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07-02-2018, 08:09 PM   #1
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Long Exposure and Filters??

Hello!

I just got myself a new Pentax K-70, how do I start taking long exposure photos with this camera? Are ND filters necessary for long exposure shots? When do you use filters and when do you not?

I have been doing quick google searches for these questions, but everyone seems to have a different opinion and every camera is different. Any and all help is appreciated.

Thank you!!!

07-02-2018, 08:14 PM - 1 Like   #2
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It depends on the lighting and aperture and iso. In bright light with low iso - if you want a long exposure you will likely need a neutal density filter. An alternative involves using the interval method and averaging the pictures to get a similar effect. But I have little experience in either method so I hope some experts drop in.
07-02-2018, 08:16 PM - 1 Like   #3
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QuoteOriginally posted by Jrolandphotography Quote
Hello!

I just got myself a new Pentax K-70, how do I start taking long exposure photos with this camera? Are ND filters necessary for long exposure shots? When do you use filters and when do you not?

I have been doing quick google searches for these questions, but everyone seems to have a different opinion and every camera is different. Any and all help is appreciated.

Thank you!!!
You don't really need a ND filter unless you're shooting moving water or something else that portrays motion.

Check out our article on this here:
Daylight Long Exposures Using a ND Filter - Articles and Tips | PentaxForums.com

Adam
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07-02-2018, 08:26 PM   #4
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QuoteOriginally posted by Adam Quote
You don't really need a ND filter unless you're shooting moving water or something else that portrays motion.

Check out our article on this here:
Daylight Long Exposures Using a ND Filter - Articles and Tips | PentaxForums.com
Thank you for the article, this is helpful! Do you know how I set up a long exposure shot with the Pentax K-70?

07-02-2018, 08:50 PM - 1 Like   #5
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Setting the K-70 to manual is a good start. You should understand exposure triangle well before making this leap. Do you have basic knowledge of ISO/Aperture/Shutter speed relationships?
07-02-2018, 08:56 PM - 1 Like   #6
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QuoteOriginally posted by Jrolandphotography Quote
Thank you for the article, this is helpful! Do you know how I set up a long exposure shot with the Pentax K-70?
QuoteOriginally posted by UncleVanya Quote
Setting the K-70 to manual is a good start. You should understand exposure triangle well before making this leap. Do you have basic knowledge of ISO/Aperture/Shutter speed relationships?
I've got another article to answer that

The Fundamentals of Exposure - Introduction - In-Depth Articles

For really long exposure shots, there is also a timer in B mode that allows you to go up to 20 minutes. But for what you're aiming to do, the 30 second limit in M mode is more than enough.

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07-02-2018, 08:59 PM   #7
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QuoteOriginally posted by UncleVanya Quote
Setting the K-70 to manual is a good start. You should understand exposure triangle well before making this leap. Do you have basic knowledge of ISO/Aperture/Shutter speed relationships?
I would not say I completely understand the basics. I have spent quite a bit of time on YouTube and Pentax Forums, however understanding concepts and putting them into practice are two different things.

From my understanding ISO has to do with light sensitivity, aperture has to do with depth of a photo, and shutter speed is how quickly an image is capture. Is this correct?

07-02-2018, 09:17 PM - 1 Like   #8
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QuoteOriginally posted by Jrolandphotography Quote

From my understanding ISO has to do with light sensitivity, aperture has to do with depth of a photo, and shutter speed is how quickly an image is capture. Is this correct?
Not entirely. Aperture is the diameter of the opening in the lens that lets the light through, and it is measured in gauge kind of like wire. (Smaller number is a bigger opening). It is called the f-stop. The lower the f-stop number, the more light comes in while the shutter is open and the narrow the depth of focus is. The ISO is the sensitivity of the sensor/film setting and the larger the number more sensitive and therefore the faster an image can be recorded. Higher the ISO, the grainier the image. The relationship of ISO number to quality of image is inverse. Shutter speed is just how long the shutter is open to allow light through.
Therefore, to maintain an exposure value (ev), high shutter speed requires low f-stop and high ISO. High f-stop requires low shutter speed and high ISO. High ISO allows high shutter speed and high f-stop.
Essentially, all three actions affect the amount of light getting to the sensor. If you want a high quality image, then low ISO (100-400) is the goal, and if you need a lot of field depth from a high f-stop, you are going to need a long exposure and a really steady hand...also known as a tripod.😁
07-02-2018, 09:25 PM - 1 Like   #9
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QuoteOriginally posted by Jrolandphotography Quote
I would not say I completely understand the basics. I have spent quite a bit of time on YouTube and Pentax Forums, however understanding concepts and putting them into practice are two different things.

