| Author |
Message |
    
Mareklew
Tinkerer
Username: Mareklew
Post Number: 50
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 12, 2010 - 02:00 pm: | 
|
As mentioned in the thread about buying CdS sensors (https://kyp.hauslendale.com/classics/forum/messages/2/18472.html) I have started a longer write-up on CdS meters.
If any one of you is interested in this topic, I'd love to hear some feedback, before I proceed further - I'm just not sure if it is of any use, and if it is understandable - English isn't my native language, leave alone all the problems of structuring one's thoughts. There are 9 pages right now, as free time allows I'd proceed further - finish the thing on "mercury battery" type meters and start about bridge circuits, light metering "types" and then discuss adjustments.
The final conclusion I'm aiming at is adjusting light meters in one shot. I have managed to adjust my Gossen Lunasix 3 and a Praktica meter in one shot, by taking some measurements, computing necessary pot values and setting them to the computed values. Both meters were dead on (to better than 1/3 stop throughout full range, I have no better reference to check against) afterward. I'd like to put down the theory needed to do it in writing.
The PDF can be found here: http://lwow.home.pl/photoblog/index.php/on-cds-meters/
The linked page is going to be updated as the PDF file is revised.
Marek |
Ron_g
Tinkerer
Username: Ron_g
Post Number: 15
Registered: 07-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 12, 2010 - 04:05 pm: |
|
I read some of what you have written but I have found over the years that I cannot retain all the things I need to know and I don't need everything that I know all of the time so my aspiration is to be able to find the info that I do need when I need it to either learn for the first time or refresh what I used to know and have forgotten.
Your article is a great resource and reference work and it is not unappeciated,I hope that you will continue to add to it as time permits.Ron G |
Nickon51
Tinkerer
Username: Nickon51
Post Number: 127
Registered: 05-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 13, 2010 - 03:47 am: |
|
This is a comprehensive work on the "simple" CDS meter. Well done so far. |
Dirbel
Tinkerer
Username: Dirbel
Post Number: 33
Registered: 04-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 13, 2010 - 07:23 am: |
|
I really like your article; and yes is perfectly readable, language as well as structure (but note that I am no native speaker either).
Dirk |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 52
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 14, 2010 - 02:38 pm: |
|
Thanks for the encouragement!
I will proceed as time allows and notify on updates.
Marek |
Clay
Tinkerer
Username: Clay
Post Number: 30
Registered: 12-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 14, 2010 - 07:54 pm: |
|
Very nice and timely.My Gossen Lunasix III is on my
last mercury cells. (Lunapro in North America).
Keep up the good work.
Best regards,
/Clay |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 54
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 15, 2010 - 12:56 am: |
|
Clay, if your meter is metering good on mercury cells, DON'T readjust! There's a trick to mod a CdS meter for silver oxide without re-trimming. I will be describing it in that PDF.
Marek |
Richb
Tinkerer
Username: Richb
Post Number: 3
Registered: 04-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 15, 2010 - 09:31 am: |
|
Marek -
I have just started restoring some older CDS meters, your article is excellent and most helpful.
Your article is a perfect combination of theory and practical.
I am looking forward to your next post on this subject.
Richb |
Clay
Tinkerer
Username: Clay
Post Number: 31
Registered: 12-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 15, 2010 - 05:25 pm: |
|
I understand. Been looking into the alternatives,
zinc-air hearing aid batteries, Wein Cells,
Schotsky diode and silver oxide cells. The
Gossen uses the same mercury cells as my
Minolta SRT101 and Minolta HiMatic 7S. Glad my
Nikon F2AS uses silver oxide, ha!Why are we forced
to buy curly flourescent light bulbs with more
mercury than the batteries? Only in North America!
Best regards,
/Clay |
Glenn
Tinkerer
Username: Glenn
Post Number: 768
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 15, 2010 - 05:59 pm: |
|
Clay,
Contact Gossen direct in Germany or their Agent in North America and get their battery adapter. Works fine with two standard silver cells and no messing about with stupid modifications or readjustments needed.
If you visit Gossen's German site and look in the photography section, you will find contact details/specs etc. |
John_shriver
Tinkerer
Username: John_shriver
Post Number: 55
Registered: 12-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 15, 2010 - 06:40 pm: |
|
While the Gossen adatper for Silver Oxide cells is very nice, I did find that I had to pay to have the meter recalibrated anyways. |
Clay
Tinkerer
Username: Clay
Post Number: 32
Registered: 12-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 15, 2010 - 06:45 pm: |
|
Thanks Glenn, I've seen them on Evil-Bay and on
B&H's site in New York.Read good reports about the
adapter, be about $40.00 Canadian. Nearest big
city to me is Toronto.Have a camera show this
Sunday and I shall poke around there first.
Best regards,
/Clay |
Clay
Tinkerer
Username: Clay
Post Number: 34
Registered: 12-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 20, 2010 - 08:38 am: |
|
No joy at the camera show, picked up some filters
for B&W: Red, Yellow, Orange, Green, and a book
that I've wanted since 1968: 'AMP Nikon F Handbook
of Photography',loose-leaf. My F2 is just an F with
bugs removed.
Found this at photo.net: 'The last of the mercury cells didn't use the chemistry that gave a super stable 1.35V, but a slightly different chemistry that gave higher energy capacity, but a slightly different and less stable voltage. Thus, "black market" batteries are worthless for our purposes anyway. The correct chemistry mercury cells have been unavailable for far longer than is commonly believed. If you put an accurate meter on a mercury cell and see even slightly different than 1.35V, it's not the right one. No mercury battery is legal to sell anymore, in spite of the fact that every CFL contains mercury!'
Also check this link I found last night:
http://www.graphic-fusion.com/lunapro.htm
Best regards,
/Clay |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 60
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 27, 2010 - 01:10 am: |
|
Updated the document today, not much new text, but some figures to illustrate things.
http://lwow.home.pl/photoblog/index.php/on-cds-meters/
Marek |
