View Full Version : An online lens/subject/format simulator

7-Sep-2016, 05:14

This is something that might be useful for those projecting large format cameras or trying to figure the behaviour of a new combination lens/camera. So many times I took paper and pencil to undergo these calculations that I decided to do it once for all. I hope you will like it. Case you find any trouble, or have any suggestion for improvements, please get in touch. This is a sort of beta version. Cheers Wagner

http://apenasimagens.com/en/focal-length-distances-and-framing (http://apenasimagens.com/en/focal-length-distances-and-framing/?preview=true)

Tin Can
7-Sep-2016, 07:32
A quick look on iPod is not enough. I will check it out on my desktop.

I like the concept. :)

13-Sep-2016, 04:32
Hello, After some tests and feedbacks, I just uploaded a final version:

1- Not cluttered by share buttons
2- Improved for viewing in smart-phones and tablets


Steven Tribe
13-Sep-2016, 13:01
Well, it works - even the image is upsidedown!

You could use it work out the focal length of an unknown lens by using something of known length and checking the size of the image on the ground glass and real distance with the presented results and then adjust to get the correct focal length.

Tin Can
13-Sep-2016, 13:07
Of course!

13-Sep-2016, 17:36

I think it is a good idea. It could be even based on lens and object displacements to avoid the predicaments of knowing exactly from where on the lens side should we measure. It could include a set of measures consisting of 3 figures: image size x lens board displacement x object displacement, plus a fixed object size. The result would have in this way more statistical significance. Using a digital calliper and a laser meter (quite affordable nowadays) I think we could expect very good results by sampling several instances. I will definitely work on that. Thanks for your suggestion.

Tin Can
13-Sep-2016, 18:12
I want in an App as then it will be faster to deploy.

I will lose it on a iPod when stored as Link.

I use this iPod 6 for many things and it very useful for Photo Apps.

I'm an advanced Luddite. I blame Sputnik. I saw it. :(

Steven Tribe
14-Sep-2016, 00:36
I'll check a couple of known and unknown focal lengths to-day using the system.

Steven Tribe
15-Sep-2016, 02:38
I did a couple of focal length checks to-day. And it works!

What I did was select one of the standard framings. I choose the full figure which has a framing of exactly 2 meters.
I placed a white 2 meter tube at about 5 meters away from the camera. I selected 300mm as the focal length and measured the distance from the WHS to the 2 met marker. The image of the rod was 13cm on the ground glass, so I selected the format 13x13cm. The focussing distance shown in the calculator was a little shorter. So up to 320mm - takes seconds to adjust - still a little short. 330mm turned out to be the right answer.

I know all this can be done by hand caculation, but the ease of trying different focal lengths to find the match struck me as easier than messing about with notes.

I'll try a few known focal lengths late, whilst the weather is OK.

M Harvey
15-Sep-2016, 12:06
This is great-- a really good resource for all of us here. Thanks for putting this up!

As far as suggestions for further development:
1) I think that my main use for a lens comparison tool of this nature would be for selecting lenses before I enter a studio or go to a site where I want to photograph. So it's helpful to know how far away I might have to be from, say, a cathedral to photograph it with a 150mm lens on 4x5 film. What I'd really love, however, would be to be able to see what a given optic's field of view is from a given position. I wonder if it might be possible to start with a very wide image and show field of view from a given distance (by "zooming in" or adding frame lines).
I realize that one of the challenges we get into here is that your model assumes an ideal lens, and so a user won't really have a true feel for using a 75 vs. a 150 on 4x5.

2) Any thought to offering a drop-down box with some standard formats? I love that one can put in any odd format (in inches, mm, or cm!)-- especially useful for the users of a site like this! But it might be nice to additionally-- not instead of-- have a drop-down that offers standards like 35mm/"full frame" digital, APS-C digital, 6x7cm, 4x5 in, etc. I think this could also be very useful for people from cinematography, many of whom often use adapted still lenses and digital sensors built around super 16mm and super 35mm sizes.

3) You have a little typo in "pick a stantart portrait type"-- should be "standard." :-)

Again, awesome work! Already very useful, and I could see it becoming even more valuable. An app form would indeed be cool, too.

Steven Tribe
18-Sep-2016, 01:54
There is another typo. Milimeter instead of millimeter. This is due to the widespread use of "mini" in English!