the anti-reflection coatings, cleaning marks, or signs of internal fungus. Although not cosmetically attractive, these flaws will have no discernible effect on the image quality, unless pointing the lens at or near a bright object (such as the sun). Use of a lens hood will minimize light scattering from bright objects. But for the ultra-fast lenses in this Listing, they are meant for low-level light situations, so would not normally be pointed at bright objects.
Note 2:
Thoriated glass has been used in the manufacture of optical systems, specifically photographic lenses. It is useful because of its high refractive index. Thoriated glass is radioactive and over time can develop a brown tint, slightly reducing transmission and interfering with neutral color reproduction.
Some of the old camera lenses made from the 1940s to the 1970's contained up to radioactive thorium. Many of these old lenses are still highly regarded today, due to their optical excellence.
A radioactive lens containing Thorium emits around 0.01 mrem/hr. For comparison, a chest X-ray emits 10 mrem, and none of us died from it. According to Nuclear Regulatory Commission, Americans on average receive 620 mrem each year. So, even if you had your Thorium lens with you at all times you would receive a yearly dose of less than 100 mrem.
In conclusion – no, you can’t get sick or die from radioactive lenses. You’d have to spend months in a room filled with thousands of them in order to feel any consequences, so,don’t be afraid to use them.
PLEASE READ CAREFULLY:
Even though I supply all the relevant lens information in my Listings, I get numerous emails asking whether this (or similar) fast lenses will fit on Nikon, Canon, Olympus, etc. full-frame cameras, or 4/3 Cameras, MFT cameras, Sony NEF cameras, etc. and achieve infinity focus.
Please note the following:
1.  This lens will NOT mount directly to your consumer camera!!  You will need an adapter.
2.  The lens does NOT have a focus ring or aperture ring, unless specifically stated in the Listing that it does.
3. To achieve infinity focus the quoted Back Focal Distance (distance from the rear of the lens to the focal plane) must equal or exceed the flange distance for your camera.  If you do not know that distance for your camera, google the Wikipedia article titled “Flange Focal Distance”.
4.  You will also need to fabricate an adapter (using the thread on the lens barrel, or a press-on adapter) that will allow the lens to mount to your camera, and this adapter (in most cases) will add to the distance between the lens and the focal plane.  With some lenses you may be able to have part of the rear lens projection insert part way into your camera, depending on the available clear inside diameter of your camera lens mount.  For focus adjustment, the lens can be turned by its thread in the adapter that you would design and fabricate.  Alternatively you may be able to buy a helicoid adapter (eBay) for focusing (but this will add to your rear flange distance).
5.  If the lens cannot achieve infinity focus, You CAN still use the lens for close-up macro work, as then the image is in focus at a larger distance from the rear of the lens.  The maximum object distance at which the lens will focus will depend on how close you can get the lens to your focal plane.
6.  Here is the calculation:
F  =  focal length of lens
d  =  back focal distance of lens (from rear of lens mount to image plane), as specified in the Listing.
f  =  camera flange distance (look up for your particular camera)
s  =  maximum object distance
Then:   s  = F x (F – d +f)/(f-d)
Example:      if F=90mm, d=6mm, f=18mm, then s = 765 mm (30”)
Note only if d > f will the lens focus at infinity.
So please consider carefully before bidding. No returns because you later decide the lens will not work with your camera.