Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-15-2011, 08:50 AM   #31
Site Supporter
Site Supporter
les3547's Avatar

Join Date: Jun 2010
Location: Sebastopol, California
Photos: Albums
Posts: 1,874
QuoteOriginally posted by tuco Quote
I don't think I'd mix colored filters. I'm having a hard time visualizing what the results on your BW film would look like. Maybe a polarizer and colored filter would be a better choice.

Another thing to consider when after a long exposure is the film's reciprocity characteristics. Some BW films are pretty resistant while others need a lot of correction.

For example, Kodak Plus-X needs a 50 second exposure for a metered 10 second shot and 200 seconds for a metered 30 seconded shot. On the other hand, 100 Acros does not need any correction up to 120 seconds and after that only 1/2 stop of additional exposure is needed. T-Max films are pretty resistant too.

I tried to find the reciprocity characteristics of that Adox/Efke film but these small companies are short on technical data.
Darren Rouse in this article at the website "Digital Photography School" suggests joining a circular polarizer and a linear polarizer in order to create a variable ND filter. What do you think of that?


Last edited by les3547; 07-15-2011 at 09:04 AM.
07-15-2011, 09:20 AM   #32
Pentaxian




Join Date: Jul 2009
Location: Seattle
Posts: 7,103
QuoteOriginally posted by les3547 Quote
Darren Rouse in this article at the website "Digital Photography School" suggests joining a circular polarizer and a linear polarizer in order to create a variable ND filter. What do you think of that?
Yeah, that is an old trick to make a variable ND filter. Certainly an option. The only problem might be knowing how many stops it is. That is, when you're going after exposures well beyond the camera's meter, you may need to figure out the exposure by taking into account the number of stops the filter has. But maybe if you meter through the various densities and mark on the filters how many stops it is you'd have an effective solution.

And another potential problem is filter stacking on wide angle lenses. You can get vignetting.

Last edited by tuco; 07-15-2011 at 09:28 AM.
07-15-2011, 02:48 PM   #33
Site Supporter
Site Supporter
les3547's Avatar

Join Date: Jun 2010
Location: Sebastopol, California
Photos: Albums
Posts: 1,874
QuoteOriginally posted by tuco Quote
Yeah, that is an old trick to make a variable ND filter. Certainly an option. The only problem might be knowing how many stops it is. That is, when you're going after exposures well beyond the camera's meter, you may need to figure out the exposure by taking into account the number of stops the filter has. But maybe if you meter through the various densities and mark on the filters how many stops it is you'd have an effective solution.

And another potential problem is filter stacking on wide angle lenses. You can get vignetting.
Thanks, I will be experimenting.
07-17-2011, 06:50 AM   #34
Pentaxian
ChrisPlatt's Avatar

Join Date: Nov 2007
Location: Queens NYC
Posts: 4,865
With many lenses vignetting may occur when two or more filters are stacked together.
It's wise to test any potential combinations before taking any once-in-a-lifetime photos.

Chris


Last edited by ChrisPlatt; 07-19-2011 at 02:49 PM.
07-24-2011, 12:40 AM   #35
Senior Member




Join Date: Jun 2009
Location: Italy
Photos: Albums
Posts: 182
QuoteOriginally posted by tuco Quote
On the other hand, 100 Acros does not need any correction up to 120 seconds and after that only 1/2 stop of additional exposure is needed. T-Max films are pretty resistant too.
Which are the reciprocity characteristics of the Kodak T-Max films?
Are identical at the Fuji Acros or very similar?
And about Ilford film have you find the reciprocity characteristics?
07-24-2011, 08:02 PM   #36
Pentaxian




Join Date: Jul 2009
Location: Seattle
Posts: 7,103
QuoteOriginally posted by alexfoto Quote
Which are the reciprocity characteristics of the Kodak T-Max films?
Are identical at the Fuji Acros or very similar?
And about Ilford film have you find the reciprocity characteristics?
T-Max films are not the same as Acros but pretty close. To find the reciprocity characteristics of a film, look up the data sheet for it. The major brands usually list a table or chart.

