A surprising observation (well, to me, anyway) (1 Viewer)

I've been noticing that the shots I have taken over this winter seemed to be less sharp than the ones I got late last summer and fall. Thinking about it, I realized I have been lazy, and have been shooting a lot from inside the house, through an open window or door during the cold weather. Could the temperature difference between inside and outside create enough air turbulence to affect IQ?

So today I did a little test. Took a shot from inside (68 deg F) to outside (48 deg F), then moved the camera far a couple of feet forward so that the objective lens was well outside and took another shot from basically the same position. Used live view to get good focus both times. Even in live view I could see a difference, and when I compared the shots on the computer I was stunned. The indoor-to-outdoor shot was much, much softer. I mean, not even close. This may be old news to most of you, but it was a revelation to me!

So I guess I need to get out more ...

I found that doing some indoor test shots across several rooms of the house that I got air distortion when the hot air furnace was on. I would expect only a few degrees difference between the air currents. In doing some scope testing I did it late at night, when the air was still, over lawn, using a lighted target at about 200 feet. Seemed to work well. Gene

Shooting through an open window creates a lot of heat shimmer, I've noticed this in the past, especially where the temperature difference is big. If I need to photograph from indoors then I photograph through the glass and make sure the scope is as square on to the glass as possible to minimize the chance of getting a double image.

Paul.

I find that quality of image can certainly be acceptable when shooting through modern window glass, which is much much flatter than it used to be years ago. Especially if you shoot square on, as Paul says, and also pick your spot...trying different parts of the window.

To avoid the turbulence when shooting through an open window, make a thin cardboard tube to fit your scope and about 18 inches long so that it will be able to poke through main area of turbulence where hot air meets cold.

Tom

tjd said:

To avoid the turbulence when shooting through an open window, make a thin cardboard tube to fit your scope and about 18 inches long so that it will be able to poke through main area of turbulence where hot air meets cold.

Tom

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That's a really simple idea and should be very effective - I'll definitely try it.

Read somewhere that if scopes are to be used in environments where there is a significant temperature difference, about 20 ~ 30 mins are required for the temperature between scope's lenses & tube to equalize with the environment.

tbc

tbc said:

Read somewhere that if scopes are to be used in environments where there is a significant temperature difference, about 20 ~ 30 mins are required for the temperature between scope's lenses & tube to equalize with the environment.

tbc

Click to expand...

This is true. I keep my scope outside in the garage purely to keep it at around the same temperature as the outside air. In winter this means I can use it straight away without any fear of getting condensation on the glass and it fogging up.

Paul.

I've seen this same phenomenon when shooting out the widow of a heated car when it's very cold outside. Even when I stick the scope or camera lens out the window I can sometimes see waves of heat distortion as the hot air rushes out of the car window.