David,Originally Posted by davidwrogers
I do not understand this post. Is this a response to what I wrote?
David,
I do not understand this post. Is this a response to what I wrote?
Ole, I believe that what the person commenting addressed was not what you are addressing. The light fall off he spoke of comes from the distance from the lens to the baseboard and with even a 138S and conventional 200 watt Thorn lamp the falloff at that degree of enlargement would be excessive and the exposure times would be more than I would want. I have 1200 watts inside my 138S and that would handle what this fellow wants to do.
For the original poster, I would never consider enlarging a 4X5 negative that large. I find my limit for the quality that I am after is a 16X20 print. I enlarge my 5X7 negatives to that size and do notice a distinct difference between 4X5 and 5X7 negatives on a 16X20 print. I realize that a lot of us become enamored with big prints but smaller and better quality prints are really very nice.
Yeah, 16x20 seems more feasible from the point of view of my inner accountant. I'm hunting down enlargers on ebay now.
That's not light falloff, that's simple inverse square law.
Simply stated, the light you have available has to be spread over a larger area so that there is only a quarter of the illumination when making a 16x20" print as there is for the same crop on a 8x10" print.
Falloff is light loss in the corners due to other optical constraints, and can be controlled through optics and light collimation - but not eliminated completely, and using a larger enlarger does NOT help.
The OP never stated his intentions for larger prints, so I assumed he has a vision he wants to work towards.
He never mentioned he would frame and hang them........
When I was kid I would go by the studio of an architectural photographer with a large studio in Old Montreal. Every month he made a huge print, at least 30x40, most probably larger, and tacked it to a nice wooden framed cork board that was mounted on wheels (much like a rolling rack in the garment trade). He would place it about 3 feet from the studio window so that people walking by could look in and see his work, the studio had some light from the window, but no one could see in the studio at the same time.
I would bet the prints weren't museum quality (the way they were pinned them with large tacks to the board) but it was certainly very effective, everyone who walked near the studio looked in, I traveled there just to look at his work.
I would agree with your point for prints that are going to be hung in a house, where viewing distance is not more than 10 ft. usually. Larger viewing distances, however, can allow for large prints of surprisingly lower resolution. A bank used my images for a billboard a few years ago, and I was shocked to see how good a 100mb image can look from a couple of hundred yards away.
John Youngblood
www.jyoungblood.com
You are getting hung up on a difference in terminology. Granted that you are probably correct but I am willing to cut someone that may not use the correct terminology some slack...that is something that you are probably to perfect to grant.
So you are saying that a larger format enlarger with a higher wattage bulb would not increase illumination on the baseboard? Interesting, most interesting!
No, I did not say that a higher wattage bulb wouldn't give more illumination - but the SAME bulb in a 8x10" enlarger would give LESS light than the same bulb in a 4x5" enlarger, even if both had the perfect set of condensers for the 4x5" negative and the lens used.
My solution to this is unusual, and forced by the lack of big strong bulbs: I use a compact fluorescent bulb in my 138S. I turn it on when I come in, leave it warming up as I mix the chemicals, and use the lens cap as a "shutter". I don't turn it off until I'm done for the day.
That gives enough illumination to make 24x30cm prints from 4x5" negatives with an exposure time of around two seconds unless I stop down a further two stops, so it should be good for 1x1.4m (40x56") at reasonable exposure times.
Exposure time for 4x5" negatives to the same size print are about double, a little less with the correct condensers for the setup - but I tend to use the same 180m lens for both sizes.
Next step is to mount the enlarger lens in a shutter, I think.
I knew there was someone out there what would want this: http://www.ebay.com:80/itm/ELEC-SHUT...item4150e44f94
Next step is to mount the enlarger lens in a shutter, I think.
LOLnever listen to the inner accountant when it comes to art.
Sounds like a fun project, I did a 32x40 enlargement from a 4x5 neg years ago when I was in art school. I could not afford the gear to make a real one so I improvised by using a vertical enlarger horizontally and for paper I used 4 sheets of 16x20. I was real happy with the results, but got what I expected, 32x40 has 64 times the surface area as the 4x5 negative I used. your 40x50 will be 100 times the size of the negative and I imagine 100 times the headaches. The amount of light falloff is absolutely mind boggling. Be prepared to use lots of paper, I used 8x10 paper for test strips and although I don't remember off the top of my head exactly what the exposure times were, I recall they were very long.
Posting Permissions
Reply With Quote
Bookmarks