Does Orange filter on an APO lens change the focus plane?

[xiaubauu2009]

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Does adding orange filter on an APO lens such as the VM AA35/50 or Sumicron AA35/50 will change the focus plane?

if so, does it change it at infinity or close focus distance?

[a.noctilux]

I tend to say no change.

Depending ont the lens correction and filter quality, I'd say.

With LV/EVF it's easy to find out.

 

I had only done some 'testing' with longer lens Leica Apo-Summicron-M 75mm and 90mm, nothing change focus plane, wide open or close down a bit,

with LV/EVF and shooting with red, IR and orange filters I have in Leitz/Tiffen/Posso/Cokin/Hoya/Heliopan/B+W/Minolta/Nikon.

 

[pgk]

No. Or at least it most certainly shouldn't.

[xiaubauu2009]

55 minutes ago, a.noctilux said:

I tend to say no change.

Depending ont the lens correction and filter quality, I'd say.

With LV/EVF it's easy to find out.

 

I had only done some 'testing' with longer lens Leica Apo-Summicron-M 75mm and 90mm, nothing change focus plane, wide open or close down a bit,

with LV/EVF and shooting with red, IR and orange filters I have in Leitz/Tiffen/Posso/Cokin/Hoya/Heliopan/B+W/Minolta/Nikon.

 

I used a resin filter. I can’t be sure of the quality. Cause I have a suspicion that mine worsen the IQ. Just trying to be sure. 

[ru2far2c]

I have had more issues with B&Ws red 90 & 91 regarding focus shift than with the B&W orange 40.  I use a B&W 40 all the time, with very few problems on an M10M or M246. YMWV

[fotomas]

Could be. Guess not so much because of the visible light. For this the APO should be corrected, but because of the infrared that becomes more present. Nearly all these filters have no impact on the infrared radiation and the sensor is quite sensitive for it.

[jaapv]

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3 hours ago, xiaubauu2009 said:

I used a resin filter.

Not a very good idea. It will degrade the image quality considerably. On a good lens, especially a (Leica) APO, use only the best quality optical glass filters.

[jaapv]

33 minutes ago, ru2far2c said:

I have had more issues with B&Ws red 90 & 91 regarding focus shift than with the B&W orange 40.  I use a B&W 40 all the time, with very few problems on an M10M or M246. YMWV

On an APO lens there will be no focus shift, not even red.

[xiaubauu2009]

7 hours ago, jaapv said:

Not a very good idea. It will degrade the image quality considerably. On a good lens, especially a (Leica) APO, use only the best quality optical glass filters.

that might be the case. I have never put any color filter on while using MM, so this is pretty new to me. Time to invest in a better filter!

[stefanusj]

color filter doesn't cause missfocus.

for my case, it is 100% my own eye.  

[LocalHero1953]

The whole point of Apo lenses is that they are designed so that all frequencies focus at the same point. Removing all except orange should do nothing.

That's the theory! I suspect that in practice there may be a shift depending on how well the apochromatic design works at different focal lengths and with specific frequencies - it's not an exact definition, and not all lens makers are rigorous in how they use the term.

[davidmknoble]

My only addition is that it depends on the lens, but the lens is probably the culprit, not the filter.  Many of the APO Summicron 90’s have focus shift when focusing close - the APO Summicron 75 has FLE and not so much a focus shift.  You also have the manual nature of the lens and the cam in the rangefinder, which can have focus shifts.  So, if you find you are missing focus with a filter, try the same without the filter and see if it is just the lens.

[IkarusJohn]

On 3/8/2022 at 7:10 AM, jaapv said:

On an APO lens there will be no focus shift, not even red.

That has been my experience, even with red filters ...

[jaapv]

4 hours ago, davidmknoble said:

My only addition is that it depends on the lens, but the lens is probably the culprit, not the filter.  Many of the APO Summicron 90’s have focus shift when focusing close - the APO Summicron 75 has FLE and not so much a focus shift.  You also have the manual nature of the lens and the cam in the rangefinder, which can have focus shifts.  So, if you find you are missing focus with a filter, try the same without the filter and see if it is just the lens.

Not probably, certainly. The culprit is chromatic aberration in the lens. An APO lens has superior correction for this error.

[fotomas]

Instead off guessing I made a quick test with the APO-Summicron 90 ASPH on an M 246. Here are the results:

Distance was about 1,7 m. Fully open, focussed with the EVF on the center of the chart.

First a overview with the total scene:

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2. Detail with no filter

3. with a clear UV/IR cut filter

4. Yellow filter

5. Orange filter

6. Red filter

7. Dark red filter

8. IR 715 filter

As you can see there is a slight focus shift to back-focus the longer the wavelength got. The filters used are the top models from B+W or Heliopan.

Edited March 16, 2022 by fotomas

[davidmknoble]

4 hours ago, jaapv said:

Not probably, certainly. The culprit is chromatic aberration in the lens. An APO lens has superior correction for this error.

I agree with that point, my point is that even APO lenses can have mechanical issues that could appear to be caused by colored filters.  We may be saying the same thing, but not sure.

[Bernd-B]

With my Apo-Summicron 75 it depends on the filter. By using the Leica orange filter - which is closer to a dark yellow filter compared with the wratten standard - my answer is no. If I use a (significantly darker) orange filter from Heliopan my answer is yes.

[jaapv]

45 minutes ago, Bernd-B said:

With my Apo-Summicron 75 it depends on the filter. By using the Leica orange filter - which is closer to a dark yellow filter compared with the wratten standard - my answer is no. If I use a (significantly darker) orange filter from Heliopan my answer is yes.

To consider: An Apochromatic lens is only corrected fully at three (Leica: four) points of the visible spectrum. All wavelengths in between (and outside)are assumed to be adequately corrected for photographic purposes, at any rate more so than a non-APO lens. That means that you can only expect 0 focus shift if your filter is close to one of the corrected wavelengths and you may see a minor focus shift for filters of other wavelengths.

[xiaubauu2009]

14 hours ago, fotomas said:

Instead off guessing I made a quick test with the APO-Summicron 90 ASPH on an M 246. Here are the results:

Distance was about 1,7 m. Fully open, focussed with the EVF on the center of the chart.

First a overview with the total scene:

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

2. Detail with no filter

3. with a clear UV/IR cut filter

4. Yellow filter

5. Orange filter

6. Red filter

7. Dark red filter

8. IR 715 filter

As you can see there is a slight focus shift to back-focus the longer the wavelength got. The filters used are the top models from B+W or Heliopan.

Excellent test! So it will influence slightly, but at infinity, I am sure it probably won't matter much, right? But for portraiture, nailing critical focus on the eyes, yellow is probably the safer filter to use?

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Hallo,

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[stefanusj]

13 hours ago, xiaubauu2009 said:

Excellent test! So it will influence slightly, but at infinity, I am sure it probably won't matter much, right? But for portraiture, nailing critical focus on the eyes, yellow is probably the safer filter to use?

Yellow filter is a useless filter for me. almost zero effect on skintone, except on the mustard closeup photos. just kidding.