***Imacon Scanners***Replacement of tubes

Since some years OSRAM is not producing furthermore the tube 8 Watt 12-950. They produce further 950 in length 59cm; but not the right with 24cm.
Replacement is now with 12-954 with colour rendtion 92%.
The old 950 has rendition 98% near maximum 100. (Hence 950 is always the best for printers and enterprises with high fidelity of reproduction (eg dentist for second teeth).

QUESTION
1) anyone has seen quality differences after replacement of tubes ?

This could arrive because the rodenstock lense (adapting to the diminuished light) must now applicate wider aperture (adapting at 92) ; hence with wider aperture the DOF is lesser.
Hence the scanning on the border (of the line scanner by 4x5) could be very altered because the distance from the rodenstocklens/point is always greater on the two ends of line than in the centre.
Hence the ends could be visible out of DOF now by the wider aperture.
This would say:
The whole scanned image is on the two borders not so sharp than in the centre (but parallel lines).

In consequence the simple tube could lose all quality efforts of the famous scanners.

2) I assume that after a nomenclature (international reference values) change the °Kelvin of 950 and 954 are the same 5400°

Hi

I replace the light tubes on my Flextight last year. I contacted Hasselblad UK, and they posted replacements to me the next day. Have a chat with your Hasselbald rep.

There is also an Imacon group at Yahoo (Imaconusers). There're a good bunch and may be able to help as well. HTH

Thank you much.

I think they have replaced with 954 (the only available now) on yur scanner. It is written on the tube (but some work to open for replacement).

I have mailed some questions to Hasselblad Stockholm.
It is their meaning: no problem. But in the original instruction book they have written on 4.20 ONLY 950 with 98%. (At that time the 92% tube was produced but not recommended hence.)
And OSRAM is not willing anymore to produce this tube in length 24cm; too little market, so only 954 in future.

It could be that no great dfference.
But in general the more %, the more power the transmitted light, I think the better.

Replaced the lamps in my Precision II with the 954 lamp from Hasselblad at the start of this year & I've not seen any noticeable difference.

The lens in the Precision has a fixed aperture so you don't need to worry about DOF changing - it can't.

Given lamps will fade with age anyway, I think the chances are the newer lamps would be brighter than a set 5 years old.

Thank you very much for the fix aperture hint

IMPORTANT

Change of ligth tube (available for 8 $ in markets OSRAM 12-954)

I attach pdf, on page 16-17 extremly important instruction for fixing the rotating tube:
Only 1-2mm more rotation of the black protect cover case about the tube and you receive ugly colour or no colour.
So you must readjust and the position is very exact on page 16.

Extremly important.



http://www.photoworkshop.com/static/...hotoManual.pdf

INSTRUCTION tube change (see pdf)

Open both side plates of the scanner (Precision), only attached with magnets.
Replace the tube(s) after pdf .
Then give power enlighting the tubes.
Than you coud see where the long placket of black cover is directed (must be exactly vertical).
In case not vertical: take a little srewdriver and with his point you could screw slowly mm for mm the black cover in order to be vertical direction (where rodenstock lense position of scanner is located and the tube must give light in exactly this direction).
Then make a control scan. In case you are verticaly right, this scan is without blame.
When not vertical you would receive visible extrem ugly colours and you must readjust for vertical position.