Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
01-30-2019, 01:20 PM   #1
New Member




Join Date: Jan 2019
Posts: 9
Exposure difference between Live view and ovf when using m42 tak 35mm f/3.5

Hi, I'm wondering if anyone might explain why I need a -2 stop exposure comp if I use my takumar 35mm f/3.5 screwmount on my K-S2, BUT no exp comp is needed if I use Live View. If I use my auto Chinon 28mm f/2.8 K mount, there isn't any problem. I have used Manual mode with green button, as well as Av with the Tak, same result. I am ok with using exp comp but I just don't get it. Is this normal? btw I do stop the takumar down before pressing for metering and it is in manual .

01-30-2019, 01:30 PM   #2
Loyal Site Supporter
Loyal Site Supporter
UncleVanya's Avatar

Join Date: Jul 2014
Photos: Gallery | Albums
Posts: 15,199
My understanding is the green button manual is used on K mount non-A series lenses. I thought with screwmount the correct method was to use M or to use Av and simply use the aperture ring in manual (stop down) mode.
01-30-2019, 01:40 PM - 1 Like   #3
Administrator
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 48,557
QuoteOriginally posted by DeanG Quote
Hi, I'm wondering if anyone might explain why I need a -2 stop exposure comp if I use my takumar 35mm f/3.5 screwmount on my K-S2, BUT no exp comp is needed if I use Live View. If I use my auto Chinon 28mm f/2.8 K mount, there isn't any problem. I have used Manual mode with green button, as well as Av with the Tak, same result. I am ok with using exp comp but I just don't get it. Is this normal? btw I do stop the takumar down before pressing for metering and it is in manual .
Matrix metering is unavailable through the viewfinder when using manual lenses, so that could partially explain the difference in exposure. Generally speaking, live view will be more accurate with manual lenses.

Adam
PentaxForums.com Webmaster (Site Usage Guide | Site Help | My Photography)



PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

01-31-2019, 02:56 AM   #4
Loyal Site Supporter
Loyal Site Supporter
pschlute's Avatar

Join Date: Mar 2007
Location: Surrey, UK
Photos: Gallery
Posts: 3,064
QuoteOriginally posted by DeanG Quote
Hi, I'm wondering if anyone might explain why I need a -2 stop exposure comp if I use my takumar 35mm f/3.5 screwmount on my K-S2, BUT no exp comp is needed if I use Live View. If I use my auto Chinon 28mm f/2.8 K mount, there isn't any problem. I have used Manual mode with green button, as well as Av with the Tak, same result. I am ok with using exp comp but I just don't get it. Is this normal? btw I do stop the takumar down before pressing for metering and it is in manual .
Have a look here How to use/meter Manual & M42 Lenses on all Pentax DSLRs (K-1, K-3, K-5, K-30, etc) - PentaxForums.com

1. "Enable Aperture ring" setting in the camera should be on

2. M mode green button action should be set to Tv shift

3. Your lens has a M/A setting on it. Place it in M.

When you look through the viewfinder and turn the aperture ring the scene should darken/lighten. So focus, then set aperture, then in M mode press the green button and you should get a correct shutter speed set by the camera. But with M42 lenses it is easier to use Av mode. Because the aperture actually stops down as you turn the ring Av mode will give you correct exposure without the need to use green button metering (nb this is not the case for k-mount manual lenses).

Give this a try and see how you get on.

01-31-2019, 06:31 AM   #5
New Member




Join Date: Jan 2019
Posts: 9
Original Poster
QuoteQuote:
When you look through the viewfinder and turn the aperture ring the scene should darken/lighten. So focus, then set aperture, then in M mode press the green button and you should get a correct shutter speed set by the camera. But with M42 lenses it is easier to use Av mode. Because the aperture actually stops down as you turn the ring Av mode will give you correct exposure without the need to use green button metering (nb this is not the case for k-mount manual lenses).

Give this a try and see how you get on.

Yes thank you, I have been following this procedure, but my question is why, given identical method, the K-S2 meters differently in Live View (correctly), but not when shooting with viewfinder . With Viewfinder the camera overexposes by about 2 stops.

