Changing Print Sizes With Equal Exposures

[@cuxietube]

Great video. However, at 3:50 you say that you 'raise' the enlarger. On your equipment you raise the table to reduce paper to lens distance but most enlargers, at least the ones I have used, you lower the enlarger to reduce image size. Also, for those folks who are just getting started and are looking for a cheaper light meter alternative, Ilford EM-10 darkroom exposure meters can be found on Ebay for $10.00 and up.

[@SamStinson]

I've done this light meter way as well, and it works well. It doesn't matter how the enlarger works mechanically as far as focusing moving the lens or the table or the enlarger head, as at the end of the day the light intensity is all that matters, and checking at both sizes allows you to easily adjust the exposure in any of the 3 ways (time, aperture, filtration). I personally use the f stop ruler from Darkroom Automation to check the exposure change. Print out the free PDF and tape it to a yardstick, then use it to measure the lens to easel distance at different magnifications, and you get your exposure difference for the print sizes. Yes, it gives you f stop difference and I see from another comment you don't use f-stop printing. But you could easily convert the f stop difference the ruler gives you to colorhead values or ND filter to keep your times the same. I went the other way and made a chart to convert my dodge and burn times based on exposure time changes, but it would be simpler to keep the exposure time the same and I can see the value in that. The math is only simple subtraction of small numbers (something like 2.7 - 1.5 = 1.4 stops) which you have to do with the light meter anyways. I prefer it as it allows me to quickly adjust for ANY size change while printing. Once I have the test print nailed, I can then change the crop or print any arbitrary size and get it right the first time. Also I don't have to go dig my light meter out of my camera bag, and I can do it all with the darkroom lights on. At the end of the day, though, it's whatever works best for you and thanks for giving us insight into how you do things. I learn something in almost every video, so please keep making them!

[@jeffparkes314]

If you are adjusting for the same light level, why does keeping one point fixed, in your case the lens, make any difference? why can’t you adjust the head and lens as would normally be done on a bench mounted enlarger. As long as the same light level is achieved, what difference would this make? I’m trying to avoid boxes and can see how easy it is if you move the bench, but most enlargers are bench mounted.

[@anthonyknight5114]

@The Naked Photographer There is quite a bit of information missing in this process. What ISO setting is being used on the meter to get your aperture setting? What shutter speed on the meter is being used? Bothe ARE important for this to work. If you set the meter for ISO 100 @1/160s, the meter will not give you an aperture to use because there would not be enough light to obtain a reading based on those settings.

[@TheNakedPhotographer]

Since you are only looking for a relative difference the ISO setting is unimportant. The meter is not being used to find an aperture setting or exposure time, or even the speed of the paper. It is only being used to find the difference in brightness. Any Lux meter or print exposure meter would do the same thing.

[@anthonyknight5114]

@The Naked Photographer So in essence, set the meter however you need to to get a reading and then adjust your light output to obtain the same reading at the other distance. Is that correct?

[@terrywbreedlove]

There is an iPhone app called enLARGE that also makes these calculations. I have never used it but I hear good things.

[@josephasghar]

Great tip! I have a colour head and spot, so I’ll try it out!

[@bigshahan]

Recently joined a community darkroom, and been wondering exactly this! Thank you

[@enLARGE.darkroom]

bigshahan Another option is to use the iOS app enLARGE available on the Apple App Store for iPhone, iPod touch and iPad running iOS 9 and higher

[@domenicming9551]

@@enLARGE.darkroom is it vry effective?

[@domenicming9551]

LMAOOOO you MADE the app so I guess I can't count an unbias opinion

[@enLARGE.darkroom]

