The Light is on

[stevesutt89]

I've just bought myself a Pentax K100D Super and heres one of the first shots i got with it. What annoys me about this photo is 1, the fact that it is the globe that is out of focus a tad and the background that is in focus and more importantly, the composition, it just doesn't seem right to me. '



Exposure: 0.003 sec (1/350)
Aperture: f/38
Focal Length: 50 mm
ISO Speed: 200
Exposure Bias: -2 EV
Flash: Flash did not fire

[clockdoc]

Hi Steve. Did you manually focus this shot or use auto focus? Is this full frame or cropped? My only observation would be to straighten the bulb abd have the hot filament at the 1/3 / 1/3 point. The sharpness appears acceptable at this size. What is the range of f/stops on your lens? Is it the macro version?

[stevesutt89]

I used the auto focus for this shot, which probably caused it to focus on the screen behind. I took this shot with the kit lens on the Pentax K100D, (well the sigma kit lens) so i had to crop it a fair bit to get this close. At 50mm, the f stop range of this lens is f/5.6-f/40

I shall try to take the photo again using my 55mm prime lens reversed and post the results.

[jiminyClickit]

stevesutt89,

Viewfinder or LCD screen: which do you use to assure focus is on what you want?

[clockdoc]

One thing you mentioned caught my eye. It was that your lens is capable of being stopped down to f/40. Experience has shown me that stopping down to such points does sometimes affect the overall sharpness of an image. Two to three stops from the end may provide a better "sweet spot." Only testing will provide the 'best' aperture setting. I suspect you had to stop down because of photographing the raw lamp. Try using a lower ISO and faster shutter speed to allow for a bit larger aperture. How far were you from the subject for this shot? Moving a little farther away will buy you a little more depth of field as well.

Help me out here. I just looked at all the Sigma 18-50mm lenses on their website and all showed a maximim aperture of f/22. What am I missing? Is this a special lens? (macro?)

[stevesutt89]

Sorry about the delay in replying. The Sigma lens i used does claim to have a minimum apeture of f/22---at 18mm, however at 50mm (where i was shooting) the max aperture is f/40

Anyways, I've retaken the shot, trying to put into practice the suggestions, this time with a reversed 55mm prime lens. Here it is:



settings used:

1/4000th sec
f/11
ISO 200

I think it corrects a few of the errors i made with the first one, ie sharper (click the image for a larger version) shallower depth of field, and possibly a better composition. Although i still do think that the bulb needs to "pop out" a bit more cause to me it still blends into the background, so i may gimp it just to darken the reflector behind the bulb a little.

[stevesutt89]

Almost forgot:

JC: I did use the viewfinder to check the focus before taking the first shot, but as i'm not very good at gauging focus, i couldn't really tell the auto focus was not what i wanted anyway.

The second shot i just set the camera to drive, made sure i was focusing as close a possible behind the bulb, and then slowly moved the camera out as it look shots. I then chose the sharpest one.

[jiminyClickit]

Originally Posted by stevesutt89

I think it corrects a few of the errors i made with the first one, ie sharper (click the image for a larger version) shallower depth of field, and possibly a better composition. Although i still do think that the bulb needs to "pop out" a bit more cause to me it still blends into the background, so i may gimp it just to darken the reflector behind the bulb a little.

Well said, and agreed.

[clockdoc]

Much sharper using the 55mmm reversed. This may be an interesting candidate for High Dynamic Range. Shoot two shots, one as you have and another with the lamp off and combine the two using HDR.

[stevesutt89]

Well thanks for all the help JC and Clockdoc. I'm much happier with the second shot. Oh and thanks for the HDR idea. I'll give it a go!