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Thread: Aerials: 125-150mm sharp@ f/8 for 4x5 minimal vignetting

  1. #21

    Re: Aerials: 125-150mm sharp@ f/8 for 4x5 minimal vignetting

    I've done quite a bit of aerial photography, albeit all digital. There are a few things I've learned that you may find helpful.

    1) Normal to short telephoto lenses may be the most useful. Except when working from a helicopter with the door off it is hard not to include parts of the aircraft when using a wide angle lens. When working from a Cessna 172 with the window wide open, a short telephoto is best to exclude the wheel strut, however with some effort a normal lens is OK.

    2) Shutter speed should be 1/500 or faster. I find it challenging to get consistently sharp images at less than 1/800 when using the digital Hasselblads. Most large format lenses that claim 1/500 don't actually perform at that speed and are more like 1/400 or 1/300. You may wish to have your shutter serviced and certified that it will actually run at 1/500. Make repeated passes and shoot multiple frames of the scene you want to ensure the best chance of getting a sharp frame.

    3) For sharp images practice remaining loose and flexible and not bracing yourself when releasing the shutter. The idea is to use your body to decouple the camera from the vibration of the aircraft. It took some effort and practice for me to get this right.

    4) A well balanced helicopter rotor or aircraft propeller will make a very significant difference in aircraft vibration. Fly with a fanatic who insists on having the propeller or rotors in perfect balance.

    5) Consider renting a medium format camera outfit for this shoot, one that offers high shutter speeds. (Yeah - I know this is heresy on the LF forum!) With an MF normal lens you can shoot at f4 or f5.6 and get dead sharp, evenly exposed results across the frame. While I have not used one in the air, I have seen some nice aerial work done with a Fuji GW690. Again, I'd have the top shutter speed verified.

    6) Whatever camera you use, set it for infinity focus on the ground and lock or tape the focus before flying.

    7) If the camera is big - verify that you will have enough room inside the aircraft to manage it without getting it into the slipstream.

    Let us know what you decide and how the shoot comes out.
    Seasons best,
    Bill

  2. #22

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    Re: Aerials: 125-150mm sharp@ f/8 for 4x5 minimal vignetting

    Quote Originally Posted by Photomagica View Post
    I've done quite a bit of aerial photography, albeit all digital. There are a few things I've learned that you may find helpful.

    1) Normal to short telephoto lenses may be the most useful. Except when working from a helicopter with the door off it is hard not to include parts of the aircraft when using a wide angle lens. When working from a Cessna 172 with the window wide open, a short telephoto is best to exclude the wheel strut, however with some effort a normal lens is OK.

    2) Shutter speed should be 1/500 or faster. I find it challenging to get consistently sharp images at less than 1/800 when using the digital Hasselblads. Most large format lenses that claim 1/500 don't actually perform at that speed and are more like 1/400 or 1/300. You may wish to have your shutter serviced and certified that it will actually run at 1/500. Make repeated passes and shoot multiple frames of the scene you want to ensure the best chance of getting a sharp frame.

    3) For sharp images practice remaining loose and flexible and not bracing yourself when releasing the shutter. The idea is to use your body to decouple the camera from the vibration of the aircraft. It took some effort and practice for me to get this right.

    4) A well balanced helicopter rotor or aircraft propeller will make a very significant difference in aircraft vibration. Fly with a fanatic who insists on having the propeller or rotors in perfect balance.

    5) Consider renting a medium format camera outfit for this shoot, one that offers high shutter speeds. (Yeah - I know this is heresy on the LF forum!) With an MF normal lens you can shoot at f4 or f5.6 and get dead sharp, evenly exposed results across the frame. While I have not used one in the air, I have seen some nice aerial work done with a Fuji GW690. Again, I'd have the top shutter speed verified.

    6) Whatever camera you use, set it for infinity focus on the ground and lock or tape the focus before flying.

    7) If the camera is big - verify that you will have enough room inside the aircraft to manage it without getting it into the slipstream.

    Let us know what you decide and how the shoot comes out.
    Seasons best,
    Bill
    A Rollei 6008 with any of the PQS shuttered lenses will shoot at up to 1/1000 in 1/3rd steps at upto 1 ˝ FPS.

  3. #23

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    Re: Aerials: 125-150mm sharp@ f/8 for 4x5 minimal vignetting

    Not to be a complete idiot or anything, but the shutter speed needed to avoid motion blur depends on the altitude, lens' focal length, and ground speed. All we know about ground speed is that the OP's going to be in a Cessna. Which Cessna, how fast it will be flying and at what altitude are unknown questions.

    OP, if you know how high and how fast you're going to be flying and the lens' focal length, calculating how far the image will move during exposure given shutter speed isn't that hard. The results will tell you whether you can accomplish what you want with a lens in leaf shutter.

    You might want to consider renting an aerial camera that has a fast focal plane shutter instead of using a press camera. Or shooting from a hovering or nearly hovering helicopter instead of from a Cessna, if the Cessna can't be flown safely at speeds slow enough to reduce the effects of image motion to an acceptable level. And use a film fast enough to let you use the shutter's highest speed.

  4. #24

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    Re: Aerials: 125-150mm sharp@ f/8 for 4x5 minimal vignetting

    Vibration tends to be a factor as well.

  5. #25

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    Re: Aerials: 125-150mm sharp@ f/8 for 4x5 minimal vignetting

    Quote Originally Posted by Dan Fromm View Post
    Not to be a complete idiot or anything, but the shutter speed needed to avoid motion blur depends on the altitude, lens' focal length, and ground speed. All we know about ground speed is that the OP's going to be in a Cessna. Which Cessna, how fast it will be flying and at what altitude are unknown questions.

