How to Take Really Long Exposures

[milleniummuppet]

I have recentaly woken up to the fact that you can take photos with long exposures.
I knew it was possible, then the other day I thought 'Now how exactally is that done?'.

Colin, I know you were saying that some of your pics contained images that had been exposed for a whole minute.
How do you achieve this without producing a 'White-out'?
Is it something to do with aperture?
Or Filters?
I don't know.

[iPhillip]

Usually its for night photography, otherwise no matter how you fiddle with settings in the daytime - with a minute exposure your sure to get a white out.

To get these long exposures the camera I use and generally most cameras have a "B" option with which you manually set the exposure time by holding down the shutter button. Otherwise set exposure times only go up to a 30 seconds if I recall correctly (on the pentax at least).

[milleniummuppet]

Nope.
Colin had a photo, rocks, water, and sky, that was a blend of photos with exposures up to 1 minute ( and it wasn't at night).
I know, I couldn't understand it either but it can obviously be done.
Also my canon power-shot can reach up to 64 seconds.

[Zephyrize]

Are you talking about this one ?
http://photo.net/photodb/photo?photo_id=7485303

Me too, would like to know it's breathtaking.

[McQ]

With an SLR you will need to use "bulb mode" with a manual exposure setting. You press the shutter once to start the exposure and then again to stop it. An external trigger device is preferred though if you want to minimize camera movement during the exposure. The Canon timer/remote device is one option.

In order for your images not to be too overexposed, you will need to either (i) take the photo when there is barely any light or (ii) use settings that minimize the amount of light reaching the sensor. For night time shots, a small aperture of f/11-f/16 usually guarantees a very long (multiple minute) exposure). For daytime shots, you will need to use a neutral density (ND) camera lens filter. Another option (although often with less smooth results) would be to take multiple regular photos and average them. However, depending on the subject matter, this can sometimes create a "jumpy" or discrete look to anything which moves predictably in between exposures. Sometimes this works for water though, if enough images are averaged...

[milleniummuppet]

'http://photo.net/photodb/photo?photo_id=7485303'
Yes this is the photo I am talking about.
Colin, I would really like to know how it is done! =)

Also, I have some custom addon firmware for my camera, and in this firmware is a setting called "ND filter state" with the options 'off' 'in' or 'out'.
With this turned to 'in' I notice that it lets in considerably less light, and I can get away with exposures up to about a second.
Is this setting trying to emulate a lens filter?

[iPhillip]

I think McQ sumed up nicely what I was trying to get at.

[Colin Southern]

Hi folks,

Happy to tell you all about it ...

... but will have to wait a few hours until I get home.

The short version however can be found at ...

http://singhray.blogspot.com/search/...lin%20Southern

Cheers,

Colin

[Colin Southern]

I reckon this McQ chap might know a thing or two about low-light photography

Seriously, there's a touch of "full circle" here - I first heard of Sean in a feature article in pbase magazine ...

[http://www.pbase.com/magazine - quick side note - if you haven't read pbase magazine, you're really missing out on something. In my opinion it's almost the PERFECT photography magazine - AND - it's free (despite the fact that I'd pay good money for a magazine like that)]

[Another quick tangent - download http://i2.pbase.com/o1/mag/pbase_mag...l6_jul2006.pdf

and say hello to our esteemed leader - just do it quick before Sean sees this and edit's it out!]

... anyway (back on topic - see, I do learn from my mistakes) - Following Sean's debut in pbase magazine I checked out his tutorials here - and somewhere along the way answered a question I could never get a definitive answer to: What to set layer opacities to when blending multiple exposures. I use that technique myself - and here I am passing that knowledge on to the next "generation"!

Regarding the shots, Sean summed it up well of course. With after glow type shots you can start getting shutterspeeds down to around the 30 second mark, but it's not often you'd be doing multi-minute stuff without filters.

I do a lot of multi-minute exposures because I work with water a lot - and long exposures smooth water out to give an effect that I like.

Filters are the key - and I have 3 that I work with a lot - all made by Singh-Ray (who in my opinion make the best) ... The first is a classy bit of kit called a Vari-ND - it lets you vary the attenuation between 2 and 8 stops, which is great as it allows you to choose the shutterspeed you want (for the effect) - choose the Aperture you want (for DOF control) - and then simply twist the filter to get the exposure correct. This image is a blend of 4x 30 second shots done in exactly this manner ...



