Long exposure question

Clarity · 12-27-2014, 10:11 AM

Originally posted by LesDMess

If you are not aware, the Pentax LX (film SLR) is the only camera ever made - by any manufacturer, that can aperture priority auto expose a scene for as long as it takes while monitoring the scene for changes in lighting and adjusting exposure accordingly. Since it takes it's exposure off the film plane, it doesn't require a cover for the viewfinder and stray light entering there does not influence the meter.

I have successfully conducted low light shots with very long exposures as shown below.

This one is on Kodak Ektar 100 for about 40 minutes . . .

This one on Kodak Gold 100-7 for more than 3 hours . . .

Impressive! Both photo's look really nice they have some sort of surreal feel to it

LesDMess · 12-27-2014, 01:08 PM

Originally posted by Clarity

Impressive! Both photo's look really nice they have some sort of surreal feel to it

Thanks!

zekewhipper · 12-27-2014, 04:57 PM

Originally posted by UncleVanya

Number 2 isn't going to occur with any SLR since the mirror is up during the exposure and no light can reach the sensor from the eyepiece while the mirror is up except with leaky seals.

Nope, that is not the case. Because after you take your head away from the viewfinder but before the camera has actually taken the shot, the camera is still metering. Ergo, it can change what exposure it wants to take the shot at by the time it actually takes it.

**UncleVanya** · 12-27-2014, 07:34 PM

Originally posted by zekewhipper

Nope, that is not the case. Because after you take your head away from the viewfinder but before the camera has actually taken the shot, the camera is still metering. Ergo, it can change what exposure it wants to take the shot at by the time it actually takes it.

I want a digital LX... sigh. LOL

powasky · 12-27-2014, 08:36 PM

Originally posted by LesDMess

If you are not aware, the Pentax LX (film SLR) is the only camera ever made - by any manufacturer, that can aperture priority auto expose a scene for as long as it takes while monitoring the scene for changes in lighting and adjusting exposure accordingly. Since it takes it's exposure off the film plane, it doesn't require a cover for the viewfinder and stray light entering there does not influence the meter.

I have successfully conducted low light shots with very long exposures as shown below.

This one is on Kodak Ektar 100 for about 40 minutes . . .

This one on Kodak Gold 100-7 for more than 3 hours . . .

Does the OM series not do this as well? I was under the impression that my OM2n actively monitored the scene and adjusted exposure appropriately.

LesDMess · 12-28-2014, 08:09 AM

Originally posted by powasky

Does the OM series not do this as well? I was under the impression that my OM2n actively monitored the scene and adjusted exposure appropriately.

The OM2 was the first production camera that incorporated off the film metering and can aperture priority auto expose a scene for some minutes while monitoring the scene for changes in lighting and adjusting exposure. There are significant differences between the plain OM2 and OM2n and you can read more about this at -> TP - OM-2/2N if you're interested. The OM4 is even more limited in exposure time.

All other aperture priority cameras that I have tested generally set exposure time at the time of shutter firing and will stay the course. The Canons hard coded a 30 second limit while all the others - each brand and model, vary the time from seconds to minutes but generally unpredictably. It is possible I may have missed an old/new, model/brand that can aperture priority auto expose a scene for as long as it takes (or batteries die) while monitoring the scene for changes in lighting and adjusting exposure accordingly and accurately but so far only the Pentax LX can do this.

BTW, with regards to light entering the viewfinder and influencing the meter, there are some cameras that have viewfinder blinds built-in with a lever to activate it or a cap on the strap to cover the it.

**Spodeworld** · 12-29-2014, 07:08 AM

@zekewhipper - And, if you are in manual mode and already set the exposure before you pulled your eye away just before shooting, why would this matter based on what you said?

Originally posted by zekewhipper

Nope, that is not the case. Because after you take your head away from the viewfinder but before the camera has actually taken the shot, the camera is still metering. Ergo, it can change what exposure it wants to take the shot at by the time it actually takes it.

**Spodeworld** · 12-31-2014, 11:25 AM

On page 47 of the K-3 manual it says "..exposure may be affected if light enters the viewfinder. In such case, use the AE Lock function or attach the option ME viewfinder cap..."

That suggests to me that if you are in manual mode and set your exposure before pulling your eye away, then the exposed viewfinder should not cause a problem, assuming there are no manufacturing defects.

zekewhipper · 12-31-2014, 12:33 PM

Originally posted by Spodeworld

@zekewhipper - And, if you are in manual mode and already set the exposure before you pulled your eye away just before shooting, why would this matter based on what you said?

In M mode it obviously does not make a difference. Only when the camera is in P, Av, Tv, or TAv does the viewfinder need blocked.

