modded dslr or not?

[Russe]

How big of

Modded DSLR's are a great intro to AP.  I use mine all the time (when the sky is clear at any rate) despite having a CCD now.

How big of a difference would you say it made in terms of raw data - unmodded vs. modded?

[Merlin66]

A modded Canon gives a 50% increase in the Ha signal.....

[Russe]

Would you have a comparison pic?

[wavydavy]

Im real sorry guys out there for the delays in getting the pics posted, with differences in mod...unmod, and CLS.........Stupid blumming brit weather is playing up with me showing any comparable pics, but rest assured ive not forgotten, and as soon as I can I will post straight away...again my apologys. Currently modding a 1000D.............

[Russe]

Is it possible use narrow band filters with a modded DSLR? Or is that a waste of money??

[Merlin66]

Using narrow band filters on either a modded or un-modded camera still gives the problems of the colour Bayer matrix and loss of resolution etc.

An Ha narrowband would still just pick up on 1 in 4 pixel...albeit with a bit more efficiency on a modded camera....

[Russe]

In other words - why mod in the first place??

[Thalestris24]

Hi

There is the option of buying a debayered/monochrome Canon which increases sensitivity but the cost obviously goes up too. Personally, I wouldn't want to attempt to do the debayering myself - I just know it would end in tears! Then there's still the long exposure noise issue. I've been considering getting one of the JTW ultimate cooled versions. They currently work out at about £1150 for the modded colour 1100d or £1400 for the debayered monochrome. Seems a lot for a dslr but still - virtually no noise (no darks needed!) and a big sensor. I still haven't made up my mind on this! I can't really afford a good cooled ccd and even the cooled dslr's are expensive. They do seem nicely engineered though. On the other hand, just getting a standard modded one would be a lot cheaper but still have noise issues though not worse than I have at the moment. I'm keeping the standard modded version an option. My local lp limits my exposure times to a few minutes anyway. Decisions, decisions! I'm also not sure if it would be straightforward to set up a monochrome dslr with filters / filter wheel. I don't have much backfocus - only about 10mm of my focuser showing. Maybe a coma corrector would help? Wondering if anyone has managed to use a dslr on a Skywatcher newt with a filter wheel or even managed just with separate filters?

Louise

[Merlin66]

The reason for modding is to gain that increased sensitivity in the red......

(If you remove both internal filters - an increase in wavelength coverage from 400nm - 700nm to 360nm - NIR.)

[carastro]

If you are going to stick with a DSLR then modding is the way to go.  I took a big leap forward once I got my 450D modified.  

I only have one image from my early days BEFORE I modded:

and this is what i got AFTER modding

[Russe]

Thanks! That's a great comparison! By mod you didn't mean debayer, but IR/UV filter removal I suppose. Is the lower image still only one shot colour or LRGB filter?

[Russe]

The reason for modding is to gain that increased sensitivity in the red......

(If you remove both internal filters - an increase in wavelength coverage from 400nm - 700nm to 360nm - NIR.)

Thanks! The reason is clear, the result is what I'm after. Am I p***ing 100£ in the wind, or does it actually give a noticeable result. I should think so theoretically, but in practice?

I'm currently not sure which way to go. Save for an Atik throughout next year? And the following? Or spend the money for an upgrade...

[Merlin66]

Saving up for a good cooled mono CCD is the way forward.....

However, many of us will never have the time, dedication or funds to go there....

The one shot colour modded Canon is a cost effective way of getting "acceptable" images....

You pay your money, you take your chance....

[Thalestris24]

Hi

I was just looking at the other images on Carole's site (Carastro - link above). Some lovely images there! Thanks Carole! After perusing her site and thinking about it lots, it makes me think that a modded dslr is the way to go. Opportunities to image are few and far between here in Glasgow and the need to take separate LRGB images and separate flats plus the expense of filters makes that route less desirable for me. I still haven't finally decided but I'm leaning towards a cooled dslr - probably a 1100d with virtually no noise. There was the thought that narrowband imaging would help me combat the lp but really it's for nebulas and whereas I'd like to image some, I'm more interested in clusters and galaxies.

Well, hoping the stars might yet come out tonight! Eyes on the skies!

Louise

[wxsatuser]

Personally I would'nt waste the money on a cooled dslr.

Get or mod something like a 1100D or 600D and spend the cloudy nights doing libraries of darks.

Find out your sky brightness, you need to know how long your subs can be without saturation.

Test your sky with the histogram, it's about right at 20>25%.

Here I have found depending on sky conditions that 180, 300 and 600secs are doable.

I am in the process of making darks for these sub lengths both at 400 and 800 ISO.

Do lots of darks, I mean lots and use software that can scale the darks.

It is possible according to Jerry Lodriguss to use darks taken at every 10degrees.

