Hot answers tagged

40

If I have built my device with the correct distance between the flange and the optical plane, does this mean the (inexpensive) lens I am using is bad? If you had built your device using the proper specified flange distance of 17.526mm instead of rounding it off to 18mm you probably would not be asking this question. 0.474mm doesn't seem like much, but it ...


12

I can't summarize the whole optical physics theory behind pinhole (mostly because I don't have the proper knowledge!), but I try to explain why there are different values for constant C. One reason that there are different values for C is the fact that one parameter in the calculation of optimum diameter of hole is missing! Let us refer to the wikipedia ...


12

The most available large sheet material is corrugated cardboard. If you have a single layer sheet, you should first glue at least another single layer sheet on top of it to make it more stable. Rotate one of the sheets by 90° so that the "grain directions" of the layers cross each other. Like plywood. For the reflective surfaces: White paper provides a ...


11

The Ray-Ban B-15 created for the US Air Force. These are brownish and block 100% of all UV rays and only 15% of the remaining visual rays. The most popular for general use is the Ray-Ban G-15, a green + gray pigment. The Ray-Ban B15 XLT are also green + brown but with lower density. The key fact for a filter to be distortion free is both surfaces are ...


11

The following method worked for me to stiffen up a generic fakey-pod (i.e., meaningless name / brand gorillapod clone). This may or may not work for your version. I only had problems with a few joints. These lacked stiffness when being bent and would not hold position. The joints push together – ball-end into socket. They dismantle by being ...


11

whether lens could be repaired without loosing big amount of money? Whatever the damage, repairing the 18-55 almost certainly isn't worth it. People upgrading sell them for not very much, just get a new one.


10

No, there's no conversion for LCDs — and you wouldn't have anything approaching the resolution you'd want for a print that size anyway using a digital projector. The usual procedure for making alternative process prints from digital files is to print a negative on transparency film. It's the go-to method for cyanotypes, as well as for platinum/palladium and ...


10

The black obstruction looks like a detached aperture blade. This is a seriously damaged lens. Repairing it would at least require it to be dismantled and the aperture blades replaced. Possibly there is even more damage. As the lens seems to be on the cheaper side, it seems to be more economic to replace it - maybe with a used one from one on the various ...


9

If not, do I move the lens away or closer to the optical plane to fix the problem? If the lens will focus on near subjects, but not on a subject at "infinity," then that means that the lens is too far from the sensor. You need to move it closer.


9

Focus is not the issue here. The issue is coverage. Any lens gathers light from a cone in front of it (angle depending on the focal length), and projects it to a cone behind it (angle depending on coverage). So long as the lens is far enough away from the film plane, there exists some plane in the real world that will be focused on the film plane. But......


8

As a welder and new to photography I recently researched the possibility of filming the welding process, my research found many sources including this site and the post to which this attached... and although this is an old post I though my research to date might be useful to people on the forum Malcolm Diamond College of Western Idaho


8

Automotive windshield reflectors can function well as photographic reflectors. The best ones are the shiny silver accordion-fold ones (they often have a "bubble wrap" -like core).


8

Both the official Canon replacement part and many of the third party replacement parts offered on eBay show 3M tape already attached to the back of the replacement grip. I'd follow their lead as others have suggested and use 3M VHB, 3M 300LSE, or 3M 200MP (for other grips on the 550D), as it seems to be what Canon and third party makers use. Or you could ...


8

Most commercial photographers who use smoke a lot buy a commercially made "fog machine" that converts a fluid into dense vapor. The fluid is primarily made of water and glycerin. The machine simply heats the fluid in a semi enclosed space, producing the fog/smoke. You can create such a machine yourself easily. You just need something that can hold the fluid ...


7

A large piece of foam core board (or mat board) is good for portraits. Clamped on a stand opposite of a soft box (key light) just outside of framing. It could be black on one side for absorbing light for more dramatic shadows. Or paint it gold or...?


7

Sadly, you can't, without taking them apart to find out. Unfortunately, it's not reliable to assume anything about the construction of photographic equipment. Even if two instances of what is marketed as the same lens contain optically identical elements, which isn't always guaranteed, you may find that a bevel on the edge of a particular element (or ...


