Talking Technical on Tech Cameras

[arvedg]

As a very beginner in the Tech Cam world this is one of the most helpful threads I've read so far. Still heavily on the learning side for me these posts are of such incredible value in so many ways.

Thousand Thanks Jae for starting and to all others for contributing loads of knowledge to this great discussion!!

Arved

 

[photomgraphy]

i've tried the tilt-calculator app which awolf mentioned today, but can't get it right so far... :-(

i set the sensor type, and the focal length (unfortunately there is no 43mm lens so i set it to 45mm).

situation: my gardenfloor - grass and concrete entranceway
43mm schneider lens - wide open / 130mm hight of the lens axis above ground / no camera tilt

it calculates: 2° lens tilt / focal distance: infinity to set the plane of focus to the ground

but that didn't work - the ground was sharper than without tilt, but not sharp.
if applied 3° tilt it was tack sharp at the bottom of the image, but it seemed that the POF was pointing downwards - only the foreground was sharp...

you can set the actual FD to get a different angle of the POF. so i tried to focus at 15m it seemed to get quite right. (the calculated near limit of the DOF is -76,9° and the far limit -93,4° / -90° = right-angled to the sensor plane without camera tilt)

but basicly if i set the POF to the ground, it should be tack sharp.
but it wasn't...

but i can't figure out why.

jae moon, could you please verify the given calculation (see screenshot) with your formulars?

 

[Malaba]

in reply to Photomgraphy's test of the Snapi app :

I checked as well as I could the results of the Snapi app, using the Merklinger formulas and Snapi seems to be working correctly. Although I am not super at math.

About the rm3di : The only thing I disliked about the rm3di is the tilting mechanism. The knob that sets the tilt, has some play in it. At least on my camera.
So I checked with an iphone bubble level app (not the most precise tool) whether a setting of 3 degrees on the rm3di was tilting the lens by 3 degrees and the conclusion was that it was closer to 2,5 degrees. I tried different settings with the rm3di and my impression is that the play in the tilt-knob results in about half a degree less tilt that you want to set.
What seems to give more accurate settings on the rm3di is to first turn the knob to maximum tilt (5 degrees) and then turn it back to the desired setting. This has worked fine for me. This may explain your results, why your test seemed to work better when dialing in more tilt than Snapi indicated.

 

[Jae_Moon]

About the rm3di : The only thing I disliked about the rm3di is the tilting mechanism. The knob that sets the tilt, has some play in it. At least on my camera.

As I also discussed in my previous post, the 'wheel' to adjust the lens tilt in Rm camera is the weakest design feature which should be improved upon immediately. However, I think the problem you have (some play in it) is a defect and you should contact your dealer for repair.

Jae Moon

 

[Jae_Moon]

jae moon, could you please verify the given calculation (see screenshot) with your formulars?

I am posting this to let everyone know that I communicated with Thomas concerning his question via PM. I prefer not to comment on someone else's products without thorough evaluation in a public forum.

Jae Moon

 

[dougpeterson]

About the rm3di : The only thing I disliked about the rm3di is the tilting mechanism. The knob that sets the tilt, has some play in it. At least on my camera.

I agree with Jae. The knob is not my favorite part of the design, but it works well, and it should have no play at all. I'd take it to your dealer for inspection/adjustment/service.

 

[Jae_Moon]

Free Trial of NuvoFocus (Spreadsheet version)

A while ago, I posted (and removed soon after) a short story concerning my experiences of developing an App called NuvoFocus, which performs several critical tasks for Tech Camera users.

I decided not to bring the App to market after extensive beta testings and market studies. There were several reasons for my decision and the following were most critical.
1. iOS App Store does not allow 'free trial' period.
2. Selling and maintaing an App via iOS App Store requires a substantial investment both in money and time.
3. Difficulty of providing technical supports.
4. iOS App Store is not designed to sell an App which is 'professional, expensive and with small potential market.' (Today, the average price of an iOS App is16¢, while 90% are free and 6% is at 99¢)

I have decided to give it another try, this time as a spreadsheet running on iPhone or iPad, and distribute it independently, since I strongly believe many benefits to Tech Camera users.

The program have following functions:
1. Calculate HFD (for given focal length, aperture and CoC settings).
2. Calculate the DOF for a given subject distance (for given focal length, aperture and CoC settings).
3. Calculate the focus distance for given Near and Far DoF distance.
4. Calculate the required Lens Tilt Angle, with or without camera tilt, and required focus distance setting.
5. Indexed Focus Setting with Lens Equation (translate focus distance into an index)

The program is designed in three separate modules; Simple DoF (items 1, 2 and 3 above), Lens /Camera Tilt Calculator (item 4), and Indexed Focus System (item 5).

I am starting Free Trial Tests with anyone who would sends me a PM with her/his email address and name. I will send you a Free Trial version in EXCEL format.

The Free Trial version is a fully functioning with following limitations:
1. The trial period is for 14 days, and the program will not function after that.
2. It is 'encrypted and protected' so you will not see the mathematical equations.
3. It cannot be exported to NUMBERS.
4. Simple DoF module will function beyond the free trial period.
5. Lens Equations for SK35XL, one for AS RM focus system and another for ALPA (or Cambo) HPF focus ring, are included for you to experience the benefits of Indexed Focusing System.
6. Up to three user's lens data can be added for Simple DoF and Lens/Camera Tilt without Lens Equations.