@@domenicming9551 Hi Domenic, yes I made this enLARGE app so naturally you will hear a ‘pro’ argument from me about it, terribly sorry! However, because I made this app I have a unique understanding of how it works and how it solves this particular problem of computing an exposure time adjustment when you move from one print magnification size to another. Some people think that all you need to do is mathematically compute the ‘Inverse Square Law’, which says that for each doubling of the projected image size, eg. moving from an enlargement of 5” length to 10” length, you simply multiply the required exposure time by a factor of 4, eg. from 10 sec to 40 sec. Unfortunately this method is not strictly accurate with a photographic enlarger, and that’s because an enlarger is a complex optical system with an optical property called ‘vergence’, meaning that the system contains an inbuilt amount of optical magnification or reduction, which is different to the simpler ‘point light source’ - being a tiny dot of light emission, which is imagined to exist in the Inverse Square Law. Instead, the use of an enlarger presents us with two problems. The first has to do with a change in the focal length of the enlarging lens, eg. when you change from one enlarging lens focal length to another, and the second problem is the nature of enlarger’s lamphouse. To explain the problem with the lamphouse, consider that when you change the enlargement size with your enlarger, the distances between the enlarger head, the lens, and the print paper, all move into specific positions to give you a sharp image at a desired size. These related positions are called ‘optical conjugates’. Now what about the inside of the lamphouse? The lamphouse is designed to give you the brightest and most even illumination across the negative field. And here’s the problem: in actuality the conjugate distances which exist inside the lamphouse - being the distances between the lamp, the internal reflective surfaces of the lamphouse, any condenser/s and/or mixing or diffusion boxes, and the negative plane, should all change too, with each change in enlargement magnification, in order to maintain the same illumination brightness at the negative plane. But they don’t change, because in practically all enlarger lamphouses the positions of these various parts is fixed, and this produces a change in brightness at the negative plane as the enlargement magnification is changed. As a result, even if you work out the change in magnification, and somehow account for a change in lens focal length, and you then compute the simple Inverse Square Law, your exposure result will be wrong, because your negative plane is changing in its brightness at different magnifications, and you’re not making any allowance or correction for it in your computation. So how do you correct for this error? As it turns out, this change in brightness at the negative plane follows a predictable rate of change - called the negative brightness slope - through the magnification range, and if you know what the difference in brightness is at any two different magnifications then you can compute and correct the error for all magnifications, and this is what enLARGE does. So here is how enLARGE works. During an initial calibration process, enLARGE records the relative brightness at the surface of the print paper between two different projection magnifications, ideally being at the smallest and largest print sizes that you typically make with your enlarger. It also records the focal length (mm) of the enlarging lens. It then uses this data to accurately compute any changes in exposure time needed for all prints made using the ‘calibrated’ system at different magnifications. The computation is internally complex but is done instantly and with perfect accuracy using the iPhone/iPod touch/iPad’s internal computing power. Additionally, to make it easy to use the app in the enlarging process, you only need to measure and type into the app the negative-to-print distance of your enlarger, when set for any particular enlargement, and then enLARGE works everything out instantly using this single measurement. Hope this helps! If you go to the enLARGE blogspot you’ll see that you can actually perform the enLARGE calibration process - being the measurement of your enlarger’s relative brightness difference at two different print magnifications - without owning or using enLARGE at all. You can then purchase and download a copy of enLARGE onto your iOS device. Then if you find that the app doesn’t work for you, for any reason whatsoever, then simply return it to the AppStore promptly(!) and you’ll get a full refund. Also please feel free to contact me for more help or info. I have sold copies of enLARGE to many users in many countries since its launch in mid 2017 and never had a single complaint about it. Andrew

[@domenicming9551]

@@enLARGE.darkroom wow, ok I see. I figured the square invers law for sure. I'm gonna deff check out the app, and when I do get my darkroom set up fully (right now it's so shabby and in the boiler room at my workplace I'll prob get your app casue it would totally be useful.

[@dirkvandamme]

Hi, I use the following formula to calculate the new timing relative to the desired height. Tn = Ti*(Hn/Hi)TPO2 - Tn : new calculated time - Hn : new height - Hi : initial height - Ti : initial time - TPO2 : (Hn/Hi) to the power of 2 You can apply this formula to calculate the timing by filter applied or to calculate total time which you then divide relative of the filters used. it works regardless using f-stops, % or just absolute time very easy and no test strips to be made

[@TheNakedPhotographer]

Yes, but...math

[@gumanow]

@@TheNakedPhotographer Isn't it just a matter of going from 10 as the longest side to 20 as the longest side?

[@bringmore146]

How does one need to adjust time by filter applied? I tried this method an unfortunately it didn't work (I used a 4.5 filter, it was a reallu low contrast scene). I used the the markings on the enlarger head column as heights in the equation. Should that value be adjusted (is the 'height of the light source' same as height stated on the enlarger)? Thanks!

[@dirkvandamme]

@@bringmore146 hi, the formula gives an indication of the time needed to light the paper for a new height of the enlarger head given the filter applied initially. You can take the height indicated on the column for the initial height and then set in the column the new calculated height - i hope this clarifies it. Success!!

[@bringmore146]

@@dirkvandamme Thanks for the reply. I did just that, but the exposure doesn't match. Any theories why?

[@alfepalfe]

If you are using an enlarger that has no electonics and uses an incandescent lamp (not halogen since those curcuits can have transformers) would it not be possible to simply hook your enlarger up to a dimmer or would the slight shift in color temperature as the lamp dimmed be too big. I am not asking this because I intend to try it, I am a beginner and I so far only have one size of paper (15×10cm) I just wondered since my enlarger's only electric components are a switch, lamp and power cable.

[@Raevenswood]

Rather than dialing in filtration or using an ND filter couldn't you also just increase the exposure time for the 16x20 print to compensate for the two stop difference?