---------- Post added 01-31-19 at 06:35 AM ----------

QuoteOriginally posted by DeanG Quote
Yes thank you, I have been following this procedure, but my question is why, given identical method, the K-S2 meters differently in Live View (correctly), but not when shooting with viewfinder . With Viewfinder the camera overexposes by about 2 stops.
I meant to add that this only applys to the screw mount lens. I have verified that I am stopping down to meter. In any event if I metered wide open I would expect to get underexposure, not over exposure, after stopping the lens down to shoot.
01-31-2019, 07:45 AM   #6
Pentaxian
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 33,059
What do the images look like?
01-31-2019, 07:47 AM   #7
Loyal Site Supporter
Loyal Site Supporter
pschlute's Avatar

Join Date: Mar 2007
Location: Surrey, UK
Photos: Gallery
Posts: 3,064
QuoteOriginally posted by DeanG Quote
Yes thank you, I have been following this procedure, but my question is why, given identical method, the K-S2 meters differently in Live View (correctly), but not when shooting with viewfinder . With Viewfinder the camera overexposes by about 2 stops
Try this. In both M and Av modes, does the camera meter correctly wide open ? If yes then try at various apertures and see if there is a pattern....ie progressive overexposure the more you stop down ?

can I assume you have changed the two camera settings I mentioned ?
01-31-2019, 09:19 AM   #8
New Member




Join Date: Jan 2019
Posts: 9
Original Poster
I will post some examples later. Thanks!

01-31-2019, 09:48 PM   #9
New Member




Join Date: Jan 2019
Posts: 9
Original Poster
Well I never got around to getting some examples posted, but I checked again and the camera reads exposure differently in view finder operation vs Kive View all else being equal, for example Live View will read 1/40th while switching to viewfinder with no other changes reads 1/13th . And it happens that the LV reading is correct. I am wondering if somehow my screw mount adapter could have anything to do with the operation in viewfinder mode as it makes no contact with the flange leaving the electronic contacts exposed. Does normal viewfinder operation make use of these and not LV? I am just grasping at straws, and I think I should just shut up and use exposure comp! Thanks for all your input. 😐
02-01-2019, 01:57 AM   #10
GUB
Loyal Site Supporter
Loyal Site Supporter
GUB's Avatar

Join Date: Aug 2012
Location: Wanganui
Photos: Gallery | Albums
Posts: 3,287
QuoteOriginally posted by DeanG Quote
Well I never got around to getting some examples posted, but I checked again and the camera reads exposure differently in view finder operation vs Kive View all else being equal, for example Live View will read 1/40th while switching to viewfinder with no other changes reads 1/13th . And it happens that the LV reading is correct. I am wondering if somehow my screw mount adapter could have anything to do with the operation in viewfinder mode as it makes no contact with the flange leaving the electronic contacts exposed. Does normal viewfinder operation make use of these and not LV? I am just grasping at straws, and I think I should just shut up and use exposure comp! Thanks for all your input. ��
One little thing that may be happening when you are using the green button -- The eyepiece needs to be covered to stop light pouring in it affecting the light meter. I don't think this will happen in LV.
Took me ages to work out why my exposures were naff - all because I pulled my head away to find the green button.
02-01-2019, 04:44 AM   #11
Pentaxian
altopiet's Avatar

Join Date: Sep 2010
Location: The Gem of the Karoo, South Africa
Photos: Gallery | Albums
Posts: 2,307
QuoteOriginally posted by DeanG Quote
Hi, I'm wondering if anyone might explain why I need a -2 stop exposure comp if I use my takumar 35mm f/3.5 screwmount on my K-S2, BUT no exp comp is needed if I use Live View. If I use my auto Chinon 28mm f/2.8 K mount, there isn't any problem. I have used Manual mode with green button, as well as Av with the Tak, same result. I am ok with using exp comp but I just don't get it. Is this normal? btw I do stop the takumar down before pressing for metering and it is in manual .
I had the same problem with my manual lenses and green button metering on my K-30, this was just after I had an aperture block repair, and I thought I'm not going to send it back but decided to assign one of the user modes to LV with a 2 stop exposure compensation, as a workaround, could never figure out why it happened, as it was a normal about 1/3 stop difference with my auto lenses...
02-01-2019, 06:12 AM   #12
Loyal Site Supporter
Loyal Site Supporter
pschlute's Avatar

Join Date: Mar 2007
Location: Surrey, UK
Photos: Gallery
Posts: 3,064
QuoteOriginally posted by GUB Quote
One little thing that may be happening when you are using the green button -- The eyepiece needs to be covered to stop light pouring in it affecting the light meter. I don't think this will happen in LV.
A good point but the OP is getting overexposed images. If light from the VF was affecting the exposure it would be under.

