Shooting through glass - need some help

[Overread]

Yep I'm after more glass, but not lens glass.
Essentially I want to be able to use a pane of glass so that I can photograph the underside of insects without having to flip them over (which normally causes both distress and also a lot of moving around as they try to right themselves). However most times one shoots through glass (at close ranges) there is a strong chance of getting two imagse resulting - one from each side of the glass.

Is there either a method or a type of glass on the market, that would reduce or eliminate this problem?

 

[Dwig]

...
Is there either a method or a type of glass on the market, that would reduce or eliminate this problem?

Completely eliminating the reflections that occur at the boundary of two media with different refractive indexes (e.g. glass and air) is not possible. The best method of reducing the intensity of the reflections is optical coating, as is done on camera lenses. Your best best is to use a large diameter multi-coated UV filter as your glass plate.

Also, there is some refractive effect that causes a loss of image quality when shooting through a glass flat at an angle. To reduce this to a minimum you should use a long FL lens so that the angle from the lens to the edge of the field of view is reduced.

 

[Overread]

Thanks Dwig!
There go my plans of using my 70mm for ease - guess the 150mm has to come out for this. That is going to be tricky when it comes to filters though, I think I'll have to take some exact measurements and see if I can't get an ideal size of filter worked out for this, though I might just go with a 77mm so it fits my lens as well. I guess a UV filter is the best for this use since I don't think there are multicoated clear glass filters on the market (unless I am wrong)

 

[Overread]

Sending this back up as I was going through some of my older glass shots which were very simply a dark blue base with the glass sheet placed on top (only cheap regular glass) and I got this result

Any idea what is causing the slightly blurred second reflection around the moth? I've had repeat reflections before, but only really had this blurryness in this series of shots.

 

[skieur]

There is a non glare/non reflective glass that is used as an accessory for a camera stand. The glass is used to flatten paper, books etc. I have shot through it frequently and it works very well. You might be able to find it at a photo supply store.

skieur

 

[semiferger]

I spend a lot of time photographing animals at zoos and aquariums. Knowing and capturing the subject is obviously the most important part. Some technical challenges often arise, however, when you have to shoot through glass windows or aquariums. It is not always easy to produce clean images. I have accumulated a few tricks over the years, and I thought I would share them. If you have tricks of your own, then please share them as well. I am always interested in learning anything that will help me improve my own images. To see my work, head to and check out the “animals” section of the gallery. Here goes…

1) Beware of reflections on the glass. A reflection can make the image look washed out, even if no discernable details are visible in the reflection. For best results, bring the lens all the way to the glass, so that the front of the lens or hood makes a seal against the glass. That way, the only thing reflected will be the lens itself or the black inside of the lens hood.

2) Beware of diffraction from the glass. Diffraction blurs the image or can even create a ghosting effect. It increases with the thickness of the glass and the angle of the shot. For best results, shoot exactly perpendicular to the glass. If you are tracking a moving subject, try to move your entire camera in the plane of the glass, rather than tilting the camera. This takes some getting used to, but produces good results.

3) Beware of wide-angle lenses when shooting right up against the glass. The center of the image will be taken perpendicular to the glass and will therefore be fairly sharp. The edges of the image, however, will become increasingly blurred, due to shooting through the glass at more of an angle. This blur will be circular in nature, and can be pretty distracting, even in out-of-focus areas.

4) If you can’t get the lens or hood all the way to the glass, or if you need to shoot at a slight angle, then shield the opening between lens and glass. Use a dark cloth, sweatshirt, specialized glare hood. If nothing else, use your hand.

5) Beware of double pane glass. Even if you block all reflections on the front pane, light may seep in from the sides. Such light will wash out the image and may introduce distracting reflections. The only real solution is to block the reflections with in a wider circle around the lens. Your hand will not always be enough. Use a larger black cloth, sweatshirt, or glare hood. It is important that the “hood” be solid black, because it will be reflected into the image. Solid black will have the least impact on the exposed image.

6) Beware of dirty, cloudy, or scratched glass. Try to find a clean patch if you can. I often carry a few paper towels and a small spritzer bottle of glass cleaner. Sometimes I can clean a patch to shoot through, but often the problem is on the far side of the glass.

7) If outdoors, try to avoid shooting into the sun, even at a glancing angle. The glass may produce a distracting flare effect. The light may also illuminate dirt or smudges on the glass. This will result in some combination or washed-out colors, loss of shadow detail, and soft white dots. You can avoid most of these problems by making a seal between camera and glass with the sun behind you.

