Filter query for RGB Mars with ASI290MM

[Tommohawk]

I'm hoping to have a go at Mars sometime before it disappears for another couple of years, weather and commitments etc allowing.

In the past I've got very pleasing images of Jupiter and Saturn with my ASI290MM and RGB filters but I've always struggled with Mars.  At some point I concluded that an IR filter is necessary, though I think at that time I was still using a DSLR. 

I dabbled with an ASI290MC for a while so maybe  my conclusion that an IR filter is required relates to the use of the ASI290 colour version only?

Anyhow, the question is - do the ZWO RGB filters block IR? Looking at the data this seems to be the case, but can someone confirm this please. Also is there any benefit in adding IR data, possible as a LUM layer for example?

Many thanks!

[Ibbo!]

I use a mono cam.

I have found an IR helps this time round with the planets being so low .

i have used a 742 until recently as I have acquired a 642 which has been slightly better when seeing is not bad, I use the 742 if its worse and have even run the 807 when the conditions have been really poor ( but you need a larger scope for that)

And yes I have found using the IR as Lum is of benefit.

[Tommohawk]

Hi Steve - OK thanks for that.

But I'm not sure if you're saying the IR filter is necessary if using RGB filters.... or maybe if processing in mono with no RGB filters?

If the RGB filters block IR would a specific IR filter really help?

[Ibbo!]

My rgb filters do have an IR blocker layer as well.

Here are the stacks from the other night - not the best i have had this season but it gives an idea

IR642

 

red

 

green

blue

 

642 prodded in PS

RGB

final process

IR RGB

 

 

not sure it helps but gives you an idea

[Tommohawk]

Hey that's really helpful - and a pretty good final result given the low altitude and dust and all. The 642 as LUM seems to give a really useful gain. 

At the risk of labouring a point :

2 hours ago, Ibbo! said:

My rgb filters do have an IR blocker layer as well.

Do you mean you've added a separate IR blocker? Or the RGB filters themselves block the IR? 

Either way it looks like I'm going to need a 642 or similar. Also need to think about how to get it into the train. Need to check whats in my EFW - I think its RGBL + 3NBs - so I should have a spare slot. 

Is the weather going to clear though before Mars disappears??? 

[Ibbo!]

The filters block the IR.

 

I do hope we get another chance as I have the tripod on some 8" blocks so i have a longer window of oppurtunity and I think before i did not clear the wall properly.

I may have some better data from the other night , I have just got to run it through when i have enough spare time.

[Tommohawk]

3 hours ago, Ibbo! said:

 

I do hope we get another chance as I have the tripod on some 8" blocks so i have a longer window of oppurtunity and I think before i did not clear the wall properly.

 

Fingers crossed.

[Pete Presland]

Looking at the wavelength chart on FLO's website, it does look like the RGB also block I/R as well as the dedicated I/R cut filter. As Tom said also, i always use a I/R cut filter when capturing in mono. Usually the 642 filter, but also sometimes the 742. The 807 i have mostly used on the Moon or Venus.

[astroman001]

Yes the RGB filters will not pass either IR or UV except for a small overlap at the red and blue end.

I would recommend taking 4 filters, R G B and IR.  Produce both images as usual, the RGB will be washed out both by dust and the low altitude The IR will show nice details (less affected by atmospheric turbulence and Mars dust). Then combine using the IR as a luminence channel. This can all be done in WINJupos.

Best regards

Peter

[Tommohawk]

OK thanks guys all useful stuff.

So my understanding is:

If imaging with a colour camera with a Bayer matrix which doesn't block IR, an IR block filter will be useful to stop the IR smearing the RGB channels.

If imaging with a mono camera, to create a grayscale image, an IR pass filter could on its own to create a grayscale image.

If imaging with mono camera using RGB filters, an IR pass filter be used to create a LUM layer.

One point that confuses me though - terminology type thing maybe:

On ‎15‎/‎08‎/‎2018 at 07:46, Pete Presland said:

i always use a I/R cut filter when capturing in mono. Usually the 642 filter, but also sometimes the 742

642 and 742 filters are presumably IR pass filters, no? Doesn't an IR cut filter block IR? Maybe I have this wrong?

Also: Currently I use ZWO filters and ZWO EFW so probably makes sense to keep with them. I notice that their IR pass filter is 850nm though. The 290 response curve shows some sensitivity at 850, but this seems quite different to the filters you guys are using. What do you think? Just use a different brand? Thanks again for the guidance! 

 

[Pete Presland]

1 hour ago, Tommohawk said:

OK thanks guys all useful stuff.

So my understanding is:

If imaging with a colour camera with a Bayer matrix which doesn't block IR, an IR block filter will be useful to stop the IR smearing the RGB channels.

If imaging with a mono camera, to create a grayscale image, an IR pass filter could on its own to create a grayscale image.

If imaging with mono camera using RGB filters, an IR pass filter be used to create a LUM layer.

One point that confuses me though - terminology type thing maybe:

642 and 742 filters are presumably IR pass filters, no? Doesn't an IR cut filter block IR? Maybe I have this wrong?

Also: Currently I use ZWO filters and ZWO EFW so probably makes sense to keep with them. I notice that their IR pass filter is 850nm though. The 290 response curve shows some sensitivity at 850, but this seems quite different to the filters you guys are using. What do you think? Just use a different brand? Thanks again for the guidance! 

 

Yes, sorry IR pass filter. This is the one I mostly use with my mono camera https://www.firstlightoptics.com/astronomik-filters/astronomik-proplanet-642-bp-ir-pass-filter.html

The 742 is a slightly narrower wavelength, so lets less light through.

 

This is UV/IR cut for the colour camera

 

 

[Tommohawk]

OK great, thanks - just need the magic combination now of clear sky, time, and somewhere with any kind of view to the South!