Durst M670 bw incredibly bright.

[CarlAbrahams]

Hi all,
I'm new to the forum and was after some advice, I have recently aquire a Durst M670 bw enlarger I have no instruction manual and have not been able to get any real info from Google searches, my problem is it seems incredibly bright and I can get an 8x10 print from a 6x6 neg. in about 10 seconds lens stopped down to F16. Is this normal for this enlarger? It as a 150 watt enlarging lamp that I was previously using in an opemus 6 for 35mm and that seemed fine. If anyone has got any experience with this enlarger or can give me any pointers as to what the problem may be I would be very grateful. First time doing medium format, the negative I'm using are just some test shots but seem reasonable in density, I also tried some 35mm negs that I have printed before and these were the same reaching maximum black in a matter of seconds.
Thankyou

 

[RobC]

seems odd. The correct lamp is a 150W opal bulb. There is nothing to stop you from using a 75W bulb instead.

Perhaps there is something missing. I assume it has the Vegaset 66 condensor set for 6x6 negs. There was also the Vegaset 67 condensor kit for 6x7 negs.
Which condensor does it have? The Siriocon 80 or the Vegacon 100 which will be brighter and is designed for 6x7 negs.

Also, are you sure your enlarger lens is actually closing down, some have an adjustment dial AND a close down lever.

Also I think there may be an adjuster (not sure about this) which allows you to adjust the condensor to suit the focal length of the lens. This could casue overly bright light if its not set for your particular lens FL, especially if you have the Vegacon 100 condensors.

 

[RobC]

Also forgot to say that if you did your test without a filter then yes, print times will be short. If you weren't using a filter then use one as that will make a big difference.

If you weren't using a filter then the 150W is probably fine when you do use one. Start with a Grade 2 filter.

If you were using a filter then:
sometimes when a bulb is reaching the end of its life it will become brighter. Suggest you try a new bulb and also get a 75W bulb for when you're making small prints.

 

[CarlAbrahams]

Thankyou for the replies, it as a siriocon 80 and I'm using a el nikkor 80mm lens, the bulb is only a couple of months old with very little use but I do have a spare that I may try just in case. The enlarger seems to all be there and seems fairly straight forward in assembly so I don't think anything is missing. I may try changing it back to the 35mm and testing with a different lens.thankyou for your help.

 

[RobC]

were you using a filter?

 

[CarlAbrahams]

Just thinking about it is there any ground glass that goes in the light path ,in the opemus here is a ground glass in he filter tray which diffuses the light somewhat but the Durst doesn't seen to have this. Thankyou.

 

[CarlAbrahams]

Yes, #2 filter.

 

[RobC]

it's a condesor enlarger so there should be no diffusion between condensor and film.

If filters are above condensor then you can put diffusion in filter tray but its not designed to have that as far as I know.

However, if you need to control the light levels then I use Lee Filters ND lighting filters which is very cheap to buy and you can cut to size of your filter tray and layer as many as your need.

http://www.pnta.com/lighting/gels/lee-298-0-15-nd/

0.15 is half a stop so a double layer will be 1 stop etc.

 

[CarlAbrahams]

Thankyou, I will order some and give it a go, got to be cheaper than getting a 75w lamp. Thanks for all your help I will post back when I have the filters.

 

[Bob Carnie]

I would be very happy with the fact that the enlarger pumps out a lot of light... usually the problem is reversed.

The sweet spot for exposure time IMO is 10 - 15 seconds , and you can use a lower wattage bulb if you think f16 is a problem.
Also neutral density filters can help you here.

 

[RobC]

just remember these are lighting filters and are not for optically correct light transmission. i.e. don't use them under the neg or lens, only between light source and neg and not too close too neg either. i.e. not directly on top of neg otherwise they may inroduce some grain into the image.

 

[CarlAbrahams]

Thankyou for the info Rob I will put the nd filter in the filter drawer, just looking at Bob Carnie's post and maybe the Opemus enlarger I was using before wasn't bright enough. I'm trying to get a process down using the Fred picker method this involves the minimum printing time to produce maximum black using a zone 0 negative. The negative I was using (Delta 100 120 roll film) was basically transparent unlike the 35mm zone 0 negs I'm used to looking at. I know the 120 roll film as a lower fb+fog density but even when I was stopping the enlarger lens right down and doing a strip test I was getting maximum black in about 6 seconds and not much inbetween so am unable to obtain an optimum developing time using this method and was wondering if maybe the enlarger was at fault but if 10 to 15 seconds is the sweet spot for exposure than maybe I'm not to far away.

