Tag: aperture

27 Nov

A fairy’s light source – a critique for @PeteGlogiewicz

Chris Lane / Critique, photography / / 0 Comments

Pete (on twitter here) recently sent me a photo for critique in a project style that he has never done before. Here is the photo:

Pete's original photo

Issues in the metadata

Here is the metadata from the image: 255Kb (in the original that he posted on his website), shot on a Canon 400D/XTi with an EF28-80mm f/3.5-5.6 USM lens. It was shot at ISO 200, f/11 and 1/80th of a second. The focal length was 28mm.

In the metadata I can see a couple things generally wrong with this. First, the size of his file. This is minor, but I know for an image that is only 900px wide, he should be able to compress that file down a lot more without any issues. If he is using Photoshop, he should be using the Save for Web function instead of the Save As function. The file sizes will be dramatically smaller. This isn’t an issue with the photo itself of course, but in the scheme of things it is important. If he wants his website found, Google does use page load speed as one of it’s parameters for search results.

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21 Aug

Is your UV filter screwing up your photos?

Chris Lane / Camera parts, photography, review / / 4 Comments

I recently watched a little video from Kent Weakley about the dangers of using UV filters on your lenses. This is common practice by many photographers for a variety of reasons. It was done partially back in film days because of damage UV rays could do to the film itself. Now I think it is primarily to protect the lens from scratches, bumps, etc. He didn’t seem to go into absolutes on what exactly the effect to your photos would be, so I went ahead and tested it. I took a variety of photos on a 50mm 1.8 Canon lens with a Tiffen UV Protection Filter on a Canon 40D in different situations, with the exact same settings once with the UV filter and once without. This way I could see whether the color, light level, or anything else was affected. I decided to also test my ND filters to see what happened with those. In that case, since ND filters specifically reduce the amount of light into the camera, I only adjusted the shutter speed to compensate. Also, I made sure to clean my lens and filters thoroughly before the experiment. These are my results:
First up, my granary. Shot at ISO 200 1/250 f/3.5
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26 Apr

What’s the deal with ISO?

Chris Lane / Camera parts, photography / / 0 Comments

In short, ISO is the sensitivity of the film or digital sensor.

To give you the best example of what changes in ISO does to a photo, I made a chart below. Using a ribbon origami rose that I made, these photos are taken with a Canon 40D, so different cameras will have different results. The large picture at the top is taken at the lowest ISO of 100 to show what the entire picture is. Below that I have images of each ISO setting at 1/3rd increments. These are 100% of the pixel size right out of the camera. For each ISO change I had to also change the shutter speed. The aperture was the same in each at f/5.6.
At the beginning I have the two extremes of the highest and the lowest next to each other to show the dramatic difference. Then at the very bottom that full photo is taken with 1600 ISO. The reason I did this is to show, depending on the use (here being the web), a high ISO will still be a suitable option. At this small size on a website, the noise is barely noticeable. But blow it up to a 16×20 print and the difference between them will be quite intense. I very rarely would use 3200 ISO, and isn’t really native to this camera (thus the H). But it is nice to have available in a pinch.

ISO Comparison chart

So what is it all about then?

ISO is a standardization that was
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26 Oct

Camera Basic – Shutter Speed

Chris Lane / Camera parts, photography / / 2 Comments

The shutter is what really makes a camera. In essence a camera is just a box that holds some film or a sensor with a hole in the end that opens and closes to let in light. This is evident from as far back as the camera obscura which helped artists essentially trace a picture of a person to resemble their likeness. Similar to that is the pin-hole camera, where a piece of film or printing paper is placed inside a camera and literally a pin-hole is punched in the other end which can be uncovered to take some surprisingly phenomenal photographs. Only slightly more complex from this is a typical 35mm camera. This can introduce aperture, which is actually dependent on the lens. It also gives the ability to adjust mechanically the time the shutter is open. The size of the opening through the lens dramatically decreases the amount of time that the shutter need be open in comparison to pin-hole cameras. Then with DSLRs (Digital Single Lens Reflex) cameras, the only thing that is really changed is instead of the shutter opening to a silver halide film plane, it opens to a light sensor of some kind. Today the typical is the CMOS sensor, which is beyond the scope of this post to explain.

Shutter speed generally adjusts from 1/8000 of a second to as long as you want it open,
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