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Old Oct 8, 2004, 12:42 PM   #1
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Sorry about such a basic question... I'm just getting started. I've read that I should not add a filter in front of a lens converter because it will cause various problems with the quality of the pictures (such as vigetting(??) ).

I'm hopeful that that will not stop me from using a0.8x lens converter with a Polarier filter.... is it possible to put the filter *between* the camera lens and the converter lens? And -if so- will that approach cause any picture quality issues?

I imagine that there might be some slight issues due to the fact that the converter lens is now further away from the camera lens. If so, to what degree will with quality of the picture be, assuming a fairly thin filter?

Thanks.
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Old Oct 8, 2004, 4:20 PM   #2
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The issue is with wide angle converters...using an extreme wide angle converter with a filter on it, or using a filter between a wide converter and a camera set to the wide end, or using a wide converter with an opening the same size or smaller than the lens can all cause vignetting.

For instance, although my lens is about 37mm across and it takes a tube that has a 55mm thread, with the camera at wide angle it can vignetting if I put a filter in between the lens and the 55mm thread of the wide angle converter.

But there's another issue with using polarizers between the converter and lens...the polarizer is one of the few filters that are actually two separate rotating pieces put together in such a way that the weight of a converter lens could actually pull the two sections apart and send your lens falling to the ground. If you do use a polarizer like this, you should support the weight of the converter with your hand so that the polarizer doesn't break apart.
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Old Oct 10, 2004, 10:59 AM   #3
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Thanks Mikefellh,

Does that mean that it is impractical to try to take large, scenic pictures withfilters? It almost seems that the vignetting problem occurs in all cases where you use a converter lens and filter. Is it just something that everyone lives with, or is there some why to combine the benefits of both within the same picture?

Thanks for any help you cangive me.
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Old Oct 11, 2004, 8:42 AM   #4
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Allow me to supplement Mike's advice with an observation of my own. I'm using a Olympus C-730 with the Oly CLA-4 adapter tube. The CLA-4 has a 55 mm filter mounting ring. I keep a B+W UV filter on all the time - physical lens mechanism protection plus helps to keep dust "and other stuff" away from the lens. I just came in taking a picture of a golden colored maple in the back yard using an Olympus WCON-07 lens (also 55 mm mount) which I had mounted on the UV filter. There was no vignetting at full wide angle.

It's a different story if I put on my polarizing filter on top of the UV filter and then put on my wide angle adapter (not recommended for a number of reasons, especially as Mike notes, if the lens should fall off!) Then I get a moderate amount of vignetting. I need to zoom in some to get rid of the vignetting but then I've also cancelled nearly all the advantage of having the wide angle adapter on in the first place. I estimate that the total vignetting (both corners combined and at full wide angle) takes about one quarter to one third off the of the short side of a picture with this combination (if that makes sense!)

With only the polarizing filter on theadaptertube with the wide angle adapter (i.e., no UV filter,) I get some vignetting but not nearly the amount as with two filters. I could live with this by croping.

One possible way around this problem (vignetting when using a polarizing filter with wide angle adapter) is to try a very short panorama - 2 (or maybe 3 in a pinch) pictures stitched together - withoutthewide angle lens. This howevercan bevery difficult to do with a polarizing filter as the light can change dramatically as you turn to take the panorama series of pictures.

Paul in NoVA
C-730 B-300 WCON-07
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Old Oct 11, 2004, 11:40 AM   #5
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Thanks Paul. That was a lot of helpful information.

It sounds like vignetting is dependent (among other things) by the type of filter, and that it might not be too bad if I don't mind cropping my pictures to some detgree.

I do have one quick question though- my camera (a Minolta A1) has a built in range of 28mm - 200mm. If I were to use a polarizerfilter on top of the camera lens, and take a picture at 28mm, will I see vignetting also? Or does the problem only exist with the combination of filters and converter lens?

I'm kicking around the idea of buying a polarizing filter, mostly for scenic pictures, but if itcauses problems at the angle that I prefer it might not be worth it.

I appreciate any help you can give me.


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Old Oct 11, 2004, 7:52 PM   #6
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basquedude wrote:
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I do have one quick question though- my camera (a Minolta A1) has a built in range of 28mm - 200mm. If I were to use a polarizerfilter on top of the camera lens, and take a picture at 28mm, will I see vignetting also? Or does the problem only exist with the combination of filters and converter lens?

My guess is a definte maybe...

I don't know a lot about the A1 other than it takes great pictures. I suspect that you can add a polarizing filter without worrying about vignetting, even at 28mm, wide angle view. But, don't quote me on that! Suggest you check down on the Konica Minolta forum here.

Paul in NoVA
C-730 B-300 WCON-07

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Old Oct 14, 2004, 1:33 PM   #7
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Yes, definitely pick up a polarizer

It is a great filter to have.

Problems with vignetting can easily overcome by "framing" your shot to "accomodate" the vignette that you know will occur.

In other words, imagine a slightly smaller area (rectangle) than your actual viewing area in your viewfinder.

FYI...I shot a few wide angle shots recently with filter between (not my choice but filter was stuck at the time). Vignetting was minimal and easily cropped out without loss of intent of pic.

Hope that helps.
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Old Oct 14, 2004, 3:15 PM   #8
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Thanks digcamfan,

One last question- is the amount of vignetting dependent onhow wide the angle is? For instance, can I expect more vignetting on a 24mm shot than a 28mm shot?

If so,it stands to reason that I should probably"frame" a 24mmshot more than a 28mm shot, correct?

Also, I've decided to geta polarizer filter, andjust live with whatever cropping is necessary.Thanks for the advice.
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Old Oct 15, 2004, 3:09 PM   #9
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basquedude wrote:
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Thanks digcamfan,

One last question- is the amount of vignetting dependent onhow wide the angle is? For instance, can I expect more vignetting on a 24mm shot than a 28mm shot?

If so,it stands to reason that I should probably"frame" a 24mmshot more than a 28mm shot, correct?

Also, I've decided to geta polarizer filter, andjust live with whatever cropping is necessary.Thanks for the advice.
The answer to your "one last question" is YES, you will experience more vignetting at a wider angle (such as 24mm) than you would at, say, 28 mm. It is also very dependant on the depth of the polarizing filter itself (duh!)

As discussed by Digcamfan, you can lessen the impact from vignetting by framing your shot. I would however be surprised if you encounter any vignetting at full wide angle on your A1 with just a polarizing filter.

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C-730 B-300 WCON-07
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