 

[Bob Carnie]

Carl
10 -15 seconds is the absolute sweet spot for me in my darkroom, this allows for % printing that I do by counting and if you use 10 seconds as your base then it pretty easy from there.

Use a glass carrier , and make sure your enlarger is aligned, many good lenses out there, and centering the negative to the bulb, condensors, negative, easel blades are all part of getting a good setup.

Bob

Thankyou for the info Rob I will put the nd filter in the filter drawer, just looking at Bob Carnie's post and maybe the Opemus enlarger I was using before wasn't bright enough. I'm trying to get a process down using the Fred picker method this involves the minimum printing time to produce maximum black using a zone 0 negative. The negative I was using (Delta 100 120 roll film) was basically transparent unlike the 35mm zone 0 negs I'm used to looking at. I know the 120 roll film as a lower fb+fog density but even when I was stopping the enlarger lens right down and doing a strip test I was getting maximum black in about 6 seconds and not much inbetween so am unable to obtain an optimum developing time using this method and was wondering if maybe the enlarger was at fault but if 10 to 15 seconds is the sweet spot for exposure than maybe I'm not to far away.

 

[RobC]

I aim for around 20 seconds. This gives time for burning and dodging. Bob must be quicker than I am.

 

[CarlAbrahams]

Hi guys, just an update, I just took the head off of the enlarger and noticed the bottom 1/4 inch of the bulb was clear glass, the fitting it screws into as a thumb screw that allows you to move the bulb up and down, I moved it down so the clear glass in the bulb was covered and there is a good 2 stops difference in brightness. I'm keen to get up there and have another go at printing some stuff if the wife falls asleep.......perhaps I'll slip something in her tea. Thanks for all your help I really appreciate it.

 

[Bob Carnie]

Maybe , I doubt it though.. but there is this misconception that one needs more time for dodging and burning... basically a 10 % dodge will be the same result on a 10 second, 20 second exposure..so I just got good at it as I hate long print times.

so you need quick hands.. I cut my teeth making very small RA4 wedding prints and my old guy insisted I dodge and burn every print, hated him then , appreciate him now god rest his soul.

I aim for around 20 seconds. This gives time for burning and dodging. Bob must be quicker than I am.

 

[RobC]

the reason the bulb slides up and down is so that you can center the bulb element in center of image. You can also rotate the bulb for same reason as element may be slightly off center to one side. The point of this is to make sure you get the most even lighting across the image. There will always be a bit of light fall towards edges of print but if bulb is not centred then one side will be brighter than the other or top brighter than bottom or both which will make one corner brighter than others.

 

[CarlAbrahams]

Thankyou once again Rob, I have an ilford enlarger exposure meter I'll set it up with that, I was probably a bit to keen to get something out of it and maybe rushed putting it together.

 

[ac12]

I put a 75w bulb in my Durst M600 for the same reason, the original 150w bulb was way tooooo bright. f16 at 3 seconds. No time to dodge or burn.
In fact sometimes I felt that even the 75w bulb was too bright, I would love a 25-30w bulb to get my exposure time up to about 15 seconds. But I do not think they make a PH211 size bulb smaller than 75w.

I did not put a ND filter into the filter drawer, but that is an option.
As is a ND filter screwed into the front of the lens.

 

[ic-racer]

the bottom 1/4 inch of the bulb was clear glass, t

That won't produce even illumination. The bulb needs to have a uniform white inner coating.

 

[RobC]

I think ic-racer has a point. The only thing is that there are different types of condensor enlarger, those with light bulb directly above/perpendicular to the condensors and those like your m670 which have the light bulb offset up and 90degs to condensors and use a mirror to direct the light down to the condensors.
By the time all the light has bounced around in the top of the head and then been reflected downwards it will be a lot more diffuse than an enlarger which has the bulb directly above the condensors. Thre will be a hotspot though and that should be centred.

The condensors will do their best to collimate the light but I think they won't do it as well on an M670 as they will on some other enlargers. The point being that a less than optimal bulb may work OK except its a bit too bright.

 

[CarlAbrahams]

Thankyou to everyone for all the information, much appreciated.