Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-12-2015, 01:33 PM   #31
Veteran Member
Cuthbert's Avatar

Join Date: Nov 2013
Photos: Gallery
Posts: 1,573
QuoteOriginally posted by lesdmess Quote
do you know of another camera that will dependably aperture priority autoexpose as long as the pentax lx? From all that i have tried - past and present by any other brand, there are none.


k2dmd.


I measured 35 minutes.

10-12-2015, 03:30 PM - 1 Like   #32
Pentaxian
Digitalis's Avatar

Join Date: Mar 2009
Location: Adelaide.
Posts: 8,739
QuoteOriginally posted by chickentender Quote
It never occurred to me to let the LX take the "tinkering" out of lightning exposures.
Basically a built in lightning trigger.

Last edited by Digitalis; 10-13-2015 at 12:21 AM.
10-12-2015, 03:44 PM   #33
Site Supporter
K David's Avatar

Join Date: Oct 2012
Location: SF Bay Area
Photos: Gallery
Posts: 1,296
QuoteOriginally posted by kai_in_paisley Quote
the fact that, beyond 1sec exposures, films become 'less sensitive' and need extended exposure times or adjusted aperture.
Depends on the film. Ilford films are all one second. Kodak is generally two seconds on their slow-to-medium films. Fuji Acros is 120 seconds (yes, two minutes) before reciprocity failure begins.


QuoteOriginally posted by kai_in_paisley Quote
I assume that the auto-exposure on the LX doesn't compensate for this by itself ?
I believe that to be correct. Some advanced cameras do, I think, compensate for reciprocity failure. Typically, people who shoot long enough exposures where reciprocity failure occurs will be able to also calculate the reciprocity failure compensation.

I'll be taking my LX on a two-week trip (starting next week) and a big part of that is astrophotography. So watch the Forum front page in December for the next installment of the Astrohotography Series for a bunch of long-exposure film shots using the LX.
10-12-2015, 03:58 PM   #34
Pentaxian




Join Date: May 2011
Location: Santa Cruz, CA
Photos: Albums
Posts: 2,030
QuoteOriginally posted by Cuthbert Quote
k2dmd.


I measured 35 minutes.


I never had a K2DMD and if this is true - and repeatable, that makes it only second to the LX in duration.

10-12-2015, 04:31 PM   #35
Loyal Site Supporter
Pioneer's Avatar

Join Date: Aug 2009
Location: Elko, Nevada
Photos: Gallery | Albums
Posts: 1,229
My K2 won't go that long on Auto. The K2DMD must have had some changes beyond just allowing the attachment of a motor base.
10-12-2015, 11:30 PM   #36
Veteran Member
Cuthbert's Avatar

Join Date: Nov 2013
Photos: Gallery
Posts: 1,573
QuoteOriginally posted by LesDMess Quote
I never had a K2DMD and if this is true - and repeatable, that makes it only second to the LX in duration.

Out of curiosity yesterday I set the ASA to 16, closed the diaphgram at f22 and pointed at a dark place....the shutter remained open for more than 1 hour and 42 minutes, then I got bored and reset it...to be honest when I see these long exposures I wonder if the camera has some problems, it would be interesting to see if it stops by itself, sometimes I think the camera has some issues.


QuoteOriginally posted by Pioneer Quote
My K2 won't go that long on Auto. The K2DMD must have had some changes beyond just allowing the attachment of a motor base.

I think the lightmeter circuit was modified to get the AE lock working, like many DMD owners I never had the opportunity to get the motordrive.

Last edited by Cuthbert; 10-12-2015 at 11:36 PM.
10-13-2015, 04:46 AM   #37
Pentaxian




Join Date: May 2011
Location: Santa Cruz, CA
Photos: Albums
Posts: 2,030
QuoteOriginally posted by Cuthbert Quote
Out of curiosity yesterday I set the ASA to 16, closed the diaphgram at f22 and pointed at a dark place....the shutter remained open for more than 1 hour and 42 minutes, then I got bored and reset it...to be honest when I see these long exposures I wonder if the camera has some problems, it would be interesting to see if it stops by itself, sometimes I think the camera has some issues.