The next filter I use is called a Mor-Slo which is a straight 5-Stop ND that screws onto the Vari-ND (or can be used in place of it) that can give me up to 13 stops of attenuation (pretty serious stuff!) ...

The last that I typically use is either a Graduated Neutral Densite filter (GND) or Reverse GND to balance the copious amounts of light in the sky with some of the darker foreground detail (so the detail can still be recovered). The Mountains and the Mist Revisited shot was done with one of these (although I did blend a different interpretation of 1 copy of the RAW image for the sky to give a psudo-HDR composition (sould have done it without doing that, but would have required more work).

The Vari-ND and Mor-Slo filters are screw-in types, where the GNDs are 6" x 4" (postcard size) in a Lee holder (so they can be moved up and down) to meet the horizon.

Other than that, it was pretty much just as described in the Singh-Ray blog - not quite dark, but getting fairly dim. It's almost ironic that the thing thats being pushed more and more with new cameras is high ISO performance - whereas in reality us landscape shooters need the exact opposite (the 1Ds3 goes to ISO 50, but I don't often use it as it also chops about 1 stop out of the dynamic range).

The long exposures are mostly spot metered with a hand-held light meter and then programmed with a Canon TC80-N3 timer.

Hope this helps

Cheers,

Colin - pbase.com/cjsouthern

[shreds]

A lot of photographers shy away from long exposures because it is not handed to them on a plate, but for me, the challenge of knowing through (sometimes painful) experience how long to keep a long exposure running especially at night is part of the challenge, especially in todays world where a lot of the experimentation and guesswork have disappeared. I read this week that something like 11% of photographers never try this form of photography which is sad as it is quite satisfying.

Firstly review your surroundings and light levels and bracket all your exposures. Always ensure the camera is rock solid on a tripod and use a timer to trigger your shutter rather than touching the camera.

Bear in mind that anything that moves in the field of view can be recorded as a blur (depending on the length of exposure), and also consider that over exposure at night is usually less critical than during daylight hours.

[iPhillip]

If I was going to buy just the one ND filter for now, which would be for me the most versitile for generally taking shots with a reasonably long exposure, trying to expand my knowledge base and just plain "experimenting".

Because I don't really want all ND2 ND4 and ND8 filters (atm) I would like to know what the most useful/verstile stop for me is.

[Colin Southern]

Because I don't really want all ND2 ND4 and ND8 filters (atm) I would like to know what the most useful/verstile stop for me is.

The single most versatile ND filter - without a doubt - is the Singh-Ray Vari ND - it gives you everything from 2 stops all the way through to 8 stops, with no colour shifts or casts.

They are expensive, but once you have it, you have it for life - it's an extremely high quality piece of kit.

It's available in 77mm (std or slim mounts) and 82mm (std mount) (only the std mounts have front filter threads).

Take a look at ...

http://www.singh-ray.com/varind.html

Happy to answer any questions about them (I have two) (Vari-NDs that is, not questions!).

Cheers,

Colin - pbase.com/cjsouthern

[iPhillip]

Thanks for that Colin, I did read your previous posts and gathered that the Vari-ND probably was the way to go, but after seeking it out a bit more I realized (being a student and all) its out of my price range. Thats why I was wondering about which single ND filter would be the best for me - Considering the price is an issue.

[Zephyrize]

Because I don't really want all ND2 ND4 and ND8 filters (atm) I would like to know what the most useful/verstile stop for me is.

I'm interested to know as well. Those Vari-ND look tasty but far too expensive

From what I understand, I think it's better not buying the smallest but rather a bigger f-stops? Like 3 or 4 f-stops. The worst scenario would be too dark, necessitating a longer exposure time.. is that right?

[Colin Southern]

"Thanks for that Colin, I did read your previous posts and gathered that the Vari-ND probably was the way to go, but after seeking it out a bit more I realized (being a student and all) its out of my price range.