7

As far as I can tell, at least in my two Canon DSLRs you cannot wrap a wire around the battery contacts in the battery compartment. So you could have to implement some sort of connector, for instance by disassembling an old battery(*). You also have to make an outboard receptacle with outgoing wires on which you can insert a camera battery, assuming you ...


7

In addition to what has been said, you cannot be certain that a given camera design can deal with the extra (ohmic or inductive) impedance long wires introduce. The power supply circuit could get rather confused when it experiences a larger than expected voltage drop when attempting to draw a quick current pulse, and could do things like suddenly assume a ...


6

The earliest investigation of the right constant c that I am aware of is Petzval's 1859 On the camera obscura. The paper is predominantly about a new lens design he has created but he begins with an investigation of the optimum radius of a pinhole for resolution of the image. Resolution is defined as the ability to discern the difference of two very close ...


6

That's a 'focusing screen'. You can easily obtain it either from the manufacturer directly, or from a camera store. For example from Adorama Typically, for one model of camera there will be a few types of focusing screens that work with it. Your camera's manual will tell you which one has been installed by default, and which ones you can substitute for ...


6

I hike with cameras a lot, most DSLRs are much more robust than most people think, and providing you protect the lens surfaces you normally don't need much to keep it safe. Padding Put the camera away from hard edged items, most hiking gear is soft, there's no point in carrying extra weight for padding, when you'll already have some spare clothes in you ...


6

Almost every piece of every modern lens from the major manufacturers has a part number. If you can access the service manuals for the two lenses in question you can compare the part numbers. If the numbers are not identical, they're not the same part. Perhaps one lens uses part # 123xyz and the other lens uses part # 123xyz-a. This would indicate that a ...


5

You should know that the big astronomical observatories sport giant telescopes that are actually telephoto lenses for specialized cameras. That being said, you can mount most any camera to binocular or telescope. Mounts and clamps are available on the web that clamp most any camera (with its exiting lens) to the eyepiece of common telescopes. This position ...


5

For a large reflector go to a stationery shop and buy a large sheet of white paper for card. It's not as portable or durable as a proper reflector, but does the job.


5

It's a lot harder than you probably think it is Disassembling, cleaning, and reassembling a modern lens is a daunting task for anyone who does not have the proper training, experience, and tools. There are so many things that the novice is not even aware of that can go wrong that it's practically inevitable that one such error will make the lens unusable. ...


5

Another method of producing "smoke" is to dump some chips of dry ice (frozen CO2) in water (hot water will produce more "smoke" more quickly, but dry ice is cold enough that the water usually won't stay hot very long). About the only danger I can think of is that the dry ice is cold enough you normally want to wear gloves when you handle it. In gaseous form,...


5

Digital cameras are not made to be end-user reparable. It is likely that there are tiny ribbon cables and other small connectors, pieces fit into place just so, and even things glued together in a way that makes working very inconvenient. If you are used to working with this kind of thing — and I have many D.I.Y. electronics-enthusiast friends who are — the ...


5

The self-timer should work. If the camera is still shaking after 2 seconds, even with a big telephoto, you need a stronger tripod. Another choice is to use a separate card as a shutter. Set the camera for a 10 second exposure and hold a piece of cardboard in front of the lens. Trigger the shutter, wait 8 seconds, and take the card away.


5

I am assuming that if I use a shutter of a smaller diameter than the lens, the properties of the lens will change (for example, it will become less fast), because of the smaller aperture ring behind it? That is not necessarily the case. The physical size of the aperture is (almost?) never the same size as the objective lens element; because its physical ...


4

You can actually buy barn door trackers! As a hobby I make and sell them. Been doing it for a while. Much cheaper (but obviously lower performance) than the Orion mounts mentioned above. Check out https://nyxtech.us I've taken 5 minute exposures at 25mm and 10 minute exposures at 15mm with this tracker.


Only top voted, non community-wiki answers of a minimum length are eligible