Final pricing has not been determined yet but I am planning for a two-tiers pricing for the program.
1. Simple DoF and Lens/Camera Tilt calculator at $$
2. One Lens Equation for Indexed Focus Setting at $$, and additional equations at $$ each.

The final release program will be in NUMBERS format, so it can be used in either iPhone or iPad. You will need to buy a copy of NUMBERS (iOS spreadsheet program from Apple at $10).

Notes on Lens Equation:

Simply put, a lens equation is a mathematical formula that translate the lens calibration data into a simple computer code by means of regression analysis. For example, an AS RM mount lens is provided with a 44 points calibration data on a laminated card. An ALPA (or Cambo) HPF style lens is available with calibration data which are in 7 pages of PDF file.

AS RM camera has built-in Index to set accurate focus while an HPF ring has tick marks and distance marking at each 5 degree rotation. A thin adhesive plastic strip, with a linear scale of 0-270 will be provided with each lens equation purchase, to be affixed on the top of HPF ring scale.

General notes:

It will be easy to understand the program to many of you. However, it requires a little bit of mathematical knowledge and full understanding of Disto operation. I hope to answer any technical questions in this forum during Free Trial Period. 14 days trial period starts from the date when I email you the program.

I will follow up with a "Quick Start' intro of the program.


Jae Moon

 

[Jae_Moon]

Free Trial of NuvoFocus (Spreadsheet version)

NuvoFocus has three sheets; PROG, DATA and CALC. CALC is protected and cannot be viewed.

Cells that are shaded in Light Blue is for user INPUT and in Light Yellow is calculated OUTPUT.

DATA PAGE​

You enter data only once, when you first start. Select prefered Unit of Distance, meter or feet. All measurement should be in decimal. NOT 5 feet 2 inch, BUT 5.17 feet.

Next, enter DB and Lens information. Up to 5 lenses data maybe entered. For Free Trial Version, first two spaces are reserved for SK35XL, one for AS RM mount and another for ALPA (or Cambo) mount with HPF ring, and Lens Equations are pre-installed.

Try to get an accurate data for lens focal length. SK35XL has nominal focal length of 36.4 mm instead of 35 mm according to their data sheet.

Select the type of Lens Mount; AS RM or ALPA (or Cambo). I made a BIG assumption that no one would have both AS RM camera and ALPA (or Cambo) camera.

In Trial Version, lens # 1 is AS RM mount and lens # 2 is ALPA (or Cambo) mount.

PROGRAM PAGE​

DOF

Select a lens to be used. The same lens is assumed for both DOF and Lens Tilt Calculation.

Select CoC as # of pixel pitch. It can be any number, ie, 2 or 3.3 or 1.4142. The same CoC value is used for LENS/CAMERA Tilt calculation.

All distance measurement should be done with a Disto mounted on a tripod or on camera, especially, if you want to do Lens/Camera Tilt. You have to measure two distances once Disto is mounted; the horizontal distance between Disto sensor and DB sensor and the vertical distance between the axis of camera lens and Disto Sensor. The program expects you to enter the 'horizontal distance offset' into a Disto. My setup has 50 mm distance between Disto sensor and DB sensor, so I entered 50 mm as OFFSET into my Disto, and the Disto reading automatically shows the distance between the DB sensor plane and Subject.

One way a Disto can be mounted
​

A2 in the diagram is the horizontal distance between Disto sensor and DB image sensor, D is tripod height and C is the distance between Lens Axis and Disto Axis.



LENS/CAMERA TILT

Enter the height of Tripod and the vertical distance between the two axis, Disto and camera lens. My set up has 119 mm distance between two axis. The camera height is calculated by adding these two numbers.

Now make two distance measurement using a Disto, Near and Far Subject (both horizontal and vertical distance). Learn how to do it by reading Disto Manual pg 11, 'Direct Horizontal Distance'.

Enter Camera Tilt Angle (if you are tilting the camera in addition to the lens tilt). The program use the convention that the tilt angle is POSITIVE when the camera is tilted forward (however, Disto displays forward tilt as a negative value).

The program provide the required Lens Tilt Angle and the focus distance. It also calculate the Wedge of Dof at a specific distance.

The program will display the message, 'Indexed Focus is not abled for this lens' if you select other the lenses without Lens Equation (Lens # 1 (with AS RM camera) or Lens # 2 (with ALPA (or Cambo) HPF mount with Trial version).


INDEXED FOCUS SETTING

With this option abled, all calculated and/or measured subject distance will be displayed in simple and easy to use Index Numbers.

OUPUT with AS-RM mount Lens​

HFD, Subject Distance, Target Distance with Near/Far DoF and Lens /Camera Tilt Subject Distances are displayed in both in distance measurement unit (meter or feet) and also in AS-RM Focus Index, including the Color designations.

