LPL7700 Exposure Times

[Robin Guymer]

Recently completed my darkroom setup with a LPL7700 Pro colour enlarger. Using F5.6 & F8 (el nikkor 50mm f2.8) I am having to expose for around 60 to 80sec using split grades of 40+40 secs on 8x10 new multigrade paper. I have cleaned the lamp house, filters, lens etc. The enlarger had not been used for 20 years and came with a lot of old paper of which I tried a few sheets and was able to get a fogged but half reasonable print of a high contrast neg but taking over 120sec to expose. The exposure times seem too long on the new paper. Should I try a new globe and switch to below lens filters instead of mixing on the dichroic head?

 

[Svenedin]

I would try a new Quartz-halogen bulb (12V 100W) and just check it is set for the correct voltage. The exposure times do seem excessive.

 

[NJH]

I have one of those enlargers, even with a new lamp I am seeing exposures well over a minute sometimes ( into 2 min + actually with burn ins) to get tone from the sky on very dense negatives. On normal density negatives not a problem at all. Its one of the reasons why I recently bought an el nikkor 50 f2.8 to replace my el nikkor 50 f4 such that I can use f4 if I have to and not worry so much about soft corners like the f4 lens seems to give at f5.6. Have to say this is dealing with lab developed negs that are way to dense, I don't have this issue with negs and I have developed myself.

 

[Molli]

Good morning, Robin. I have precisely the same set up you have and noticed a sharp increase in exposure times earlier last year. From reading around, I suspected both the globe and also the ceramic holder. After having a poke around and finding the ceramic holder was a bit crumbly, I made some effort to replace it but couldn't for the life of me find my way in to where the pigtails at the back of the holder connected. I took it to a friend (Mick Fagan on here) and he couldn't find a way in either, he did, however, clean the contact points for me and I got back a full stop of light. That being said, my times are a) still more than a stop longer than the same prints made previous to last summer and, b) a great deal shorter than yours. I went from f/11 15 seconds for a 'normal' grade 2 8"x10" print, to f/5.6 35- 40seconds. After the contact cleaning, I'm back down to f/8 18 seconds or thereabouts.
If you can make use of a new ceramic holder and/or lamp, do let me know as I deliberately ordered a back up for my backups just in case anyone local had need of them. I spent a great deal of time chasing my own tail before I got a hold the items and would like to spare anyone else the hassle

 

[voceumana]

Someone posted a similar problem recently and the bulb (globe) had slipped down and was no longer centered over the opening in the mixing chamber. You might check to see that it is properly positioned.

 

[Robin Guymer]

Problem solved. Enlarger has an incorrect wattage globe. Thank you all for the informative responses.

I would try a new Quartz-halogen bulb (12V 100W) and just check it is set for the correct voltage. The exposure times do seem excessive.

Thanks #Svenedin, I had previously glanced at the globe and thought it okay. Now pulled it right out and checked it under a magnifier. The blurred writing now shows it is just a 50w 12v. Unbelievable what some people do. The 100w globes are not that hard to get but previous owner has just gone to the local auto shop and bought the 50w. Talk about make life hard for oneself!

Good morning, Robin.........
If you can make use of a new ceramic holder and/or lamp, do let me know as I deliberately ordered a back up for my backups just in case anyone local had need of them. I spent a great deal of time chasing my own tail before I got a hold the items and would like to spare anyone else the hassle

I appreciate your offer #Molli. I wouldn't want to take your spares though. There are globes available on eBay http://www.ebay.com.au/itm/Philips-...var=511577869057&_trksid=p2055119.m1438.l2649 that look like they will work okay so I shall order a couple now. Your other info is interesting regarding the connections and these are worth checking with a multimeter as to what is coming out of the transformer. I have found the wires from the globe have frayed insulation that could (or will) have been leaking current to the body.

I have one of those enlargers, even with a new lamp I am seeing exposures well over a minute sometimes ( into 2 min + actually with burn ins) to get tone from the sky on very dense negatives. On normal density negatives not a problem at all. Its one of the reasons why I recently bought an el nikkor 50 f2.8 to replace my el nikkor 50 f4 such that I can use f4 if I have to and not worry so much about soft corners like the f4 lens seems to give at f5.6. Have to say this is dealing with lab developed negs that are way to dense, I don't have this issue with negs and I have developed myself.

Thanks #NJH, your exposure times give me some comfort that these are what is typical of these types of enlargers. No doubt I will see some improvement with a 100 watt globe.

 

[Svenedin]

Great news Robin.

The bulb is this one (but the Philips bulb you link to will also work. In the UK they are about £6.50 each):

 

[ic-racer]

40+40, as you have discovered gives effective neutral density, prolonged exposure times and middle contrast as expected.

 

[pentaxuser]

40+40, as you have discovered gives effective neutral density, prolonged exposure times and middle contrast as expected.

What is 40 +40? Thanks

pentaxuser

 

[NJH]

The one above from Osram is exactly what I have. Another pointer is that I noticed the new lamp seems colder in tone (and of course brighter) than an old one, I wonder if it effects the "grade" of light output through the mixer.

 

[Robin Guymer]

What is 40 +40? Thanks

Split grade printing. An 80 second exposure is split between Grades like 0 and 5. http://www.darkroomdave.com/tutoria...ing-ilford-multigrade-under-the-lens-filters/ Combine with Dodge & Burn and you've got the hardware version of PhotoShop.

 

[Robin Guymer]

The one above from Osram is exactly what I have. Another pointer is that I noticed the new lamp seems colder in tone (and of course brighter) than an old one, I wonder if it effects the "grade" of light output through the mixer.

There is a thread about this subject that concerns the use of LED enlarger lights with the variation in warm tones like 2700k to cold tones of 6700k. I think I read somewhere that the Osram globe (I just eBayed one) is 3500k. This probably drops away with age.

 

[pentaxuser]

Split grade printing. An 80 second exposure is split between Grades like 0 and 5. http://www.darkroomdave.com/tutoria...ing-ilford-multigrade-under-the-lens-filters/ Combine with Dodge & Burn and you've got the hardware version of PhotoShop.

Thanks. I had never heard of the consequences being expressed this way such as neutral density and I couldn't work out if the three consequences were inevitable nor whether they were good or bad

pentaxuser