Durst Laborator 1200 VLS 501 head

ciccioder · Oct 11, 2010

Hi, i'm new on he forum, and i have to submit a question:

i early buy the enlarger in object with VLS 501 Head and i don't understand if when i change the contrast i have to change even the exposure time.

Quiet stand up to the time, I used it without dichroic filter inserted, but now i'm using VC papers, so that this function of the head could be usefull.

My problem is that when i make test strip at WL (white light) and than choose exposure time, if i change contrast, my print becames too darker: it's like the internal diaphram lets pass too much light (when is inserted - Automatik position).
I don't understan if i make some mistake calculating exposure time or if is a problem of the Head of the enlarger.....i've read that the head could change contrast without modify exposure time but in my case it isn't so!!!

Someone could help me, please? i've red some post on the forum, but none explain well the head functioning.

regards

paul_c5x4 · Oct 11, 2010

You need to make a test strip with the filters in place, not under white light (WL). With the filters in place, changing the grade should not affect the required exposure unless you want grade 0 or grade 5. The data sheets that came with the paper should tell you if the exposure needs changing at higher grades (or lower).

ciccioder · Oct 11, 2010

But are we speaking about the DURST VLS 501 HEAD?
Anyway: i have to do a test strip with choosen filter, not at WL, then, after i have choose the "correct exposure time", if i choose a different grade, the head will automatically vary the quantity of light for correct exposure with the new filter?
And why not i have to do a test strip at WL?
It's not as the same things as i do that with any other filters?

thanks

RalphLambrecht · Oct 11, 2010

You need to make yourself a table such as the graph attached.

You'll find how to make it here:

Dead Link Removed

Scroll down to 'Paper exposure Compensation'.

ciccioder · Oct 11, 2010

Sorry, but i don't still understand.....the DURST VLS 501 HEAD should automatically change the quantity of light when you change the grade....or i'm wrong?
why i have to do myself a table if the head make the work alone automatically?

mhulsman · Oct 11, 2010

The VLS 501 head does automatically change the amount of light according to the grade.
So if you have a correct exposure time for grade 00, you can use the same exposure time for grade 5
from the manual:

* DURST VLS 501
Diffused illumination systen for black and white
enlarging using variable contrast papers
The contrast is continuously adjusted with a control knob.
The system provides also automatic density compensation

But when you start the initial exposure time do not use the handle in "white Light" position.

I made a set of all grades starting from 00 until 5 with 0,5 step grades.
That will give you a nice overview of all the grades the head can give you, and you can test if the density compensation is working.

Regards.
Mike

RalphLambrecht · Oct 11, 2010

ciccioder said:
Sorry, but i don't still understand.....the DURST VLS 501 HEAD should automatically change the quantity of light when you change the grade. ...

How could it possibly do that?

How does the VLS 501 know what paper you're using, and how does it know which print tone you would like to keep consistent?

It simply doesn't.

Sorry, there is no such thing as automatic exposure compensation with contrast changes. You need to run a test and record it in a table for future work.

RalphLambrecht · Oct 11, 2010

mhulsman said:
The VLS 501 head does automatically change the amount of light according to the grade. ...

Unfortunately impossible. The advertising claim is referring to the, so-called, speed point, which is part of the ISO standard but has little in common with actual printing practise. The exposure compensation required for contrast changes differs with paper and target tonality. Of course, the VLS 501 is unaware of both.

One can read similar claims about contrast filter sets, but those claims are misleading too. It only works if you want to keep the speed-point density consistent, and who wants to do that?

Marco B · Oct 11, 2010

RalphLambrecht said:
Unfortunately impossible. The advertising claim is referring to the, so-called, speed point, which is part of the ISO standard but has little in common with actual printing practise. The exposure compensation required for contrast changes differs with paper and target tonality. Of course, the VLS 501 is unaware of both.

One can read similar claims about contrast filter sets, but those claims are misleading too. It only works if you want to keep the speed-point density consistent, and who wants to do that?

Ralph: while your answers are technically true, for most "ordinary" darkroom workers like myself that do not "fine-tune" our printing practices in every detail, the automatic "compensation" of some of these systems (I have Ilford's 500H Multigrade head), does offer a good starting point, and I think most people will make any exposure adjustments in a more relaxed and unconscious way by thinking:

"Oooh, I changed the grade from 2.5 to 3 and now it looks to dark! Got to take off a few seconds! :confused:"

instead of consulting "tables" each time they do an adjustment.