I'm reminded of the line in Risky Business where Tom Cruise says "Porche - THERE IS NO SUBSTITUTE!" - in my opinion, it's a bit like the Vari-ND. To replace it with quality fixed ND filters would probably cost you a lot more - to buy 2 or 3 and stack them might get you the same attenuation, but you'll almost certainly get vignetting issues. So in a way one could ask "what will it cost you NOT to get the Vari-ND"?

It's a tough one. When I started out I picked up a cheap (and nasty) ND from our national equivalent of eBay - and for reasons I don't understand, everything shot through it was blurry. It took me a while to figure out what was happening - filter looked OK - AF locked on just fine, but all the images were quite considerably OOF. In the end I cured the issue with a simple 2-Step process; I took it off the lens - took two steps to the rubbish bin - and dropped it in! No regrets!

If you really can't beg / borrow / "steal" / sell-your-soul to get a Vari-ND then I guess a more conventional one from other sources is the only option - I'd probably go for something like a 2 & a 4 stop, so you could do 2, 4, and 6 stops. Can be hard to use though because if you're aiming for a long 30 sec to several minuetes exposure, you can't see through the view finder to focus without taking them off - then you have to reattach them without moving the focus ring (in manual at this stage) - with the Vari-ND you can set it to minimum - focus - and then dial in whatever attenuation you need.

"The worst scenario would be too dark, necessitating a longer exposure time.. is that right? "

Kinda-sorta. Depends on what you're shooting really. If you're trying to do the classic waterfall shot then once you get past a few seconds it doesn't change a lot after that, but if you're working with waves then shutterspeeds around 1/4 sec to 2 sec often give nice effects, and you need to be able to expose them correctly. It wouldn't be impossible without a Vari-ND (people have been doing it for centuries), but in my opinion it just makes it harder - you have to work more around the limitations of the equipment (which I hate) rather than having the equipment work for you. Still quite doable, but can be harder in some situations.

Cheers,

Colin - pbase.com/cjsouthern

[iPhillip]

Thanks for that Colin, I have actually had a look on trade-me for filters but have put off buying anything prior to some advice.

I won't be buying a ND filter for the time being, next holidays I will be working and should have plenty of time to decide on what I shall get whether its a Vari or not.

EDIT: I have brought a circular Polarizing filter though.

[Colin Southern]

"Thanks for that Colin, I have actually had a look on trade-me for filters but have put off buying anything prior to some advice."

That's exactly where I got my "problem" one from. The chap who sells that brand sells a lot of cheap items like that - he's a wonderfully nice chap to deal wth - but the bottom line for me was, unfortunately, "I got what I paid for".

Cheers,

Colin

[john w revie]

Matt
An other way of achieving the look of Longer exposures is to stack multiple exposures in photoshop.
A free to down load photoshop action I have written (CS2 and above) can be found on my web site at
http://web.mac.com/jwrevie/
If you would like to try this, download both the action and the instructions. then load the action into the photoshop actions pallet
I have also found that some nice effects can be achieved by changing the blending mode of the layers before flattening the image.
To only requirement to run this action is the photographs must be taken using a tripod as no movement between frames is required.
A quick explanation of the of the outcome, anything in the photo that has movement will blur and any static objects will remain sharp.
The normal frame count to run this is nine frames. 9 times 30 sec = 4.5 minutes, the most frames I have run through this action is 81(9 times 9) Total exposure time 40.5 minutes
To achieve this I ran the frames through the action in batches of 9 Flattened and save the 9 resulting frames where then run through the action.
If you try this please let us know your results.
john

[Slipstick]

I have heard that stacking two circular polarising filters and varying them relative to each other can produce the same effect as the Vari-ND filter. One polariser cuts out about 2 stops, the other one can remove variably whatever light is left, as a maximum.

Has anyone tried this technique, and if so, does it work?

Inexpensive polarisers can be bought that lose little quality compared to the top brands. This could offer an inexpensive alternative to the Vari-ND.

[john w revie]

Tony
I have tied that way the problem that I found was with 2 filters fitted you get a colour shift
and unless your camera is one of the top end Canon or Nikons the lenses require a f stop of 1.4 or greater this is because the lower end cameras will not auto focus at less that f 5.6
ie. f1.4 *2*2= f5.6 if both the filters are maximum clarity, taken you back to the high cost. the only way round this problem is to focus without the filters change to manual focus and refit the filters running the risk of moving the focus ring.
John