LPL VCCE Head

[Stephen Weston]

I have recently acquired an LPL 7451 ( I think it would be a Saunders in the US) which has both colour and the VCCE modules. Now my understanding with the VCCE head is the exposure time will remain constant no matter the grade selected. I tried this out on a quick test the other night using MG V. Using the Durst easel that opens up into quarters on 10x8 sheet ( can't think of the official name) I printed at grade 0, 2, 3.5 and 5. the lower grades were fine but 5 needed twice the exposure. I know this applies when using the Ilford filters but I wasn't expecting it with this head. So my question is - is this normal even with these type heads or am I missing something?

 

[bripriuk]

Yes, this is normal on an LPL enlarger, and I think most others as well.

Brian P

 

[voceumana]

And the concept of "constant exposure" is somewhat limited, as with different degrees of contrast we may prefer (artistically) a darker or lighter print--i.e., it gets you in the ball park but may need some tweaking.

 

[MattKing]

With the older MGIV you may have needed adjustments at the grade 4 level as well.
The thing to remember with any speed matching system is that they are keyed to one particular tone. That tone is usually a high mid-tone, close to light coloured Caucasian skin.
If you are basing your exposure decisions on lighter or darker subjects, the speed matching won't work exactly. It does get you closer though.

 

[Nicholas Lindan]

It all depends on the shade of grey you want to hold 'constant' between grade changes.

The Ilford papers & filters:

• MGIV RC & FB hold 0.55OD constant for grades #00-3.5, and hold 0.95OD constant for grades #4-5;
• MGIV WT holds 0.90OD constant for grades #00-3.5 while grades #4-5 don't have any place where the grey tone holds constant.

0.55OD is halfway between ZV (18%, 0.70OD) and ZVI (skin, 0.47OD).
0.90OD is around ZIV (light shadows, 1.00OD).

Reference the HD graphs provided at http://www.darkroomautomation.com/support/index.htm

 

[Stephen Weston]

Thanks all for coming back. I figured this was the case but having previously used under the lens filters prior to obtaining this head wasn't to sure.

 

[Danner]

It all depends on the shade of grey you want to hold 'constant' between grade changes.

The Ilford papers & filters:

• MGIV RC & FB hold 0.55OD constant for grades #00-3.5, and hold 0.95OD constant for grades #4-5;
• MGIV WT holds 0.90OD constant for grades #00-3.5 while grades #4-5 don't have any place where the grey tone holds constant.

0.55OD is halfway between ZV (18%, 0.70OD) and ZVI (skin, 0.47OD).
0.90OD is around ZIV (light shadows, 1.00OD).

Reference the HD graphs provided at http://www.darkroomautomation.com/support/index.htm

You must be a wizard

 

[Nicholas Lindan]

You must be a wizard

Just call me "Rincewind"