Support our Sponsors, they keep FADU free:   AG Photographic   The Imaging Warehouse   Process Supplies   RH Designs   Second-hand Darkroom Supplies  

Notices

Go Back   Film and Darkroom User > Equipment > Darkroom

  ***   Click here for the FADU 2015/2014 Yearbooks   ***

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 12th June 2020, 04:34 PM
martinhupfer martinhupfer is offline
Friend
 
Join Date: Apr 2020
Posts: 14
Default Dever 507 dichro head multigrade

Hi all,
My dichro head is running out of control using filters for multigrade.
With two filter method i get exposing times of aprox 30 sec. using grade 2.
Going down to grade 1 it takes 10 times more and I don't really think that's ok.
Now I use multigrade filters below the lense.

Do filters age?

What do so think can I do?
__________________
"I’m not interested in a Walt Disney view of the world,
I’m interested in the reality of it."
Joe Cornish
Reply With Quote
  #2  
Old 13th June 2020, 12:12 PM
Terry S Terry S is offline
Friend
 
Join Date: Dec 2011
Location: Southend on Sea, Essex, England, UK
Posts: 3,796
Default

Filters definitely do degrade Martin.

I wasn't getting the full range of tones in recent work, so invested in a new set of Ilford's MG filters recently.

A full new set was too expensive for me, and as I rarely use 1/2 grade filters, I bought the student selection of just full grades from Ilford directly, as shops wanted me to order about a minimum of 100 sets! They only cost me about £10.

I substituted the new filters, after trimming them to size, into the holders easily and am looking at trying them out soon.

But, looking at the old ones and the new ones next to each other, there's a very big difference in colour and density.

So as I said, yes filters do degrade and I can only imagine that the ones in dichro heads do the same, unless anyone knows otherwise?

Terry S
Reply With Quote
  #3  
Old 13th June 2020, 12:51 PM
MartyNL's Avatar
MartyNL MartyNL is offline
Friend
 
Join Date: Sep 2010
Location: based in The Netherlands
Posts: 3,341
Default

Bulbs also "degrade" leading to much longer exposure times. I know this because my Durst Multigraph measures and calculates the exposure taking into account the "aging" of the lamp.

In all honesty, the factors you're describing, I would have thought it was more due to a weaker light source. The filters would have a greater impact on contrast rather than the exposure surely?
__________________
MartyNL

“Reaching a creative state of mind thru positive action
is considered preferable to waiting for inspiration.”
- Minor White, 1950
Reply With Quote
  #4  
Old 13th June 2020, 02:18 PM
Bill's Avatar
Bill Bill is offline
Moderator & Keeper of the Calendar
 
Join Date: Sep 2008
Location: Barrow - in - Furness
Posts: 1,803
Default

Quote:
Originally Posted by Terry S View Post
So as I said, yes filters do degrade and I can only imagine that the ones in dichro heads do the same, unless anyone knows otherwise?

Terry S
Terry, I think the OP is talking of dichroic filters not the plastic under lens ones from Ilford which do fade with time. Regarding the dichroic ones when I had perceived problems with one of their colour heads I spoke to the guy in Odessey who services De Vere enlargers and he told me he had never seen a dichroic filter that had faded whatever the age even when used for long hours in professional darkrooms or colleges. This is also supported by a number of sources on the internet although there are also those who maintain that they do.

Martin, I think the suggestion regarding the lamp may be a better route to explore as lamps do lose power and change colour temperature over time. However the time difference is larger than I would expect from just that. Have you checked the filters are moving correctly in the head and the cyan is not coming into play thus adding neutral density? Have you also checked the pins on the lamp base and in the holder as you get a build up of corrosion which can have an intermittent effect but that is unlikely to affect one grade and not others? They are both worth checking and cleaning though.

Bill

Last edited by Bill; 13th June 2020 at 02:39 PM. Reason: Additional information.
Reply With Quote
  #5  
Old 13th June 2020, 02:50 PM
Mike O'Pray Mike O'Pray is offline
Friend
 
Join Date: Oct 2008
Location: Daventry, Northants
Posts: 8,968
Default

Martin I would agree with Bill about dichroic filters so yes there is something else at fault. It may be possible that as you turn the Y and M dials the filters are not being moved properly or are sticking. It might be worth checking. The check is simple. Just turn each dial and see if the colour on a white easel changes as you do it.

Really Bill has covered everything.

