Double exposure times for high-contrast filters? Not mine.

[BetterSense]

I got a full set of Ilford MG under-lens filters recently with no box or instructions. I always heard that for filters above 3.5, you were supposed to double the exposure time. I don't see that at all when I use mine. From right to left, grade 2.5 at 10s, grade 5 at 10s, and grade 5 at 20 seconds.

weird?

[ic-racer]

I see your point. I also don't see much contrast change between the 2.5 and the 5, so perhaps your 5 filter has faded.

Here are the instructions if you have not already located them: http://www.ilfordphoto.com/Webfiles/...0201152306.pdf

[RalphLambrecht]

Please remember that exposure changes for contrast filters are designed for a print density of 0.6. Any other density needs a different exposure factor.

[ath]

Ralph is of course right. And additionally every set of filters is designed for a specific paper. Other papers sometimes behave significantly different.

[pentaxuser]

Based on what the OP has said, it is safe to assume that the filters were secondhand. On the recent Ilford tour I think that Simon Galley hazarded a guess that the filters need replacing every 20 years or so. If the problem is fading of the grade 5 filter, how does he go about ascertaining whether this is the case? Once he establishes whether fading of the grade 5 filter is the problem or not he can then move on to a solution such as replacement or further investigation as to other causes.

I cannot help here as my knowledge is nowhere near good enough but so far I feel that collectively we haven't helped him get much closer to a solution either.

pentaxuser

[RalphLambrecht]

I think pentaxuser has a point. ic-racer made the point that the filters may have faded. BetterSense needs to do a contrast test for the set of filters in question to see if the contrast does change with each filter. If conducted with a simple step tablet (Stouffer), the actual contrast delivered by each filter and the exposure factor required for a filter can be determined.

[Nicholas Lindan]

The constant-exposure density changes with the paper and even with the developer and toner:

• MGIV FB: 0.45 OD
• MGIV RC: 0.55 OD
• MGIV FB WT: 0.9 OD
• MGIV FB WT/A130/Se 1:9 to completion: 1.3 OD

[RalphLambrecht]

The constant-exposure density changes with the paper and even with the developer and toner:

• MGIV FB: 0.45 OD
• MGIV RC: 0.55 OD
• MGIV FB WT: 0.9 OD
• MGIV FB WT/A130/Se 1:9 to completion: 1.3 OD

Nicholas

What is this?

[BetterSense]

I was using MGIV RC glossy paper of uncertain age. I bought the filters used, and I don't know how old they are. I also got some Kodak variable-contrast filters. In the interest of not wasting paper I would like to test the effects of these filters, but I'm not sure how to proceed. I do have some new MGIV satin paper. I don't have a step wedge, but I have a Kodak Projection Print Scale.

[RalphLambrecht]

I was using MGIV RC glossy paper of uncertain age. I bought the filters used, and I don't know how old they are. I also got some Kodak variable-contrast filters. In the interest of not wasting paper I would like to test the effects of these filters, but I'm not sure how to proceed. I do have some new MGIV satin paper. I don't have a step wedge, but I have a Kodak Projection Print Scale.

The Kodak Projection Print Scale is not good enough. You either need a step tablet (stouffer) or a timer (an f/stop timer with 1/3 stop increments would work well). Anyway, the step tablet does it all in one exposure, any timer will require multiple exposures, which is frustrating.

I suggest to invest a few $ and call Stouffer. You can use it for many tests, not just this one.