Go Back   Steve's Digicams Forums > Digicam Help > General Discussion

Reply
 
Thread Tools Search this Thread
Old Mar 25, 2003, 12:41 PM   #1
Member
 
Join Date: Jul 2002
Posts: 42
Default Digital Filters vs. Attached Filters...

Hey all. Question for anyone with experinece with both attached filters (like Tiffen, Hoya, et.al.) and the "Digital Filters" (i.e., adjustments in many cameras to compensate for incandescent light, fluorescent light, cloudy conditions, etc.).


I've played around with some filters on my Coolpix 5700 (yes, I have the "Bernie" Coolfix adapters, and a set of new 46mm Hoya filters I got on eBay for $10 to experiment with.

Is one better than the other? Are some situations better for the digital adjustments, while others to attach a filter?

For example, I can set my camera settings to shoot Black & White, but can I use the digital settings to adjust to the same compensation as applying a 25A filter (which is supposed to be effective for increasing contrast for BW shots, for example dramatic cloud effects in landscapes).

What has your experience been? Looking forward to your thoughts...

Lynn
crowmama is offline   Reply With Quote
Sponsored Links
Old Mar 25, 2003, 12:55 PM   #2
Senior Member
 
Join Date: Jun 2002
Posts: 1,050
Default

I've not experimented myself but the white balance might be a problem if left on auto - just a thought.
steve6 is offline   Reply With Quote
Old Mar 25, 2003, 1:07 PM   #3
Senior Member
 
Join Date: Aug 2002
Posts: 2,162
Default

I'm only a humble electronics Engineer, but my guess is adding external filters often introduces light attenuation at the lens, which either gives the cam lower sensitivity, or if it's increased in the cam to compensate, worsens signal to noise.

Whereas, changing the Red Green Blue voltage levels way after the ccd sensor, will provide white balance without the penalty of worse signal to noise, since this is most prevalent at the first (ccd) stage.

I'd need to remind myself of the native sensitivity curves for the sensors and the additive/ subtractive light processing for electronic and film. But lets say in a low light situation you added a Tungsten filter to the lens. My feeling is the gain you would need to put into the camera, or open its stop, would increase noise, compared to no lens filter and a Tungsten electronic white balance correction. Often in tungsten shooting you are in low light, so more likely to not have the sensitivity with some cams to get a normal exposed pic.

Remember, do not assume electronic sensors have the same colour response as film, so I'm not sure if add on filters will give the correct match. I can see no benefit using colour temperature correction addon-filters. The exception is clear filters like UV and polarisers. Special warp effects are better done in editing where you can always change your mind if you don't like the result.
voxmagna is offline   Reply With Quote
Old Mar 25, 2003, 1:23 PM   #4
Senior Member
 
Join Date: Aug 2002
Posts: 1,910
Default

With regards to white balance, I've found the automatic does a good job most of the time (at least on the Oly C-700). I did an exeriement where I pointed the camera at a wall hanging with various colours and I tried Auto, Fluorescent (the correct setting for the available lighting) and Manual (holding up a white card to set the white balance)...the Auto was the closest to the original image. You can see my results at http://www.pbase.com/mikefellh/c700_topics (the three pictures of the ship wall hanging).

As for filters, with the ease and power of computer photo software, I prefer applying filter effects within the computer rather than the camera. There's some you can't duplicate on a computer, like a polarizer filter when you want to see through glass that's reflecting light, but other than that you can do amazing things with the computer, plus I have the original photo intact in case I want to try different things with it...but if I have a camera filter that distorts what the camera sees, then it's harder to get back to the original scene.
Mike_PEAT is offline   Reply With Quote
Old Mar 25, 2003, 1:33 PM   #5
Senior Member
 
Join Date: Aug 2002
Posts: 2,162
Default

I've become quite curious about the white bal. functions on my 602. When set to external flash which is not connected, It appears to accept manual white bal settings, at least you see differences in the viewfinder but not on the saved image. I suppose that's logical since the shot is expecting daylight flash, but confusing.

The other disaster area is movie mode in low tungsten light. You can use manual tungsten balance for stills and get good shots, but the cam doesn't seem to carry across a manual WB setting in movie mode. Result is orange pics - sad really, since the auto WB is not working.
voxmagna is offline   Reply With Quote
Old Mar 25, 2003, 11:13 PM   #6
Senior Member
 
Join Date: Oct 2002
Posts: 579
Default Re: Digital Filters vs. Attached Filters...

Quote:
Originally Posted by crowmama
Hey all. Question for anyone with experinece with both attached filters (like Tiffen, Hoya, et.al.) and the "Digital Filters" (i.e., adjustments in many cameras to compensate for incandescent light, fluorescent light, cloudy conditions, etc.).

Is one better than the other? Are some situations better for the digital adjustments, while others to attach a filter?
The "Digital Filters" you are referring to is actually the "white balance" feature. The counter part of "attached filters" are the color compensation and color correction filters. For a digital camera with manual white balance, White Balance Preset in Nikon's case, color correction and compensation filters are in general unnecessary because one can achieve the same effect with white balance or color balance in the post-processing stage.
This also applies to the 25A filter mentioned in your post. I would not recommend to increase contrast using the on-board software which is usually inferior to a good post-processing system such as Photoshop. One can shoot the highest resolution and do post-processing (increasing contrast included) afterward.

However, not all "attached filters" can be replaced by "digital filters." The most important is the polarizer. One can use software to darken the blue sky; however, one cannot remove reflection with any software. The second one is the neutral density (ND) filter used to reduce the intensity of the light that can reach the CCD. With one or more ND filter, one can reduce the shutter speed significantly to produce motion blur, or open the aperture for shallower depth-of-filed. These effect may be doable with an image processing system; however, it is going to be a significant effort. The third one is the gradual ND filter that is capable of reducing the intensity of a portion of the scene. For example, in landscape photography, the sky may be 2 or more stops brighter than the ground. If the sky (resp., ground) is exposed properly, the ground (resp., sky) would be under-exposed (resp., over-exposed). A gradual ND filter may be used to block the sky so that the intensity levels of the sky and ground may be brought to approximately the same level.

Take a look at the Filters section of my 4500 user guide and the White Balance section of my 995 user guide for more details.

Hope this answers your question.

CK
http://www.cs.mtu.edu/~shene/DigiCam
Nikon Coolpix 950/990/995/2500/4500 user guide
shene is offline   Reply With Quote
Old Mar 26, 2003, 8:57 AM   #7
Member
 
Join Date: Jul 2002
Posts: 42
Default Thanks for all the input!

As always, I'm amazed at the depth of knowledge folks are willing to lend here. I always learn alot!

The white balance works pretty well on my camera, but sometimes, according to *my* eye, the bluejeans are too blue with the adjustment for incandescent light, too grey with the auto feature ... the fluorescent setting is really great, though!

The idea of a graduated ND filter is great! And I've already found some uses for the two regular ND filters I acquired -- it really calms that "bleached" look that my flash lends to indoor shots. And some things just need to be done with an attached filter, like the polarizer.

I do digital imaging at work with Photoshop 6, so I'm used to color correcting and adjusting TIFs and JPEGs, but there are limitations to what the program can do for a digital photo -- you're end product is only as good as the original you start with. That's where my interest in attached filters came in, to help correct some of the problems that the camera can't compensate for, and to not have to doctor every single shot I take with Photoshop to balance bright sky/dark ground issues.

In the end, I have two ND filters that are very useful, and five "experimental" filters to play with -- all for only $10. Now that's fun on the cheap!
crowmama is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 4:48 AM.