![]() ![]() I have some acrylic mirror sheets and I plan on cutting four strips and place them at a 45 degree angle on the face of the panel just where the active area ends. I realise there are many cheaper, less time consuming and more effective DIY flat field panels ideas but seeing I've bought this I might as well give it a go and log my progress here. Here's some individual flat frames just stretched in PI Of course in a proper workflow one would calibrate and optimize the individual flats by subtracting a scaled down version of the master dark to match the dark current in the flat frames. So my question is, if hears some use exposures in the range of seconds for their flats, would that not introduce enough dark noise into the flats that would require more processing later on to remove. So just wondering if I could actually get away with this as I if I needed lower ADU flats I'd need to find a way to reduce the light output of the panel as 0.001s is the camera's minimum exposure time.Īlso on this note I know the ideal flat duration is one where you expose for long enough so that the sensor read noise is overpowered but not so long that you start inducing unnecessary dark noise in the image. I know the duration of flats mainly depends on the camera's full well, gain factor and ADC levels, but I remember a while back when I started imaging I calculated all this somehow and the sweet spot for my Atik 414EX was between 10 and 15k ADU. Now there's a few opinions on the duration of flats as far as I'm aware, some say between 10-15k ADU, others swear by 25-30k and some even prefer 40-45k. That's what I was using for my flats with my previous setup with the Atik and they seemed to work great. I could get both SII and Ha down to about 10-15k ADU by reducing the exposures. So last night tried the bare panel in front of the dew dew shield and got the following results with my narrowband filters and Atik 414EX: On the issue of the emitted light peaking at the green spectrum, I don't think that'll be much of a problem as when taking RGB flats one would probably vary the exposure times for the individual RGB filters anyway. Or I may go the route of a separate power supply as the panel works on 27 - 42V at 280mA. You're right, I think the panel is much too bright and I may just borrow your idea of fitting a current limiting resistor so the flats can have the proper exposure. By adjusting the value of the series resistance it was possible to bring the intensity down to a more sensible level. In the end I did away with the mains driven 'starter' unit and drove the LEDs with a low voltage DC. Commonly used LEDs have a spike in the green part of the spectrum, and so using semi-opaque filters ends up shifting the spectrum towards the green. And yes, they are very bright, so much so that I had to find a way of reducing the intensity. ![]() Internally, they consist of an annular strip of LEDs on a tape (see my posts and ), and do give what seems to be an even light. Yes, I constructed a similar flats light but using a smaller circular LED light panel. Has anyone attempted this before? Any ideas for what I could place in front of it? Also it's VERY bright at 800-1600 lumens so that provides some flexibility in choosing what material goes in front of it. The panel has a 120 degree beam angle so I think this should work. I'm thinking of placing some sort of semi-transparent sheet 50mm in front of the panel and that should in theory expand the beam of light enough so that it would cover the scope. ![]() The active area of the panel is only 250mm x 250mm so a bit small for the RASA's 279mm clear aperture so I'll have to figure out a way to cover that entirely. The waves seen in the images are a result of the camera's shutter I believe and are not visible in real life Comes with an LED driver and was only £13. It's a 295mm x 295mm LED ceiling panel which I think has an incorporated diffuser sheet as the light is very uniform. So I scoured the net for cheaper alternatives, there's the bare EL panels but for the dimensions I'd need prices are in the range of £60, not exactly cheap for what it is. Having looked at astro flat field panels I came to the conclusion that paying around £200 for one is a bit steep and I'd rather use that to buy me an LRGB filter set. Having just received my new mount capable of holding my RASA I am now in need of a flat field panel large enough to cover the scope's aperture. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |