That frame looks like an early Kelty with an added top bar. My early 60s Kelty draws a lot of attention on the trail.

This discussion goes on and on yet nobody seems to have addressed the central question of what "excessive manipulation" is. I would venture that is a decision for the individual photographer based on what his/her visualization of the image and/or need for the photograph is. A logical discussion of anything is not possible without first having a clear agreement on what the topic is.

I spent many hours in the darkroom dodging, burning, cropping, selecting contrast levels, etc. Were those prints "highly manipulated"? What I ended up with was not a literal copy of the original scene but my interpretation of that. My interpretation began with composing and determining exposure (zone system) even before the film was ever exposed or processed.

Let's see:

For the instantaneous force on an object traveling in a circular path . . . [instantaneous radial force = (mass x instantaneous velocity squared) / radius]. This force during launch would gradually build from zero until it reached the necessary launch velocity for the satellite to coast into orbit. Don't forget to add in the negative force resulting from gravity on the upswing. For a linear acceleration (launched by rocket) . . . [force = mass x (change in velocity / time)]. That force would be determined by the selected acceleration rate and could remain relatively constant (obviously low enough that a human body can withstand it). I guess this device would work if you don't mind your satellite getting squashed.

For an object that cannot have its trajectory corrected once it is launched wouldn't the needed launch velocity also depend on wind, atmospheric density at the time of launch, etc.?

And, to add to montephoto's response, I would guess that it is black to contrast with a white base and make it easier for the umpire to see that they are actually touching the base.

Perhaps someone will correct me if I am wrong. However, my understanding of the purpose of a UV filter is to reduce the effect of randomly scattered light (short wavelengths/UV) caused by the light traveling through a significant amount of atmosphere. If that is the case, the effect observable in a close-up shot would be minimal. There must be some purpose to a UV filter or equipment manufacturers would not have gone to the trouble and expense to build UV filtering into their lenses and sensors.

[quote=davidrb]Granny, plz let sleeping bears do just that, sleep!

Yes!!! Please recognize that our national parks are not petting zoos and the wildlife is just that, wild. I was bicycling in Yosemite and came upon a tourist who had pulled his car over to see a sow and her cub that were near the side of the road. I got there just in time to stop him as he was carrying his toddler toward them with the intent of putting the child astride the cub for a photo.

Way back in the dark ages with my first 35mm camera and fixed 50mm lens I had to estimate the distance to the subject, set that distance on the lens, and then take the photo. With that system I don't remember any focus problems even with slides projected onto a large (seven foot) screen.

Other than specific items of equipment (mentioned in other responses) I have had in setting up a darkroom in a space that was not originally designed to be a darkroom has been getting good light traps on all parts of the ventilation system (ones that do not restrict air flow but let none of the dark out).

The summer after graduating from college in 1968 I participated in a workshop with him at U.C. Santa Cruz where we produced a photographic book for use by one of our government agencies. It was amazing just how much exposure information he carried around in his head. If we named any reasonably common object he could tell us its luminance under various lighting conditions. When we would check with a meter he was always right on in the context of the zone system. In addition, using a blank, white, sunlit wall he set up his camera and (with Polaroid Type 55PN) produced a perfect ten step gray scale in a matter of minutes. Once we had our needed photographs it didn't hurt that Nancy and Beaumont Newhall were also there to help us put them into a book form. We also had an opportunity to visit his home darkroom and to hear him play his grand piano. I would not trade that time for anything.

The Manfrotos I have have set screws under the plate on which the head is mounted. Releasing the set screws allows the heads to be unscrewed from the 3/8" bolt. I suspect something similar is true of most reasonable quality tripods.

It seems to me that the obvious issue here is how obvious your gear is. The more obvious your gear is the more aware of your surroundings you need to be. A thief is unlikely to ask the specifications or manufacturer of your gear before deciding to try to steal it. I think your question should be how big and obvious should your gear be not whether it is full frame or crop sensor.

Since you asked your question for a physics answer, here is a physics answer:
A point source object seen at infinite distance is at infinity when two rays of light from that object arrive at a lens parallel to each other. A lens focusing those rays when set at infinity is then able to focus those rays as a single point at its focal plane. The problem is that if you are able to define such a distance you could then also define a distance one millimeter farther away and your original definition would no longer apply. Since that distance cannot be achieved, we need to settle for a more practical definition. If we construct a device that emits two point sources with parallel beams (at best a very close approximation since black holes demonstrate that light is effected by a gravitational field) the lens is focused at infinity when it focuses those two beams as a single point at its focal plane. In yet more practical terms, a lens is focused at infinity when a point source at a great distance (potentially different for each different lens) is focused as a circle of confusion at the focal plane such that the circle of confusion produced remains within an acceptably small size when viewed under normal viewing conditions.

"The Kodak Brownie Hawkeye was my very first exposure (pun intended) to cameras / photography. . . . . I believe it used 120 film."


620

Interchangeable? They must have changed their approach between the model 1s and the model 3s. My model 3s each have a tripod socket but they are definitely permanently installed. What options did they offer to interchange?