Old Darkroom Bits

[Martin Aislabie]

Over the past few months I have noticed I was not getting consistent changes in paper grades when I swapped between my under the lens MG Filters

Well it’s hardly surprising, calculating I have had these Filters about 10 years – doesn’t time fly when your having fun

No problem, I invested in a new set.

Curious how the old and the new set would compare, I got out my Stouffer 5x4 Step Wedge, put it in my Enlarger and proceeded to make prints with each of the old and new MG Filters, keeping everything else the same including exposure time.

With the new Filters I got what I expected – a progressive increase in contrast as I moved up through the Filter Grades.

With the old Filter set, I got some consistency and some surprises.

Most were fairly reasonably spaced but old Grade 4 and old G2.5 were now the same grade, as were G3.5 and 4.5.

I was expecting this sort of “funny” result and didn’t really come as too much of a surprise.

However, I was not expecting there to be so much flare in my old filter set.

Light from Stouffer Step 1 (the most clear step) flared over several inches of the 10x8 paper – so that the only readings I was confident of using for the dense steps (20 & 21) were towards the edge, beyond the numeric window.

Looking at the new Filter set I realised they to were not completely free from flare either.

I then fitted my newer Enlarging Lens; the older of the two is now about 25 years old and the newer only about 10years old.

With the newer Enlarging Lens and the new filters I could not detect any flaring.

I have previously been unable to detect any detectable difference in sharpness between the two lenses and therefore considered the two lenses to be virtually identical.

My conclusions from my tests are :-

* Old MG Filters do over time loose their contrast and periodically need replacing – it isn’t just Ilford marketing hype

* Over time (and for what ever reason) Under the Lens MG Filters can generate flare which can veil the highlights in your prints.

* Enlarging lenses can also be a source of flare – even though they shows no other signs of problems – no scratches, no clouding, no dents or dings or any other sign of a problem.

As a result, I have now retired my old Enlarging Lens to paper weight duty and the old Filters are set to go to landfill.

Has anyone else a similar experience?

Martin

 

[ic-racer]

I always contact print the wedge if I am testing for paper contrast vs filtration color. As you have demonstrated, flare will alter the results if you project the wedge (unless one is actually testing for flare). What I would like to know is the magnitude of the bad filters' flare on contrast grade. You could test that by doing the contact prints and comparing them to the projected prints for both the bad lens and bad filters and comparing to the good ones. Again, just curious.

I was looking for a clever way to test for flare since I started looking up at my enlarging lenses. There had been a thread a while back about painting everything black to prevent spurious rays from fogging the paper. However, on every on of my enlargers, the brightest source of 'spurious light' was from the aperture of the lens (this is off-axis, non-image light). Worse on some lenses and better with others (because of various levels of flare in the lenses, presumably). Either way it was orders of magnitude larger than any light reflecting off the darkroom walls or enlarger body.

So, naturally I'm also curious if you 'flare' lens is visually brighter when you look up at it outside of its image axis.

 

[pentaxuser]

Martin. Despite having a dichroic head I had toyed with the idea of buying, secondhand, an under the lens set of MG filters from e-bay. Most are likely to be 10 years old.This has certainly made me re-consider this idea or at the very least ask about their age. I thought i recalled Simon Galley at the last Ilford tour saying that under the lens filters could last 20 years so if I recall what he said correctly,10 years sounds like only half the expected life. I suppose it depends on usage so the grade 2 -3.5 would generally waer out faster than the other less used ones.

You've set me thinking about my enlarger lenses as well. Both mine were acquired secondhand( a 50mm El Nikkor and 80mm Rodenstock Rodagon) and while appearing to give good service I now wonder about their life as well. The real test is actual prints. Have you tried the same neg at say 8x10 print with both lenses? If so is there any discernible difference in print quality?

pentaxuser

 

[Martin Aislabie]

I always contact print the wedge if I am testing for paper contrast vs filtration color. As you have demonstrated, flare will alter the results if you project the wedge (unless one is actually testing for flare). What I would like to know is the magnitude of the bad filters' flare on contrast grade. You could test that by doing the contact prints and comparing them to the projected prints for both the bad lens and bad filters and comparing to the good ones. Again, just curious.

