Lens Filters

[Kobus2]

I have read a lot about lenses over the last few months, but one thing still confuses me a bit. Filters.

Could I for example use a UV filter and a Circle polarising filter together? Would this make sense, or would I somehow run the risk to create something negative in the mix? I have a canon 75-300 and would like to use a UV filter, but am unsure if I should keep it on when using the polarising one.

Same applies for mixing filters, in general. What are the benefits and/or risks involved.


regards

Kobus

[Geurt]

Kobus,
As to UV's and polarisors, there are two camps about this.
There are the chaps that saveguard their lens investment against scratches and uses UV filters to accomplish this. The opinion being that UV's are cheap, but a scratch implies a lens being written off.

Then there are the chaps that have the attitude that you made an invested with an expensive lens and then you deteriorate that "excellence" with a cheapy UV filter! Not on, they maintain!

In my experience, I used UV's on a lot of lenses and kept the UV's on permanently. Whenever I used a polariser, I just screwed this onto the UV with, in my opinion, no ill effects.
Geurt

[Kobus2]

Thnx Geurt. Experience is something I dont have yet, and I appreciate your advice. I will try it out, UV filter is cheap - lense not.

regards

Kobus

[markthomas]

I have recently taken off all the UV filters on my lenses and have seen a slight difference in quality. It also seems that I have less flare on the 20mm and it seems like I'm getting more light through - maybe it's just a case of seeing something thats not there because I want it to be so.

The coatings on the latest lenses are very scratch resistant and hardy - most damage to lenses comes from over-cleaning anyway.

Cheers

[SimonDP]

Instead of UV's, I prefer Skylight 1B filters as always on protection. The "visual effect" is less than with UV, which is already not really noticeable.

Make no mistake, filters do protect lenses! If you work outdoor a lot, rather use a filter. Although coatings are very scratch resistant these days, they still take a hammering with regular cleaning, plus they are not strong enough to withstand the impact of a pebble thrown up by a passing rally car, (Enzo Kuun does'nt do it slowly) which went in under my lens hood, striking the filter on the rim and cracking the glass. I just threw away the filterand kept the lens!!!

If you do buy filters, get the best quality from a reputable manufacturer - why spoil the excellent optics on the lens with inferior polished glass on a cheap filter?

[James Mitchell]

The reason I like skyligh filters on my lenses is that the screw-in thread on the lens itself is protected by having the wear and tear happen on the filters thread. If you cross thread a skylight filter with a poloariser, it is a lot cheaper to replace the skylight than repairing the lens thread.


I had a Chinon Genesis that I took to a wild Nature Conservation class party, and the next morning the filter was craked through. The camera was fine, including the lens. I still don't know what happened, but I do recall rolling down a bank with some classmates...beers...camera....

[Hendrik van Rooyen]

Hi,

At high altitude, like up here on the highveld, the skylight is a choice better suited. It helps with blue colour casts in shadow areas.

I removed all my "protective" filters about 3 years ago. Now I use what I need. Polarizers, ND grads, soft/hard edge grads, some warm up if I need.

Regards.

[James Mitchell]

Hi

I agree with the use of the Skylight, as where I am, in northern KZN, we are also quite high up. However, that does not mean that I would not use it at the coast. It is just as useful at lower altitudes.

I still feel that it protects the primary threads on the lens, and can be a 'sacrificial' piece of glass should things go pear-shaped!

[John Paul]

Hello to you.

The use of UV or Skylight filters is a personal thing. I have always suggested using them for protection of the front element and the filter thread.

There is a difference between the two. The UV filter filters out Ultra Violet light which causes a blue tint to your photograph whereas the Skylight ( 1 A or B ) has a very mild orange colour and is therefore considered as a warming filter. It is more suited for photographing people ( white ) to give them a more " Fleshy " or natural skin tone. Early morning or late afternoon, when the light is warmer and you are using a Blue based film eg Fuji. It is advisable to use a 1A or B to get that warming effect.

By using a Polariser, whether it is Circular or Linear, together with an UV or Skylight will make such a little difference that it is unnoticeable. Please be carefull when doing this that you do not cause vignetting of your photo. Especially when using a Wide Angle lens. This is the blackening off of the corners caused by the " seeing " angle of the lens being restricted by the filters.

[James Mitchell]

I have also read that UV filters have a greater effect on film / slide than on a CMOS or CCD and are thus less critical on DSLR's than on conventional cameras.

Can anyone confirm this?

