Redcat51 image train issues

[David_Scotland]

Hi,

Any redcat51 users out there that have an optolong l-enhance filter in there image train.

I currently have my filter in my scope, the place where WO suggest, a 2" extension tube, then my camera (Altair Hypercam 183C Protec), so far all i've managed to capture is unstackable images and horizontal banding noise. Without the filter i have no issues capturing images, see below.

My question is, is the filter (2" Optolong L-enhance)  in the correct location in the train, does it need to be close to the camera sensor (as someone on social media had said) and do i need to worry about backfocus as i can easily get focus on the current setup i have.

Kind off at my wits end, in the past i would buy stuff willy nilly and get nowhere, i'm afraid my pockets are starting to get very lean and cant afford just to buy what i think i need anymore, i need results

 

Cheers

[Pompey Monkey]

How do you focus without the filter?

How do you focus with the filter  fitted? If you can focus, then you should at least get some stars on your subs!

 

[Davey-T]

Do you mean 2" diameter or 2" long ? the thread on the rear is 2" and I have screwed a LP  filter onto that between it and DSLR T ring, not sure how your camera is connected.

Dave

[David_Scotland]

I can get focus on my stars, with or without the filter, that is definately not an issue, granted when testing the filter it was partly cloudy and the stars where not as bright as normal, but still woulod have thought sharpcap would have been able to livestack some of them

2" extention long tube (the one that comes packaged with the Hypercam), i have ordered a filter holder for my filter, if this is not the issue then at least i will have an easy way to take the filter in and out.

 

The image i posted was taken with the exact image train (without the filter) so definately not a focus issue, unless the filter does weird stuff with your focus.

I would test it again but people keep buying astrophotography gear

Cheers for the replies.

Edited April 30, 2020 by David_Scotland

[RayD]

The RedCat is a Petzval design so almost certainly adding the filter will mean you need to refocus, but I'd be surprised if it was by enough to cause your issues.

The Optolong L-enhance is a NB filter so not only will you need to select the right targets to see anything (M81 is probably not one of the best) you will also probably need to take much longer subs than you would be without the filter in (this would account for the banding).

I'd try to pick a good emission nebula and try again with a sub of about 2 minutes, then see if you have anything.

[david_taurus83]

Hi Dave. It was me on FB that was saying the filter is in the correct position and you dont need to worry about back spacing on the Redcat. Can you post up a couple of fits files as they come from from the camera? One for the image above with no filter and another one with filter and banding so we can have a look?

[David_Scotland]

5 minutes ago, RayD said:

The RedCat is a Petzval design so almost certainly adding the filter will mean you need to refocus, but I'd be surprised if it was by enough to cause your issues.

The Optolong L-enhance is a NB filter so not only will you need to select the right targets to see anything (M81 is probably not one of the best) you will also probably need to take much longer subs than you would be without the filter in (this would account for the banding).

I'd try to pick a good emission nebula and try again with a sub of about 2 minutes, then see if you have anything.

Thanks for that, makes sense, due to the clouds and the less than bright stars i was taking short exposures just to test the filter, will increase the exposure length next clear night i get (at a premium at the moment). 

What would you consider a good filter (bortle 6 sky) for non-emission nebulas and galaxies?

 

5 minutes ago, david_taurus83 said:

Hi Dave. It was me on FB that was saying the filter is in the correct position and you dont need to worry about back spacing on the Redcat. Can you post up a couple of fits files as they come from from the camera? One for the image above with no filter and another one with filter and banding so we can have a look?

Hi Dave,

Thanks for sending me here, fun friendly place

i deleted all the images from the night i tried the filter, more in anger than from anything else, next night i'm out i'll try get some images if what RayD says doesn't work.

 

So basically bought a filter holder for nothing, oh well at least i can take my filter in and out now without touching the filter too much.

 

Cheers

[RayD]

21 minutes ago, David_Scotland said:

Thanks for that, makes sense, due to the clouds and the less than bright stars i was taking short exposures just to test the filter, will increase the exposure length next clear night i get (at a premium at the moment). 

What would you consider a good filter (bortle 6 sky) for non-emission nebulas and galaxies?

The Idas LP filters are very good but, as with most things that are very good, they're not that cheap.

IDAS LP filter

[RayD]

Is there a specific thing you are looking to achieve from a filter?  Is it just light pollution you want to fight, or are you specifically wanting to shoot NB (Ha, OIII and Hb as you would with your Optolong)?

[David_Scotland]

Light pollution is a big part of my query but not just that, my main interest in the night sky is nebula which is why i went for the optolong to focus more on Ha, OIII and Hb. Obviously nebulas are not up all year round, right now is a good example, nebulas are at a preminum and with the dwindling hours at night looking to at least get some galaxies and clusters to add to my image collection, so i suppose my answer would be something that allows me too capture the other stuff in the night sky without having to worry about light pollution too much, i know you can never get rid of it all, but every little helps. The example you gave above is probably more than i would like to spend, just spent 166 on the optolong, so possibly i will look for a little bit cheaper, bout 100-120. Eventually i will be going mono imaging, probably next year or the year after. Will this filter be usuable with mono imaging?

[RayD]

8 minutes ago, David_Scotland said:

Light pollution is a big part of my query but not just that, my main interest in the night sky is nebula which is why i went for the optolong to focus more on Ha, OIII and Hb. Obviously nebulas are not up all year round, right now is a good example, nebulas are at a preminum and with the dwindling hours at night looking to at least get some galaxies and clusters to add to my image collection, so i suppose my answer would be something that allows me too capture the other stuff in the night sky without having to worry about light pollution too much, i know you can never get rid of it all, but every little helps. The example you gave above is probably more than i would like to spend, just spent 166 on the optolong, so possibly i will look for a little bit cheaper, bout 100-120. Eventually i will be going mono imaging, probably next year or the year after. Will this filter be usuable with mono imaging?

That's fine.  I would keep eye on ABS as they often come up used, but get snapped up.

Yes as you say, late for decent nebulae now, so you may want to ditch the Optolong for the time being as it will remove colour from any galaxies you're imaging, unless you are wanting to add a Ha element.

The RedCat is a great little OTA so I doubt any of your issues are related to that.