[caryjames]

Hi again everyone: I am sure I am just missing something but would like to pick your brains again .

Usually to keep the back of the ring in focus I move up the f-stop function to around 75 and that keeps everything sharp and crisp.

For the ring I am trying to render now it doesn't seem to matter what f-stop I use the back of the ring is always out of focus.

Am I missing something? Thanks again as always for your responses!
Cary

[iker]

Units?

[Tim Ellis]

Might be a scale issue as iker mentioned.

Don't forget that F-Stop works with shutter speed to produce dof.

Here's a useful DOF - Fstop/shutter speed chart that I find useful.



Tim.

[caryjames]

I think I have it solved. I was trying to render a ring with a large finger size so what I did was set a high f stop and back my camera off of the piece and then use Render blow up. I think it may have worked... still rendering. Thanks for the chart of f stop depth of field ratio's that will come in handy!
Cary

[caryjames]

I am not sure how to change the units if that is what is incorrect with the render. I have the f stop all the way to the max but the back of the ring is still out of focus. Is there another lens that can be selected i.e. macro? Here are a couple of shots of what is going on. Thanks again

[Thomas An.]

Cary,

How would you shoot this, if you had a real camera ?

[caryjames]

Hi Thomas: If I had a real camera I would put it on Macro and raise the f-stop, add a ton of diffused light and fire away. My camera does not have a great Macro setting so what I usually do is set the camera back a bit (still on macro) take a shot and then zoom in using Gimp or Photoshop.

The thing that is puzzling to me is that this technique usually works in Maxwell- I have rendered maybe 20 rings and always raising the f stop brings the entire object in focus. With this ring raising the f stop seems to have little or no effect. Any thoughts.... thanks
Cary

[Thomas An.]

Hi Thomas: If I had a real camera I would put it on Macro and raise the f-stop, add a ton of diffused light and fire away. My camera does not have a great Macro setting so what I usually do is set the camera back a bit (still on macro) take a shot and then zoom in using Gimp or Photoshop.

What type of camera do you have. Is it a compact film camera ? Digital ? What focal length does it use ?

I am assuming your ring is in the 20mm range ?
You can try a few things.
Set the focal length to 35mm, fStop11 and set your Rhino camera to be about 30 cm away. This will give you a 45mm DOF (crystal clear ring).

Another thing is to emulate a small digital CCD (which always gives more depth of field). Open your scene in Studio and set your film dimensions to 1/2.5'' (5.76 x 4.29 mm) and focal length to 8.3mm (which is the 50mm lens equivalent for a 35film camera). Now if you keep your camera at least 15cm away then you will get a 37mm depth of field at f11; enough to keep your whole ring in focus. You can do the same thing through Rhino, but when you set the viewport to 8.3mm it will look funny (because Rhino still thinks you are using a 24x36 film)

[caryjames]

Hi Thomas: My focal distance is set in metres and I can not change the value to mm nor can I seem to change it to 0.0035m to make it equivalent to 35mm. Am I missing checking a box or something? Thanks again your suggestion makes a lot of sense. I have a digital camera but I am not sure what focal length it is set to.
Cary

[Thomas An.]

Alright. First things first.

When you go to Rhino Options --> Document Properties -->units.
Is it set to cm ? mm ? Ideally for Jewelry you would be working in mm. Right ? Also, in Rhino if you measure the diameter of your ring ... how big is it ? 20meters ? 20 mm ? It is important to always work in the correct scale when it comes to rendering. You may have done all these things already, but it is good to make sure there are no scale issues for sure.

Now assuming you work in Rhino. Position your camera to the vantage point you want and then type Maxwell_PickCameraFocalDistance in the command line. Now make sure the little rectangle target is on you ring and read the distance number it gives you as feedback. If that distance number is less than 30cm then zoom out a little until it reads 30cm. (this is assuming you are going with the first option of using 35mm lens on 24x36 film size and f11)

[caryjames]

Hi Thomas: O.k. Here goes...

I am building in mm, the ring like you said has an inside diameter of 18.5mm so definitely in that range. But in Maxwell the units are set to metres instead of millimetres. How do I change that, I looked but could not find a way to correct.

Also I did check my focal distance and it is about 44cm away





I tried to find out if I am using a 35mm lens but could not find that option- unless I am looking right at it and not understanding it. If I use f11 the entire ring is out of focus. I don't know why this one is so strange all of my other renders worked fine, oh well I am learning as I go... thanks again for your patience I appreciated the replies!!!
Cary

[Thomas An.]

But in Maxwell the units are set to metres instead of millimetres.

That is ok. As long as the Rhino scale is right and the ring is 18mm, it doesn't matter what Maxwell says (0.018m = 18mm so we are good).

Also I did check my focal distance and it is about 44cm away

That is not enough. It is not enough to merely focus your camera to 44cm because you maybe focusing beyond the ring. It is important that the ring is also at the 44cm distance. Otherwise you will be focusing behind the ring making it look blurry.

Did you use type Maxwell_PickCameraFocalDistance in Rhino ? Did you zoom in and out untill the little rectangle is exactly on the ring and reads at least 30cm ? Also, did you right-click on the title of your perspective viewport, select viewport properties and change the focal length to 35mm ?

[caryjames]

Thanks again Thomas! I had forgotten how to change film size.. checked and it was set to 46mm so switched it back to 35mm. I used both the Maxwell_pickfocaldistance command as well as used the FD button on the Maxwell toolbar and picked the focal distance as close to the top of the ring as possible. To do this I picked the spot in the Right viewport window that was closest to the top of the ring.

I must be too close to the ring. I will back off render and then see how she goes. Thanks so much! I will post a finished render if it turns out nice!
Cary

[Thomas An.]

Cary,

Your scene should look exactly like this:


See how far the camera is ? Also, see that the focal distance reads 30cm (in my case it is 29.27). If you are in mm then your distance would read 300 or so.

Once your camera distance and focus are correct then select the "B" button from the render toolbar and draw a rectangle around your ring in the perspective viewport. This will give you a nice close-up render with no DOF.

[caryjames]

Thomas: Thank you so much for posting that, it really helped! A successful render is on the way I'll post it when it is done rendering. I have learned a lot in the last couple of days... thank you guys so much!!!
Cary