[Hendrik van Rooyen]

Hi,

Filters of any kind affect the light entering the lens.

The light doesn't care what you use to capture the image with.

Regards.

[John Paul]

Hi MATATAZELA.
Most cameras which record images electronicaly, have built-in White Balance filters which can colour correct the scene whether it be Sunlight, Incandescent, Flourescent or Tungsten lighting, either Automatically or Manually.
With celluloid type imaging, various filters need to be utilised to achieve the desired results.
This is not to say that using Special effect filters does not work on digital cameras, they certainly do.

[elsahoffmann]

Macro question

I have a D70, use a 60mm Nikkor macro lens. (1.5 x 60 equates to a 90mm)

Problem:

This is not good enough to photograph something very small eg ant, mosquito.

What am I supposed to use? please?

[GerhardT]

Macro question

Hi Bluepixel,

Mosquito can do! Ants is a different story.

Firstly the limitations of the lens:

1. Its minimum focal distance is 22cm. An ant is still very small at 22 cm. To get closer you can use extension tubes.
2. It has a magnification of 1:1 That means that the ant will be lifesize on a 35mm slide. Still pretty small. As a rule of thumb the mag factor of extension tubes can roughly be calculated as follow: (Focal length + extension tubes lenght) / Focal lenght. This means that if you shoul put a whole set of tubes (68mm) on the 60mm lens it should render a magnification of 2.1x which will help with the mozzies but the normal ants are still pretty small.
3. I inserted some links of articles I have written on the subject for you should you wish to read up on the choices you have.

The problem is not the lens, most macro lenses (Canon too ) only renders a magnification of 1:1 Hope it helps.

Macro diopter filters

Techtalk on macro (Part1)

Techtalk on macro (Part2)

[elsahoffmann]

Many thanks - I shall read and digest

[elsahoffmann]

GerhardT -

I have read and tried to digest your articles/notes where you directed me to. (difficult with such beautiful pictures around) You got my vote.....

Your pictures are exactly what I want to do - those small blerrie things is exactly where I am heading (sorry SimonDp)

I see that I can get Nikon extension tubes for a 35mm lense - 8mm, 14mm, 27.5mm, and 52.5mm. Hopefully there should be something like that for a 60mm.

I would prefer to go the extension tube route as I can then get closer to the subject (underwater that helps a lot i think)

which would you suggest to be a good all-rounder?

Wonder I hedrus stocks these things?

[GerhardT]

Hi Bluepixel,

I see that I can get Nikon extension tubes for a 35mm lense - 8mm, 14mm, 27.5mm, and 52.5mm. Hopefully there should be something like that for a 60mm.

As far as I know the extension tubes should fit any lens. They fit between the lens and the body. It fits the standard Canon/Nikon lens mounting and has some connections for AF and the like. It has no glass and will not give you distortions as with the macro diopters but, you will loose light. The more tubes you stack the more light you will loose. The macro diopters fits to the front of the lens and are therefore filter size specific but not lens specific.

I do not know if they are waterproof or will fit the housing you use. You have to make certain of that.

To advise you on which lens will be most suited for close-ups with extension rings is very difficult. It depends on the size of the subject and the working distance. A good rule of thumb is the shorter the lens the larger the magnifiction factor but you have less working distance and less DOF. I have tried it on lenses ranging from 400mm to 50mm, with extensions ranging from 12mm to 68mm. The longer the lens the more working space but it needs more light and has a smaller maginification factor.

You will have to experiment in the shop with something similar in size and at a workable working distance. On a 50mm lens with 68mm of extension the working distance is about 1cm in front of the lens. On a 100mm lens with 68mm of extension the working distance is about 50cm. Not ideal for fish but workable for coral and anemone should you be able to get enough light on the subject. It is important to consider getting light onto the subject as it still is the problem I have to bridge most often. I would still love to try tubes on a proper 100mm macro lens to see results.

Please remember that I do not have any underwater shooting experience and that I am uncertain to the the results underwater.

Hope it helps and please shout if I can help you more.

Kind regards
Gerhard

[SimonDP]

Hi BP,
Keep in mind that going to macro photography means getting very close to your subject, underwater where you live this means that your lightsource should be so adjustable that you can accurately, literally, throw light on your subject. Also your overall length camera lenth will increase, check that your watertight housing will accomodate this.

those small blerrie things is exactly where I am heading (sorry SimonDp)

One day you will regret that you did'nt rather take up motorsport photography. Don't really know if there are any underwater races though!

Have fun with the sharks!