At least, that is how I partly find my way to the final print...

While I admire your attention to detail, and your book is still hot on my list of "things to get" , it is not the only way to look upon this.

Marco B · Oct 11, 2010

RalphLambrecht said:
The exposure compensation required for contrast changes differs with paper and target tonality. Of course, the VLS 501 is unaware of both.

Actually, interestingly, looking at the manual of my Ilford 500H Multigrade head, it says it was specifically designed for one specific paper: Ilford Multigrade II VC.

So, in a sense, it does know at least one paper , but I don't know how modern papers compare to that old Multigrade II version.

In addition, the light output of the lamps is microprocessor controlled, and it literally says:

"Once the exposure is established at a particular contrast level, the Ilfospeed Multigrade 500C control unit adjusts automatically the intensity of light to ensure exposure times remain the same right across the contrast range" (0-5 for the unit)

However, the old control unit is not sophisticated enough to be able to "store" compensation data for multiple new papers. I guess that with a modern day unit of RH Design or so, you will be able to store it all, but I haven't had a good look at it all. As long as it all keeps working, I will stick with what I have now.

RalphLambrecht · Oct 11, 2010

Marco B said:
... and I think most people will make any exposure adjustments in a more relaxed and unconscious way by thinking:

"Oooh, I changed the grade from 2.5 to 3 and now it looks to dark! Got to take off a few seconds! :confused:"

instead of consulting "tables" each time they do an adjustment. ...

Marco

Isn't it better to look at the table first before wasting a sheet of paper? I prefer to get no surprises when fine-tuning the contrast. Actually, I bet most people hesitate to fine-tune the contrast because they are afraid of these surprises. This can be avoided, and the reward is more flexibility, and in the end, better prints. Isn't that what it is all about?

Anyway, it's important to understand why the head cannot do what the customer expected. As you said, it is calibrated for one, very outdated, paper.

ciccioder · Oct 11, 2010

Many tanks...but...what i have to conclude, that the head should only fine work at WL? So that it was useless? There is a way to use it??

RalphLambrecht · Oct 11, 2010

ciccioder said:
Many tanks...but...what i have to conclude, that the head should only fine work at WL? So that it was useless? There is a way to use it??

Of course you can use it. It will do fine work too, but you must correct the exposure trial-and-error, as Marco suggested, or go through the effort and make an exposure compensation table, as I suggested. This is nothing special. Every darkroom worker has to make that choice with MC papers, no matter what equipment they use. It's a common characteristic of multi-contrast paper. Once the material is learned and understood, it becomes a very powerful tool. There is no magic, just a lot of hard but rewarding work.

ciccioder · Oct 12, 2010

Many thanks, really!!!

Concluding, seems understand that the head is calibrated for the old Ilford RC paper II (or in general for old type of multigrade paper) that needs more light in any grade of contrast!!!! For this reason i have to make an exposure compensation table.....but i have to do that for any type of paper that i use (Multigrade RC - FB and so on)??????

So the functioning of the head is ok, i hope....it's normal that if i choose an exposure time for a grade of contrast and after i change it with another (usually higher than before) the print is too darker (because the internal diaphram - when in use - let pass more light, according to the old settings for the old ilford's VC paper which is calibrated for).

So, the question is: could i use the VLS 501 HEAD in position AUTOMATIC (with the internal diaphram inserted) or i have to switch off?
Sorry....i'm hard understanding for my poor practice....but when i saw the laorator 1200 i could not resist.....and i buyed it!!!
Regards

Marco B · Oct 12, 2010

ciccioder said:
Many thanks, really!!!

Concluding, seems understand that the head is calibrated for the old Ilford RC paper II (or in general for old type of multigrade paper) that needs more light in any grade of contrast!!!! For this reason i have to make an exposure compensation table.....but i have to do that for any type of paper that i use (Multigrade RC - FB and so on)??????

A few extra and correcting remarks based on yours that hopefully clarify things up:

- First, you are going in the right direction with your conclusions, so that is good!
- The outdated old Ilford Multigrade II paper I mentioned is, is specific for the Ilford 500H Multigrade exposure head that I use with my L1200. It was the paper my head was designed for. It may be the same paper your Durst VLS 501 head is calibrated to, but it might also well be another paper...
- Yes, as Ralph suggests, if you want to work very precise and concise, you have to make an exposure compensation table for every paper type you use.

