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  • Joined: 24 Jun 2019
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Light Gun accuracy between CRTs
Post Posted: Mon Jun 24, 2019 11:50 pm
Hello all! I've never actually posted to these forums before but I used to play around with Meka and other emulators for years before I started collecting original hardware when Flash carts (Everdrives) became the standard.

(I originally posted the below text to a couple Reddits but no one seemed to care)

I've been testing CRTs for my home setup and found some interesting results when it comes to how well light guns work and would just like to share. If anyone has any insight, please chime in!

Rather a long read but I'll try to break it down. I have a 20" and 36" trinitrons, both flat screens. I also have a 32" Sharp that was recently picked up. The 20" does not have component while the other ones do. I have two blue Konami justifiers for my model 1 genesis (one is modified to act as a player 2). I recently picked up a Sega master system and two light phasers for it.

The justifiers are spot on with the Trinitrons. However, they are a little high and to the left on the Sharp. Weird. The light phasers are spot on with the Sharp but they hit a few degrees directly to the right on the Trinitrons. They aren't entirely unplayable but its difficult to remember to compensate for the inaccuracy in the heat of the moment.

Combinations I have tried include using a power base converter on my genesis for the light phasers, multiple games (Lethal Enforcers 2 for the genesis has a nice calibration function, why couldn't all light gun games have that??), HD retrovision cables, standard composite video, not yet tried RF (does it even matter at that point?). They all produce the same results between those TVs. (I just realized I haven't tried my NES on the Sharp, yet. It works great on the Trinitrons.)

I've been reading how a lot of later CRTs had some sort of geometry calibration that messed with the timing and also to avoid 100Hz bulbs. That sucks because I really enjoy the picture of the 36" trinitron with the HD Retrovision cables. I'm also worried because I want to collect light guns for the other systems I have that have light gun games; Snes, Saturn, Dreamcast, PS1/2/3. If it was just the SMS that had the issue (hopefully) I wouldn't mind finding a smaller and older CRT just for that but, I would rather not have multiple large TVs in my little apartment to go back and forth with depending on the system. Is it possible to find a similar sized and screened trinitron that would play both guns accurately?

One last thing I wonder is if the Master System games could be hacked and have a calibrator installed. Sadly, I'm not the one for that job. Maybe I can come up with "sights" that I can stick onto the light phasers that would help aiming.

Updates: I've picked up two 20" TVs with component inputs to test out. One is an insignia flat tube just like the FD Trinitrons and it has has the same results with the light guns. The other is a Daewoo with a fully rounded tube and the justifiers are off to the right slightly while the phasers are off to the left slightly. Ugh. Maybe it's time to look into RGB modding all the regular tubes I keep finding without component inputs.

I've also been told that after the 16-bit systems, most light guns games had built in calibrators.
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Post Posted: Tue Jun 25, 2019 8:35 pm
SegaTime wrote
One last thing I wonder is if the Master System games could be hacked and have a calibrator installed.


That would be an amazing thing to do indeed, I hope someone gets motivated by such project :)

We could even select among variety of light phaser polling functions.

Also see www.smspower.org/forums/17367-LightPhaserCodeAlgorithm
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  • Joined: 28 Mar 2002
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Post Posted: Wed Mar 15, 2023 3:13 am
SegaTime wrote


One last thing I wonder is if the Master System games could be hacked and have a calibrator installed. Sadly, I'm not the one for that job. Maybe I can come up with "sights" that I can stick onto the light phasers that would help aiming.

Updates: I've picked up two 20" TVs with component inputs to test out. One is an insignia flat tube just like the FD Trinitrons and it has has the same results with the light guns. The other is a Daewoo with a fully rounded tube and the justifiers are off to the right slightly while the phasers are off to the left slightly. Ugh. Maybe it's time to look into RGB modding all the regular tubes I keep finding without component inputs.

I've also been told that after the 16-bit systems, most light guns games had built in calibrators.


I've manually patched Gangster Town yesterday to offset the the delay introduced by Wega Trinitrons. In my case, everything was a bit offset to the right, indicating a bit of an input lag. The fix was to subtract an amount from the HCounter readings and that seemed to have fixed the problem.

Allowing this "fixed amount" to be adjusted by the player is not the end of the world, but most of these games don't have a settings screen, so one would need to be created for this.
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  • Joined: 05 Jan 2006
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Post Posted: Wed Apr 19, 2023 7:04 pm
Rene Dare wrote
SegaTime wrote


One last thing I wonder is if the Master System games could be hacked and have a calibrator installed. Sadly, I'm not the one for that job. Maybe I can come up with "sights" that I can stick onto the light phasers that would help aiming.

Updates: I've picked up two 20" TVs with component inputs to test out. One is an insignia flat tube just like the FD Trinitrons and it has has the same results with the light guns. The other is a Daewoo with a fully rounded tube and the justifiers are off to the right slightly while the phasers are off to the left slightly. Ugh. Maybe it's time to look into RGB modding all the regular tubes I keep finding without component inputs.

I've also been told that after the 16-bit systems, most light guns games had built in calibrators.


I've manually patched Gangster Town yesterday to offset the the delay introduced by Wega Trinitrons. In my case, everything was a bit offset to the right, indicating a bit of an input lag. The fix was to subtract an amount from the HCounter readings and that seemed to have fixed the problem.

Allowing this "fixed amount" to be adjusted by the player is not the end of the world, but most of these games don't have a settings screen, so one would need to be created for this.


Thats sweet. Care to share the patch you made?

From my work testing these I know the older light guns are particularly finicky about display brightness (gamma and contrast, too). I was able to get very different results with tweaking those. Never heard of geometry issues across monitors though, that sounds interesting.

IIRC gangster town calibrates your shots during the training mission. Mighy be worth debugging with other titles as well.
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