I was looking for a clever way to test for flare since I started looking up at my enlarging lenses. There had been a thread a while back about painting everything black to prevent spurious rays from fogging the paper. However, on every on of my enlargers, the brightest source of 'spurious light' was from the aperture of the lens (this is off-axis, non-image light). Worse on some lenses and better with others (because of various levels of flare in the lenses, presumably). Either way it was orders of magnitude larger than any light reflecting off the darkroom walls or enlarger body.

So, naturally I'm also curious if you 'flare' lens is visually brighter when you look up at it outside of its image axis.

I was suprised - I wasn't expecting anything like this much flare

Sadly I will never again be able to bend far enough to be able to look up just off axis into my enlarging lenses.

I had condsidered doing a couple of contact prints for comparison, I will give it a go.

I thought when I was doing this I could see this flare on the print but put it down to imperfect human eyes flaring from themselves.

You should try projecting your Step Wedge - you might be suprised at the results - pleasantly or otherwise

Martin

 

[bsdunek]

I use above the negative filters. I have a set for my Durst that are about 45 years old! They seem to work OK, but guess I should do a test. Maybe a new set is in order. Thanks for the heads up!

 

[Martin Aislabie]

Martin. Despite having a dichroic head I had toyed with the idea of buying, secondhand, an under the lens set of MG filters from e-bay. Most are likely to be 10 years old.This has certainly made me re-consider this idea or at the very least ask about their age. I thought i recalled Simon Galley at the last Ilford tour saying that under the lens filters could last 20 years so if I recall what he said correctly,10 years sounds like only half the expected life. I suppose it depends on usage so the grade 2 -3.5 would generally waer out faster than the other less used ones.

You've set me thinking about my enlarger lenses as well. Both mine were acquired secondhand( a 50mm El Nikkor and 80mm Rodenstock Rodagon) and while appearing to give good service I now wonder about their life as well. The real test is actual prints. Have you tried the same neg at say 8x10 print with both lenses? If so is there any discernible difference in print quality?

pentaxuser

After my little experiment, I wouldn't recommend 2nd hand under the lens filters to anyone.

The test suprised me too, I wasn't running the test for the flare only the contrast - but the flare issue was too obvious to overlook.

As for the Lenses, I have previously done the same print with both Lenses for comparison and I had always thought the newer Lens (Rodagon) had always given a slightly crisper print than the older lense (Componon-S).

However, I couldn't put my finger on what the difference was, I knew it wasn't sharpness - they were pretty much equal to my eyes when printed big and viewed with a Loupe.

I had pretty much convinced myself the print differences were wishful thinking on my part - I had never considered slighly variations in contrast.

Martin

 

[BetterSense]

This thread is very interesting to me, but I don't understand it.

What is this "flare"? I'm trying to figure out what it could be. I know when you take a picture into the sun, especially with a wide-angle lens, you can get weird flares that look like the shape of your lens aperture, but I have never experienced this when enlarging. Are you talking about getting shapes like this on your print? You say that this flare differs both between your two enlarging lenses and your two sets of filters. This is quite puzzling to me.

By the way, is there any reason one couldn't use above-negative filters as under-lens filters? In otherwords, are the colors the same between the two types of filters, or is there some difference?

 

[ic-racer]

Flare in the enlarger system? Think of a dime placed on a glass negative carrier with the perfectly focused-shadow projected down toward the baseboard. Now, the shadow should be perfectly black, with no light. However, some light does spill over onto the shadow. That is the flare. It comes from the lens and also (to a lesser extent) from light bouncing off the walls etc. If one had an enlarging meter (like the Darkroom Automation meter) you could measure how black the shadow of the coin is and quantify the flare in the system.

In Martins case, he got more flare with a certain lens and got more flare when the older filters were placed in the light path.

Flare does not show up in contact prints. So comparing a projected step wedge to a contact-printed step wedge can also show the level of flare.

 

[BetterSense]

I understand now. I had always dismissed worries that under-lens filters degraded image quality on the grounds that they were placed in an area so out of focus that they could not effect sharpness. I never considered flare as a factor.

 

[Martin Aislabie]

I understand now. I had always dismissed worries that under-lens filters degraded image quality on the grounds that they were placed in an area so out of focus that they could not effect sharpness. I never considered flare as a factor.

Nope - I didn't consider flare to be a significant issue either - I wasn't really testing for it and came as a complete surprise

Neither the old MG Filters nor the older of the two Enlarging Lenses look damaged or scratched.

I will in future run occasional checks for flare - even if its to reassure myself its not a problem

Martin