Now if you want long exposures, reciprocity can be your friend. That fountain shot I posted, for example, was in bright sun and was a 45 second exposure. It took a 9-stop ND filter plus an orange filter for a total of 11 stops plus stopping the lens down to f19 with Acros. I could have had a 120 sec exposure for the same filters/aperture with T-Max or 350 sec exposure with Plus-X. Or better yet, backed the lens off to f16 or f11 and still had a decent time.

The advantage Acros may have though is that you don't need to carry a reciprocity chart around, don't need to adjust development time like Kodak recommends for their films and you get really consistent results with long exposures and Acros.

Last edited by tuco; 07-26-2011 at 07:57 AM.
07-25-2011, 11:37 PM   #37
Senior Member




Join Date: Jun 2009
Location: Italy
Photos: Albums
Posts: 182
On that image i found particullary interesting how is possible avoid people (at least people that walk as happen on your shoot) simply using really long exposure.
On that shoot you have used even an orange filter only for obtain sufficient stop or for other reasons?
I never use filter, no on analogic and no on digital, which brand are good for ND filter?
Always hoya and b+w, as happen for their polarizers?
On MF (medium format) camera, where the viewfinder generally is big but don't much bright, is possible use the same filter even at night (for example you have inside a 400 Asa film and you can't change the magazine - as happen for pentax MF camera?). Or perhpas the viewfinder of Pentax MF are bright so is a no issue?

Thanks Tuco for being an inexhaustible source of information.
07-26-2011, 08:28 AM   #38
Pentaxian




Join Date: Jul 2009
Location: Seattle
Posts: 7,103
QuoteOriginally posted by alexfoto Quote
On that shoot you have used even an orange filter only for obtain sufficient stop or for other reasons?
In this case the orange filter served two tasks. First, I needed the extra stops it provided and secondly it was used for the sky. The orange helps render a blue sky a darker tone. I also carry a 3-stop ND filter around too.

QuoteQuote:
I never use filter, no on analogic and no on digital, which brand are good for ND filter? Always hoya and b+w, as happen for their polarizers?
For BW film or digital converted to gray scale, either ND filters from Hoya or B+W filters are fine. But for color, you need to read reviews. That 10-stop ND from B+W, for example, causes a color cast. Not all ND filter are very "neutral". The NDX400 (9-stop) from Hoya is pretty neutral I've found.

QuoteQuote:
On MF (medium format) camera, where the viewfinder generally is big but don't much bright, is possible use the same filter even at night (for example you have inside a 400 Asa film and you can't change the magazine - as happen for pentax MF camera?). Or perhpas the viewfinder of Pentax MF are bright so is a no issue?

Thanks Tuco for being an inexhaustible source of information.
The view finder on my MF cameras are very bright. It is a big surface area I'm looking at. I use a waist level finders instead of prisms. During the daylight, you can not see very well at all with a 9 or 10 stop ND filter on. You have to take it off. But it is okay for say a 3-stop ND filter. And of course in the twilight or dark forget it. You'll have to focus first and then put on the filter. But neither of those is a problem with my medium format Mamiya 7II rangefinder camera because you don't look through the lens.

Yes, you can change the magazine on some cameras in mid roll. My Hasselblad 500C/M has hot-swapping backs. I can shoot color film on one shot and and BW film on the very next shot. Or shoot 100 ISO film on one shot and 800 ISO on the next. What a sweet deal.


Last edited by tuco; 07-26-2011 at 08:37 AM.
07-26-2011, 12:26 PM   #39
Senior Member




Join Date: Jun 2009
Location: Italy
Photos: Albums
Posts: 182
Yes MF rangefinder are nice (the feautures that i like the most is their silence and, after that, they are generally light) despite they have too some pitfalls for example:
- impossible use the polarizers
or for certain camera as for example:
- Rollei the WLF is big but don't bright - because is made from glass instead of plastic, so someone customize its solution using that found on the mamiya, after cut it to the proper size.
On the meantime i read some articles about the various model of pentax, seem that from the 645N and so on its improved.
Your camera probably have the best viewfinder on their category, its a pity that they are soo expensive ...
However using the Hasselblad 500C/M during night the exposimeter work?
Or you using an external light meter for take long exposure?
For example on MF Pentax i don't sure its exposimeter work.
Thanks.
07-26-2011, 12:39 PM   #40
Pentaxian