[@TheNakedPhotographer]

The point of it for my workflow is to allow consistent aperture and exposure times. I only have to turn the white light dial on my enlarger head to change from a small test print to the larger final print. That workflow may not be best for everyone.

[@Raevenswood]

@@TheNakedPhotographer I understand why you are doing it the way you are doing it. That said, wouldn’t increasing the exposure time also remain consistent? I mean say for example you have a 30 second exposure for the 8x10 print . There is a two stop difference between your 8x10 and 16x20 prints caused by raising the enlarger head or in your case lowering the table (because your enlarged is massive). Wouldn’t doubling the exposure twice (120 seconds) accomplish the same thing as the two other methods you are showing? In other words it seems to me that there is a 3rd option to remain consistent when sizing up for folks that don’t have a dichro head and or an ND filter to place on the lens. Is there something I’m missing with the math that wouldn’t make what I’m asking about feasible?

[@TheNakedPhotographer]

Yes it would work to change the time.

[@flutgraben13]

What is the sense of the same time? I just calculate the new time by a well known equation without metering. D&B is in f-stops, so remains the same on the new time basis.

[@TheNakedPhotographer]

I’ve been printing for over 20 years and have never used f stop printing, nor will I change to it. I use percentages, and I’m not going to use math to calculate a new printing time. My method allows me to simply drop my table, switch the filters off and expose exactly like my small test print. Quick and easy.

[@milesmetcalfe94]

@@TheNakedPhotographer excuse the newbie question but what is D+B?

[@TheNakedPhotographer]

Dodge and burn.

[@domenicming9551]

What's the equation?

[@Pixelwaster]

Woo Hoo!! White light printing. Sort of. Still 637 (at the time of comment) now have an idea of the concept. Thanks! I have a short segment somewhere on a hard drive where Dean Collins gives a short explanation of the process, if I find it I will post it. There is also a video on BW standardization on my channel that has a brief "side note" on it but the video is more about controlling the contrast on a (whole) roll of film under different lighting and picking an Exposure Index and development time.

[@Pixelwaster]

Found it, cut it out, and posted it - kzbin.info/www/bejne/qaa4ppdtYrSCsNk

[@JimSollows]

Brilliant! I love this! Thanks!!!

[@phillipP8848]

Excellent vidéo as normal from you. Thanks.

[@xpost92]

Love this video. Large prints done on a smaller sheet is Cleary the way to go. This is for colour of course where you can add neutral density. For black and white what is the best way? Maybe can only use ND filter for that if you want same aperture/time etc

[@TheNakedPhotographer]

I do this for black and white exactly the same way

[@xpost92]

@@TheNakedPhotographer sorry I am using an Ilford 500H for my black and white so no colour head. Many won’t be using a colour head for black and white so any thoughts on this? Cheers

[@andytymon9795]

Smart thinking.

[@bringmore146]

In stops, how much is 10 points of all colours in a color head?

[@sommerpetter]

Great video!

[@jean-paulbeaumet6946]

Very interresting, I have a question : if the lightmeter said f8.0 for the large print then F16 for the small one , can i reduce half the exposure time ? Does it work ?

[@TheNakedPhotographer]

Yes, that works fine

[@nickfanzo]

Question for you since I’m stumped on my enlarger: All my prints are lighter on the right side. It doesn’t matter which negative it is or how it is developed, it’s always like that. It’s not in a vignette shape but an actual straight bar down the right side from the edge of the paper towards the center- nearly 30% of the paper is lighter on the right side. For example if I expose a paper at f8 for 20 seconds, I need to burn in the right for an additional 20 seconds to get it to match the rest of the exposure- very frustrating. What do you think this is from? I checked my alignment with laser. It’s ligned up with the baseboard and the lens as well as the baseboard to the carrier. I can’t change where the bulb is, there is no way to move it in my machine. I can’t change where the condensers are either. They o my have one shelf for both condensers. They are in as pictures in the manual. Lens is 50mm 3.5 and came with the machine brand new. It’s frustrating because I am spending a lot of time just getting the exposure even with burning instead of making artwork. Thank you

[@TheNakedPhotographer]

What enlarger model?

[@nickfanzo]

@@TheNakedPhotographer beseler printmaker 67

[@TheNakedPhotographer]

I recommend you join the Discord server. The link is in the video description. There is a section for asking this question and posting pictures of the prints and enlarger so we can better help you.

[@nickfanzo]

@@TheNakedPhotographer joined . I also added some photos and if needed I can take more.

[@fiveminutephotography]

Late to the party but my question is… If you’re using the colour head to reduce exposure time, I’m guessing that you then can’t use the colour head to do split grade printing?

[@TheNakedPhotographer]

Probably not, but I wouldn’t anyway. Moving the dials to their extreme ends over and over like that may stress the mechanics too much

[@fbraakman]

Would you not need to remove the 16x20 easel from the base, and then place the 8x10 easel down for the readings?

