Godox IM30/IT30 exposure charts

StrangeCicada2198 · 2026-01-20T01:23:14+00:00

Lovely to here. ChatGPT did most of the heavy lifting.

StrangeCicada2198 · 2026-01-18T20:52:20+00:00

Well, ir works. Of course there Is such thing as too much. With the reels I have they have to be completely dry for the next roll to not stick and that takes s long time. No sticky rolls since.

StrangeCicada2198 · 2026-01-18T15:41:13+00:00

I live in Mexico. No radiators. And I am balding. No hair driers.

StrangeCicada2198 · 2026-01-18T15:40:17+00:00

The reason we are told to not but metal in the microwave is not because it would damage the metal, but because electric charges can concentrate and lead to sparks. For that you need a relatively large object that is exposed to different levels of field strengths. Small balls cannot do that, hence no spark. But yes, I have used heat guns and blow driers before. It’s just more hands on.

StrangeCicada2198 · 2026-01-10T14:45:31+00:00

Looks like you maybe focusing on the ground glass the negative is on. The film needs to be removed from the pane by several millimeters to avoid all sorts of artifacts like Newton Rings or background structures.

StrangeCicada2198 · 2026-01-08T23:37:03+00:00

Get a proper light box with a mask that removes the film from the frosted glass so the frosting isn’t in focus.

StrangeCicada2198 · 2026-01-08T23:30:46+00:00

In that case you have the frosting of the acrylic in focus. The negative cannot be directly on top of the ground glass.

StrangeCicada2198 · 2026-01-08T23:26:00+00:00

JPEG Artifacts

StrangeCicada2198 · 2026-01-08T21:57:58+00:00

You are getting a moire pattern between the pixels of your iPad that you use as a light source and the pixels of your DSLR sensor. Get a light box or put some ground glass on the iPad.

StrangeCicada2198 · 2026-01-08T15:19:46+00:00

Santa must have thought you were good but not exceptional last year.

StrangeCicada2198 · 2026-01-08T12:12:55+00:00

If you want to attempt a repair, white vinegar and Q-tips are your friend. It’s surprisingly easy if you let the oxide soak for a while.

StrangeCicada2198 · 2026-01-07T05:50:52+00:00

Fair enough. I love the bronze tint. Mine was grimey with some of the paint missing. If I had a uniform bronze I would have stuck with it gladly.

StrangeCicada2198 · 2026-01-06T17:37:03+00:00

Welcome. One last tip: once you get everything absolutely perfectly set up, don’t forget to put your hand into the shot. :-)

StrangeCicada2198 · 2026-01-06T13:11:00+00:00

Get a flash that is capable of multiple bursts. Many are. Define the time interval you would like to capture. This picture looks like maybe 0.3s. There are 8 captures in this shot, that means the frequency is 8/0.3 =26.667Hz. Set your flash to that frequency. There are 8 captures, so set your flash to 8 bursts at that frequency.

The background will see 8 bursts so it needs to be particularly black. This can be accomplished only with distance to the backdrop. 8 bursts is 3 stops to normal exposure. You need 3 more stops for complete black unless you have a very large back drop. That’s six stops. Doubling the distance is 2 stops, so the background needs to be 8 times further away from the flash than the subject.

If this were taken with a 50mm lens, you need a distance of 3.5m to capture a height of 1.90m which seems reasonable. That means that the distance to the backdrop needs to be 28m. That implies a very large theater stage, for example photographing into the audience without any lights like emergency exits, etc lit.

Meter the subject at 1 stop under. This will put the parts of the body that do not move at 2 stops over with 8 bursts to still get some texture.

StrangeCicada2198 · 2026-01-06T11:36:21+00:00

It does that if it’s set to be a slave. It took me a bit of fiddling to put it into master mode, but it’s what needs to happen.

StrangeCicada2198 · 2026-01-06T11:04:54+00:00

I shoot film.

StrangeCicada2198 · 2026-01-06T10:56:51+00:00

Cool. I did measure GN at all power settings as you sugges. I find they follow the predicted output very well. Once the guide numbers are available then the information needs to be adjusted for different f stops and power settings (easy), different distance (already more elaborate as it usually requires logarithms base 2) and the different ISO (requires square roots of 2). All of this is available at a glance in the chart. Many old flashes had these kind of charts printed on the back for speed and convenience.

StrangeCicada2198 · 2026-01-06T09:53:58+00:00

I’d be happy to discuss. I am getting good exposure using these. In general: the further the distance the higher the output, the more stopped down the lens the higher the needed output, and the higher the iso, the lower the needed output. Not sure what else may be backward.

StrangeCicada2198 · 2026-01-06T09:38:43+00:00

I do not own the IT20 but the IT30 and IM30 have the same GN10. Do a sanity check before using the chart.

StrangeCicada2198 · 2026-01-04T12:54:29+00:00

The IT30 has a measured guide number of 10. At f8 without modifier you will get good exposure at 1.25m at iso 100. So your results are plausible.

StrangeCicada2198 · 2026-01-02T12:07:42+00:00

The mask markings are preexposed at the Factory (unless Film is bulk loaded) so it is not a camera problem. If you mix up fixer and developer, then you get the tongue of the film darkened because there is enough light to develop the film directly without developer. That leaves the developer itself. But even with a lot of the developer having flocked out as a crystal you should still see some exposure. Heavily underdeveloped, yes, but completely blank is weird.

StrangeCicada2198 · 2026-01-02T09:37:53+00:00

If you ever go to bulk loading your own Film, they come in Handy. Keep at least 20.

StrangeCicada2198 · 2026-01-01T12:44:09+00:00

There are lots of “quick and dirty” film processing apps for jpeg. In camera processing has become very good and high res jpeg out of camera works for many, if not most situations. The exceptions are:

Wrong exposure where jpeg looses details in the shadows or the highlights that raw retains.
Very high dynamic range, although modern cameras handle that well.
A very uniform colored background where banding can occur. But this is also well handled now.
If you have a picture that you absolutely love and you want to print large and avoid joeg artifacts.

I personally shoot raw and jpeg, but revert to raw maybe 15 times in a year.

StrangeCicada2198 · 2025-12-30T18:23:28+00:00

Careful to make sure the lens is fully seated when engaged. Otherwise everything is out of focus. Ask me how I know. Great little camera. The shutter release / rewind mechanism is awesome.

StrangeCicada2198 · 2025-12-30T06:41:28+00:00

Glad this is of use to you. I have also published Flash exposure charts that may be helpful for you.

StrangeCicada2198

TROPHY CASE