Two other things......get lots of subs......a handful does'nt cut it......think in hours not minutes.

If you have LP, like a lot of us, go and buy a really decent LP filter, imo Hutechs the best, don't scrimp.

[Thalestris24]

Personally I would'nt waste the money on a cooled dslr.

Get or mod something like a 1100D or 600D and spend the cloudy nights doing libraries of darks.

Find out your sky brightness, you need to know how long your subs can be without saturation.

Test your sky with the histogram, it's about right at 20>25%.

Here I have found depending on sky conditions that 180, 300 and 600secs are doable.

I am in the process of making darks for these sub lengths both at 400 and 800 ISO.

Do lots of darks, I mean lots and use software that can scale the darks.

It is possible according to Jerry Lodriguss to use darks taken at every 10degrees.

Two other things......get lots of subs......a handful does'nt cut it......think in hours not minutes.

If you have LP, like a lot of us, go and buy a really decent LP filter, imo Hutechs the best, don't scrimp.

Hi Mike

Thanks for the advice. Yes, I could make a library of darks but, as with cooled ccd's, it does seem desirable to have a cooled sensor - why would anyone bother with cooling at all if it's not useful? If I were to buy a ccd it would certainly be a cooled one. Yes, a basic modded 1100d would be a lot cheaper than a cooled version. I use an Astronomic cls-ccd for the lp. It makes a big difference - without it, I could hardly do anything useful. Of course, like everyone, what I really need is dark skies. At the moment, I'm restricted to the number of subs I can take in any one session and the lp limits exposures to 300s max @ iso 800. Mostly I'll expose for less - say, 120s. I live in a flat and the scope is set up in my living room (!) and my view of the sky is restricted to what I can see through one, not especially wide, window!! So the camera isn't much below room temp and the sensor temp is usually around 24-26 deg (from the camera data). I intuitively feel it would benefit from cooling. I'm not sure how beneficial the higher QE of a ccd would be. However, I've noticed with the (uncooled) qhy5l-ii guide camera that I can see a lot of detail with just the 2 secs guiding exposure. I suspect, though, that its increased sensitivity will apply to the lp too. Still, I'll have to have a go at using it to capture some images. Maybe a ccd would be the best way to go but even more expensive for a decent sized sensor. Whenever I can, I image the same object over multiple sessions to increase the total number of subs. The Glasgow weather isn't helpful... It will take me years to build up libraries of subs! Any images I make now are works in progress so purely intermediate efforts until I can get a decent number of subs. I've only had the 150pds for less than 3 months - it's all very early days for me!

Cheers

Louise

[Russe]

Personally I would'nt waste the money on a cooled dslr.

Get or mod something like a 1100D or 600D and spend the cloudy nights doing libraries of darks.

Find out your sky brightness, you need to know how long your subs can be without saturation.

Test your sky with the histogram, it's about right at 20>25%.

Here I have found depending on sky conditions that 180, 300 and 600secs are doable.

I am in the process of making darks for these sub lengths both at 400 and 800 ISO.

Do lots of darks, I mean lots and use software that can scale the darks.

It is possible according to Jerry Lodriguss to use darks taken at every 10degrees.

Two other things......get lots of subs......a handful does'nt cut it......think in hours not minutes.

If you have LP, like a lot of us, go and buy a really decent LP filter, imo Hutechs the best, don't scrimp.

Great opinion!

What do you mean (exactly) by test your sky with a histogram - do a (let's say) 600s exposure and see where the histogram ends up in? Hopefully by 25%? Did I get that right?

[wxsatuser]

I see so the camera is basically indoors.

As for temperature that does'nt matter so much, the higher the temperature the more darks you need.

Remember the noise is reduced in a master dark by the square root of the total number of darks.

A third of the noise would be added to lights for nine darks, a quarter for sixteen , a fifth for twentyfive , a hundred darks would be a tenth.

If it were me I would reel off say 50 darks or more for each exposure length and iso and go from there.

Of course if a cooled cam is what you want, don't let me put you off.

[wxsatuser]

Great opinion!

What do you mean (exactly) by test your sky with a histogram - do a (let's say) 600s exposure and see where the histogram ends up in? Hopefully by 25%? Did I get that right?

Exactly!

I normally start with a 120sec exposure, that will get the histo away from the lefthandside.

Then I up the exposure until the histo sits just past the 20% line, thats the best exposure for your sky brightness.

20% gets your data well out of the read noise of the camera.

The mountain of the histogram is basically your sky, stars and everything else resides down low on the right.

You can of course expose longer and err on longer than shorter but you don't want to drive the histo to far right

as the data you want will be clipped.

