Uv/ ir cut filter

[geordie85]

I've been imaging with a qhy183c camera for a few months now and recently came across a post on here that was directed at a member using a OSC CMOS camera from asi that said something along the lines of "because your using a OSC camera, you'll need to use a uv/ ir cut filter". 

It was said that it will makes stars sharper. I do notice a slight bloating to my stars which has lead me to wonder maybe I should be using a uv/ ir cut filter. I don't use a light pollution filter as i sold my idas a short while back (which I do regret) so my question is, do I need one? 

[Thalestris24]

Hi

I think it normally comes with a uv/ir blocking glass window but can optionally be fitted with AR glass that passes uv/ir. If you bought it in its standard form, then no worries.

Louise

[Adam J]

9 hours ago, geordie85 said:

I've been imaging with a qhy183c camera for a few months now and recently came across a post on here that was directed at a member using a OSC CMOS camera from asi that said something along the lines of "because your using a OSC camera, you'll need to use a uv/ ir cut filter". 

It was said that it will makes stars sharper. I do notice a slight bloating to my stars which has lead me to wonder maybe I should be using a uv/ ir cut filter. I don't use a light pollution filter as i sold my idas a short while back (which I do regret) so my question is, do I need one? 

Its actually the other way around OSC tends to come with a UV/IR cut and mono tends to have a clear sensor window.

Bloating will be your optics or using the camera at too high a gain. 

[geordie85]

10 hours ago, Thalestris24 said:

Hi

I think it normally comes with a uv/ir blocking glass window but can optionally be fitted with AR glass that passes uv/ir. If you bought it in its standard form, then no worries.

Louise

Thank you. You just saved me some money. 

1 hour ago, Adam J said:

Its actually the other way around OSC tends to come with a UV/IR cut and mono tends to have a clear sensor window.

Bloating will be your optics or using the camera at too high a gain. 

To be fair I may be the cause of bloating by too aggressively pushing my data. I set gain to 11 and offset to 76.

[Allinthehead]

A quick internet search tells me that the 183 has an Ar coated window so you would need an ir cut filter. I use one on my 071 as it's recommended to help with star bloat.

[Thalestris24]

I believe the qhy183c sensor glass is AR but the camera's window is IR cut, in common with other osc. So you shouldn't need an additional filter. If you use a lp filter that will likely also be a UV/IR cut filter anyway The 183c does have a very high QE - about 83% (higher than most guide cameras) so exposures need to be short.

Hth

Louise

[geordie85]

I must say I'm still rather confused by it all and the FAQ in the online manual doesn't help matters much so I emailed Bern at modern astronomy, but he doesn't know either. Although he did tell me how to test it so I'll try and figure it out tonight. 

Here's a screenshot from the I line manual. 

[geordie85]

2 hours ago, Thalestris24 said:

I believe the qhy183c sensor glass is AR but the camera's window is IR cut, in common with other osc. So you shouldn't need an additional filter. If you use a lp filter that will likely also be a UV/IR cut filter anyway The 183c does have a very high QE - about 83% (higher than most guide cameras) so exposures need to be short.

Hth

Louise

I'm not using any filters at the moment since I've only been using a maximum of 120 second exposures. 

I did do 1 300 second exposure at the end of an imaging session the other night to see what the result would be and my histogram was still on the left hand side. 

[Thalestris24]

Hi

Maybe only the mono sensor has the 83% QE, I'm not sure. I don't know your particular camera but I wonder if you need to set up the gain and offset for it?

Perhaps post a sub then people here can make a judgement but I doubt you need an extra UV/IR cut filter.

Louise

[geordie85]

After a quick email conversation with Bern at modern astronomy I've just taken 2x 5 second subs. The first is without the remote and the second is with the remote active. 

The sub with the remote on is definitely brighter than without. 

I've also added a 120 sub unstretched.