Air Ministry 36inch f6.3 lens

[Dan Fromm]

Randy, I really don't know. I shoot flowers and such closeup and landscapes, not people, so I have no idea what magnification a pleasing head shot on 8x10 requires. I can sort of visualize it, but I'm just not sure what good practitioners do. Please help me out by telling me typical magnification.

Oh, and by the way, I believe the lens is a telephoto. If so, perhaps not the best possible for closeup. But with wet plate, who knows. Several years ago I gave a 914/8 B&H monstrosity in horrible condition to a wet plater. I told him how ugly the lens was, how horrible the glass, and he replied that it would be good enough for wet plate.

[Tin Can]

Dan,

8X10 Head shots can be face at 50 to 75%. Or much smaller with chest at 25%.

But some of us are doing 100% on 11x14.

I have shot a head with 900mm Jena at 100% aka 1 to 1, 75" extension Deardorff Studio SC11. Macro. Difficult in my space.

Deardorff SC11 offered an optional 47" Artar for perspective corrective, catalog production. I need to try that, next winter...Big movements need giant IC or so they tell me. I have not done it. That's for my upcoming wheelchair years.

[Struan Gray]

A user here (jb7 / joseph) has posted experience of using one of these beasts. Also on 8x10 I think. Samples and pictures of the setup on Flickr:

http://www.google.co.uk/search?hl=en....0.vPorm2zxnOY

Some of the reasons why lenses are long and big are given in the descriptions of known current systems, such as the RAPTOR pod flown by the RAF, and others. https://en.wikipedia.org/wiki/RAPTOR

Several of the users here at LF.info used these systems for real. There are discussions in the archives. My father worked on recce and airborne early warning aircraft, but only remembers the cameras as a royal pain in the arse to work with :-) My wife's grandfather hung over the side of a Sopwith on the Western Front, trying to fly the plane with one hand, while taking pictures with the other. Things have changed a tad.

One technical point: many aerial systems scan to build up an image from a linear sensor. That means they can use shorter focal lengths for any nominal image size. There were scanning cameras before, but digital makes it easier and better. That said, my impression is that lenses have become even larger in the digital age, both those on aircraft and in satellites. The Tornado pod, for example, has a 110" focal length and an 11" aperture. Satellite optics are probably mirror based with wavefront compensation, like the big telescopes.

The 36" I have is a telephoto. I reckoned a pair of 18" rails would more than suffice for using it.

[Nodda Duma]

Which makes one wonder: why were giant lenses needed for recon then, but aren't now? Drones have very high resolution imagery, from very small and light modern lenses. Then it came to me: the digital sensors really ARE that good, that you no longer need to shoot onto a large piece of film. The technology has advanced, and there will probably never be a need for a giant Aero lens again.

Large optics are still in use and still being made in applications where large swaths of terrain must be imaged at once. The imagers are large high resolution linear digital arrays used in a sort of "push broom" scanning mode as Struan Gray says above, and not film of course. The optics still have to correct for the large image circle at a higher resolution than was needed for film. So expect interesting optics to continuously - eventually - trickle into the market.

[goamules]

Yeah, I know all about SAR and imagery. But it's not large optics that allow large swaths to be taken, it's the movement of the sensor. I used to be a systems engineer on such programs, and later worked to train Stealth Fighter pilots, and "other" air breather platforms. They don't have large optics anymore. Which was my point.

[Struan Gray]

<innocent voice>
What do they have?
</innocent voice>

[goamules]

<research>
Google
</research>

[Dan Fromm]

For USAF data sheets on lenses bought no later than 1967, see: http://1drv.ms/1TJazop

For an interesting doctoral dissertation on aerial reconnaissance photography, see: theses.gla.ac.uk/1151/1/1978elhassanphd.pdf

Jason, USAF used a number of swing-lens panoramic cameras, for example the KB-18. These beasties shot 70 mm film, used 75 mm planar and similar lenses. According to the data sheets, Fairchild made a better 3" planar than Zeiss.

[Nodda Duma]

Yeah, I know all about SAR and imagery. But it's not large optics that allow large swaths to be taken, it's the movement of the sensor. I used to be a systems engineer on such programs, and later worked to train Stealth Fighter pilots, and "other" air breather platforms. They don't have large optics anymore. Which was my point.

I do lens design goamules. For the defense and aerospace industries. I'm in the thick of it and pretty well tapped in, and I'm telling you there are large optics being designed and fielded today. I wouldn't have mentioned it if it wasn't true. Not sure why you're trying to argue...what I said didn't negate anything you posted. I'm currently working on a 30" F/4.2, for example.

"They" is a bigger set of customers than just recon a/c. Scanning systems have their place, but having no moving parts while covering large fields of view is very desirable. Technology is available which makes that happen, as the cost of very large digital arrays (linear or 2D) come down. When the SWaP-C allows it, these large arrays are being implemented with larger optics used out in front. This is particularly true in the multi-billion dollar (and growing) mini- and micro-satellite industries. Optics that go up obviously don't come down, but spares are always made and eventually surplused. So -- as I was pointing out -- expect interesting optics to continue to trickle out into the market.

[goamules]

I'm sure your work is very important.