Bestparabolic mirror telescope

When referring to polarization states, the p-polarization refers to the polarization plane parallel to the polarization axis of the polarizer being used ("p" is ...

So can competency in printing on consumer grade paper. I've taken the same set of negatives to two or three different minilabs to have them reprint a couple of frames and the results were significantly different in color and contrast.

Let me get this straight. You guys are actually willing to go through the hassle of paying a surcharge to pull process amatuer print films to reduce contrast, but not willing to use a moderate contrast film like NPH/Reala/NPS/Portra NC in the first place.

Find a lab that will print on good quality paper (Scott has written some advice about this in previous threads). That can make a difference between crappy prints and decent prints even with consumer grade film.

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Pulling an amatuer C-41 film because of high contrast lighting is like putting instant coffee in a microwave. Not very logical.

The difference in stops between the brightest and darkest part of the scene (overall scene contrast) often DEcreases because often in bright sunlight with or without a little haze the sky is the brightest part of the scene and filtering out part of this light makes it darker whereas (for reasons I don't quite know) darker parts lose less light and hence the difference between the shadows and the highlights (scene contrast) DEcreases

First, use Reala if it's sunny out vs 'Fuji shareholder profit generators' like Superia. Superia 100/400 is crap, harsh, grainy, contrasty, and the excuse that it's cheaper and more convenient to use is simply absurd considering I'm sure you're willing to order other things off the internet.

When light hits a surface that it can't travel through, it bounces back. If the surface is smooth, like a mirror, the light will reflect in a predictable way. If the surface is flat, the angle at which a beam of light approaches the mirror will be equal to the angle at which the beam is reflected, so i = r in the diagram below.

Oh, you mean if it wasn't a high contrast scene? And if it is a high contrast scene (like what he is asking about) the highlights won't be printable except as pure white with no texture.

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Change film and/or don't shoot. Photography, surprisingly enough, is all about the light. It's rare to have an outstanding picture that doesn't have good light. Have bad light? You'll have bad pictures, as a general rule. Oh, sure, there are excpetions. Doing every shot as a silhouette will get old really quickly, though. :)

Or, to answer the original question, you can (somewhat) reduce contrast by overexposing and underdeveloping your film -- called a "pull". So, with the films you give above, you'd shoot the X-Tra 400 at EI 200, and ask the lab for a one-stop pull. That will cost you extra, and you probably can't get it at all at the one-hour places, but it should reduce both contrast and, with color films, grain. The key here is the underdevelopment -- you're not just overexposing the film, which by itself would (as you said) tend to increase saturation with negatives or decrease it with slides; you're compensating by reducing development, which will (more or less) return saturation to normal, but at the "cost" of reduced contrast.

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Local contrast definitely can INcreases e.g. in the classic clouds sky case, because the sky gets much darker than the clouds do. When you filter out specular reflections from water for example local contrast can also DEcrease.

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Reflecting telescopes have many advantages over refracting telescopes. Mirrors don't cause chromatic aberration and they are easier and cheaper to build large. They are also easier to mount because the back of the mirror can be used to attach to the mount. Reflecting telescopes have a few disadvantages as well. Because they are normally open, the mirrors have to be cleaned. Also, unless the mirrors and other optics are kept at the same temperature as the outside air, there will be air currents inside the telescope that will cause images to be fuzzy.

I am familiar and comfortable with pushing slide films like Provia and Sensia, and together with increased grain and loss in sharpness, increased contrast is a 'side effect' of pushing. So pulling has opposite effect of reducing contrast (and reducing grain); That is helpful, thank you. I will give this a try with negative films - I am lucky since I do not pay extra for push or pull.

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It is the " or.... " that the man is seeking an answer for. Underdevelopment should work. I don't know how much to cut the development time for a one stop pull with that particular film, but the guy at the lab should know.

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When the long Canadian winter ends, I mostly start using my manual cameras (XD-11, X-GM), and the big, auto sensor, non-TTL flash I have for that system is not an option for street photography.

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LCO's 1.0 meter telescopes are quasi-Ritchey-Chrétien telescopes. A true Ritchey-Chrétien has a hyperbolic primary and a hyperbolic secondary mirror. In the design of LCOGT's 1.0 meter telescopes, the shape of the mirrors has been changed a bit in order to find a more optimal optical design for the system as a whole. Because the mirror shapes have changed, the 2 mirrors alone no longer are a Ritchey-Chrétien telescope in the strict definition of the design.  It is still close though, hence the name, "quasi-RC".

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Curved mirrors can bend light and make parallel light rays converge to a focus. This focus is directly in the path of the incoming light, so there are several ways of making images from the mirror visible. One is called a Newtonian reflector, where a flat mirror is used to point the light rays out to an eyepiece.

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BTW, this works the same for slides -- overexpose and pull will reduce contrast, because contrast is controlled by the first dev, which is a negative dev (prior to bleaching and reversal); it's the first dev that's adjusted for a push or pull with slide films. Expect some color shift with slide films, though; it's there with negative, too, but is usually compensated out with filters in printing.

Certain microscope objective lenses are needed for specific applications. Learn about types of microscope objectives like Achromatic, Semi-Plan, and more.

Pulling/pushing color negative film and getting accurate color from the result is a lot more difficult than carrying some rolls of low contrast portrait film and using them in harsh lighting conditions. By all means, though, experiment. Figure out what's possible. And then finally settle into a routine of not shooting in bad light. :)

Because the incident laser beam is scattered onto a conical surface, the light scatter back to the incident side can be greatly attenuated.◦BD-40 for small ...

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There are several other types of reflectors that solve the issue of where to focus the light in different ways. Cassegrain reflectors have a convex secondary mirror and a hole in the middle of the primary mirror. Prime focus telescopes have no secondary optics and the observer or camera observes the image from near the focal point. Coudé telescopes use a convex secondary mirror like a Cassegrain and an angled mirror like a Newtonian reflector to move the light rays to a focal point away from the telescope. This arrangement is useful when optical equipment is being used that is too heavy to mount directly on the telescope.

"Let's say you are stuck with high contrast film (100 or 400) in bright mid-day sun light; what can you do to reduce contrast?"

Just because it is completely and utterly moronic doesn't mean it is not a good idea. If all you have with you is Superia 100 (shame, shame!) and you see a dynamite scene that is just a bit too contrasty for the film, you can either forget the whole thing or ....

Different reflectors use different shapes of mirrors. Parabolic mirrors will focus all incoming light rays to a single point. However, images from a parabolic mirror will have  a defect called coma, where images far from the center of the field of view are elongated. A spherical mirror surface is relatively easy to make, but different parts of a spherical mirror have slightly different focal lengths, so images will be fuzzy. Mirrors in modern telescopes area made in various shapes to correct for these errors. Some telescopes use a combination of mirrors and lenses. Schmidt-Cassegrain telescopes use a spherical mirror with a correcting plate that corrects the focus.

A. Taner, if you like NPH and Reala, you can order 36-exposure rolls of it in bulk from Adorama or B&H so you'll always have plenty, refrigerate it, and pay about the same total cost per frame after developing/printing as Superia. Not that I think Superia is "crap," but I agree that NPH and Reala are better choices.