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LRGB Help

Singlin

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Singlin

Singlin

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Thank you for the replies.

My new Atik has just arrived and I am still at the stage of looking at it in awe.

My latin teacher used to say ti us "careful, calm and deliberation disentangles every knot"

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Oddsocks

Oddsocks

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If you are taking all images using the same binning, exposure time and sensor temperature then you just need lights and flats for each filter position plus master dark and master bias which will be applied equally to all the RGB or L-RGB channels.

The dark and bias frames have no relationship to the optical path, just the exposure time, binning and sensor temperature so one set of master dark and master bias can be applied equally to each individual light channel.

For some objects you can gain extra colour sensitivity by binning 2x2  for the RGB channels and for detail image at 1x1 binning for the L channel then cut down either the number of colour subs taken or the exposure time per sub but this means you have to take extra flats, darks and bias for each colour channel to match the binning setting, which actually means more work during acquisition and post processing.

When I started CCD imaging I used only one exposure time and one binning setting for each light channel to keep everything simple.

As I became more comfortable with acquisition and post processing I found the resulting images had lower colour noise if I imaged bin 1x1 for luminance and bin 2x2 for the colour channels so this is the process I follow even though additional work for the extra darks flats and bias is a pain at times.

For some objects you won't need a luminance channel at all, just image RGB

I notice that for the quiet Sony chipped cameras many imagers are recommending not bothering with the dark frames as some data is lost from the lights during subtraction, they use only a master bias.

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ollypenrice

ollypenrice

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To be honest I no longer bother with flats for each colour. Using an electric filterwheel means everything stays clean inside the optical path. What I suggest is that you try using a Lum flat for everything and see if it works for you. If it does, leave it. If it doesn't, go back to individual flats.

Binning colour depends on a number of things. If your sampling rate is already coarse don't do it. Your stars will suffer. If you are sampling at high resolution then the price you pay in star quality will be much lower.

If, as I do on images with a fair amount of clear starfeild, you want to avoid applying the luminance to the starfield then you shouldn't bin. You want the nice tight, unsaturated stars you can get best in RGB only and best resolution.

Olly

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Singlin

Singlin

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Thank's Oliver.

I have just installed the baader lrgb and Ha filters in the wheel.

The instructions that came with the wheel stated just to drop the filters in. I saw that this is not the case and the photo of the wheel in the instructions is not the same.

I found a reference on line stating that the little v etched on the side of each filter must point towards the telescope.

I then put the o rings in and washers and screws.

What are sealed silver packets with what feels like pool cue tip heads for ?

Their are 3 in each packet.

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Singlin

Singlin

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Thanks Uranium, I have ordered one.

I use the following coma corrector 

http://www.firstlightoptics.com/coma-correctors/skywatcher-f4-aplanatic-coma-corrector.html

It states that I need 55mm back focus.

The 383 and filter wheel are a total of 39.5mm.

Does this mean that I need to buy a spacer that is 15.5mm thick?

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Singlin

Singlin

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Well!

I have installed the software and drivers but my Windows 7 64 bit does not pick up the camera when plugged in.

I have looked for it in devices and Printers and it does not show up their either.

I tried via devices and printers to install the 64bit version of the atik driver but couldn't due to the fact that it does not show up.

Any suggestions?

Rgds

Simon

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Nicho

Nicho

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I have problems with my 314+ if I don't plug everything in its specific order . So attach USB to camera and computer first then attach the power after that . If I do it the other way my computer does not see the camera at all. I hope this helps

Nick

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Oddsocks

Oddsocks

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Thats right Simon,

I assume you have the EFW2 wheel which ATIK states to have a 22mm thickness plus the 383 front flange-face to chip distance is 17.5mm = 39.5mm total and leaves 15.5mm to take up for the coma corrector.

You won't be able to find a single extension of 15.5mm so you have to build the correct length by adding several components to achieve as close as possible to the correct back focus distance, there is a small tolerance in the coma corrector distance but it is best to try and get a close as possible.

The easiest way to do this is with a Badder 15mm T2 extension tube (T2 male to T2 female with 15mm optical length), part number 1508154 and a single 0.6mm Delrin ring spacer from the Badder spacer ring pack, part number 2458102, this would give you 15.6mm total which is close enough.

The T2 extension tube and Delrin ring will fit between the camera and the filter wheel.

The Baader Delrin rings are very tight to fit, I have used them for many different correctors and usually I tip them in a pan of boiling water for a few minutes to soften them, then stretch them a little using wooden chop-sticks while still hot before fitting them to the corrector.

If you can't find a Baader stockist in Italy then you can buy the Baader adaptors from Telescope Service in Germany but ignore their english translation pages, there are often errors, you can double check the description direct at the Baader Planetarium website.