However, as I suggested, there is also the possibility to "go-with-the-flow" and use the results your exposure head gives as a guide and go from there with a bit of trial and error and using test strips.

Please note Ralph Lambrecht is one of the most experienced and advanced darkroom workers on the globe... He sometimes forgets that while explaining things ... His working methods may be a bit "over your head", which is nothing to be ashamed of, as I learn something new too each time he posts these kind of things.

ciccioder said:
So the functioning of the head is ok, i hope....it's normal that if i choose an exposure time for a grade of contrast and after i change it with another (usually higher than before) the print is too darker

Most likely: Yes!

But please mind the remarks paul_c5x4 made about your Durst VLS 501 head and about not using the WL light setting for determining base exposure, but using a contrast setting instead.

ciccioder said:
So, the question is: could i use the VLS 501 HEAD in position AUTOMATIC (with the internal diaphram inserted) or i have to switch off?

As I said, I personally have the Ilford 500H Multigrade exposure head with my Durst L1200 enlarger, not your Durst VLS 501 exposure head...

So I can't comment on the AUTOMATIC setting. Most likely Paul_c5x4 can answer your question, as he seems to own one.

ciccioder said:
Sorry....i'm hard understanding for my poor practice....but when i saw the laorator 1200 i could not resist.....and i buyed it!!!
Regards

Don't worry, the Durst Laborator 1200 series enlargers are some of the best enlargers ever made, so you got an excellent buy.

Marco B · Oct 12, 2010

RalphLambrecht said:
Isn't it better to look at the table first before wasting a sheet of paper? I prefer to get no surprises when fine-tuning the contrast. Actually, I bet most people hesitate to fine-tune the contrast because they are afraid of these surprises. This can be avoided, and the reward is more flexibility, and in the end, better prints. Isn't that what it is all about?

Anyway, it's important to understand why the head cannot do what the customer expected. As you said, it is calibrated for one, very outdated, paper.

Ralph, I basically theoretically agree with all you said . I think the two valuable lessons you taught us here in this thread is 1) Needed exposure changes with changing contrast filtration, 2) There are marked and important differences between different VC papers and brands of paper.

I am just afraid the advanced calibration you suggest, may be a bit to complicated for the average novice darkroom worker, and might scare them even of, so that is why I suggested the "trial-and-error" route as at least an alternative to "going-all-the-way" and fine-tuning and calibrating your entire work-flow up to a level you are used too.

RalphLambrecht said:
Actually, I bet most people hesitate to fine-tune the contrast because they are afraid of these surprises. This can be avoided, and the reward is more flexibility, and in the end, better prints. Isn't that what it is all about?

Personally, I have never hesitated adjusting exposure times or contrast whenever results were unsatisfactory. It has learned me a lot doing so, and I encourage everyone else to do so too.

GeorgesGiralt · Oct 12, 2010

Hello,
May I give you a work flow ?
Choose one of your favorite negatives not too hard to print (one which can print strait is ideal)
Dial a grade #2 on the head, put a paper on the easel; and using the filters ON make a test strip to find a correct time for the delicate highlight which is important on your image.
Once found, make a full print at that time and contrast and check the shadows. Too light and you need to increase the grade setting, too dark and you need to decrease the grade setting.
Make one full print at the same time setting you found previously and new grade. If the highlight is still good, your head is doing a very fine work. If not you have to compensate with exposure to get this tone right.
If the second is true, then you'll have to re calibrate the head (by making a chart as Ralph explained).
I bet you will be quite good without calibration "for government work" ;-)
Another option is to buy an RH designs Analyser Pro, with a set of under the lens filters from Ilford and use your head in white light position. You won't regret your buy !
Hope this help.
P.S : If the first print is good in highlight and shadow at grade #2, select a lore difficult neg ;-)
Do not forget to dry all papers before making comparisons in order to account for paper dry down.

ciccioder · Oct 12, 2010

paul_c5x4 said:
You need to make a test strip with the filters in place, not under white light (WL). With the filters in place, changing the grade should not affect the required exposure unless you want grade 0 or grade 5. The data sheets that came with the paper should tell you if the exposure needs changing at higher grades (or lower).

paul, from your words, i understand that the head must work alone (if diaphram was inserted - Automatic position) once you choose your correct exposure time.....meanwhile, all others say me that i have to create my exposure compensation table.....to determine my correct workflow with any filter, for a determinate paper.
thanks

Marco B · Oct 12, 2010

ciccioder said:
paul, from your words, i understand that the head must work alone (if diaphram was inserted - Automatic position) once you choose your correct exposure time.....meanwhile, all others say me that i have to create my exposure compensation table.....to determine my correct workflow with any filter, for a determinate paper.
thanks

Cicicioder, whether or not to use an exposure compensation table, is entirely up to you. See what works for you.