[@TheNakedPhotographer]

I place the smaller easel on top of the larger when doing this, so metering that way makes sense for me. If I printed with the larger easel gone then I would meter that way too.

[@TheJanisyt]

Good video, pity it won’t work on normally used enlargers like Durst ones (unless you put boxes underneath which creates risks of both moving and bad alignment). Btw. I have same boxes of ilford fb paper, one is 13x18cm and other is 30x40 cm… I did test strips based on 13x18, and I eventually ended up in wasting time and sheet of 30x40 paper. It should be the same, but papers from those two boxes were so different omg…what a bad performance from ilford

[@gabrielsilvaz4199]

There’s actually a very simple equation to figure this out without a light meter or anything else as long as you’re using the same paper type and you don’t change the f-stop or anything else like whatever filters you may be using from your first print to your new printer size. So you just get the measurement in centimeters from one side of your old print it doesn’t matter if it’s the long side or short side or if your print will be square. Now get the measurement on the same side of your new print size. Divide the new print measurement by the old print measurement and square the answer, then you multiply that by the old exposure time and you will get your new exposure time for your new print. It’s pretty simple. Hopefully I explain that well enough. But it will work every time for any size change. One more thing that I am not sure I made clear the print measurement need to be made according to the light projection on your table. you measure that from both old print size to the new print size.

[@alasdairdougall7868]

On my LPL C7700 and use maths just calculate the difference. Will experiment with the scale on the shaft and work out the process, but good idea to use a light-meter.

[@derekkonigsberg2047]

I wonder where the common "assertions" over paper box/batch variations come from. I'm assuming that there was a time when paper manufacturing process control wasn't as good, though I wonder how long ago that time actually was. Personally, I cut all my test strips from 8x10" paper, regardless of what size paper I'm actually using to print.

[@SilntObsvr]

Small test strips are great for checking overall exposure, but useless for working out the dodge and burn plan (and not much help for split filter or filter grade choice). When I learned to print (1970s) there was enough variation from batch to batch of the "same" paper that you could sometimes see a difference in prints from the same negative at the same exposure. It was hard to sort out what was due to light source aging (incandescent bulbs get dimmer as they age), variation in developer (freshness, and precision of dilution) and variation in inspection light (same issue as with the enlarging light) to be certain, but at the least, you had to do new test strips every time you opened a new box (at my scale, I never had a bunch of boxes from the same emulsion batch). Of course, in high school, we didn't care about that much, but I remember the photography teacher talking about it and demonstrating it (consecutive prints from oldest non-expired and newest paper, same kind, same size, had visible variation).

[@fredbosschaert5622]

Good idea's But what about contrast??? The larger the more contrast you need. If you want less paper to use, think also about the splitgrade printing of Jurgen Heiland (Heiland Electronics)

[@TheNakedPhotographer]

Size is relative here. I stated I was set up for a 4x5 negative. The enlargement is negligible so contrast remains constant. If this were a 35mm negative printed at these sizes I might have a change in contrast.

[@enLARGE.darkroom]

Fred Bosschaert You should find that print contrast doesn’t change with a change in magnification, instead it stays exactly the same!

[@fredbosschaert5622]

@@enLARGE.darkroom for MF (Durst 805 Splitgrade) difference between 15/15cm and 50/50cm is 0,5 Gradation. Tested with the calibration strip from Heiland. For 35 mmit will be more.

[@enLARGE.darkroom]

Fred Bosschaert Surprised to hear it! When I work with the enLARGE app I find it’s the same. Best regards.

[@bringmore146]

Is there a way to calculate needed contrast change to equations for calculating exposure times for different sizes?

[@jacopotassinari]

Great content. You moved from a 8x10" to 16x20" sheet of paper, this means a 4 time bigger print. For the law of the inverse square distance it's going to be sqr(4) the factor that change the exposure. Did i get it? Cheers^^

[@TheNakedPhotographer]

That’s basically it

[@jameslane3846]

Never thought of using the light meter! Thanks for this! If changing the printing time wasn't too important, could you use the light meter just to calculate the new printing time from the change in brightness? Ie if the light meter said f8 for the 8x10 and the printing time was 10 secs and f16 for the 16x20, would the new printing time for the 16x20 be 40 secs?

[@TheNakedPhotographer]

You would have to do some testing to see if theory matches reality.

[@jameslane3846]

@@TheNakedPhotographer will do and will share my results :)

[@re1lly]

@@jameslane3846 so?

[@jameslane3846]

@@re1lly it's not accurate enough as my light meter is quite fat and does 1/10th of a stop which isn't precise enough

[@re1lly]

@@jameslane3846 ok thanks for the reply

[@Tracks777]

nice content