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I'm looking for a good way to get "perfect" focus on lower light environment.

I'm doing product photography (top down) of textiles with two flashes.

The flashes have a model light (is that the correct english term for that?). But at max brightness of the modelling light the camera can't set a good focus. I think this is a combination of low light and the texture of the textiles (no sharp edges etc.).

The camera sits about 70cm above the object. The textile is approx half a centimeter "high".

Would it be a good idea to print a paper with text or something "sharp" on it and focus on that? Or will the height difference of 0.5cm (between paper on the table and the textile surface) screw up the focus again?

To set the focus I use auto focus or by eye or in live view in Smart Shooter 4 by Tether Tools. The problem with liveview is that it's not super high res and super noise due to low light, so that's also not very accurate.

Any suggestions for this situation?

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  • \$\begingroup\$ Split the buttons for focus and shooting. And use flashlight to focus. \$\endgroup\$ Commented Mar 4, 2022 at 14:37
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    \$\begingroup\$ Yes, I already split them. I focus first and then shoot. You mean a normal flashlight, shine at it, focus, turn it off? Or do you mean the light of my flash? \$\endgroup\$
    – jona
    Commented Mar 4, 2022 at 15:56
  • \$\begingroup\$ The first assumption \$\endgroup\$ Commented Mar 4, 2022 at 16:26
  • \$\begingroup\$ Using live view, you should be able to zoom in to 100% (and more than 100%) which allows critical focusing. Some cameras can be set up so a button on the back sets zoom to 100% when using live view and reviewing images. You can also use a work light to temporarily illuminate your subject when focusing which is hands-free. \$\endgroup\$
    – qrk
    Commented Mar 4, 2022 at 16:40
  • \$\begingroup\$ Is the minimum focus distance of your lens less than 0.7m? \$\endgroup\$ Commented Mar 4, 2022 at 18:45

3 Answers 3

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The simple solution is to install a bright third lamp with push-button on/off switch. You turn this lamp on to elevate the ambient light, now you can compose and focus with ease. When ready for the shot, turn off this lamp and take the shot.

Additionally, substituting a printed target or removable focus aid object will work.

Will the ½ centimeter difference between target and object impair focus? Not likely, especially if you are using a f-stop below the middle range like f/11 or better f/16. These small apertures provide sufficient depth-of-field allowing tiny focus errors to become moot.

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  • \$\begingroup\$ Thank you very much! Will try that \$\endgroup\$
    – jona
    Commented Mar 4, 2022 at 16:37
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Use a good tripod. This way, you only need to focus perfectly once, with live view at 100% or more, and all the light you want. You don't want to miss critical focus because of "just" 0.5cm, so focus at the correct distance. You can also use another textile as a stand-in, e.g. with a clear geometrical pattern.

If you want to be sure the focus doesn't change, you can set the focus to manual, and use a camera trigger.

Once everything is set-up correctly, you could get excellent pictures of hundreds of different textiles in under an hour.

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As I mention in to the comment you first separate focus and shoot functions (set to different buttons) then you use ordinary flashlight, light it on, focus switch off the flashlight and then take a photo.

If you continue to have unreliable focus you can (temporary) add some object with edges, focus,remove the object and take a photo.

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    \$\begingroup\$ Thank you. I will try that. Not sure who to give the "correct answer" now... \$\endgroup\$
    – jona
    Commented Mar 4, 2022 at 16:37
  • \$\begingroup\$ @jona just try and see which one is more convenient in your case :) \$\endgroup\$ Commented Mar 4, 2022 at 16:41

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