10 stop ND filter-screw in -v- slot

Les McLean

Les McLean

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Following on from these threads

http://www.talkphotography.co.uk/forums/showthread.php?t=116774
http://www.talkphotography.co.uk/forums/showthread.php?t=116689
http://www.talkphotography.co.uk/forums/showthread.php?t=116639

In which various options were discussed regarding the use of a 10stop ND filter, and some of the problems caused by a 'slot-in' type.

Lee (68lbs) very kindly sent me his slot in 10 stop ND filter (formatt) to try out, he had reported problems using it, notably 'blobs' of light appearing on his images.

I used the slot-in on a 24mm f1.4 lens, lee holder, Canon 1DS MKII, with the filter in the slot nearest the lens.

I also tried a comparison with a screw in ND x10 (B&W), this was on a 50mm F1.4, 58mm filter, and to compare I held the slot-in filter against the lens.

Suffice to say, on all the shots using the slot-in on the 24 mm lens, I experienced the same 'blobs' as Lee did. I tried varying apertures, light, shooting in shade, sun behind, in front etc, regardless , the blobs appeared sometimes prominent, sometimes faint.

Here are some examples, please disregard any cast, exposure, the exposure times were guestimates, I normally fine tune exposures when shooting with a 10 stop grad to get it right.

Also, the times I took exposure readings through the filter (never an exact science) there was quite a variation between the two types.

24-30_f22.jpg


VK0I0460.jpg


This was the best I achieved-they are still present around the bottom of the image.

VK0I0470.jpg


Comparison shot between screw-in and slot (on a 50mm F1.4 lens), the blob problem didn't occur, but a funny looking magenta splodge in the middle of the image did.

screw-in
VK0I0421.jpg


slot-in
VK0I0422.jpg



above at f22, tried similar at f11, fainter, but still there.

screw-in
VK0I0448.jpg


slot-in
VK0I0449.jpg



I'll let you draw your own conclusions (you usually do anyway :) ), but for me, it's a great pity the slot in doesn't really cut-it, it would be a lot easier in use than the screw-in, particularly as you need to take the filter off every time you want to compose, set focus, check light etc.

Once again many thanks to 68lbs for letting me test drive the slot in filter.
 
Great comparison. I have just ordered the screw in. I am happy that I made the right decision over the slot in filters, despite the inconvienience in composing a shot :thumbs:

Nice one Lee for letting Les test them :thumbs:
 
Thanks for doing this test and also Lee for loaning the slot in filter. :clap:

Has provided a useful insight into the magenta issue.

Like Sara I have decided on the screw in version.
 
I use a B&W 10 stop screw-in.

I imagine the slot-in problems are due to light leakage?
 
Thank you very much for taking the time to test this.

It's obvious there is an issue with the slot filter, which I am sure Lee should report it to Formatt (I believe it is a Formatt filter). Not for the refund, only, but to also bring this matter to their attention. I am sure they'd like to fix this, and if it's only something to do with Lee's copy then they may well replace it for him.
 
puddleduck said:
I use a B&W 10 stop screw-in.

I imagine the slot-in problems are due to light leakage?
Click to expand...

I think so, I know Messiah Khan had similar problems?
 
Many thanks for taking the time to have a play Les. What sort exposure times were you using here as I note that the magenta cast I have been getting is much less in your pics. Your second shot in this thread is about the best I've ever managed.

The main attraction of an ND 3.0 for me is exposures running into minutes that allow for extensive cloud blurring. Something it seems I'm not going to achieve with a slot in.
 
68lbs said:
What sort exposure times were you using here as I note that the magenta cast I have been getting is much less in your pics.
Click to expand...


It was quite bright, so around 30 seconds(ish) at f16-f18
 
Les McLean said:
It was quite bright, so around 30 seconds(ish) at f16-f18
Click to expand...

Thanks. That's what I was thinking. Oh well, at least I know it's not my sensor that's f*****!

I will indeed give formatt a call once I've got the filter back. It was purchased directly from them, so we'll see what they say. Interestingly, before I purchased, Teamwork did have reservations about the filter and weren't too keen to sell me one. They questioned whether 10 stops of block could be achieved with a neutral density resin filter.

Is the B&W screw in glass?

Teamwork also tried selling me a screw-in 10 stop... I think it might have been a Heliopan one, but I can't remember. I might see what kind of deal I could get with one of those instead. It was mega-bucks, I remember that much!
 
puddleduck said:
I use a B&W 10 stop screw-in.

I imagine the slot-in problems are due to light leakage?
Click to expand...

Sort of, yes. The problem is actually flare, which has obviously been caused by a light leak which then bounces off of the very dark surface of the filter.
 
Incidentally, Teamworks has Heliopan screw-in ND, but the ones they have are only up to ND 1.2 that retails at £79.20 for the 77-mm. Robert White has B+W 10 stop ND which retail for £76. I believe both are excluding VAT.
 
Interesting post Les. I bought one fo these ND's from Formatt a couple of weeks ago; I havent had a chance to try it out yet, but now I fear the worst. It would be interesting to hear Formatts reply to the problem.
 
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