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  #41  
Old 2nd January 2017, 05:07 PM
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I just thought it meant that you had to have your toga on straight.


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  #42  
Old 2nd January 2017, 06:44 PM
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Quote:
Originally Posted by Brock View Post
I just thought it meant that you had to have your toga on straight.


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Nothing to do with that I'm afraid - but I'll give you a clue:

It is not polite to hi-jack someone Else's thread.

Neil.
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  #43  
Old 2nd January 2017, 10:18 PM
Mike O'Pray Mike O'Pray is offline
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Deciding when and if a thread has reached the end of its life in terms of answering the OP's needs is always difficult.

Frankly compared to another forum I can think of, where threads have reached more than 30 pages and then bear no resemblance to the original topic we are a paragon of virtue here on FADU and generally we have the right spirit to maintain this.

The main thing is that we maintain this kind of bonhomie and goodwill that characterises this forum.

In my opinion we are all still defined by the meaning of "the reasonable man on the Clapham omnibus".

No small achievement after about 10 years of existence

Mike
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  #44  
Old 2nd January 2017, 11:56 PM
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It's not at all clear to me that this thread has either been hijacked or gone far off-topic. I have found it interesting. The only change in it is that has developed from brief information-giving to wider discussion, in which the OP has also participated. Certainly no Colosseum antics here.
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  #45  
Old 3rd January 2017, 12:04 AM
alexmuir alexmuir is offline
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Quote:
Originally Posted by EdmundH View Post
My one disappointment so far with B&W is the number of blank skies I get. Although I don't produce many landscapes in the usual sense, many of my photographs do include sky. Somehow there rarely seem to be any individual clouds around when I take my camera out, just cloudless blue, or overall cloud cover. Basing the exposure on ground based subjects frequently leaves the sky bright and featureless. Would a yellow filter help? - I recall reading somewhere that it's quite usual to always have a yellow filter fitted, but I don't necessarily want to increase contrast in the scene overall.


I don't think this has been said yet, but the problem arises because most panchromatic B&W films have a greater sensitivity to blue than other colours. Unfiltered, therefore, blue will appear lighter than it would if the film had a uniform sensitivity to all colours. White, however, as we see the sky quite often in the UK, should be recorded quite accurately by the film. The other thing that comes into play is the relative brightness of the sky, even if it's overcast. It might be beneficial to test the extent of this by metering an overcast sky, then comparing the reading to an average tone on the ground. Certain films, as mentioned above, seem to give more detailed skies. These tend to be films with an extended red sensitivity, approaching the near infrared spectrum. Fomapan and Rollei Retro films have this property. It might be worth giving them a try. I agree with the advice already given about filters and printing techniques. There is a filter described as 'minus blue' which I have heard of, but never found an example. Perhaps someone else would know of a manufacturer producing this today. The problem of a subject projecting into a featureless sky is something I have struggled printing. The Cartier Bresson example above works, in my opinion, because of careful composition. That's probably the most important consideration, although like you I'm not keen on featureless skies in my own work.
Alex
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  #46  
Old 3rd January 2017, 12:13 AM
EdmundH EdmundH is offline
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Please calm down people. I'm pleased that my query has raised such a lot of interest and discussion. I don't necessarily agree with all sentiments expressed, but I now have some very good recommendations which I'll be trying out in the coming months. For the record, I like my prints to be fairly representative of the original scene, with smoothly graduated mid tones. Not gritty or ominous.
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  #47  
Old 3rd January 2017, 05:54 PM
Mike O'Pray Mike O'Pray is offline
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Alex, interesting that you mention a "minus blue" filter. I think it is David Allen who is a friend here who highly recommends this filter for skies.

I think his posts on this are elsewhere but it appears that then usual yellow filter may not be as good as the "minus blue" and no doubt he has given an explanation in those aforementioned posts but I cannot recall why the minus blue is a better filter than a yellow.

Hopefully he might chip in if he sees this thread

Mike
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  #48  
Old 3rd January 2017, 10:18 PM
Mike O'Pray Mike O'Pray is offline
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I have just done a bit more research. The minus blue appears to be have a wratten 12 designation whereas my yellow filter has a K-2 designation. Both filters have a factor of 2X so are equal there but the K-2 only blocks light below 465nm whereas the minus blue blocks light below 500nm


My knowledge of light wavelength theory is poor but I take it that by blocking light higher up the scale, the minus blue increases the effect on the colour blue's range such that more of blue light is blocked this improving the effect of this filter compared to the yellow.

David Allen says on more than one occasion that a minus blue is quite different from yellow filters. In fact from my research even a deep yellow only blocks light below 470 so is still 30nm less than the minus blue.

I take it that when David says that it is quite different from yellow he is effectively saying that this 30-40nm increase in its light blocking range is enough for a user to see the difference in two shots of the same scene, same light etc between the yellow and minus blue

I cannot say as I do not have a minus blue nor can I compare a minus blue with an orange which will block up to 530nm but it looks as if an orange filter, based on its light blocking range, may give a darker look to a blue sky compared to a minus blue but the "improvement" of orange over minus blue will be slightly more marginal than a minus blue over a K-2 which is usually the yellow that most users will have or be sold if they ask for a yellow filter

It might also be that the 30-40nm extra range that the minus blue has takes you to the end of the blue colour range and the extra 30nm that orange then provides becomes more marginal. It is also worth noting that an orange increases the exposure factor compared to a minus blue which, all things being equal, is a drawback.

The proof of the pudding is always in its eating so ideally two prints of the same scene with a yellow and a minus blue would be worth seeing.

Feel free to comment on my statement above

Mike
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  #49  
Old 4th January 2017, 11:44 AM
EdmundH EdmundH is offline
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Quote:
Originally Posted by Mike O'Pray View Post
I have just done a bit more research. The minus blue appears to be have a wratten 12 designation whereas my yellow filter has a K-2 designation. Both filters have a factor of 2X so are equal there but the K-2 only blocks light below 465nm whereas the minus blue blocks light below 500nm


My knowledge of light wavelength theory is poor but I take it that by blocking light higher up the scale, the minus blue increases the effect on the colour blue's range such that more of blue light is blocked this improving the effect of this filter compared to the yellow.

David Allen says on more than one occasion that a minus blue is quite different from yellow filters. In fact from my research even a deep yellow only blocks light below 470 so is still 30nm less than the minus blue.

I take it that when David says that it is quite different from yellow he is effectively saying that this 30-40nm increase in its light blocking range is enough for a user to see the difference in two shots of the same scene, same light etc between the yellow and minus blue

I cannot say as I do not have a minus blue nor can I compare a minus blue with an orange which will block up to 530nm but it looks as if an orange filter, based on its light blocking range, may give a darker look to a blue sky compared to a minus blue but the "improvement" of orange over minus blue will be slightly more marginal than a minus blue over a K-2 which is usually the yellow that most users will have or be sold if they ask for a yellow filter

It might also be that the 30-40nm extra range that the minus blue has takes you to the end of the blue colour range and the extra 30nm that orange then provides becomes more marginal. It is also worth noting that an orange increases the exposure factor compared to a minus blue which, all things being equal, is a drawback.

The proof of the pudding is always in its eating so ideally two prints of the same scene with a yellow and a minus blue would be worth seeing.

Feel free to comment on my statement above

Mike
I just found this page from Kodak which is well worth a look - it contains descriptions and curves for all Wratten filters. From this I can see that a 'Minus blue' filter is basically deep yellow, but with a slightly sharper cutoff than standard deep yellow.

http://motion.kodak.com/kodakgcg/mot...rs/default.htm
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  #50  
Old 4th January 2017, 05:14 PM
Mike O'Pray Mike O'Pray is offline
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Thanks for the link, Edmund. I had a look at the minus blue curve and yellow curve and there was a difference, although how much difference this makes in a print is difficult to say without two prints from the respective filters being in front of the viewer.

However when it comes to the difference in curves between the deep yellow and minus blue they looked to be the same or as near as damn it, the same.

So I do wonder what to make of David Allen's statement that the two are quite different. It might depend on how one defines "quite" and maybe what one person's perception is compared to another.

Mike
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