Alway IR Cut vs IR Pass on Moon

[Fedele]

Moon IR Cut vs IR Pass 742
22.04.2021
Baby-Mu, ASI 222, @ f12
Upper image: Only IR Cut filter
Bottom image: Only IR Pass
Sharpcap, AstroSurface
Similar processing

IR CUT.tif IR PASS.tif

[CraigT82]

Interested to see this comparison but tifs of 50mb each is a bit large, not to mention my device won't open them! Could you convert jpeg and repost? 

Cheers

[jetstream]

@Fedele could you post the images so I can see them, very interested.

[AbsolutelyN]

22 minutes ago, CraigT82 said:

Interested to see this comparison but tifs of 50mb each is a bit large, not to mention my device won't open them! Could you convert jpeg and repost? 

Cheers

 

[jetstream]

Excuse my ignorance everyone but what does an IR "cut" mean exactly? where does it start nm wise? it

[dobblob]

Good comparison Fedele. I was at this very moment considering going to IR pass and deciding if it was worth it. It seems to be.

Just for clarification: Were equal numbers of frames stacked with same best % in each case? Same fps and exposure? How much time between the two captures?

I just worry that the seeing may have improved for the IR pass before I spend $$$ !

[Davey-T]

46 minutes ago, jetstream said:

Excuse my ignorance everyone but what does an IR "cut" mean exactly? where does it start nm wise? it

Personally I use this one for Lunar

 

Dave

[Fedele]

The IR PAss is the Astronomik 742. i will buy the Baader also. the benefits are  also in the day light and bad seeing. 

if you look at my FaceBook page there are other posts and similar A/B results

Edited April 22, 2021 by Fedele

[jetstream]

28 minutes ago, Davey-T said:

Personally I use this one for Lunar

You use the Proplanet 642?

Ok, I was wondering about the term IR cut- I have a 2" Beloptik UV/IR and also a ZWO UV/IR coming 1.25".

Do you find the 642nm pass filter helps with less than good seeing or is the starting point a bit low? I'm looking at one of these myself.

Which camera do you use?

[Davey-T]

Others use the 807 squished further to the right.

HeIps with the seeing and I think it cuts down on the glare from highlighted regions but may be just my perception.

I use the 10"SCT and ZWO ASI178MM gives some horrendous oversampled arc"/pixel rate but I'm happy with it.

Dave

Sample image, 50th anniversary Apollo 11 landing site but didn't get much processing.

[CraigT82]

There isn't much in it to be honest, seeing must have been good. Here is a zoomed in comparison (IR cut top, IR pass bottom).

Not sure what altitude the moon was for these, but the IR cut filter capture may have benefited significantly from the use of an ADC. 

Very nice images BTW! 

[jetstream]

9 minutes ago, CraigT82 said:

the use of an ADC.

Yes Ive been learning about these, interesting.  I do see more detail in the lower image- no? Which pass filter?

[CraigT82]

Yes the bottom one is IR pass, it looks slightly sharper but in terms of detail there is nothing visible in that one that isn't just as visible in the IR cut image, and the sharpness boost may just be down slightly different processing (OP notes 'similar' processing). 

As the IR cut image contains all visible wavelengths from blue to red  atmospheric dispersion will have an effect, the amount of which is  dependent on the altitude of the moon at capture.

[jetstream]

3 minutes ago, CraigT82 said:

there is nothing visible in that one that isn't just as visible in the IR cut image,

How about those nice ridges showing in the bottom image on the very right?

[CraigT82]

31 minutes ago, jetstream said:

How about those nice ridges showing in the bottom image on the very right?

I'm not sure which ridges you mean? 

[jetstream]

The whole image seems more textured and with more contrast resulting in a sharper, more defined image and therefore more detail. Actually fine detail and more contrast on everything. Dont have a way to mark images...

Maybe its my eyes.

[CraigT82]

Yeah I do see what you see too, the bottom image has more sharpness, but my point is that the difference isn't much (and may well just be down to a touch extra on the wavelets slider?), if you look at the smallest craters visible (which are a very handy indicator of resolving power) then the same tiny pits are visible in both images, which indicates to me that seeing was good during capture and if an ADC was used with the IR cut, or even just a shorter wavelength filter (G?) then the IR pass image would have been knocked into second place. 

To illustrate here is one comparison on Copernicus I did in good seeing, green filter Vs IR685. Here the benefit of the IR pass is not needed (due to the good seeing), and the shorter wavelength green has allowed resolution of finer detail. 

I do see a lot of people defaulting to IR pass filters for all their lunar images but my humble opinion is that the IR pass should only be used if the seeing won't tolerate any of the shorter wavelength filters (i.e. it is a last resort).

 

[jetstream]

44 minutes ago, CraigT82 said:

Here the benefit of the IR pass is not needed (due to the good seeing), and the shorter wavelength green has allowed resolution of finer detail. 

Yes, I agree. I looked at your stunning lunar image in blue on your astrobin under good seeing 👍