[carastro]

Gosh, lots of posts since last night:

By mod you didn't mean debayer, but IR/UV filter removal I suppose. Is the lower image still only one shot colour or LRGB 

Sorry yes, I meant filter removal, I now have a baader filter instead of the IR one.

Yes the lower image is just Modded DSLR.  

Also I should mention that the unmodded image was done from a dark site whereas the modified image was done from my LP home location.

Carole 

[Thalestris24]

I see so the camera is basically indoors.

As for temperature that does'nt matter so much, the higher the temperature the more darks you need.

Remember the noise is reduced in a master dark by the square root of the total number of darks.

A third of the noise would be added to lights for nine darks, a quarter for sixteen , a fifth for twentyfive , a hundred darks would be a tenth.

If it were me I would reel off say 50 darks or more for each exposure length and iso and go from there.

Of course if a cooled cam is what you want, don't let me put you off.

Hi Mike

Yep - I'm an armchair astrophotographer! Of course, I'd rather be able to do it outside and have much more of the sky available to me but I'm taking a pragmatic approach for now, at least. It would be easier if I was on the ground floor but I'm on the 2nd, and on my own. No car either, otherwise I'd be able to go to a darker site. Well, yes, I understand about subtracting darks. However, it would seem better not to have to! By that I mean better to reduce or eliminate the dark noise rather than subtracting it, though obviously doing that works quite well. I've not made any decisions about another camera yet, whether modded dslr/cooled dslr/cooled ccd. No rush, and I'm learning all the time - bit by bit. I'll continue to get what I can from my unmodded 1100d whilst doing background research on the various options .

Cheers

Louise

[GuillermoBarrancos]

Hi Mike

Thanks for the advice. Yes, I could make a library of darks but, as with cooled ccd's, it does seem desirable to have a cooled sensor - why would anyone bother with cooling at all if it's not useful? If I were to buy a ccd it would certainly be a cooled one. Yes, a basic modded 1100d would be a lot cheaper than a cooled version. I use an Astronomic cls-ccd for the lp. It makes a big difference - without it, I could hardly do anything useful. Of course, like everyone, what I really need is dark skies. At the moment, I'm restricted to the number of subs I can take in any one session and the lp limits exposures to 300s max @ iso 800. Mostly I'll expose for less - say, 120s. I live in a flat and the scope is set up in my living room (!) and my view of the sky is restricted to what I can see through one, not especially wide, window!! So the camera isn't much below room temp and the sensor temp is usually around 24-26 deg (from the camera data). I intuitively feel it would benefit from cooling. I'm not sure how beneficial the higher QE of a ccd would be. However, I've noticed with the (uncooled) qhy5l-ii guide camera that I can see a lot of detail with just the 2 secs guiding exposure. I suspect, though, that its increased sensitivity will apply to the lp too. Still, I'll have to have a go at using it to capture some images. Maybe a ccd would be the best way to go but even more expensive for a decent sized sensor. Whenever I can, I image the same object over multiple sessions to increase the total number of subs. The Glasgow weather isn't helpful... It will take me years to build up libraries of subs! Any images I make now are works in progress so purely intermediate efforts until I can get a decent number of subs. I've only had the 150pds for less than 3 months - it's all very early days for me!

Cheers

Louise

Outch. I really feel for you. Imaging through a window is the absolute worst conditions to image in and in all honesty really not recommended.

You will have a constant disturbance around the window due to air currents (warm air escaping out of Your own window and upward current from neighbours below). Really terrible conditions to image in.

[Thalestris24]

Outch. I really feel for you. Imaging through a window is the absolute worst conditions to image in and in all honesty really not recommended.

You will have a constant disturbance around the window due to air currents (warm air escaping out of Your own window and upward current from neighbours below). Really terrible conditions to image in.

Hi

It is challenging but I turn the heating off - nothing from the neighbours as far as I can tell. Of course, I generally attempt the imaging late at night (after midnight) when there's less lp .

Louise

[carastro]

Wow Louise, what difficult imaging circumstances you have to work in.  Hats off to you.  As you quite rightly summise a cooled CCD camera would be very beneficial to you. Mono is the best as it gives more detail, but since you have so little time to capture it would take you forever to acquire an image.

Perhaps as you say a cooled DSLR is what you need, or a OSC CCD camera.

Carole 

[GuillermoBarrancos]

Wow Louise, what difficult imaging circumstances you have to work in. Hats off to you. As you quite rightly summise a cooled CCD camera would be very beneficial to you. Mono is the best as it gives more detail, but since you have so little time to capture it would take you forever to acquire an image.

Perhaps as you say a cooled DSLR is what you need, or a OSC CCD camera.

Carole

Something like the QHY8L. It has very good cooling, an APS size sensor and doesnt immediately break the bank at 900 pounds.

Astronomyshed has some nice review youtube videos about this OSC CCD camera.