Telescope Service part numbers are the same as Baader numbers but with BA added.

TS: 15mm T2 extension tube: BA1508154, €16, http://www.teleskop-express.de/shop/product_info.php/info/p207_Baader-T2-Verlaengerung---Laenge-15mm---25A.html

TS: Delrin Spacer Kit: BA2458102, €12, http://www.teleskop-express.de/shop/product_info.php/language/de/info/p3619_Baader-T2-setting-rings---for-the-right-distance-control---15pc.html

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Singlin

Singlin

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Thanks William.

I was planning on putting spacers in front of the filter wheel, between the wheel and the coma corrector.

Is it best to put the spacers between the camera and wheel, will this not affect the efiency of the filters on the camera chip?

My coma corrector is the skywatcher f4 one for the 10" Quattro and has a male 48mm thread.

Rgds

Simon

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Oddsocks

Oddsocks

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Hi Simon,

I don't think the efficiency or performance of the filter is much affected by having the back focus spacer on the camera side of the wheel, at least I had never noticed anything in the past with my old SX cameras and Tru-Tech FW. I can't say for sure now as I am using QSI cameras with the filter wheel built into the camera, right in front of the chip window, so I will leave that question for someone else to answer.

For sure, depending on the f-ratio of the system, the size of the filters and the length of the spacer then vignetting may become an issue on a camera with a large chip. Also, with some makes of filter reflection halos can be created around bright stars, the halos will be bigger (and fainter) the further the camera chip is from the filter so this has to be considered.

I see from your earlier posts that you have bought already the 2408166 m54 female to m48 male adaptor for your wheel and the lip on that adaptor will take off about ~2mm from the back focal length leaving you ~13.5mm to adapt, you could go for the 2958214, 14mm, m48 male to m48 female, Hyperion fine-tune ring, €13.5, on the corrector side, this would give you a back focus distance of 55.5, which should be close enough, but you will need to measure the lip thickness on the m54 adaptor ring as it is not stated on the Baader or the Telescope Express web sites, if the lip is greater than 2mm thick then another option is to go for the TSVF210 m48 spacer ring, 10mm back focus, €29, on the corrector side and on the camera side fit the TST2V3, T2, spacer ring with 3mm back focus, €12, plus one of the 0.6mm Baader Delrin rings from the Baader BA2458102 Delrin kit €12.5 which would give you 55.1mm back focus and not much chance of vignetting with your fast scope.

I have seen it stated in other posts that the faster the f-ratio of the telescope then the more critical the back focus distance becomes but again I have no personal experience of this so it might just be an old astronomers saying....

If the lip of your m54 to m48 adaptor is thicker than 2mm, up to 3mm thick, then you can leave out the 0.6mm delrin ring, if it is greater than 3mm thick then you would need to look at the adaptor list again.

I bought an Atlas focuser a couple of years ago and hadn't realised before purchase that the camera and telescope adaptors typically cost around 500 euros each...ouch...so I bought  myself a metal working lathe and now happily spend as many hours turning up spacers and adaptors (of questionable quality but functional), as I spend actually observing!

17.5 mm BF   Atik 383

3.0mm    BF   TST2V3, Teleskop Service T2 spacer                     €12.6

0.6mm    BF   BA2458102, Teleskop Service (Baader) Delrin kit €12.5

22.0mm  BF   Atik EFW2

2.0mm?  BF   2408166,  Teleskop Service m54-m48 adaptor ring

10.0 mm BF   TSVF210, Teleskop Service, m48 extension tube  €29

55.1mm total BF

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Singlin

Singlin

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With the above kindly researched by William I have now decided on the following:

BA 2458102 Delrin Kit

2408166 54-48mm adapter (already ordered)

295812 14mm 48-48mm spacer.

This will allow me to place everything in front of the filter wheel.

It also has an added bonus in that I can also try and get the oag in with just the 295812 14mm spacer and still get 55mm.

If the oag fails I just use the above.

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Singlin

Singlin

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I have done a bit of measuring:

The 14mmBaader m48 extension arrived today.

When screwed to my Coma corrector the distance from the coma lens to the 14mm extender flange is 16mm.

The m54 to m48 adapter is 1.8mm thick.

16+1.8=17.8.

The distance from my camera chip to the outside flange of the filter wheel is 39.5mm

17.8+39.5=57.3

My required back focus is 55mm and with this setup I get 57.3

Is this margin of error acceptable on a f4 scope and 8300 ccd?

I am thinking that I have made a bad choice in camera and filter wheel as I can't get the right bits to achieve good focus.

Help!

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