From my understanding ISO has to do with light sensitivity, aperture has to do with depth of a photo, and shutter speed is how quickly an image is capture. Is this correct?
Buy this book:
Understanding Exposure, Fourth Edition: How to Shoot Great Photographs with Any Camera: Bryan Peterson: 9781607748502: amazon.com: Books?tag=pentaxforums-20& (use affliate links from the forum however to help the site)


Basic theory:

ISO (yes sensitivity) + aperture + shutter speed = an exposure. A given calculation for an exposure will result in a particular value chosen for all three. Making adjustments to any of them without changing in a related way others will result in an exposure with more light or one with less light than the original calculated exposure (we can pretend and call this the normal exposure for now). More light = overexposure; less light = underexposure from the "normal" one calculated. Note I'm not saying how this was calculated - you can use the camera meter, the sunny 16 rule, a light meter, etc.

Assume ISO is set to 100 and isn't changing (not set to AUTO ISO).
Assume the "normal" exposure calculated was 1/125s at f/8.
If you wanted to have less depth of field and were willing to adjust aperture - if you lowered f/8 to f/5.6 you would have increased the light by 1 "stop". This could be compensated by reducing the time of the shutter opening to 1/2 (every stop is based on this factor in time) so the new "normal" would be ISO 100, f/5.6, 1/250s. The same can be accomplished by moving the ISO so you could keep 1/125s if you adjusted to ISO 50 - but most cameras won't go that low. Alternatively if the original ISO had been 1600 and the same exposure you could lower it to 800. The only value that isn't adjusted in direct multiples of 2 is aperture which is based around ratios of openings and does relate back to 2x the light but the numbers are a bit weirder. In aperture 2x = 2 stops. So f/4 to f/8 is two stops with f/5.6 between.

It's a lot to absorb.

Neutral Density filters simply take away light and add the need for more stops of light to come from the camera so you can take a bright beach and shoot a long exposure with shallow depth of field if you want. The combinations are quite large but don't get overwhelmed. Start with the image you want to make, take a benchmark "normal" shot and look at the exposure parameters the camera set for you. Let's say it was ISO 1600, f/4, 1/250s. To get a blurred effect you might want a 1/2 sec exposure lets say. Adding light from 1/250 to 1/125 to 1/60 to 1/30 to 1/15 to 1/8 to 1/4 to 1/2 is a lot of stops (7 to be exact). You could drop from ISO 1600 to ISO 800 to ISO 400 to ISO 200 to ISO 100 (4 stops), then you could change aperture from f/4 to f/5.6 to f/8 to f/11 (3 more stops) to get the effect you wanted. (These numbers are just made up btw - the ratios are right but the numbers are just pulled out of thin air.)

Another important fact: time is in ratios of 1/time - so the larger numbers are smaller values. Aperture is a ratio of size of the opening to the focal length so again larger numbers represent smaller openings with less light admitted. ISO is a value that goes up with increased sensitivity so increasing ISO makes the needed light for a given exposure go down.

Higher ISO = higher noise (to a degree)
Higher Aperture = more depth of field, likely higher sharpness to a point and then loss of sharpness due to magical fun called diffraction
Higher shutter speeds = faster action can be stopped, flashes will not sync easily over a set value based on the camera, etc.

This is only scratching the surface.
07-02-2018, 09:26 PM - 1 Like   #10
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It sounds hard but it gets really easy once you jump in and start learning.
07-02-2018, 09:37 PM - 1 Like   #11
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Another reason for long exposures: Astrophotography Series Announcement - Articles and Tips | PentaxForums.com
07-02-2018, 10:28 PM - 1 Like   #12
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It might help to know what kind of photos you'd like to capture with long exposure. You could use it at night for city lights or stars. Or you could use long exposure to show motion blur of a dog or a car passing by. Or you could use it to make flowing water look smooth. Or you could even make people disappear from a busy street. Each of these photos will require different techniques. Some of them will require an ND filter. Most will require a tripod. Let us know what type of photo you want to try and we can give some suggestions for how to capture the shot you want.
07-02-2018, 11:30 PM - 1 Like   #13
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QuoteOriginally posted by Jrolandphotography Quote
Thank you for the article, this is helpful! Do you know how I set up a long exposure shot with the Pentax K-70?
If you are taking long exposures in daylight using an ND filter make sure that you cover the viewfinder. If you don't it is quite likely that light leakage will ruin your images. I just use a folded piece of light card inserted under the rubber viewfinder surround.

Last edited by slartibartfast01; 07-03-2018 at 04:47 AM.
07-03-2018, 03:25 AM - 1 Like   #14
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All the replies you could ever wished for, so I'll just saw welcome to the forum.
07-03-2018, 03:48 AM - 1 Like   #15
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Welcome. I would also recommend buying the K-70 eBook for sale on this site. It will explain a lot.
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