Ovi

Hello! I've been using my SW 72ED with a StellaMira 0.8x FF for the past year and I can't say I'm too happy with its performance on an APS-C sensor. The stars in the corners are all around double the FWHM of those in the centre (pic below) and no amount of fiddling with the backfocus seems to fix it. Therefore, I've been thinking of buying another FF/FR, namely the one made specifically for this scope by SkyWatcher. Any experiences with it? If yes, does it fully correct and APS-C sized area? Suggestions for other field flatteners that you might use are welcome as well. Thanks!

1 hour ago, simmo39 said:

Hi all, I have been using PI for a few years now but have never attempted to use the batch processing script. My first question ( there may be a few here ) is, Im going to be using my OSC Cmos camera and when I stacked the long way I used dark flats as part of the processing. When using the batch script where do I drop them in? is it in the Bias section or the darks section and if its in the darks section how do I add the darks? ( again I have read that darks may not be needed with my ASI 2600mc but I have been using them when stacking the long way). 

I have watched a few tutorials on Batch processing script no seems to be answering my questions on cmos stacking.

This may be the first in a long line of questions so I apologize in advance!

You add both the darks and dark flats in the darks section and they will be separated by exposure time. The script should automatically determine which is which (since the dark flats have the same exposure time as the flats and the darks have the same exposure time as the lights).

5 hours ago, ollypenrice said:

A 40% fall-off in signal is a lot. However, I have a 23% vignetting fall-off on one setup and it does calibrate out.

What's still to be explained, tough, is why the flats don't calibrate out the patterns formed on the sensor by debayering.

I have to ask this: would you not be better off sticking with a standard sensor and using a dual or tri-band filter?

Olly

I prefer seeing it as the debayered area being 60% more sensitive

As for why not sticking with a color sensor, the allure of increased sensitivity and resolution are too strong to resist. If I can't the flats to work, I'll give this project one last chance and after that I'll be content with putting it down to sleep and going down the duo-band filter path.

On 13/03/2022 at 15:23, ollypenrice said:

I, too, think the sensor is badly damaged. The flat has patches of black which presumably have no signal, or very little, so there is little or no information there for the calibration to adjust. We often see this when there is dust on the sensor: there is nothing the flats can do to correct for that.

Olly

 

The black patches are actually around 60% of the brightness of the rest (they're patches where the cfa wasn't completely removed), it's just that the flat is very stretched. While I do not think the sensor is damaged, I'm starting to think I might not get flat calibration to work at all. I'll probably try again with another sensor since I wouldn't be able to sleep at night knowing I abandoned this project while this close to success.

11 hours ago, vlaiv said:

Can you post single light, single flat and master flat cr2 files for inspection?

 

Here they are. Unlike the ones I sent before, these are uncropped.

L_0002_orion_20-52-43__1C_ISO800_120s.CR2 IMG_7340.CR2 masterFlat.tif

Hello! Recently I succeeded in debayering a Canon 450D through polishing, which left me with a mono sensor. However, I've been having some issues with flat subtraction. Here's the stacked file:

And here is the master flat:

To me it kinda looks like the flat is being over-subtracted in certain areas. For context, here are an uncalibrated and a calibrated single light frame:

You can start seeing those patterns appear in the calibrated image, although they are more subtle than in the stacked image. Any idea how I could fix this?

4 hours ago, newbie alert said:

Your sensor spacing is wrong.. so too far

How should I go about fixing it?

Hello! I have noticed while shooting that the left and right side have pretty bad aberrations (even worse in the corners). My setup is: SW 72ED, StellaMira 0.8x FF/FR, T-ring, Canon 60D. Here's a sub I took a few nights ago:

L_0006_NGC6992_23-08-08__22C_ISO800_300s.CR2

Here's a mosaic done with the aberration inspector in PI:

And here are some screenshots from CCDInspector. I have no idea what they mean but maybe it helps

I'd appreciate it a lot if someone here could help me diagnose the issue present here. My biggest fear is that this is caused by bad sensor alignment from when I astromodded my camera .

This sounds interesting. See you all in a year.

Hello! Yesterday I shot a bunch of exposures of the Rosette. The lens I'm using unfortunately has problems with focusing all wavelengths at the same plane. As such, while the G and B channels are focused, the R one is very unfocused. This leads to red halos around most medium-brightness stars (and probably loss of detail). How do I go about removing the red halos? I have access to PixInsight, Photoshop and Lightroom. Thanks!

I have attached below an rgb image and one only with the red channel.

21 hours ago, Alien 13 said:

What camera are you using? I noticed that you mentioned a Nikon lens in your post, if you are using a Nikon camera then all the vintage M42 type lenses and most others wont focus at infinity.

Alan

Sorry for not writing this in the original post. I have a Canon 60D so afaik M42 lenses will focus to infinity on my camera.

On 03/12/2020 at 21:34, SmokeyJoe said:

Sorry to but in but I have a quick question, is there any point in using such a filter with an UNmodded DSLR?  I have seen a number of images on places such as Astrobackyard but there is no mention of the camera being astro modded. 

Unmodded DSLR block around 75% of Ha signal IIRC so it wouldn't really make sense to use an Ha filter with one. 

23 hours ago, rnobleeddy said:

I'ma big fan of the dual band filters for a DSLR. They effectively split the Ha signal to the red pixels and the O-III to the G/B pixels. The width of the Ha  pass band aside, as far as I can tell, the concept is strictly better than Ha for DSLR's because you don't lose any Ha, and gain O-III for free. Practically, I imagine the Ha band is a lot wider in the dual band filters than a quality Ha filter though.

I'm always wary of posting images as I have a lot to learn - but this was less than hour of dual band data with a 450D on a night with 90% moon.

 

 

 

What dual bandpass filter would you recommend?

Those are some nice photos

Hello! I have a modified Canon 60D, Nikkor 135mm f/2.8 lens and Omegon MiniTrack LX2 tracker. Would 1 min long exposures (the limit with my mount) be enough to collect meaningful Ha data? Thanks! 

Most sites I've seen are based in the US and the import taxes are as expensive as the blank itself. Thanks in advance!

Maybe it's this one: http://astronomy.tools/calculators/field_of_view/

On the morning of the March 18th the Moon, Mars, Jupiter and Saturn will be seen close to each other. Hopefully the weather will be good

7 hours ago, John said:

SN 2020ue is a Type 1a supernova I believe. How long is it likely to stay relatively bright ?

 

I bought a 9x50 Right Angle Sky-Watcher finder, an RA motor and a Seben 9-24mm eyepiece. Unfortunately the motor wasn't in stock and I'll have to wait something like 2 more weeks.

(a somewhat late) Merry Christmas to you all!

Now that I think about it, Betelgeuse really looks like it's dimming. I remember it being almost as bright (if not as bright) as Rigel. Now it looks like Rigel is twice as bright. I've sent quite some time wondering how it would look if Betelgeuse went supernova although it's quite unlikely it will in our lifetime

Very nice! What were the steps you took to edit it?

Hi Neal! Welcome to the forum!

Hi, Dan! Welcome to the forum!