Lee Sacrey Photography – Lee's Chatter

Mainly Photography but a little of everything at times

There are questions – Who has answers?

with 2 comments


There are a couple of things that stump me when I am out taking pictures. I am going to talk about those questions and I am hoping that Photographers who are smarter than me can provide answers.

First, is weather, humidity and temperature. I easily understand what effect temperature has on my equipment. The batteries drain power quicker in the cold, moving my camera from warm to cold and back can cause condensation issues.  Humidity (rain or snow) can cause water related issues (even more so if you don’t have a well sealed camera). But, those aren’t my questions. My question is, do any of these things affect the optics? I often take pictures of the Aurora and have been finding that my photos are crisper, more clear at certain temperatures and I am guessing the same would apply to humidity levels. Even more interesting to me is that it seems to effect different lenses at different rates. So what are the true effects of the climate in which we take photographs on the quality of those photographs? If I am right about what I seem to be noticing, it means I have extra homework to do when planning to shoot. Can someone shed some light on this?

Second is, does aperture always control depth of field? I have had a few discussions on aperture, for example aperture is said to control the amount of light being let into your camera. With that said does f2.8 at 1/4000 of a second let in as much light as f22 at 30 seconds? I don’t really need an answer to that one, it just shows the effect one control has in relation to another (we could make it even more confusing by adding ISO). My question is more like this one. If I manually focus to infinity, sent my aperture to a larger opening like f2.8 and leave the shutter open, do I still loose depth of field? I ask this because for a lot of my Aurora shots the aperture is at f4.5 or f2.8, my shutter is open 30, 45 seconds sometimes as much as 3 minutes or more. When those photos are processed everything appears to be sharper. SO again does aperture control DOF always or is it a number of controls combined, i.e. does it only do that with shorter shutter speed?

I find these two questions very interesting but, I am sure some brilliant Photographer will respond with a scientific mind-blowing answer that I still may not understand. I can’t wait to hear the answers.

Thanks for reading and as always Happy Shooting.

Once again I have mentioned the Aurora and night photography in a Blog article. So, here are some Aurora shots from this week.

If you are ever wondering about the size of the Aurora in the night sky this shot might help. If you look to the lower right you can see there are three people captured in this photograph. What are they doing you ask? Taking Aurora pictures of course.

Advertisements

Written by leesacrey

March 30, 2010 at 12:47 AM

2 Responses

Subscribe to comments with RSS.

  1. Heya Lee,

    Good questions! I wish I had some solid answers for you, but I am still very much the learner.

    I would imagine that temperature and humidity can affect the sharpness in an image, especially of something like the aurora, which, as I understand it, has a lot to do with atmospheric ice crystals (is that right?).

    I can provide a little insight with regards to the second question – or at least I think I can.
    Aperture does control the amount of light let into the camera, but it also controls diffraction. A small aperture lets in less light, but what light gets in is tightly focused and doesn’t bounce around much before it hits the sensor. A larger aperture not only lets in more light, but, due to its size, also allows the light bounce around more before it hits the sensor.

    Because the smaller aperture has a lower diffraction, it creates a larger focus area and allows the space on before and beyond the focus area to be a little sharper. As the aperture opens, you get more diffraction and the area of sharp focus gets smaller and the details outside the focus area get blurrier.

    I am not sure if that makes any sense, but I hope it does and that it helps a little bit. If not you can try this article:

    http://en.wikipedia.org/wiki/Aperture

    I can’t make heads or tails out of it, but maybe you can (if you do, send me an email and explain it to me! :)).

    Cheers buddy!

    Mike

    April 1, 2010 at 1:05 PM

    • Ah! I never considered diffraction when I was asking the second question. So, although I can use a large aperture (smaller number) and focus on a far away point. I can still loose some DOF and sharpness due to distortion caused by the larger aperture setting. So although I can get a good image with a large DOF it still won’t be as sharp a DOF as if I use a smaller aperture (bigger number). It is now clear as mud, lol. I at least know the rule as I understand it still applies. Thanks Mike. Now the first question still presents a possible problem.

      And Mike it is good to hear from you again, Thanks.

      leesacrey

      April 1, 2010 at 3:20 PM


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: