10 & 20 stop b+w filter advice

rclarke80

rclarke80

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Rich
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Hi folks,

Just acquired a 10 stop & a 20 stop filter, before spending hours (especially with the 20 stop filter) is there anything i should know or watch out for?

I know to prefocus, compose and meter before putting filters on obviously but my main concern is if obviously its a broken cloud day, when the sun is in and out fairly rapidly that would effect my calculations for the filter exposure time?
 
In which case, before you start, take average of metering over a few mins? One thing to watch out for is that they might not be actually 10 or 20 stops and instead 11 stops 18 stops etc. Test out what they are at high ISO and aperture first so you don't waste time, you can do this in your room.
 
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I never thought of that, will test them for actual stops. Can also sort any white balance issues at same time.

Cheers, appreciate it.
 
RedTele said:
In which case, before you start, take average of metering over a few mins? One thing to watch out for is that they might not be actually 10 or 20 stops and instead 11 stops 18 stops etc. Test out what they are at high ISO and aperture first so you don't waste time, you can do this in your room.
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usually a bit of guesswork does the job. Just check the histogram at the end and reshoot if necessary.

Make sure you cover the viewfinder before starting the exposure, or even trying to meter in Av mode with the filter.

LV can work a treat for composing and adjusting exposure. again cover the viewfinder
 
It's the shooting for hours and checking histogram and it not being right that worries me, still a good excuse to get out and practice some more.

B+W make the 20 stop filter, when hold it up to a lightbulb there's the real faintest of light passing through it. I assume both the 10 stop and 20 stop can be stacked if had a spare day or more!

Will get out and report back with test images. Watch this space....
 
Put camera on tripod earlier, took a standard shot exposed at 1/500 sec then put 20 stop filter on and calculated 32 mins exposure was needed and glad to report all is good. Plenty of hot pixels and slight colour cast but nothing that can't be sorted. Will try and get out next week and put it some proper use.
 
Battery life may be an issue!
My 5DII can only keep the shutter open for about 4 hours using a freshly charged battery.
I bought a cheap grip from eBay which holds two batteries :)

Please post some of your results - this could get interesting!
 
20 stop....wow. A 30 second exposure will need a year's exposure with the 20 stop on!!

Why did you buy the 20 stop out of interest?

Cheers.
 
I can't think of any practical application to a 20-stop ND - excuse my ignorance but what is there that one can't do with a 10 stop that you could do with a 20?
 
travellingcello said:
I can't think of any practical application to a 20-stop ND - excuse my ignorance but what is there that one can't do with a 10 stop that you could do with a 20?
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I think can answer that...
Typical good light would be ISO 100, f16, 1/125s.
With 10 stops that's only 8 seconds. not long enough to get movement in the clouds and barely enough to tame moving water.
With 14 stops it goes up to 2 mins. I've got one of these (but haven't tried it yet).
And 20 stops gives two hours!
That'll produce the most dreamy looking skies and water that looks like soft mist.
I'd quite like to give it a go but am not sure I've got the patience to take many of them. :)
 
DuncanDisorderly said:
I think can answer that...
Typical good light would be ISO 100, f16, 1/125s.
With 10 stops that's only 8 seconds. not long enough to get movement in the clouds and barely enough to tame moving water.
With 14 stops it goes up to 2 mins. I've got one of these (but haven't tried it yet).
And 20 stops gives two hours!
That'll produce the most dreamy looking skies and water that looks like soft mist.
I'd quite like to give it a go but am not sure I've got the patience to take many of them. :)
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But what effect can you achieve in a 2 hour exposure that you can't achieve in say a 10 minute exposure?

I get the point that in bright conditions you would need something stronger than a 10 stop but in good light there wouldn't be many of those clouds anyway and over a 2 hour exposure I would think none of the picture would be very sharp if there is any wind at all....
 
travellingcello said:
I can't think of any practical application to a 20-stop ND - excuse my ignorance but what is there that one can't do with a 10 stop that you could do with a 20?
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Sunspots.
 
I did buy it for a specific reason, which I won't say just yet until I've tried it and will post images up of what I get.

Would it be any use for sunspots too or would you need a mylar (sp?) filter for that?
 
Been out with the 20stop filter today, ran an exposure for 1hr4mins in town, exposure is fine, colour cast is noticeable but nothing that can't be sorted.

The reason for the filter is to remove all evidence of people within the shot, 1hr4mins goes a good way to doing it but not quite. Is it indeed possible? Next step is 2hr8mins and see how get on I think!
 
rclarke80 said:
Been out with the 20stop filter today, ran an exposure for 1hr4mins in town, exposure is fine, colour cast is noticeable but nothing that can't be sorted.

The reason for the filter is to remove all evidence of people within the shot, 1hr4mins goes a good way to doing it but not quite. Is it indeed possible? Next step is 2hr8mins and see how get on I think!
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Removing all people? Who stays in the same place for 2hr and 8mins???
 
rclarke80 said:
I thought that with 1hr4mins but you'd be amazed.
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But isn't this just totally over the top? Presumably anybody who is still there is so blurred you can remove them in post-processing, and in any case the same effect can be done by blending much shorter exposures.
 
Oh it's extreme yes, it all started with curiosity of whether it was possible.

I agree with the photoshop thing but then again couldn't most things? There'd be no need for any filters and such?
 
travellingcello said:
But isn't this just totally over the top? Presumably anybody who is still there is so blurred you can remove them in post-processing, and in any case the same effect can be done by blending much shorter exposures.
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blending would definitely be a more suitable option, given the limitations of such long exposure, consider all the noise and the possibility of motion blur over such a long period
 
rclarke80 said:
Oh it's extreme yes, it all started with curiosity of whether it was possible.

I agree with the photoshop thing but then again couldn't most things? There'd be no need for any filters and such?
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Yes but for what you are trying to do you would get better results blending exposures - I would guess that your sharpness suffers through such long exposures and with all the hot pixels and noise whats the point? Not to mention the hassle and time it takes.

It isn't any of my business of course but just wondering why all the hassle.

Would be interested to see your results, can you post up your initial results?
 
Oh no I appreciate the advice, I know little about photoshop apart from basic enhancement of images.

I think I've already format the card ready for the weekend but will double check.
 
rclarke80 said:
Oh no I appreciate the advice, I know little about photoshop apart from basic enhancement of images.

I think I've already format the card ready for the weekend but will double check.
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If your camera can do multiple exposures, that's probably the easiest way. Exposure 1/100sec, then ten shots at 1/1000sec.
 
rclarke80 said:
Would it be any use for sunspots too or would you need a mylar (sp?) filter for that?
Click to expand...

I wouldn't risk using it for sunspots. My testing of 10-stop filters has shown me that some are only 6-stops for IR, they're letting through 16 times more IR than visible (it explains why you can't accurately meter using such a filter - the exposure metering system is IR-sensitive). And it's the IR from sunlight that's going to do nasty things inside your eye and camera.

Stick with Baader Astrosolar film. Cheap, reliable and safe when used correctly.
 
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I formatted the card when got back and checked results, so don't forget before tomorrows match. The card hasn't been used since so could they be retrieved fro the card? Will try and find time to do so if poss and post up.
 
HoppyUK said:
If your camera can do multiple exposures, that's probably the easiest way. Exposure 1/100sec, then ten shots at 1/1000sec.
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Am I wrong or is multiple exposures beyond the capabilities of a 1dmk3?
 
rclarke80 said:
Am I wrong or is multiple exposures beyond the capabilities of a 1dmk3?
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Not sure, but probably. Only the lastest Canons have it I believe, though more Nikons do.
 
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