Creative photography

[rhinorick]

Ok, anyone have any tips for getting a  good photo of a rainbow?  I searched the forums here and did not find any discussions about rainbows.

2 problems I have:

1.  It seems the sky is always gray and drab around the rainbow

2.  The rainbow never appears as vibrant in the photo as it does with my eyes

Any suggestions?

Thanks in advance.  

[Deb]

Hi there, I've had success shooting using a circular polarizing filter and underexposing a tad. :-)

[rhinorick]

Ooooooo .... a polarizing filter .... good idea!!  I need to get one of those and learn how to use it.  

Any tips on what to get?  I am not familiar with them at all.  I am sure not all polarizing filters are created equal.  Are there ones that are not "circular"?  What type is best?

Thanks Deb!!  

[Deb]

Many of the name brands will do just fine (Hoya, Tiffen, Nikon, etc.). You'll want a "circular" polarizing filter and, if you're attaching it to a very wide angle lens, you'll want to get one made specifically for that purpose. Otherwise, you'll get vignetting. If you're not going to be using it with a very wide angle lens, then you don't have to worry about that. Just get a regular circular polarizing filter.

I suggest a circular polarizer because, even though you can use either a linear or circular polarizer, some of your in-camera functions may not work with the linear type. So to be on the safe side, just get a circular one.

A quick note on use: to increase or decrease the effect of the filter, you will be rotating its outside element. IF you're lens is of the type that rotates, then focus first and adjust your polarizer afterwards. If your lens is not of this type, you can focus before or after adjusting your polarizer.

You will also need to pay careful attention to the direction of the sun. The greatest effect from the filter will be when the sun is at a 90degree angle to the filter.

Also note that you will lose some light but your camera's built-in meter will adjust for that.

There are lots of uses for a polarizing filter like reducing haze, glare, reflections, etc.  So give it a whirl and see how you like it. Have fun!

[bdery]

Just an addition to what Deb posted : if you use a DSLR, you do need a circular polarizer, because of the way the camera focuses. If you use a P&S, and do not plan to upgrade to a DSLR in the future, you could use a cheaper (price, not quality) linear polarizer and everything would be fine.

As for me, even though I currently use a P&S, I got a circular polarizer because I know at some point in the future I'll be switching to a DSLR.

[Deb]

And, actually in-camera metering can also be affected depending on the camera make/model. But, you can opt to use a hand-help light meter if you want.  

[rhinorick]

Thank you for all the info Deb and bdery.

Yes, I found that if you have a manual focus camera you need a circular polarizer.

My FZ50 allows for auto and manual focus.   I have made the switch to manual focus all the time now.  So, I will need a circular polarizer.  Thank you both for confirming that for me.

And thank you for the brand name help also Deb.

Now, another, perhaps odd, question about polarizer filters.

Since I now have a telephoto zoom lens for my FZ50, what if I want to use it with a polarizer?  It has a much larger ring/thread size than the FZ50's lens.  Will it be ok to use the polarizer on the FZ50 lens and then attach the zoom lens on the outside of the polarizer?  Or will I need to get a larger polarizer to attach to the outside of the zoom lens?

Does that question make sense?  

[Deb]

Hi rhinorick, I don't have first-hand knowledge of your setup but filters typically go on the outside of the lens where a lens cap would typically fit (unless the lens has a trap for them where the lens joins the camera like the Canon 400mm for example).

Yep, if the lens is of a larger diameter than the filter you currently have, you'll need to get a larger one. Here's a tip: when buying filters that will be used on multiple lenses of differing diameters, buy the larger size and use stop down rings to get them to fit the smaller diameter lenses.

PS: Circular polarizers are usually necessary if your camera is auto-focus. If it's manual focus only, or if you will never use the camera in auto-focus mode or auto metering mode, then you might be able to use a linear polarizer.

[rhinorick]

Thanks Deb!!  Great idea about the step-down rings!!  Much cheaper than buying another filter for the smaller lens.

I had it backwards about the circular polarizer for the manual focus cameras.    Thanks for the clarification.

I now understand .... I think.    Circular filters are for auto-focus, and will also work for maual focus.  Linear filters are for auto-focus only.

Correct?  

Thanks again.

[Deb]

Yes to your first part. Nope to the second part. Linear polarizers are NOT for auto-focus.

Theoretically, you can use either type on any camera; those with auto modes and those that are strictly manual cameras. The catch is that on many cameras with on-board metering and/or auto-focus modes, you can't use a linear polarizer because the linear polarizer changes the light that reaches the metering and/or focusing sensors. If you're not using the metering or auto-focusing modes, the linear polarizer can be used.

