Is this my consideration correct?
Many times, reading here on the forum, I am tempted to change my 178, but then I see that maybe I do too much trouble.
Given that fortunately I have hardly ever seen the infamous grille problem.
I add an image taken from Astronomy tools, for a comparison between the various fields.
Correct; if you use the IMX174 at native F7~F8.3, it's severely under-sampled. It will have low resolution, despite showing the full disc in the FOV. It's fine. But if you want to get all the resolution you can, you'd have to be closer to F20~F22 on the 5.86um pixels, but that would reduce the disc to a partial disc FOV of course on this IMX174 sensor.
The IMX178 pixels at 2.4um will sample HA at F9 or so, and so you're much closer to ideal sampling with a F7~F8.3 focal-ratio and can get the full disc FOV and the resolution will be significantly higher due to the sampling relationship. This largely would be a rather ideal budget camera for this. The only downside is that there's the issues with the grid pattern that is heavily documented. So if you try it, buy it from somewhere that allows unquestioned return policy so if you see the grid issue you can just return it. Otherwise, it would totally be a great solar camera due to its sensor size and pixel size for small solar scope full disc imaging.
Another option is to hunt Ebay for used security cameras that are being pulled from service. You can find lots of interesting cameras this way using common sensors to image with, some mono and larger format. I was able to buy two Flir cameras with IMX253 sensors (1.1" sensor, 3.45um pixels) for less than the cost of a single ASI174MM camera. This camera critically samples HA at F13 (so F14 is great) and the 1.1" size still allows full disc FOV, at critical sampling, from a 60mm F7~F8.3 solar scope like your Lunt.
Basically look up various 1" class sensors that sony produces and look up model cameras that use them. A 1" class sensor will produce a full disc image on a 1,000mm focal length basically. The rest is just adjusting things for sampling. But getting a big sensor makes life a lot easier for full disc imaging if you care about resolution and want to sample more appropriately to get the most resolution from your system that you can. Alternative, any M43 class sensor with any pixel size will also be useful for this (even more costly, but it hurts only once, no more fooling around looking for a budget camera).
Here's how that looks in FC:
Lunt 60mm F7 HA scope
2x Telenegative Amplifier (F14) with tilt adapter (to eliminate newtonian rings)
IMX253 sensor (1.1" 3.45um pixels, critically samples HA at F13)
Real view in FireCapture:
Results of that setup in one shot at critical sampling:
Edited by MalVeauX, 01 August 2021 - 12:41 PM.