Jupiter and Ganymede

[Kokatha man]

Fast frame rates in themselves have no bearing on how "dark" an image will appear when stacked - the only real influence is the exposure level which is displayed by the histogram in your capture program and is adjusted by varying the gain slider, also in your capture program - the faster the frame rate you choose the more gain you will require from any scope, barlow & camera combination.....with small scopes it might be impossible to increase gain enough to set a desirable histogram/exposure for the faster rates because the small scope might not have enough "light grasp" and trying for too large an image by using a barlow which gives too much amplification also diminishes the light available for the camera.

One should aim for a gain setting commensurate with the planet you are imaging: Jupiter will need at least 60% although I'd suggest 70% histogram is better, Mars can work down to about 45% but again 55-60% is better whilst Saturn is the most forgiving and can take down to 40%, sometimes even less.....these % values should be displayed on your capture program but for instance a 50% histogram is one that stretches halfway across the histogram graph from left to right on the x-axis!

[Barv]

Fast frame rates in themselves have no bearing on how "dark" an image will appear when stacked - the only real influence is the exposure level which is displayed by the histogram in your capture program and is adjusted by varying the gain slider, also in your capture program - the faster the frame rate you choose the more gain you will require from any scope, barlow & camera combination.....with small scopes it might be impossible to increase gain enough to set a desirable histogram/exposure for the faster rates because the small scope might not have enough "light grasp" and trying for too large an image by using a barlow which gives too much amplification also diminishes the light available for the camera.

One should aim for a gain setting commensurate with the planet you are imaging: Jupiter will need at least 60% although I'd suggest 70% histogram is better, Mars can work down to about 45% but again 55-60% is better whilst Saturn is the most forgiving and can take down to 40%, sometimes even less.....these % values should be displayed on your capture program but for instance a 50% histogram is one that stretches halfway across the histogram graph from left to right on the x-axis!

Well that clarifies that then. Many thanks Kokatha man, very useful this! 

[todd8137]

So there for a high frame rate requires more gain and expo if not it comes out dark like the first picture as you no high gain gives grainy images here's my red Chanel with dmk 21, c9.25 60fps ,no Barlow ,gain 40, 1,20 sec expo I prefer mono,cameras

Pat

[Barv]

So there for a high frame rate requires more gain and expo if not it comes out dark like the first picture as you no high gain gives grainy images here's my red Chanel with dmk 21, c9.25 60fps ,no Barlow ,gain 40, 1,20 sec expo I prefer mono,cameras

Pat

image.jpg

Yes I agree. I think you can tell a lot by studying the image hard in processing. I would automatically up the exposure and gain for a fast frame rate image. That is a nice image with the red channel, - I would imagine it was the best of the 3 because the red always shows more. Did you take any more that night with a barlow or anything Todd?

[SnakeyJ]

Poss rather odd, but I'm definitely getting my best results on green channel with my qhy5liim & 200p! I've always found longer wavelength better for lunar and saturn and thought it might be due to focusing with green and slight differences in the baader ccd filters. However, even focusing for each filter green has been consistantly sharper/more detailed. That said IR-Pass also excellent, so perhaps its time to strip the wheel & clean all the filters

typed on my mobile with Tapatalk

[Kokatha man]

So there for a high frame rate requires more gain and expo if not it comes out dark like the first picture as you no high gain gives grainy images here's my red Chanel with dmk 21, c9.25 60fps ,no Barlow ,gain 40, 1,20 sec expo I prefer mono,cameras

Pat

No, not more exposure.....faster frame-rates have shorter exposure times...it's no good setting the frame-rate to (say) 100fps but the exposure to 20 milliseconds because that would mean that each frame would be exposed to only half the optimum exposure time, which really should be 10 milliseconds in this example (ie, 1/100 second) - you would indeed need much more gain to get an acceptable histogram if you had a shorter exposure time in milliseconds to that of the frame-rate! : but possibly you meant "faster exposure time" when you said "more gain and expo"....?

It's axiomatic that a faster frame-rate is only allowing a shorter period for each frame's "exposure" to the available light.....this means that to compensate we need to amplify the signal to a greater degree to get the same histogram exposure value (and this histogram value is what is usually referred to as "exposure" although it becomes confusing, because in a lot of capture programs the shutter speed is controlled by a slider labelled "Exposure") 

This amplification is an electronic process/mode which is controlled by the "gain" slider in your capture program and results in more grain/noise (the amplifier is in the camera's on-board electronics).....the upside is that you are collecting more frames, possibly mitigating seeing factors to a degree and (again possibly) collecting more decent frames that when stacked (might!) create a smoother image than the stack captured at a lower frame-rate & lower gain (which might have fewer decent frames in the lesser-numbered stack, albeit their signal to noise ratio might be higher.

As you can read from my choice of words it can be somewhat problematical but in practise I "nearly always" find that the faster frame-rates end up producing better outcomes most of the time.....but not "always always."

So if this is what you're asking (I suspect it is...) your question should rightfully have stated: <"So therefore a high frame rate requires more gain to get the same exposure and if not it comes out dark like the first picture">

However, I'd  dispute your assertion that this particular image is "dark" as you stated beforehand.....even if insufficient gain had been set to get the type of histogram for any specific planet that I've commented upon above, as long as the histogram exposure is sufficient (ie, not too low) then post-processing applications such as stretching the image etc will fix the problem...

Of course if the exposure really is too low  (again, I'm referring to histogram values when I say "exposure") then you'll run into other problems in various cameras such as the legendary "onion rings" etc...