If your camera is strictly manual, you can use linear or circular polarizers.

However, if you have a camera that does have built-in metering and/or auto-focus capability AND you want to use these features, then you should opt for a circular polarizer.

[rhinorick]

Ok, cool.  Thanks.  I do have it right in my understanding now then.

Since my FZ50 has auto metering/focusing capabilities, even though I am primarily using manual now, I will look into getting a circular filter, just in case I switch to auto mode.

Thanks Deb!  

[Deb]

You got it!  

[rhinorick]

Cool!!  

[bdery]

Just for the sake of clarity, I want to make a distinction.

Deb says that linear polarizers cannot be used effectively with autofocus cameras. This is fully correct for DSLR auto-focus, but for P&S (which use contrast focus, not phase focus) the linear polarizer (LP) would work without problems.

Basically a circular polarizer (CP) is nothing more than a LP with another component added. That's because a LP will cut all the light along one oscillation orientation, and a camera using phase focus will need light in two orientations to focus. So the CP's second component takes half the light oscillating in the remaining orientation (after the LP) and rotates it by 90 degrees.

It is not always known that P&S use a very different (and less efficient) focusing system than DSLRs. So any autofocus system working as it does for DSLRs will need a CP, while any autofocus system using contrast will work both with LP and CP.

As a side note, "contrast autofocus" simply means that the camera looks at the image, finds a straight line, and makes it as sharp as possible. Phase focusing is more complex.

[Deb]

Thanks bdery for clarifying things! You did a great job! It even makes better sense to me now.

[rhinorick]

I'm a little embarrassed to say that I do not understand that explanation at all.   But I'm just learning. I'll catch on.

Thanks bdery.  

[bdery]

I'm a little embarrassed to say that I do not understand that explanation at all.   But I'm just learning. I'll catch on.

Thanks bdery.  

Do not be embarassed! I realized when I wrote it that it might be a little complex. I'll try to make it simpler.

The basics are (in general):

1-a DSLR uses something called "phase focusing", while a Point&Shoot (your "regular" digicam) uses "contrast focusing"

2-Cameras with phase focusing need a circular polarizer for their autofocus systems (and sometimes, for metering too, depending on how this is done)

3-Cameras using contrast focusing can work with a linear or a circular polarizer, it doesn't matter.

That being said, even though I own a P&S, I went for a circular polarizer because in the future, I might upgrade to a DSLR (who knows).

For the same price, you can often get a better polarizer if you go for a linear instead of a circular. But not always.

Clearer not that I've removed everything technical?

[rhinorick]

Thank you bdery.  Much better.

Although I still do not understand the difference in "phase focusing" and "contrast focusing". I will check digicamhelp "search" to see if there is an explanation.

And I wonder which my camera has.  I'll have to check the manual.

[bdery]

Although I still do not understand the difference in "phase focusing" and "contrast focusing". I will check digicamhelp "search" to see if there is an explanation.  

I'll try to help.

Contrast focusing: the camera looks for some sort of line, or edge (the frame of a painting, the leaves of a flower, etc), something that shows some contrast. Then, when the camera has found this line or edge, it tries to make it as sharp (or well-defined, or "contrasty") as possible. Once that is one, focus is achieved.

this is why a camera using this system will have trouble focusing on a white wall. Then again, it' really dependant on the ambient light, in bright sunlight the imperfections of the wall will probably be visible to the camera, and they will be sufficient to focus. When contrast is low (at night, for instance), the autofocus system struggles more.

Phase focusing: the camera separates the incoming light in two parts, and compares both "images" thus created to decide where is the focus point (of focus distance).

Phase focusing is in fact a more modern type of rangefinding, you might want to look that up (for instance, in Wikipedia) for more explanations if you want to.

And I wonder which my camera has.  I'll have to check the manual.

If it's not a SLR, and it has autofocus, then it's likely contrast focus. Almost only SLRs have phase focusing, because the focus system needs some space, and compact cameras usually don't have any room to spare.

[pentachris]

You will also need to pay careful attention to the direction of the sun. The greatest effect from the filter will be when the sun is at a 90degree angle to the filter.

I realize I'm late in the conversation and back tracking, but...

Rainbows are always centered on the antisolar point, which is roughly the point in the celestial sphere following a line from the top of your head through the top of your head's shadow and then straight through the earth.

In other words, rainbows are in the opposite side of the sky from the sun.

(Sorry to be such a nerd...   )