Digital Spotmeters and DSLR metering

8540tomg · 03-17-2014, 08:31 AM

Hi all,

I have a lot of legacy glass (see signature) and I often find exposure a bit of problem when I use them on my digital cameras. Yes, I am aware of the green button and its use on a digital camera with an M or K series lens attached. I have used the green button a lot and still continue to have more exposure failures than I would like.

I was wondering if the are any users out there who have used a spotmeter to deal with exposure issues while using Pentax legacy (Takumar, K, M series) glass on their digital cameras. I can't help but think it would be useful especially when using longer lenses for birding. I imagine that one degree spot might not be fooled as often as the green button seems to be when I'm trying to nail exposure of a bird in the bushes. I'm just speculating of course but I would like some feedback from those who have had some experience with spotmeters in such conditions.

In particular I would like to know if the spotmeter is more accurate than using the green button?

Is it quicker to use than the green button?

Any other observations, pros/cons you may have regarding the use of a spotmeter with a digital camera.

Tom G

aoeu · 03-17-2014, 09:44 AM

1 degree spotmeters are specialty items. I have one.

Is it quicker to use than the green button?

No.

A better question might be, "How narrow is central spot metering on modern Pentax DSLRs."

elliott · 03-17-2014, 10:09 AM

I have a Pentax Digital Spotmeter, it isn't really quick to use because it only displays EV in the viewfinder and unless you have the values memorized you have to consult the calculator. I typically only use it when I have time to be slow and really analyze the shot.

It is mostly accurate, though there is always a little variation depending on lens since one lens at f2.8 might not transmit the same amount of light as another.

The green button is usually accurate enough for me, though I have changed the focusing screen to one that has a more linear light response.

stevebrot · 03-17-2014, 11:18 AM

Originally posted by 8540tomg

In particular I would like to know if the spotmeter is more accurate than using the green button?

Different is the word.

The stop-down (green button) metering should be essentially accurate* with your K-5 in M mode and much less so with your K10D. Neither camera will meter reliably with M42 glass in Av mode. If you are unhappy with your results an external meter may be a good option.

That being said, let's get back to the spot meter. Here are a few discussion points as applied to a spot meter vs. hand-held vs. TTL meters:

Spot meters are not magic
Spot meters are not better per se, and when used improperly may actually result in badly exposed shots
The spot meter is a specialized tool that is used to measure reflected light values from a specific portion of the subject, though care should be taken to remember that the reading will result in a middle value on the final image
A spot meter, when properly used can allow for fine control when placing the original exposure with the intent for massaging the image later in processing
A regular hand-held meter may be used in a manner similar to a spot meter if you are able to take readings close in on the subject
The above point also applies to the in-camera meter
The in-camera TTL meter has the advantage of automatic compensation for light absorption by the lens glass and any filters
All three are essentially accurate in that they can be used to determine an appropriate exposure

There is at least one user on this site (Tuco) who is a regular spot meter user. He uses it primarily for his medium and large format film photography.

Originally posted by 8540tomg

Is it quicker to use than the green button?

ROFL

No...

Steve

* Accurate in the sense that metering off an evenly lit, neutral target (say a blank inside wall) will result in equivalent mid-range value distributions in the histogram at all apertures with all lenses.

(...almost never uses the spot meter feature on the camera's that have it...)

Last edited by stevebrot; 03-17-2014 at 11:29 AM.

8540tomg · 03-17-2014, 01:34 PM

Thanks guys,

I guess I was looking for a magic bullet that doesn't exist.

I've considered getting a digital spotmeter for years but it seems it would just be another gadget

in the seldom used pile if I did. I guess I'll just go back to the old trial and error method. At least it's a lot cheaper on

digital than it used to be on film.