8) When shooting outdoors, it is not always possible to bring the camera all the way to the glass. For example, there may be a fence or railing between you and the glass. In this case, try to find a portion of the glass that is in the shade. If you find such a place, you will have less glare and smudges or particles on the glass will be less pronounced.

9) If you must shoot through dirty or scratched glass, then try to find a subject that is farther back and use your lens’s largest aperture. That will at least blur the defects. It may result in some loss of contrast, but you may be able to get some of it back in PP. When the subject is right on the other side of the dirty or scratched glass, it will be difficult to remove the distracting artifacts.

10) If you must shoot through glass with reflections, you might try using a polarizing filter (circular for digital and linear for film). Rotate the filter until the reflected light is minimized. The filter may also modify the appearance of your subject, especially on reflective surfaces like the eyes or wet skin. The filter will also reduce the total available light, so a tripod or higher ISO speed might be needed to achieve the necessary shutter speed.

11) If you shoot straight at the glass with a flash, you will get a bad reflection. People often say that you should shoot at a glancing angle so that the flash does not bounce back into the lens. This can help, but it is not a perfect solution. The angle with the glass can increase diffraction (see above) and the flash will still illuminate dust and scratches on the glass.

12) Ideally, you want to prevent the light of the flash from passing through the glass that you will be shooting through. The easiest method is to make a seal between the glass and the lens (see above). If you have a long lens or a large lens hood, however, it may block the light of the flash as well. This can be solved in a number of ways. If you attach an external flash to the top of the camera, it may be high enough to clear the obstruction. If not, you could use a flash bracket to hold the flash higher above the camera. I often choose to hold the flash in my hand, connected by a spiral cord. In additional to solving the glare problem, this technique gives enormous flexibility for artistic control.

13) You can also prevent the light of the flash from passing through the glass in front of the lens by making a seal between the flash and the glass. This can be helpful if it is impractical to make a seal between the lens and the glass. For example, if you need to track fast moving subjects with the lens, it could be difficult to maintain that seal. In this case, you could move the flash up to the glass and position it to bounce off part of the environment, thus illuminating a large area. Unfortunately, you may get glare or reflections from the glass (independent of the flash), so this technique is less commonly useful.

14) Sometimes it is not possible to move the flash nor the lens all the way to the glass. For example, there may be a fence or railing between you and the glass. In this case, try separating the flash from the camera as much as you can. I often do this by holding the flash in one hand and stretching the cord so that the flash is a few feet to the side or above the camera. This will reduce the risk of flash light bouncing directly into the lens. Unfortunately, the light of the flash may still pass through the glass in front of the lens, causing smudges and particles to flare up. Another option is to angle the flash away from the direction of the lens so that the light bounces off a wall or ceiling.

 

[Dwig]

... any idea what is causing the slightly blurred second reflection around the moth? ...

The glass plate has two glass-to-air surfaces and both will create their own reflections. One is the top surface and its reflection will generally be very sharp (assuming its very flat glass like an optical grade filter would be). The second would be from the bottom surface. This reflected image can be rather smeared when it passes through the glass at a significant angle, as it does in this shot.

At these magnifications the glass is relatively thick and as a result when the angle is oblique, the two reflections can be significantly displaced and thus noticeable as separate images. The second image is also quite smeared and hence "blurry" as a result of the angle that it passes into and then out of the glass. The glass is acting like a prism when this happens.

 

[Overread]

Hmm so its the angle of the camera and lens to the glass as well as the overall thickness of the glass that is responcible for getting the blurred effect over something like this:

(for details a total accident of shooting against a window which happened to work very well)

Would you happen to know any math/simple rules/resources that would help one select the correct shooting angle so that the reflections cause are sharper rather than soft? Having more than one reflection is no problem to me provided that it is at least a reletivly defined area rather than the smear of blur in the moth shot.

 

[srinaldo86]

You may think I'm crazy for suggesting this but you could build a "bottom of the bug lens."
The idea is that blacking out the bottom of the glass you wont get a reflection, just light coming in from the top of the glass. However I suppose an issue with that would be poor illumination of the bottom of the bug. Erm.
Only reason I'm still posting this is because maybe it will help spark an idea for you.

 

[Overread]

srinaldo86 its not a bad suggestion and it is the method I used for the moth shot that I showed first. My thinking being (at the time) that flash light would reflect off the glass and light up the underside of the insect. However as the moth shows I need to have a bit better control over the flash and direction of light as it yealded very harsh shadows.
Also the reflection factor was still present and has even moved the second reflection to being a detracting feature. If I can at least control it to being a decentish second reflection that will at least clean the image up a lot.