First attempt with ND filter - advice welcome !

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1,471
Name
Justin
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#1
Hello

I finally decided to purchase a ND 10 stop filter to have a go at long exposures. I've never used any filters before (other than a CPL) and wanted to practice before a trip to Scotland next month !

I read some advice on the internet and downloaded an exposure app and followed this basic procedure.

Took a baseline shot with A/F on OIS off - ISO set to 160. With the shutter speed from this I used the calculator to give me the shutter speed with the 10 stop filter on.
Put into MF, screwed in filter- kept ISO at 160 and roughly followed advice given by my app - I found, however, that the app tended to under exposure images...
Selected timer and chose 2 seconds - pressed shutter and didnt dare move...

Does this procedure sound OK to you ?

This was the result witht the shutter speed at 25 seconds

Darley Abbey Weir
by Justa1972, on Flickr

However, when I increased the shutter times it had an odd effect on the trees in the top right corner ? Anyone know what this is ?

DSCF2344.jpg
by Justa1972, on Flickr

Thanks for looking and all advice gratefully rec'd !

cheers
 
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1,305
Name
Trevor
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#3
The process seems sound enough to me Justin. It will be the filter causing the discrepancy, not the app, they are rarely exactly as stated. It sounds like yours is denser than 10 stops. Test it a few times, comparing the app time with that of a well exposed shot and you’ll see what strength the filter actually is and then you can use that to dial the correct rating into the app.
I agree with Elliot, I think that is movement of the tree branches during the 25 secs of the exposure.
 
OP
OP
justa1972
Messages
1,471
Name
Justin
Edit My Images
Yes
#4
The process seems sound enough to me Justin. It will be the filter causing the discrepancy, not the app, they are rarely exactly as stated. It sounds like yours is denser than 10 stops. Test it a few times, comparing the app time with that of a well exposed shot and you’ll see what strength the filter actually is and then you can use that to dial the correct rating into the app.
I agree with Elliot, I think that is movement of the tree branches during the 25 secs of the exposure.
Thanks Trevor that's great :)
 
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321
Name
Steven
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#7
If you are concerned about the wind movement you can do what other people do and take two exposures. One long and one normal then blend them in photoshop.

Regards...
 
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321
Name
Steven
Edit My Images
No
#15
Serious!

I'm amazed that a piece of software can know that you want movement in certain parts of an image and sharpness in another.
The software doesn't know. You do. Load both images into Photoshop* as layers and use layer masks to blend them. It doesn't work in Lightroom as that software doesn't support layers and layer masking.

Have a search on Youtube for Photoshop image blending. Lots of videos explaining it.

*Other software like Affinity might offer the same facilities.

Regards
 
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