M Monochrome and color filters

[james.liam]

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Getting acquainted with my new friend and I have noticed that there might be an ever so slight rearward focus shift when using color filters and shooting wife-open; seemingly more pronounced with orange and red compared to yellow. At first I attributed the inaccuracy to my own inexperience or rangefinder/lens combo in need of calibration but over time it appears to me to subtly vary by filter color and distance to subject. What has been other users' experience and have you avoided these filters altogether, sticking to no filter vs UV or clear?

 

(Apologies ahead of time if this isn't the right thread location to post this or if it has been covered extensively in the distant past; wasn't certain myself).

 

EDIT:

 

I have reviewed some of the older entries from 2012 that I did subsequently find and am still not clear what would be the wiser course even after reviewing the 5 pages of entries.

Edited November 29, 2014 by james.liam

[250swb]

I suppose it is possible as different wavelengths of light will focus at different points, but if it is only 'ever so slight' why not stop the lens down?

 

Ask yourself if a slight focus shift that can be compensated for should trump the better effect that may be possible with a coloured filter? For most people it wouldn't register as a problem unless they were conducting a scientific experiment rather than making a creative photograph.

 

Steve

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This is the way optical lenses work. Normally they are designed to render just two colors in perfect focus. All other colors are render progressively out of focus, the amount depending on the distance of the color within the spectrum from the colors which are in focus.

 

I see three actions open to you:

 

Accept that some images will not be perfectly sharp when using filters.

Stop down, thereby increasing the DOF.

Find or make your own documentation, showing the difference for each lens and the most often used filters.

[jaapv]

Yes. This has been the case ever since the beginning of photography. The more extreme case is the focus shift of IR light, but many users don't realise that there is no difference in physical properties between IR light and visible light.

Lenses only focus correctly at one, two (achromats) or three wavelengths(apochromats)

They misfocus to a smaller or larger degree at all other wavelengths.

Getting acquainted with my new friend and I have noticed that there might be an ever so slight rearward focus shift when using color filters and shooting wife-open; seemingly more pron

ounced with orange and red compared to yellow. At first I attributed the inaccuracy to my own inexperience or rangefinder/lens combo in need of calibration but over time it appears to me to subtly vary by filter color and distance to subject. What has been other users' experience and have you avoided these filters altogether, sticking to no filter vs UV or clear?

 

(Apologies ahead of time if this isn't the right thread location to post this or if it has been covered extensively in the distant past; wasn't certain myself).

 

EDIT:

 

I have reviewed some of the older entries from 2012 that I did subsequently find and am still not clear what would be the wiser course even after reviewing the 5 pages of entries.

[james.liam]

Yes. This has been the case ever since the beginning of photography. The more extreme case is the focus shift of IR light, but many users don't realise that there is no difference in physical properties between IR light and visible light.

Lenses only focus correctly at one, two (achromats) or three wavelengths(apochromats)

They misfocus to a smaller or larger degree at all other wavelengths.

 

Understood, this is the Nature of optics. It seems more apparent with digital sensors than forgiving emulsions so was wondering what long-time MM users (like you, Jaap) were doing in practice with subjects shot at wider apertures and not at hyperfocal distances

 

In other words, does one stick with a light yellow filter or none at all, for near subjects at wide apertures to avoid this potential issue that robs contrast and focus accuracy?

Edited November 29, 2014 by james.liam

[algrove]

I increase DOF if possible or use no filters at all and then use SEFEX Pro to "adjust" image to my liking.

[jaapv]

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I mostly use yellow filters and when close may lean a bit, somewhat more with a red filters.