As said, I don't use exposure compensation tables, but solve it in a more "intuitive" manner requiring more test strips. Ralph does use such tables, and his entire workflow is calibrated to perfection allowing him to effectively and efficiently "dial-in" his chosen contrast and exposures without giving a second thought to the need for exposing and processing test strips of photo paper for each new negative he prints...

No one can tell you what you need to do, just do what feels right for you.

Renato Tonelli · Oct 12, 2010

The Durst Multigraph will change the exposure automatically as changes in contrast are made; I was unaware that the 501 was capable of any automation whatsoever. I use the 501 for color work only and the Multigraph for B&W only so it it never occurred to me to check it.

mhulsman · Oct 12, 2010

RalphLambrecht said:
Unfortunately impossible. The advertising claim is referring to the, so-called, speed point, which is part of the ISO standard but has little in common with actual printing practise. The exposure compensation required for contrast changes differs with paper and target tonality. Of course, the VLS 501 is unaware of both.

One can read similar claims about contrast filter sets, but those claims are misleading too. It only works if you want to keep the speed-point density consistent, and who wants to do that?

Ralph,

I do not go that deep into the technical details as you do.
I alway's make test strips the way you describe in your book with the test-strip printer and use F-stop timing.
I dial on the VLS501 a harder or softer grade, and do a test print on 13x18cm paper. (with the head focussed for the large final print)
If that is fine I make the final print.
That is working for me right now. Not that technically bit it works for me.

RalphLambrecht · Oct 12, 2010

mhulsman said:
Ralph,

I do not go that deep into the technical details as you do.
I alway's make test strips the way you describe in your book with the test-strip printer and use F-stop timing.
I dial on the VLS501 a harder or softer grade, and do a test print on 13x18cm paper. (with the head focussed for the large final print)
If that is fine I make the final print.
That is working for me right now. Not that technically bit it works for me.

I'm a big fan of test strips. Actually, I advocate doing different test strips for different areas of the print (sky, shadows, faces etc). That always works well. I just try to avoid doing them all over again when optimizing contrast, hence, the exposure compensation table. In a way, of course, the tabel is a test strip by itself, just one you can use over and over again.

Yes, you need to do them for all papers (I only use two types of paper). I also made them for Zone VII and Zone VIII, because, keeping highlights and light skin tones consistent requires different tables. But, you can simplify the process by just making one for your 'target' print tone.

MattKing · Oct 12, 2010

To satisfy my curiosity ...

Are the "auto" functions in the OP's enlarger likely to make corrections that are seriously misleading, or can they be used to "help"?

By this, I mean, can the OP create the tables that Ralph talks about, with the auto functions turned on, and end up with tables that require less supplementary correction than using the enlarger manually?

RalphLambrecht · Oct 12, 2010

MattKing said:
To satisfy my curiosity ...

Are the "auto" functions in the OP's enlarger likely to make corrections that are seriously misleading, or can they be used to "help"?

By this, I mean, can the OP create the tables that Ralph talks about, with the auto functions turned on, and end up with tables that require less supplementary correction than using the enlarger manually?

Matt

Take a look at my graph in post #8. My tables adjust for the speed differences at Zone VII or VIII density. The 'auto' function in enlargers and filter sets adjust for the speed differences at the speed point density.

It's unlikely to help. On the other hand, as Marco says, I might be too picky. After all, I optimize print exposure to 1/12 f/stop and print contrast to 1/4 (sometimes 1/8) grade. To me, any larger of a difference and the print screams for help. Others may be more tolerant.

ic-racer · Oct 12, 2010

RalphLambrecht said:
Matt

Take a look at my graph in post #8. My tables adjust for the speed differences at Zone VII or VIII density..

A table or enlarger head that pivots on such a high value would be non-intutitive. As contrast changes are commonly changes that make darks darker and lights lighter without overall impression of the print being darker or lighter. If you are keeping the lighter values constant then the overall print will look darker or lighter as contrast changes. That does not satisfy the common impression of a 'constant exposure' system.

Not saying its not a good system, just that is not what most would call a 'constant exposure' system.

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