DSLR "MODS"?

[Fatbloke-Dim]

i HAVE A QUESTION.....

I keep seeing reference to "modded" DSLR 's , mostly Canons , it seems . What does this mean ? Can a Canon 550 be so modded? And if so , does this process then render it unsuitable for general photographic use ?

As an aside to the above , my main 'scope is a Skywatcher 200 pds , 8" f5 , focal length 1 metre . Can a DSLR be used on this with the requisite T-rings and such? Anyone used this scope for DSLR imaging ? The current Skywatcher "blurb" on the back page of SAN -mag sez it can , but some folks say there's not enough back-focus on the focuser ,although the PDS model has a different Crayford contraption to the "standard" 200/8", tho' the focal length be the same .

[Psychobilly]

The mod usually involves one or more elements that sit in front of the imaging sensor.. the exact components removed depends on the camera model and what spectral response you are looking to achieve..

It's primarily done to improve the response to the astronomically useful Hydrogen Alpha (Ha) emission lines... all that lovely red stuff you see in deep space colour images... the other option is to go for a full spectrum mod ....

The 550D can be modded by removing just part of the filter stack... this will normally allow AF with camera lenses and you can use a custom white balance for normal photography or take care of the white balance in the post processing...

Beyond that you have the more extreme mods such as debayering (to convert the camera to mono) , Active cooling etc..

Peter...

[ollypenrice]

A classic Peter answer, all embracing!! Trust him.

Olly

[Fatbloke-Dim]

Food for thought , there, then . I think I'll not go tinkering just yet , at least not until I can get hold of another camera to fiddle with . In the meantime , I'll carry on tinkering with RAW files in Photoshop and such . Whilst I have anyone's attention , can anyone suggest a good starting point , exposure-wise to get a Milky Way shot from a 18mm lens on the 550D ? Does it seem possible that , given a dark enough sky , a decent capture may be made in a short enough exposure to prevent any trailing ? Wish I'd had the camera with me on the night of the Perseid's peak , in the Isle of Wight......wonderful dark southern sky right down to the sea , Milky Way as I've never seen it before . Sweeeeeettt.....

[Purplehayze104]

well i've had a go at imaging the milky way, didn't come out to bad with the stock 18-55mm lens (I use Nikon) my settings were iso800 with 30 sec subs, could of gone with less as was pointed out I had smallish star trails so would suggest maybe 20 sec subs, white balance was auto an aperture was 3.5 which is a large as it goes. I did around 25 subs, 25 darks with 25 bias, didn't do any flats, maybe idea to suggest to do more to get more detail, I then stacked in DSS then messed around with In photoshop. I had a fair bit of light pollution & moonshine to cope with an got decent enuff image so a dark sky would be a lot better for it. hope this helps, regards john

[Fatbloke-Dim]

Hi ,PURPLEHAZE...

All noted , will give this a go next time I gets half a chance . Gotta get dem dark skies.......

[RikM]

As an aside to the above , my main 'scope is a Skywatcher 200 pds , 8" f5 , focal length 1 metre . Can a DSLR be used on this with the requisite T-rings and such? Anyone used this scope for DSLR imaging ? The current Skywatcher "blurb" on the back page of SAN -mag sez it can , but some folks say there's not enough back-focus on the focuser ,although the PDS model has a different Crayford contraption to the "standard" 200/8", tho' the focal length be the same .

Canon DSLR's can be used on a 200PDS with just a t-ring needed to connect the camera body to the bottom half of the 1.25" eyepiece adaptor. The top barrel part of the eyepiece adaptor screws off to leave just the bottom part with a t-thread on top.

It is not clear whether a DSLR will reach focus on any given 200P single speed. It depends on the age of the scope and the adaptors that were included in the box. Most new (last couple of years) ones will reach focus without a problem.

[Purplehayze104]

I have about 5 - 7mm inward travel left on the focuser after attaching my DSLR with 2" adapter that's on the scope, I have a S.W. 150p pretty black white one

[Fatbloke-Dim]

My SW 200 is a P.D.S. model , with the race-proven , flight-ready and space-rated  ultra-DeLuxe (!)  2"/1.25" 2-speed focuser . About 20 months old ,the black with gold metalflake one . Common  talk suggests it should work with just the  T-ring , just wondered if anyone had used this actual scope , now it seems a bit less than clear to me if the T-ring fits the one-and-a-quarter or two inch bit of the focuser ,unless the T-rings are available in both sizes and therefore a choice.

[CedricTheBrave]

I have the 200 PDS and my Nikon fits and focuses fine without any extensions just the T Ring

I do have a coma corrector in there as well but that only adds a couple of mm

[lensman57]

i HAVE A QUESTION.....