Tom G

03-17-2014, 08:31 AM	#1
8540tomg Veteran Member Join Date: Feb 2008 Location: Waterloo, Ontario Photos: Gallery Posts: 4,461	Digital Spotmeters and DSLR metering Hi all, I have a lot of legacy glass (see signature) and I often find exposure a bit of problem when I use them on my digital cameras. Yes, I am aware of the green button and its use on a digital camera with an M or K series lens attached. I have used the green button a lot and still continue to have more exposure failures than I would like. I was wondering if the are any users out there who have used a spotmeter to deal with exposure issues while using Pentax legacy (Takumar, K, M series) glass on their digital cameras. I can't help but think it would be useful especially when using longer lenses for birding. I imagine that one degree spot might not be fooled as often as the green button seems to be when I'm trying to nail exposure of a bird in the bushes. I'm just speculating of course but I would like some feedback from those who have had some experience with spotmeters in such conditions. In particular I would like to know if the spotmeter is more accurate than using the green button? Is it quicker to use than the green button? Any other observations, pros/cons you may have regarding the use of a spotmeter with a digital camera. Tom G

03-17-2014, 11:18 AM	#4
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by 8540tomg In particular I would like to know if the spotmeter is more accurate than using the green button? Different is the word. The stop-down (green button) metering should be essentially accurate* with your K-5 in M mode and much less so with your K10D. Neither camera will meter reliably with M42 glass in Av mode. If you are unhappy with your results an external meter may be a good option. That being said, let's get back to the spot meter. Here are a few discussion points as applied to a spot meter vs. hand-held vs. TTL meters: Spot meters are not magic Spot meters are not better per se, and when used improperly may actually result in badly exposed shots The spot meter is a specialized tool that is used to measure reflected light values from a specific portion of the subject, though care should be taken to remember that the reading will result in a middle value on the final image A spot meter, when properly used can allow for fine control when placing the original exposure with the intent for massaging the image later in processing A regular hand-held meter may be used in a manner similar to a spot meter if you are able to take readings close in on the subject The above point also applies to the in-camera meter The in-camera TTL meter has the advantage of automatic compensation for light absorption by the lens glass and any filters All three are essentially accurate in that they can be used to determine an appropriate exposure There is at least one user on this site (Tuco) who is a regular spot meter user. He uses it primarily for his medium and large format film photography. Originally posted by 8540tomg Is it quicker to use than the green button? ROFL No... Steve * Accurate in the sense that metering off an evenly lit, neutral target (say a blank inside wall) will result in equivalent mid-range value distributions in the histogram at all apertures with all lenses. (...almost never uses the spot meter feature on the camera's that have it...) Last edited by stevebrot; 03-17-2014 at 11:29 AM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
manual lens and metering	adwb	Photographic Technique	32	01-27-2014 03:13 PM
Metering and blonde hair	thechumpen	Photographic Technique	15	05-21-2013 08:31 PM
Digital Foci - Digital Porter 35 not compatible with DNG and K-7 PEF.	raider	Pentax Camera and Field Accessories	4	02-22-2012 04:34 PM
DSLR metering function	Andrew Crouch	Pentax DSLR Discussion	10	12-13-2011 08:33 AM

03-17-2014, 09:44 AM	#2
aoeu Veteran Member Join Date: Sep 2010 Location: Oregon Posts: 496	1 degree spotmeters are specialty items. I have one. Is it quicker to use than the green button? No. A better question might be, "How narrow is central spot metering on modern Pentax DSLRs."

03-17-2014, 10:09 AM	#3
elliott Inactive Account Join Date: Dec 2008 Location: North Carolina Photos: Albums Posts: 1,720	I have a Pentax Digital Spotmeter, it isn't really quick to use because it only displays EV in the viewfinder and unless you have the values memorized you have to consult the calculator. I typically only use it when I have time to be slow and really analyze the shot. It is mostly accurate, though there is always a little variation depending on lens since one lens at f2.8 might not transmit the same amount of light as another. The green button is usually accurate enough for me, though I have changed the focusing screen to one that has a more linear light response.

03-17-2014, 01:34 PM	#5
8540tomg Veteran Member Join Date: Feb 2008 Location: Waterloo, Ontario Photos: Gallery Posts: 4,461 Original Poster	Thanks guys, I guess I was looking for a magic bullet that doesn't exist. I've considered getting a digital spotmeter for years but it seems it would just be another gadget in the seldom used pile if I did. I guess I'll just go back to the old trial and error method. At least it's a lot cheaper on digital than it used to be on film. Tom G