I am a complete beginner with product photography and I am trying to take a good picture of dried mangos in a jar.
I have two lights bought for product photography and a white poster that I folded against the wall as most tutorials explained.
Unfortunately, my pictures always come out very bad, and the background of the inside of the glass is very grey.
Attached are multiple pictures to help you understand the situation, and a picture of what I would like as a final result.
Well, your lights are probably big enough, but they are also very uneven in illumination.
When photographing reflective things I find it easier to think in terms of creating the environment that will be reflected rather than "lighting" perse. I.e. the dark stripe in the center of your result is where a softbox is not being reflected from. To remove that you need to move one of your lights farther forward, and probably angle it back towards the jar some. That will also help get some light into the mangos to brighten them up, and more light on the BG. You won't be able to entirely eliminate the dark reflection in the front, but you can significantly reduce it by photographing through a white sheet/paper. The lens will still reflect, but you can make it smaller by using a longer FL from father away.
I would probably start by laying the softboxes on their sides to make better use of the light and gradient (hotspot falloff). Angle them more backwards to get more light on the mangos and BG, and move the jar away from the BG some so the lights can fill in behind the jar.
The lighting in the example image is also two lights, but different. It is one light from overhead front, and one on the background (or the BG is just cutout). You would need a much different setup to reproduce that (stands/table/etc).
My two cents.
Some photographers do not know where the gray point is :(.
So, you need, either an experimenter or a gray card. There are some affordable ones on Amazon. I do not use a cheap one for white points. I use them to determine the gray point or the correct exposure.
Put the gray card in the middle of your scene. With the lights so close it is a bit tricky where to put it. You probably need to remove the jar.
Take a shoot and see the histogram. Determine what part corresponds to that gray card and make the adjustments in the aperture so that the histogram is in the middle.
You now also will see where the white of the background is. In time you will know your setups and determine viewing the white line alone if the exposure is right.
One thing to know about your camera is to take a picture with the white background alone and count how many steps you need to close to get that middle gray, so if you do not have a gray card for X reason, you now can determine the exposure using a white paper. This is around 3 steps.
On reflective surfaces is perfectly fine to blow the reflected highlights, but you can play a bit with the value you get.
When photographing flasks you could use translucent paper, a vegetal paper in the shape of the glass, and shoot a light through it. This is a must when the flask has a liquid, but it probably benefits your shoot.
In my opinion the lights are too close. Move them away. You can add a third diffuser (I am assuming your softbox has one in the interior) Put a sheet of vegetal paper some 30cm away from your softbox.
One thing to try is moving the lights not only further away, but also a bit to the back. As the reflection on the sides casts a white glow on the fruit, moving them allows you to see the color of the fruit without that much interference. But you probably need a third light, centital, so it does not produce a reflection, to have more light on the interior.
Product lighting is often trickier than it seems. A lot of tutorials aren't actually giving you the full sense of what's involved, space and placement-wise. You're mostly having to play with angles to place, shape, and adjust reflections. The standard college textbook on this is Light—Science and Magic by Fuqua, et. al.
Your lights are primarily above your subject. You need to be pointing the center of your strip boxes at the jar, not the bottom; you're not getting enough brightness out of them (if they're continuous that might be part of the weakness of the lights). You also need more control of the height and angles of your lights; they ought to be on lightstands, and the jar on a shooting table of some kind so you can do this.
The stripboxes are too big/close for your small subject, which is why reflections from them are covering most of the face of the jar, and angling straight from the sides isn't lighting the background or the mangoes evenly.
Using stripboxes pointed directly from the sides is primarily not for illuminating the subject, but to give side reflections to give shape and texture to shiny objects. See this video on shooting a wine bottle by Dustin Dolby on his worphlo youtube channel.
If you want a white background? You have to light the background from its front, or the subject from behind. Again, here's another video by Dolby with the stripbox behind a wineglass.
Which means you need to light your jar from the back (or the background from the front, which would require more distance between the back of the sweep and the subject so reflected light from the backdrop doesn't cause a glow around the subject) and the front at the same time. One more workphlo video showing this with a water bottle. Note how he has to finesse the angles for the reflections and how much space he's using. The lights are feet away from the subject, not inches.
I see you put the glass jar on near the bad, not a good idea. And your bg is very close to the "subject". You have to get more control.
One method is to burn the background in a right way. Other method is to cut with pen tool, but in your case it will not work as the gray appear inside the jar where the background is.
If you want to shoot this product and get good burned- almost pure white bg, you need to place the jar on some pedestal on baby pin wall plate, it's small. The main point is to put the background far enough from the jar and light it from below the product, and measure you are getting ~ 240-250 out of 255 range. To be more professional, you even can place 2 black strips on both sides of jar to maintain the contrast of the edge of the jar not to be burned.
I did some diagram
Still put both side lights, there are many ways to do that.
To get a really white background you have to overexpose it. If you are illuminating the subject with flashes, then in comparison the background will come out gray.
I haven't done this for a while, but I used to use a cheap flash gun out of sight but very close to the background, set to maximum power and aimed directly at the area behind the subject and triggered by a simple slave trigger.
This should be sufficient to overexpose the background compared to the subject and create that seamless white look.
For a good book on product & studio lighting, I can recommend the book "Light - Science and Magic".
I think resetting your lights to back lighting will make the inside of the jar white. As long as you light from the front or sides the density of the glass is causing the gray color. But lighting from the back should wash out the gray color in the glass.
I would suggest you watch this video on How To Get Perfect White Background Without Photoshop!!, produced by Beyond Photography.
No waffle just simple lighting skills.