What is important is repeatability. Setup light for an 8second exposure at widest aperture then close down the aperture - as well as adjust ISO, for longer exposure times and see if the K2DMD reacts predictably and if it is repeatable. This is how I tested all my cameras and how I found out which ones can go past their limits. The Canons were easy as they always stop at 30seconds as stated in the manuals. My Nikons can achieve past a few minutes but mot reliably. The Minoltas and others less than a minute. The Olympus OM4 is repeatable to 4minutes.
10-13-2015, 02:07 PM - 1 Like   #38
Veteran Member
Cuthbert's Avatar

Join Date: Nov 2013
Photos: Gallery
Posts: 1,573
QuoteOriginally posted by LesDMess Quote
What is important is repeatability. Setup light for an 8second exposure at widest aperture then close down the aperture - as well as adjust ISO, for longer exposure times and see if the K2DMD reacts predictably and if it is repeatable. This is how I tested all my cameras and how I found out which ones can go past their limits. The Canons were easy as they always stop at 30seconds as stated in the manuals. My Nikons can achieve past a few minutes but mot reliably. The Minoltas and others less than a minute. The Olympus OM4 is repeatable to 4minutes.


Today's measurements:




F1.4 9


F2 23


F2.8 39


F4 59


F5.6 220


F8 518


F11 1h 19 18


The last value is not accurate as the shutter remained open until I forgot to check and I didn't hear it closing, Ser LEs, is this "time dilatation" normal? I didn't checkt F16 and F22 because it would have taken the entire night.

10-13-2015, 05:48 PM   #39
Pentaxian




Join Date: May 2011
Location: Santa Cruz, CA
Photos: Albums
Posts: 2,030
QuoteOriginally posted by Cuthbert Quote
Today's measurements:
The last value is not accurate as the shutter remained open until I forgot to check and I didn't hear it closing, Ser LEs, is this "time dilatation" normal? I didn't checkt F16 and F22 because it would have taken the entire night.
I wonder what accounts for the slight deviations - is your light source constant?
More importantly will repeating the test - hence the light source has to be reliable, will you get reasonably close results?
10-13-2015, 11:31 PM   #40
Veteran Member
Cuthbert's Avatar

Join Date: Nov 2013
Photos: Gallery
Posts: 1,573
Yes it is, it's artificial so I don't have reason to doubt about it.

As said, all the values until F8 seemed reasonable to me, F11 has been a very long exposure, I'll repeat the test for F16 tonight.
10-15-2015, 11:41 AM   #41
Veteran Member
Cuthbert's Avatar

Join Date: Nov 2013
Photos: Gallery
Posts: 1,573
I started the F16 exposure yesterday abotu 7:30 PM, today at 7:30 AM the shutter was still closed, returned from home I found the shutter closed, I don't know when but the exposure has been very long, and now the battery is almost drained.


One thing is for sure: the K2DMD was the dry run of the LX.
10-16-2015, 04:53 AM   #42
Pentaxian




Join Date: May 2011
Location: Santa Cruz, CA
Photos: Albums
Posts: 2,030
QuoteOriginally posted by Cuthbert Quote
I started the F16 exposure yesterday abotu 7:30 PM, today at 7:30 AM the shutter was still closed, returned from home I found the shutter closed, I don't know when but the exposure has been very long, and now the battery is almost drained.


One thing is for sure: the K2DMD was the dry run of the LX.


Thanks for testing this out. Now I have to acquire a K2DMD!
10-16-2015, 05:22 AM   #43
Veteran Member
Cuthbert's Avatar

Join Date: Nov 2013
Photos: Gallery
Posts: 1,573
You won't be disappointed: the DMD is a sweet (albeit heavy) camera, even if it's one generation older than the LX for some reasons (ex. building quality) I prefer it to the Pentax deLuXe.


A pity that it was introduced too late, it was too expensive and didn't have at least interchangeble screen, if it were a complete system camera it would have probably outperformed the pro cameras of the 70s.
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!
clients, exposure, exposure and reciprocity, exposure compensation, exposures, failure / schwarzschild, films, kodak gold, long exposure, long time exposure, longtime, lx, lx long time, minutes, reciprocity, reciprocity failure, schwarzschild, time, time exposure, transparency
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Long exposure shots, ND filters and multi-exposure averaging rrstuff Photographic Technique 17 10-19-2013 12:50 PM
Landscape First time long exposure csmoore Photo Critique 4 12-19-2012 12:33 PM
Reciprocity failure in dSLR's? cbope Pentax DSLR Discussion 3 01-28-2012 06:44 AM
Long exposure time Ryalux Pentax K-r 10 01-28-2012 03:08 AM
Black & White Long exposure with the LX nickthetasmaniac Post Your Photos! 5 09-09-2010 09:45 AM



All times are GMT -7. The time now is 01:26 AM. | 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