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-   -   Times too short on Devere 504 (http://www.film-and-darkroom-user.org.uk/forum/showthread.php?t=13591)

Faraz 15th January 2021 10:26 AM

Times too short on Devere 504
 
I recently got a 504 mark IV and have started using it. I'm finding the exposure times are too short and I have to use sub-optimal aperture as a result. At f32 (my 150mm lens goes to f45) my time is 7s on Grade 00 and 2s on grade 4. Not much time then for dodge/burn etc.

I'm printing 4x5 negatives on 8x10 paper.

How I can increase times ie. reduce brightness of the enlarger? My negative density is not specially thin though I have not measured it. I'm not sure if I can use lower wattage bulbs or add a acrylic sheet to the mixing box.

Any ideas appreciated

thanks

B&W Neil 15th January 2021 11:24 AM

Quote:

Originally Posted by Faraz (Post 137759)
I recently got a 504 mark IV and have started using it. I'm finding the exposure times are too short and I have to use sub-optimal aperture as a result. At f32 (my 150mm lens goes to f45) my time is 7s on Grade 00 and 2s on grade 4. Not much time then for dodge/burn etc.

I'm printing 4x5 negatives on 8x10 paper.

How I can increase times ie. reduce brightness of the enlarger? My negative density is not specially thin though I have not measured it. I'm not sure if I can use lower wattage bulbs or add a acrylic sheet to the mixing box.

Any ideas appreciated

thanks



Which light head / mixing box are you using ?

Neil..

Faraz 15th January 2021 11:32 AM

It's the Mark 4 light head with 2 bulbs and the 4x5 mixing box.

Terry S 15th January 2021 12:29 PM

Faraz, if I recall correctly, in a not so old previous post, from someone with a similar problem, there were numerous ideas suggested - can anyone remember the link?

The one suggestion that I do remember though, was putting some neutral density lighting gel between the light and the negative, if that's possible with your enlarger? Just looking, it's not expensive and looks easy to cut to size.

NOTE: I have just found an ebay seller who sells a set of 0.3, 0.6 and 0.9 sheets, that would fit the purpose, for just £5.40:

https://www.ebay.co.uk/itm/3-sheets-...8AAOxycD9TVYcI

Terry S

Faraz 15th January 2021 12:54 PM

Thanks for the suggestion Terry. I was thinking about this but was not sure.

I've used ND filters in combination with frosted acrylic before on a smaller enlarger they seemed to interfere with the contrast filtering. In fact almost nothing would print in grade 4-5 despite seeing the image projected. I used a square 1.5mm filter designed for a camera, perhaps a thin film filter would be better.

I think this is worth a go.

mpirie 15th January 2021 12:54 PM

Just what i was about to suggest too Terry....add ND gels above the neg.

If you can buy 0.3 sheets, you should be able to add one or more to bring the times up to an acceptable level.

Mike

PS. You could try one of your camera ND filters below the lens to see if it'd work.

Faraz 15th January 2021 12:58 PM

ordered the Nd gel! I'll try this first and see how it goes

Bill 15th January 2021 02:41 PM

I have a Mk IV head and that only has one bulb. As far as I know the 2 bulb version is the Mk V. It is possible in the same fitting to get 200W bulbs instead of the 250W normally fitted. That may help.

Martin Aislabie 15th January 2021 05:20 PM

I have permanently dialled in 50CC of Y + M + C to give a ND filter on 504 Mk4 to combat the same problems of very short exposure.

You could dial in even more if you needed to - as long as you add the same amount of each.

Then, if I have a very selective enlargement from a Neg and my exposure times are getting long, I use the white light lever of knock them all out together - but I never touch the dials.

It works for me but YMMV

Martin

Bob 15th January 2021 06:04 PM

What's all this with people getting too-short times? I am insanely jealous!

skellum 15th January 2021 07:21 PM

It's Friday, and I'll admit to being a bit tired.
However, anyone know what happens if you just dial in lots of cyan?
Does that only reduce brightness, or any implications for contrast?

billcowan 15th January 2021 10:43 PM

Assuming we are talking about Black and White here, Cyan is the same as a minus red filter. Black and White paper is sensitive to Blue and Green light. Red is of course the safe light and using Cyan to block Red light just makes for the equivalent of a dimmer safe light with no effect on paper exposure.
On the other hand filters are not perfect and there may be minor changes to the small degree that the Cyan filter might actually change Yellow or Magenta light.
So yes the use of Cyan makes the visualized image dimmer but with no changes in exposure or contrast.

Uwe Pilz 16th January 2021 06:12 AM

If you yont want to buy a filter, you may simply put some sheets of frosted paper in the filter drawer. The type of paper which you use for wrap food. With times so short you may even use printer paper-

skellum 16th January 2021 01:11 PM

Thank you for that reasoned explanation Bill, makes sense.

I'd probably have gone and tested before asking, but darkroom currently out of commission.

Martin Aislabie 16th January 2021 02:12 PM

Quote:

Originally Posted by Bob (Post 137778)
What's all this with people getting too-short times? I am insanely jealous!

Dodging, short times means it is almost impossible to do it accurately or repeatedly.

Burning in can be a little less frantic - by using a smaller hole in your burning in card you effectively give yourself a smaller lens aperture.

Plus, if you make the hole in your burning in card rather soft and fluffy you increase the size of the penumbra (the soft graduated edge of the ring of light which is neither fully shaded or fully exposed) - you are less likely to leave tell-tale signs of burning in - particularly noticeable on harder grades.

Martin

Faraz 11th February 2021 10:39 AM

The ND gels have done the job. I'm now in a more sensible range.

I do use the dials to get contrast grades, it seems stable enough to do split grade printing without any movement caused between the grades.

I did think of swapping out the bulbs for 200W, but its only 20% less than the original 250W so I don't think it'd be enough on its own.


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