Join Date: Jul 2009
Location: Seattle
Posts: 7,103
QuoteOriginally posted by alexfoto Quote
Yes MF rangefinder are nice (the feautures that i like the most is their silence and, after that, they are generally light) despite they have too some pitfalls for example:
- impossible use the polarizers
Actually, it is not impossible. There are two things you can do. You can visually look through the polarizer and then place it on the lens in the same orientation. It's not ideal and is error prone. Or optionally you can buy an indexed polarize filter for rangefinder cameras.

QuoteQuote:
However using the Hasselblad 500C/M during night the exposimeter work?
I use a waist level finder on that camera as well as my Pentax 6x7 and I use a Pentax one-degree spot meter for all my metering be it day or night.

Last edited by tuco; 07-26-2011 at 02:33 PM.
07-29-2011, 01:08 AM   #41
Senior Member




Join Date: Jun 2009
Location: Italy
Photos: Albums
Posts: 182
Now i'm reading the data sheet of the Kodak Professional T-MAX (F-4016)
Code:
Exposure Time Is (Seconds) :   10            
Lens-Aperture Adjustment : +1/2 stop or Adjusted Exposure Time (Sec): 15
Exposure Time Is (Seconds) : 100
Lens-Aperture Adjustment : +1 stop or Adjusted Exposure Time (Sec): 200
So how calculate what is necessary for an exposition of 5 minutes (300 seconds)?
Is sufficient presume +1 stop for each 100 seconds?
So on that case should be a total of +3 stop or 600 seconds?

Thanks.
07-29-2011, 07:27 PM   #42
Pentaxian




Join Date: Jul 2009
Location: Seattle
Posts: 7,103
QuoteOriginally posted by alexfoto Quote
Now i'm reading the data sheet of the Kodak Professional T-MAX (F-4016)
Code:
Exposure Time Is (Seconds) :   10            
Lens-Aperture Adjustment : +1/2 stop or Adjusted Exposure Time (Sec): 15
Exposure Time Is (Seconds) : 100
Lens-Aperture Adjustment : +1 stop or Adjusted Exposure Time (Sec): 200
So how calculate what is necessary for an exposition of 5 minutes (300 seconds)?
Is sufficient presume +1 stop for each 100 seconds?
So on that case should be a total of +3 stop or 600 seconds?

Thanks.
Yeah, the new T-Max data sheet sort of suck on that. The older ones gave you a nice curve. Usually it is non-linear but I guess they want to just plot a straight line through those two data points for time not given. Note too they suggest to decrease your development time in conjunction with correcting for reciprocity.

I've had this table for T-Max films for years and I still use it today. It may have been from the older T-Max formulations

TMX/TMY

Metered Adjusted
------------------
2s      3s
5s      7s
10s     15s
20s     35s
30s     50s
1m      2m
2m      4m 30s
4m      10m
10m     30m
20m     1hr 10m
1h      3hr

07-30-2011, 01:50 PM   #43
Senior Member




Join Date: Jun 2009
Location: Italy
Photos: Albums
Posts: 182
QuoteOriginally posted by tuco Quote
Note too they suggest to decrease your development time in conjunction with correcting for reciprocity.
Please could you said where is it that suggestions on the F-4016?
I'm not pratical with these things.
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!
acros, advice, exposure, exposures, photograph
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Landscape Ocean Long Exposure KevinR Photo Critique 11 10-26-2010 03:04 PM
How long will fresh batteries last in long exposure? tnis0612 Troubleshooting and Beginner Help 6 05-18-2010 09:11 AM
Long exposure help Cosmic Debris Troubleshooting and Beginner Help 15 02-23-2010 08:02 PM
Has anyone got any success doing this multi exposure procedure technique? shaolin95 Pentax DSLR Discussion 5 09-13-2009 03:37 AM
First Long Exposure With My K7 Christopher M.W.T Post Your Photos! 16 07-27-2009 03:44 AM



All times are GMT -7. The time now is 04:49 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