I keep seeing reference to "modded" DSLR 's , mostly Canons , it seems . What does this mean ? Can a Canon 550 be so modded? And if so , does this process then render it unsuitable for general photographic use ?

As an aside to the above , my main 'scope is a Skywatcher 200 pds , 8" f5 , focal length 1 metre . Can a DSLR be used on this with the requisite T-rings and such? Anyone used this scope for DSLR imaging ? The current Skywatcher "blurb" on the back page of SAN -mag sez it can , but some folks say there's not enough back-focus on the focuser ,although the PDS model has a different Crayford contraption to the "standard" 200/8", tho' the focal length be the same .

Hi,

As peter has stated, modding ususally refers to the removal of the IR/UV cut filter in front of the sensor. IMHO if one decides to mod a DSLR for AP then there is no point worrying about the AF. The best and the easiest  option is to remove the entire low pass , IR/UV assembly and have a full spectrum camera just for AP. You can do this yourself if feeling brave or pay a premium of about £150.00 and have someone else do it for you. If you decided to use the camera for AP I see no reason why you should remove the light  stealing filters and then spend another £100.00 or so on a Baader filter to put it back on . BTW a modded camera has a 20~30 % increase in sensitivity in the red end tof he spectrum, the blue and the green remain the same. This is only useful if you want to image the nebulea that are rich in Ha ( red ), it does not make much difference if you are after galaxies.

One more point, by the time you buy a dslr, pay for it to be modded, add the cooling system of some sort or the other   then the expense has built up to an extent that you may consider a QHY8L  cooled CCD that has a  DSLR size sensor, at least it was designed for the job. I know that Olly may not approve but not everyone can fork out £2500.00 for a StarLight Xpress M25C.  QHY8L @ less than £900.00 still remains a bargain. If you are really serious about AP in OSC then you should keep that option on the table and no I do not have a QHY8L, I am happy with the Atik offerings.

Regards,

A.G

[RikM]

 , now it seems a bit less than clear to me if the T-ring fits the one-and-a-quarter or two inch bit of the focuser ,unless the T-rings are available in both sizes and therefore a choice.

A normal T-ring screws on to the bottom half of the 1.25" adaptor. You can get combined T-ring/adaptors in 2" size, but they are replace the supplied 2" adaptor rather than connect to it.

[leebca]

Have a question too. . .

When Peter wrote:

 Beyond that you have the more extreme mods such as debayering (to convert the camera to mono)

does this mean that a debayered camera will require color filters to make the colored (processed) final image?  Are you able to put filters on the modified DSLRs using them in the prime focus kind of AP?

Thanks.

[Psychobilly]

Have a question too. . .

When Peter wrote:

does this mean that a debayered camera will require color filters to make the colored (processed) final image?  Are you able to put filters on the modified DSLRs using them in the prime focus kind of AP?

Thanks.

Yes the camera becomes "mono" and so you will need separate filters to make a colour image... Either RGB or Ha, OIII, S2 etc for Narrowband

Peter...

[Rob63]

Everytime I read AP threads, my wallet quakes with fear!

I can feel myself being drawn in to the dark side even though I know I can't really afford it 

[Tinker1947]

The T-ring and Adapter ring screw in in this order.....

and end up like this.......

[Spikey]

The removal of the IR/UV filter in front of the sensor on a Canon is not too difficult a mod to do yourself if you're methodical.

[leebca]

Peter (or anyone),

I'm still not imagining what the setup is like.  I think in prime focus, the camera is attached to the scope with adaptor ring(s).  Now how do filters come into play?  The filter is put on the camera and the camera reassembled to the scope?  Then images are taken.  Then the next filter is put in?  Then images taken, etc., etc. until all filters have been used?

Are the narrowband filters combined with the color filters -- i.e., are images taken of the DSO using the colors AND the narrowband filters, or just one or the other or ?  Does this have to be done on one night (same object) or are multiple nights needed? (same object).

Still trying to grasp how this all works.  Thank you for your patience! 

[toxic]

i have the same scope 200pds black gold flec with dual speed focuser and a 2 " coma corrector fitterd to a t adapter and no problem with focus.but i removed the center part of the t adapter by unscrewing the 3 grub screws round the side and simply put the coma corecter in its place and the tighten up the screws job done.

filters screw on the front end of the coma correcter ,or in the body of the camera,or on the front of a barlow. i have the usual 1.25" color filters but just got a skywatcher 2" lp filter and srew it straight on the the coma correcter and its great.yes you can probaly tell im still new to this i have only been trying imaging for a little over year and love every photon of it.

[leebca]

Thanks toxic.  Much appreciated.