Best of luck finding the problem and solving it

Mike

Mike
Reply With Quote
  #6  
Old 13th June 2020, 04:22 PM
Bob's Avatar
Bob Bob is offline
Administrator
 
Join Date: Aug 2008
Location: London(ish)
Posts: 2,746
Default

Only other thing not covered that I can think of is to check the dichroic filters for dust.

As others have said, dichroic filters do not fade. They use a series of stacked coatings to generate interference effects to pass the required colour and reflect the unwanted ones. Both the way they are made and the fact that they reflect rather than absorb the unwanted light (including the heat) makes them almost unfadeable (if that were a real word!) in normal use as long as the coatings are intact and are not physically damaged. I imagine there are exceptions to this rule if they are badly made and the coatings have separated or similar, but I think the general rule holds true.

Last edited by Bob; 13th June 2020 at 04:29 PM.
Reply With Quote
  #7  
Old 14th June 2020, 08:20 PM
alexmuir alexmuir is offline
Friend
 
Join Date: Jan 2010
Location: Glasgow, Scotland.
Posts: 2,668
Default

It sounds like a bulb issue, rather than the filters. Do the bulbs have a mirrored reflector, or are there mirrors, or other glass elements in the light path? It would be worth checking the condition of the bulbs, and all parts the light passes through, or bounces off, to make sure they have not deteriorated. Some diffuser heads use a lining of white polystyrene foam which can also cause issues when it ages.
Alex.


Sent from my iPhone using Tapatalk Pro
Reply With Quote
  #8  
Old 15th June 2020, 11:51 AM
Terry S Terry S is offline
Friend
 
Join Date: Dec 2011
Location: Southend on Sea, Essex, England, UK
Posts: 3,796
Default

Quote:
Originally Posted by Terry S View Post
Filters definitely do degrade Martin...

But, looking at the old ones and the new ones next to each other, there's a very big difference in colour and density...

So as I said, yes filters do degrade and I can only imagine that the ones in dichro heads do the same, unless anyone knows otherwise?

Terry S
For more than the first time, I posted a reply before doing some research... But it's so easy to do, as others will agree...

But since the original question post and then my reply along with others, I have done quite a bit of reading about dichro heads and filters. Apparently they are not susceptible to fading like the under lens focusing. So that told me!!

Anyway, as I asked for info from people more knowledgeable than myself about the subject, comments have been forthcoming and the poster of the OP should now be a lot more informed.

Note to self: Only post replies to things that you actually know something about and not make assumptions!!

Terry S
Reply With Quote
  #9  
Old 15th June 2020, 12:00 PM
MartyNL's Avatar
MartyNL MartyNL is offline
Friend
 
Join Date: Sep 2010
Location: based in The Netherlands
Posts: 3,341
Default

Quote:
Originally Posted by Terry S View Post
For more than the first time, I posted a reply before doing some research... But it's so easy to do, as others will agree...
Terry S
That's one of the things which makes this forum so special, Terry, the absence of trolls. Long may it stay this way!
__________________
MartyNL

“Reaching a creative state of mind thru positive action
is considered preferable to waiting for inspiration.”
- Minor White, 1950
Reply With Quote
  #10  
Old 16th June 2020, 07:34 PM
Martin Aislabie's Avatar
Martin Aislabie Martin Aislabie is offline
Friend
 
Join Date: Nov 2008
Location: Stratford-upon-Avon, England
Posts: 2,080
Default

I'm not sure if all DeVere colour heads are the same - but I have a Mk4 504.

When I lift up the panel in order to change the bulb, I can see the dichroic filters and if I adjust the YMC dials I can see each one moving in turn.

Check yours are individually moving freely and one is not dragging the others along for the ride, so to speak.

The effect of adding the other filters in to the mix is to act an a neutral density filter.

It is only a 60 second job is you can lower the head to be able to peer in to the bulb chamber.

Martin
Reply With Quote
Reply
Support our Sponsors, they keep FADU free:   AG Photographic   The Imaging Warehouse   Process Supplies   RH Designs   Second-hand Darkroom Supplies  

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Multigrade Head Deryck Darkroom 2 12th April 2018 07:30 PM
Multigrade 500 Head PeterMcC Darkroom 2 23rd May 2016 07:25 PM
De Vere 203 with Multigrade head and lenses dsallen Darkroom 1 6th January 2016 07:13 PM
Multigrade Head Too Bright Guy Boden Darkroom 26 7th November 2010 11:34 PM
Ilford Multigrade Head Setup Neil Smith Darkroom 5 18th February 2010 03:39 PM


All times are GMT. The time now is 03:33 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.