FOV Test Chart

[ori333]

Does anyone use a FOV Test chart like the one in the link below?

https://www.arducam.com/product/arducam-lens-calibration-tool-field-of-view-fov-test-chart-folding-card-pack-of-2/

 

If so what do you use? I don't mind paying 8 bucks for their product, just want to make sure there isn't anything else around.

 

Recently got a varifocal lens to try different focal lengths for my application before committing to a quartz lens, but am getting different FOVs for different cameras. This is normal due to different crop factors, but I'm just looking for a sanity check.

 

Best

Valentin

 

P.S.

If this type of question belongs in another location or is a repeat please let me know and I'll take it down.

[dabateman]

I have never used a chart.

There is a simple calculation. Just take an image of a tape measure at a known exact distance from the film plane.

I will have to see if I can dig that up.

 

This may or may not help

https://www.edmundoptics.com/knowledge-center/application-notes/imaging/understanding-focal-length-and-field-of-view/

[bvf]

Thanks, Valentin - I had been looking for a lens-testing chart but couldn't find one. So I've ordered the Arducam one.

 

I want it for focus checking in UV & IR and for assessing sharpness. But I don't understand why it is needed for FOV. Can't you use liveview on the camera to see what you're getting? I'm obviously missing something ...

[ulf]

Test targets for close-up setups is more difficult to find.

I have been testing this, model 2, as a transmission target hanging suspended and weighted down, to keep it flat and with an illuminated PTFE sheet at a distance behind:

https://www.ebay.com...872.m2749.l2649

 

The target transmit UV reasonably well.

[enricosavazzi]

Test targets for close-up setups is more difficult to find.

I have been testing this, model 2, as a transmission target hanging suspended and weighted down, to keep it flat and with an illuminated PTFE sheet at a distance behind:

https://www.ebay.com...872.m2749.l2649

 

The target transmit UV reasonably well.

The description says among other things: "Material: transparent forest slices".

 

Is the substrate glass or a plastic film? In the latter case, it is probably just a mass-produced photographic film negative. Assuming that quality is good enough, the 10 μm lines are sufficient for many tests except for extreme photomacrography. However, commonly available microscope test targets on glass often display even thinner lines, and are better in both resolution and contrast than negative film.

 

I have been burned before with purchases of 1951 USAF resolution targets from China (of the metal-on-glass type) that turned out to be of too poor quality for tests above 1:1 magnification.

[ulf]

The substrate is a thin film like the old style overhead film in thickness.

It is thin enough to transmit UV reasonably well with a U-360 stack on the camera.

I do not think the "10µm" lines are good at all compared to chrome lithographic targets on glass, but do not expect very high quality for that price.

 

The quality is mabe not good enough for measuring, but for ocular judgement it is OK. The contrast is high.

the target is l also nice to use for measuring magnification at a random extension of the helicoid.

 

I was looking for something with a bigger area than microscope calibration targets to a reasonable price that works for UV.

 

Maybe I can find some leftover image. If so I will post it.

[ori333]

Your right, a ruler will work. This is a nice sliderule. On Amazon there is a video of it's assembly. Look like regular paper.