---------- Post added 02-01-19 at 01:20 PM ----------

QuoteOriginally posted by DeanG Quote
Well I never got around to getting some examples posted, but I checked again and the camera reads exposure differently in view finder operation vs Kive View all else being equal, for example Live View will read 1/40th while switching to viewfinder with no other changes reads 1/13th . And it happens that the LV reading is correct. I am wondering if somehow my screw mount adapter could have anything to do with the operation in viewfinder mode as it makes no contact with the flange leaving the electronic contacts exposed. Does normal viewfinder operation make use of these and not LV? I am just grasping at straws, and I think I should just shut up and use exposure comp! Thanks for all your input. 😐
try the test I suggested at a number of different apertures and see if you get a pattern developing. Does it meter correctly at wide open ?

The reason I ask is that it could be the focus screen is the issue. Back when the K10D K20D cameras were released a new bright focus screen was introduced. This had the effect (with K-mount manual lenses K and M) of causing a gradual, progressive overexposure the more the lens was stopped down when metering using the green button. Perhaps your model camera has similar problems.

Some pictures would be good.

As was stated earlier LV will use its own metering system which is separate from the VF one. With a manual lens you can use CW or spot metering only when using the VF. Have you double checked theses settings ?
02-01-2019, 07:04 AM   #13
Loyal Site Supporter
Loyal Site Supporter
UncleVanya's Avatar

Join Date: Jul 2014
Photos: Gallery | Albums
Posts: 15,199
Plus 1 for verifying metering settings in live view. These may be different from the ovf.
02-01-2019, 08:16 AM   #14
New Member




Join Date: Jan 2019
Posts: 9
Original Poster
The settings are both center weighted in either LV or VF. Oddly, I don't get an option for matrix metering as a choice for LV either. I should,correct?

here then FWIW:

manual mode, green button readings, center weighted avg metering...iso 1600

f/3.5
LV 1/40 VF 1/20

f/5.6
LV 1/15 VF 1/8

f/8
LV 1/8 VF 1/4

f/11
LV .4" VF .5"
(@ iso 6400: LV 1/10 VF 1/8 )

so about a 1 stop difference, with overexposure in VF mode, although by eye, I am favoring more like -1.7 or -2 exp comp in VF.

---------- Post added 02-01-19 at 08:28 AM ----------

QuoteQuote:

As was stated earlier LV will use its own metering system which is separate from the VF one. With a manual lens you can use CW or spot metering only when using the VF. Have you double checked theses settings ?
On my K-S2, with manual lens I get spot or CW options in either LV or VF. I have been using CW for both...according to the info screens.
02-01-2019, 09:59 AM   #15
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,690
although i cannot speak of the KS-2 or my new K1, i did a lot of work on metering issues with manual focus lenses about 5-6 years ago. the issue stems from the behavior of the metering system as a function of the "native aperture" of the lens.

for auto aperture (KA and later lenses) the camera knows the maximum aperture, and can adjust exposure for any general biases that a specific aperture has, for example, in many early cameras the tendency was to greatly under expose for large apertures (i.e. fast lenses) and over expose for small apertures F8 and higher,

if the camera did not know the aperture green button metering produced errors. newer cameras are better but still not perfect.

live view on the otherhand sets metering based upon what the sensor actually sees, so yes it may be more accurate, AND i would expect in an M42 Lens, you may need to have some exposure compensation when using AV mode for example. the trick is to know in advance, the compensation needed for each aperture because it is NOT constant over the whole lens aperture ranger
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
35mm, aperture, camera, center, comp, exp, exposure, exposure difference, f/3.5, focus, k-s2, lens, light, m42 tak 35mm, meters, mode, overexposes, pentax help, photography, tak, takumar, troubleshooting, view, view and ovf, viewfinder
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
live view noise and smc dfa 100mm f2.8 macro lens not focusing in live view tommygunn84 Troubleshooting and Beginner Help 7 11-24-2016 08:59 PM
For Sale - Sold: SMC Macro Tak 50mm f/4.0, SMC Tak 28mm f/3.5, Super-Tak 35mm f/3.5 hinman Sold Items 19 06-28-2016 07:15 PM
K-30 - exposure difference between viewfinder and live view Cornholio Troubleshooting and Beginner Help 7 10-01-2013 06:02 AM
Live view metering vs OVF evandavies1 Pentax K-30 & K-50 4 09-22-2012 02:39 PM
For Sale - Sold: m42 bellows, m42 adapter, 135/f3.5 Super Tak and 28/f3.5 Super Tak geauxpez Sold Items 12 12-10-2008 05:43 PM



All times are GMT -7. The time now is 12:01 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top