    OP, if you know how high and how fast you're going to be flying and the lens' focal length, calculating how far the image will move during exposure given shutter speed isn't that hard. The results will tell you whether you can accomplish what you want with a lens in leaf shutter.

    You might want to consider renting an aerial camera that has a fast focal plane shutter instead of using a press camera. Or shooting from a hovering or nearly hovering helicopter instead of from a Cessna, if the Cessna can't be flown safely at speeds slow enough to reduce the effects of image motion to an acceptable level. And use a film fast enough to let you use the shutter's highest speed.
    Maybe it should be pointed out that the Space Shuttle was flying around 17 or 18,000 MPH and they used Rollei 6008, Hasselblad and Linhof Aero Technika 45EL regularly. As mentioned earlier the PQS Rollei lenses reached 1/000. The Aero Technika 1/500 as did the Hasselblads. I seriously doubt flying around in something else is going to approach the speeds of the Shuttle!
    On the other hand I have, someplace, air to air shots of the SR 71 shot on the Rollei 6006 with the non PQS lenses that went to 1/500 that were shot from an under the wing pod on a Jaguar RAF fighter. Also tack sharp, even the ones at oblique angles of the Blackbird.

  6. #26

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    Re: Aerials: 125-150mm sharp@ f/8 for 4x5 minimal vignetting

    Bob, there's a doctoral dissertation on the subject. Its author points out that at low altitudes -- ~ 100 m -- with aircraft flying at ~ Mach 1 there's no practical shutter speed that will eliminate motion blur. See theses.gla.ac.uk/1151/1/1978elhassanphd.pdf

    The solution is image motion compensation, also called forward motion compensation. Elhassan says that Skylab's S190-B cameras fitted with 460 mm lenses and with highest shutter speeds of 1/200 required FMC.

    I've said it once, I'll say it again. Image motion at the film plane is determined by altitude, ground speed and focal length. It can be calculated. More work for the OP.

  7. #27

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    Re: Aerials: 125-150mm sharp@ f/8 for 4x5 minimal vignetting

    Quote Originally Posted by Dan Fromm View Post
    Bob, there's a doctoral dissertation on the subject. Its author points out that at low altitudes -- ~ 100 m -- with aircraft flying at ~ Mach 1 there's no practical shutter speed that will eliminate motion blur. See theses.gla.ac.uk/1151/1/1978elhassanphd.pdf

    The solution is image motion compensation, also called forward motion compensation. Elhassan says that Skylab's S190-B cameras fitted with 460 mm lenses and with highest shutter speeds of 1/200 required FMC.

    I've said it once, I'll say it again. Image motion at the film plane is determined by altitude, ground speed and focal length. It can be calculated. More work for the OP.
    Maybe I should point out that I was a reconnaissance photographer in the USAF and was part of the unit that received the Presidential Unit Citation for our work over Cuba during the Cuban Crisis. We flew RF101 Voodoos shooting 5” roll film for the obliques and the panoramas we also flew 9” verticals in the RB66. If you visit the Smithsonian in DC on the mall you can see one of our Voodoos on static display along with imagery that we shot at treetop height at several hundred knots per hour. They are very sharp and detailed, you can make out all of the details on the stacked AK47 rifles stacked before a camp site as we approached.
    After the original Cuban Crisis, that was shot on TDY from Homestead the Senate stated that there were still missiles there and we then flew missions over Cuba from Shaw. They were also shot at low altitude and a high speed. We had no problem not finding more missiles.
    Then it was decided that we would fly reconnaissance over the Universities of Alabama and Mississippi for potential rioters. We were again using the Voodoos at higher altitudes and high speed on 5”. We flew over the dorms and could see what was happening, if anything, on the roofs but with our LogE enlargers we could also automatically dodge between the leaves on trees and see into windows! That was also how we were able to expose and print for the missiles in the holds of the Soviet ships. We would place a probe and set a reading of the highest spectral that we wanted, then do the same for the deepest shadow (the inside of the holds) and then on a midpoint. The LogE’s cathode ray tube would then automatically scan and burn the image onto regular photographic paper. Took a long time to complete the exposure but everything we needed was shown!

  8. #28
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    Re: Aerials: 125-150mm sharp@ f/8 for 4x5 minimal vignetting

    Bob; I love these stories! First person cold-war history. I was too young for most of it but love history and technology and sometimes get to hear really interesting stories (like this) from people who applied their ingenuity and quick thinking in our defense.

  9. #29

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    Re: Aerials: 125-150mm sharp@ f/8 for 4x5 minimal vignetting

    Bob, that's nice. Thanks for telling us. But what does it have to do with image motion compensation (or not)? Which cameras flew on the RF101s and did they have FMC?

  10. #30
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    Re: Aerials: 125-150mm sharp@ f/8 for 4x5 minimal vignetting

    Quote Originally Posted by Bob Salomon View Post
    Maybe I should point out that I was a reconnaissance photographer in the USAF and was part of the unit that received the Presidential Unit Citation for our work over Cuba during the Cuban Crisis. We flew RF101 Voodoos shooting 5” roll film for the obliques and the panoramas we also flew 9” verticals in the RB66. [...]
    To add to our history, I was in the the same mission, same years, same aircraft: RF101-C Voodoo and RB66 as Bob Salomon.

    But I earned the Presidential Unit Citation much earlier.

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