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12-27-2014, 10:11 AM	#16
Clarity Junior Member Join Date: Aug 2014 Photos: Gallery Posts: 35	Originally posted by LesDMess If you are not aware, the Pentax LX (film SLR) is the only camera ever made - by any manufacturer, that can aperture priority auto expose a scene for as long as it takes while monitoring the scene for changes in lighting and adjusting exposure accordingly. Since it takes it's exposure off the film plane, it doesn't require a cover for the viewfinder and stray light entering there does not influence the meter. I have successfully conducted low light shots with very long exposures as shown below. This one is on Kodak Ektar 100 for about 40 minutes . . . This one on Kodak Gold 100-7 for more than 3 hours . . . Impressive! Both photo's look really nice they have some sort of surreal feel to it

12-27-2014, 01:08 PM	#17
LesDMess Pentaxian Join Date: May 2011 Location: Santa Cruz, CA Photos: Albums Posts: 3,235	Originally posted by Clarity Impressive! Both photo's look really nice they have some sort of surreal feel to it Thanks!

12-27-2014, 04:57 PM	#18
zekewhipper Veteran Member Join Date: Dec 2010 Photos: Albums Posts: 307	Originally posted by UncleVanya Number 2 isn't going to occur with any SLR since the mirror is up during the exposure and no light can reach the sensor from the eyepiece while the mirror is up except with leaky seals. Nope, that is not the case. Because after you take your head away from the viewfinder but before the camera has actually taken the shot, the camera is still metering. Ergo, it can change what exposure it wants to take the shot at by the time it actually takes it.

12-27-2014, 07:34 PM	#19
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,401	Originally posted by zekewhipper Nope, that is not the case. Because after you take your head away from the viewfinder but before the camera has actually taken the shot, the camera is still metering. Ergo, it can change what exposure it wants to take the shot at by the time it actually takes it. I want a digital LX... sigh. LOL

12-27-2014, 08:36 PM	#20
powasky Senior Member Join Date: Dec 2014 Posts: 105	Originally posted by LesDMess If you are not aware, the Pentax LX (film SLR) is the only camera ever made - by any manufacturer, that can aperture priority auto expose a scene for as long as it takes while monitoring the scene for changes in lighting and adjusting exposure accordingly. Since it takes it's exposure off the film plane, it doesn't require a cover for the viewfinder and stray light entering there does not influence the meter. I have successfully conducted low light shots with very long exposures as shown below. This one is on Kodak Ektar 100 for about 40 minutes . . . This one on Kodak Gold 100-7 for more than 3 hours . . . Does the OM series not do this as well? I was under the impression that my OM2n actively monitored the scene and adjusted exposure appropriately.

12-28-2014, 08:09 AM	#21
LesDMess Pentaxian Join Date: May 2011 Location: Santa Cruz, CA Photos: Albums Posts: 3,235	Originally posted by powasky Does the OM series not do this as well? I was under the impression that my OM2n actively monitored the scene and adjusted exposure appropriately. The OM2 was the first production camera that incorporated off the film metering and can aperture priority auto expose a scene *for some minutes* while monitoring the scene for changes in lighting and adjusting exposure. There are significant differences between the plain OM2 and OM2n and you can read more about this at -> TP - OM-2/2N if you're interested. The OM4 is even more limited in exposure time. All other aperture priority cameras that I have tested generally set exposure time at the time of shutter firing and will stay the course. The Canons hard coded a 30 second limit while all the others - each brand and model, vary the time from seconds to minutes but generally unpredictably. It is possible I may have missed an old/new, model/brand that can aperture priority auto expose a scene for as long as it takes (or batteries die) while monitoring the scene for changes in lighting and adjusting exposure accordingly and accurately but so far only the Pentax LX can do this. BTW, with regards to light entering the viewfinder and influencing the meter, there are some cameras that have viewfinder blinds built-in with a lever to activate it or a cap on the strap to cover the it.

12-29-2014, 07:08 AM	#22
Spodeworld Site Supporter Join Date: Aug 2011 Location: New Joisey Photos: Gallery \| Albums Posts: 1,370 Original Poster	@zekewhipper - And, if you are in manual mode and already set the exposure before you pulled your eye away just before shooting, why would this matter based on what you said? Originally posted by zekewhipper Nope, that is not the case. Because after you take your head away from the viewfinder but before the camera has actually taken the shot, the camera is still metering. Ergo, it can change what exposure it wants to take the shot at by the time it actually takes it.

12-31-2014, 11:25 AM	#23
Spodeworld Site Supporter Join Date: Aug 2011 Location: New Joisey Photos: Gallery \| Albums Posts: 1,370 Original Poster	On page 47 of the K-3 manual it says "..exposure may be affected if light enters the viewfinder. In such case, use the AE Lock function or attach the option ME viewfinder cap..." That suggests to me that if you are in manual mode and set your exposure before pulling your eye away, then the exposed viewfinder should not cause a problem, assuming there are no manufacturing defects.

12-31-2014, 12:33 PM	#24
zekewhipper Veteran Member Join Date: Dec 2010 Photos: Albums Posts: 307	Originally posted by Spodeworld @zekewhipper - And, if you are in manual mode and already set the exposure before you pulled your eye away just before shooting, why would this matter based on what you said? In M mode it obviously does not make a difference. Only when the camera is in P, Av, Tv, or TAv does the viewfinder need blocked.