How To Make Enlarged Analog Negatives

August 12, 2021  •  Leave a Comment

How To Make Enlarged Analog Negatives by Tim LaytonHow To Make Enlarged Analog Negatives by Tim Layton I get a lot of questions on how I make my 8x10 large format enlarged negatives for our Wild Horse silver gelatin gallery prints, so I decided to write this article to help you. 

The process is much easier than most people think.  You simply take your original smaller negative and make an interpositive.  The interpositive can be a contact print or enlargement and then use that to make the new enlarged negative.  You treat the interpositive just like you were making a print in the darkroom, only it is on film.  Since your source and target media will always be opposite, when you take your new interpositive and either contact print it or enlarge it, you get a new and bigger negative.  It really is that easy and I explain how to do all this in the sections below.   

First, I will share why I make the 8x10 large format negatives and then I will share the technical details so you can run with the process and make your own enlarged negatives. 

Tim Jr. and I specialize in making very large wild horse black and white silver gelatin gallery prints.  We use our Beseler 45V-XL with the 8x10 conversion kit along with the Heiland LED cold light and Splitgrade systems.

Join Tim Layton on YouTubeJoin Tim Layton on YouTube Because of the speed and mobility requirements associated with wild horses, we use 35mm cameras with big and fast telephoto glass in the field.  There is simply no way to use our 8x10 large format view camera in this scenario.  

We have found that the upper limit of print sizes from optimal 35mm negatives is about 11”x14” or 16”x20” occasionally if all the stars are in alignment.  Since we specialize in making 40”x60” silver gelatin prints, we needed a bigger size negative and this is where the idea came in to start making enlarged negatives.  We print optically using classic traditional methods, but there is the possibility of having a professional drum scan on a 35mm negative that could lead to a different workflow than I use.  I don't go down that path, so I don't have any advice or comments about a hybird approach like that.


At a high level, you need to use your original 35mm or other smaller negative and make an interpositive as the first step.  We have tried a variety of ortho films as well as Bergger print film and found that Bergger print film gives us really good results and has fewer dust problems.  

If you decide to use ortho films, you will need to find ways to cut the light down to give you more time for adjustments.  I use my Heiland LED system to help with cutting the light down because it has a feature on the controller to vary the intensity.  You can also use ND filters and similar methods as well.  When making your interpositive you want enough time to be able to dodge and burn to make some adjustments and I aim for 20 to 30 seconds for my operating time. 

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Since my source negative is 35mm for my wild horse images, it makes sense to enlarge to 4x5 Bergger print film for my interpositive because I won't really have any loss of quality at that size.  

You treat the Bergger print film just like you are making a regular darkroom print.  It is just on film versus being on paper.  Use all the same methods that you do to make a regular darkroom print to find your best exposure and development times.

I also gain the advantage of cropping and adjusting the image placement on the new 4x5 format.  Going from a 2:3 aspect ratio of 35mm to 4:5 with 4x5 large format, there will naturally be some cropping, so I tend to shoot wide in the field knowing I will be converting to 4:5 aspect ratio.

To get started making your interpositive, you will just simply need to do some trial and error to help establish some reasonable boundaries for your negatives.  Your negatives are almost certainly much different than mine and I cover some tips and guidelines below. 

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Next, I load my 4x5 enlarged interpositive into my enlarger and then I can make my new negative up to 20x24 with pre-cut sheets of Bergger film.  Yes, you read that correctly.  Bergger is making sheets of this film from 4x5 up to 20x24 and they have rolls of it even bigger.  

To find out the best exposure, just make a step wedge print, just like you do when making an initial print in the darkroom.  I like to make 2 second increments.  Once you get through the process a few times, you establish some common boundaries and the process becomes much more intuitive and easy.  But the key is "you" need to do the work and reading my article or spending time in forums won't really help you beyond getting started. 

To help get you started, use HC110 1:47 for 5 min to develop the Bergger print film interpositive. Alternatively, you could use Dektol at 1:9 as a starting place and you can work under red safelights making your life a lot easier. 

Do not over agitate the print film. Based on the contrast of your interpositive, you may need to use a different dilution. There is no way for me to give you a specific answer.  You need to test and find what works for your negatives.  

Select an exposure time that has shadow details desired and select a developer dilution that provides highlights that are not too dense (blown out).  

Thick and high contrast negatives are good for Platinum and Silver Chloride, but may be challenging for silver printing.  You need to create the negatives for your printing process requirements.  

Treat the interpositive like you are making a regular darkroom print and treat enlarged negative like it was a new in camera negative. 

HELPFUL GUIDELINES: exposure time determines shadows and developer dilution controls contrast for your interpositive.  Commit that to memory because this is counterintuitive to photographers that have a lot of experience developing black and white negative film.

Judge each step (interpositive and final negative) on light table.   Look for enough density for good highlights and enough transparency for good detail in shadows. I tend to make a test strip at 2 sec. increments, and then select best time paired with a developer dilution that gives me the desired contrast. Since each step in the process builds contrast, you need time and experience to make judgement calls along the way.  There is not way for me or anyone to give you answers to making enlarged negatives from your film.  

Now it is time to make your full working interpositive at the best exposure time and developer dilution. I tend to make a couple different ones and then if it is a common scene or subject, I take good notes and then I have a solid starting place in the future. 

Use the guidelines and tips above to help you determine when you have a good interpositive and new enlarged negative. For my enlarged negative I like to use FP4 and other people like to use many different films ranging from T-Max 100 to even ortho films.  If you use an ortho film, just know that you won't be able to use contrast filters with your printing process.  I typically rate my FP4 at EI 50 to help slow down the exposure time and then adjust my HC110-B development time accordingly to give me the contrast and density desired for my target printing process.  I mostly make enlarged negatives for making big silver gelatin enlargements, but I also make them for contact printing processes like AZO silver chloride and platinum too.    

The Bergger printfilm is coated on a 175 micron PET base and has a special red colored anti-static layer on the back of the film which is part of the reason for its very high resolution. 

The film is mainly sensitive to blue light and it is safe to use under regular darkroom safelights too. The new print film also has an anti-static layer which should help with all those little annoying dust particles that drive us nuts.

I hope this article helps get you started making analog enlarged negatives and making the types of analog prints that you enjoy creating.

You can also refer to the third edition of the Darkroom Cookbook for some additional information on making enlarged negatives that may help you as well. 

The best thing you can do is take the guidelines that I shared with you above and get started with the process.  Only time and experience will lead you to your desired state.  

-Tim Layton

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