OUTPUT with ALPA (or Cambo) HPF Ring Lens​

Again, HFD, Subject Distance, Target Distance with Near/Far DoF and Lens /Camera Tilt Subject Distances are displayed in both in distance measurement unit (meter or feet) and also in in degree of rotation (0 - 270).


PM me with your name and email address if you want to try a Free Trial version of NuvoFocus. I will start send you the copy beginning next Monday, August 19.



Jae Moon

 

[Jae_Moon]

Free Trial of NuvoFocus (Spreadsheet version)

I forgot to state clearly that the Trial version runs on computers not on iOS devices; iPhone or iPad. It may run on iOS devices if you have MS Office 365 (I don't have the service and don't know if it works or not).

Jae Moon

 

[Jae_Moon]

Free Trial of NuvoFocus (Spreadsheet version)

The Free Trial is still available. In the mean time, I would like to show a 'Sneak Peek' of the Release version on iPhone, running on NUMBERS.

You can re-size and scroll the program.

Screen Shot:

​

PM me if you want to have a free trial copy of NuvoFocus.


Jae Moon

 

[jagsiva]

Jae,

the trial version is working well so far. I have not put it fully through its paces yet, but it is looking very good. If you release an IOS version, you can put me on the list. As per previous posts, I think your pricing is in line with the functionality, just my two cents

 

[PeterL]

Jae,
The screen shots of the iPhone 5 'trial' in your post above does not show for me.

Cheers, -Peter

 

[Jae_Moon]

Jae,
The screen shots of the iPhone 5 'trial' in your post above does not show for me.

Cheers, -Peter

Move the pics to Flickr. Hope it works better.

Jae Moon

 

[Jae_Moon]

Free Trial of NuvoFocus (Spreadsheet version)

A quick note.

If you open the web page with iPhone 5, you can size the screenshots to see the approximation of NuvoFocus's look running on NUMBERS.

Jae Moon

 

[Jae_Moon]

Jae,

the trial version is working well so far. I have not put it fully through its paces yet, but it is looking very good.

Jag:

Make sure you try lens/camera tilt before the free trial runs out. If you have a Disto, it will be reasonably quick even without a 'fixed' Disto mount.

Jae Moon

 

[jagsiva]

Jag:

Make sure you try lens/camera tilt before the free trial runs out. If you have a Disto, it will be reasonably quick even without a 'fixed' Disto mount.

Jae Moon

Thanks Jae. I do have a Disto, and will put it to test.

Thanks again for all the hard work on this.

Jag

 

[Jae_Moon]

Free Trial of NuvoFocus (Spreadsheet version)

Many have asked about the Disto mounting method and the reason for a fixed mounting platform.

It is critically important to have accurate positional relationship between camera and near/far object locations if you want to calculate the lens tilt and the required focus distance.

By industry convention, the center point of camera is the center of DB sensor plane instead of the nodal point of lens. Therefore, one should measure the distances (horizontal and vertical) between the center point of DB sensor and both Near and Far object using a Disto. Having a 'Fixed Mounting Platform' for both Camera and Disto makes this process much easier.

My 'Fixed Mounting Platform'​

A/S Cube or similar device is the perfect tripod head for Lens Tilt application since it gives very accurate 'pitch' control. I am using a clone, PhotoClam.

I have RRS MPR-CL II as a base plate to mount both camera and Disto. RRS Mini Clamp Package is used for mounting Camera on MPR-CL II, and Disto is attached to Oben QR-10 and lock onto the integral clamp of MPR-CL II.

Making Measurement​

Two 'offset' measurement are needed to make repeated Disto readings easier. Horizontal offset is the distance between Disto sensor and DB image sensor planes, and Vertical offset is the distance between axes of Disto sensor and camera lens.

You are recommended to enter the 'horizontal offset' into Disto setup so the reading will automatically compensate the offset.

Vertical offset should be entered into NuvoFocus data sheet (only once).

You are also required to measure the Disto height from the ground, so the sum of Disto height and vertical offset gives us the camera height.

Jae Moon

 

[johneaton]

Hello Jae,

The software appears to work great -- though I did have to go read my Disto manual for the tilt measurements

Many thanks for the effort and thought that you've put into this, and for all of your useful and informative posts.

Best, John.

 

[johneaton]

Hello Jae,

To elaborate a bit more on my previous post -- my context to evaluating Nuvofocus is that almost all my work with my Rm3d is architectural, especially interiors. So my primary interest is in the indexed focus -- this is great! -- just what I've wanted to stop me having to do interpolations in my head every time I measure the distance to focus a shot.

I've very rarely used tilt (probably less than 10 times) -- hence the reason why I had to go find the Disto manual! So I just tried a simple set-up here at home hand-holding the Disto to see whether I could understand the process and mechanics using your (excellent) instructions & software and get what seemed sensible results -- I'm pleased to say that I could follow it all and it seems to work, so maybe I will get to use tilt a bit more in the future!

Best, John.

 

[jagsiva]

Jae, with the Disto setup, I assume you'll need to adjust an offset number if you're using a rot amount/rotaslide and removing the spacer ring on the lens. Doing this has a net effect of moving the entire system back about .5", so subject distance would increase by .5". Am I correct in this thinking?

Cheers...