modded DSLR?

[alexthegreek]

Hi everyone ?

I have a CANON 10D and I'm thinking or having its filter removed but not replaced .
 I have compared it to a NIKON D50 that I now use and I like the CANON results much better .
   Right now I have no problem capturing the Calcium H& K lines and a bit more to blue part .
  The camera also sees beyond the Ha line(whixh is mostly needed fro the Oe stars ) as well . 
Will I really benefit from the filter's removal ? I think that this will help me  go further into the red region of the spectrum  and I remember Robin's report about the Eps Auriga (769.9nm) .
I'm going to use a spectrograph of about R800 .

I guess the answer depends on the targets as well .
 Shall I go for it ?Right now I don't care using a modded DSLR for shooting images .

Greetings from Greece
  Alex
   

[Merlin66]

Alex,
I used a standard canon 350 and a Baader ( 400-700) modded canon 300.
The responce in the red was certainly much better with the mod, just a little in the blue.
I've recently "upgraded" to a 300D with filter removed.....(wanted to go below the 400nm cut-off)
Haven't had the opportunity to fully test it, but I can already see it has a very good responce at Ha and seems to go further into the UV.
Weather permitting I'll get some transmission curves.
I'd say removing the filter would give you as good a DSLR QE curve as possible?????

[alexthegreek]

Thank you Ken !

 Looking forward to seeing your transmission gratings .I'm interested in seeing how much it sees into the UV .
I'd say that I'm pleased with the CANON even unmodded .( I can see CaK and CaH already ) .
I don't know about the QE , but I guess it would improve it even a little bit .


 Have fun
 Alex

[alexthegreek]

Ken here's what an unmodded 300D does with my spectrograph .
 I wanted to show you so that you can compare .

It's burned at the center , but now we are just interested in the blue part .

[Merlin66]

Haven't had the opportunity to trial with a solar exposure ( clouds and work!)
I did an exposure with/ without a Baader UV-IR cut filter (420 -700nm).
First with the 300D ( no internal filter) second set with the 350D std.
Using AA4 to measure ADU and pixel distances:
300D
Dispersion with 300D - 4.06A/pixel
Difference in blue limit( with/ without UV Baader): 21 pixel
350D std
Dispersion with 350D - 4.68A/pixel
Differnce in blue limit ( with/ without UV Baader): 13 pixel

Assuming the Baader website is correct @ 420nm cut-off:
300D(no filter) limit:335nm
350 std, limit: 360nm

The above represents an "absolute limit" with very low transmission. It does show the 300D without the filter can go deeper into the UV. Hopefully will be able to verify this on the solar spectrum later this week.

[Merlin66]

Finally managed to get some sun!
Set up: ST80 (with a 4mm stop), 140mm Classic Spectro+600lpm+135mm Tamron lens+Canon 300D (no internal filter)

The first series photos show the blue responce which goes well below the H-K lines!!!
The second series shows the extended red responce with all the Telluric lines and into the 2nd order spectrum

I did find problems focusing the 300D without it's filter with the telelens..it needs just a touch move movement beyond the infinity setting....Hmmm another challenge!!
I'll import the spectrum into Vspec and actually measure the UV responce. So far so good.

[Merlin66]

And the extended red photos.

[alexthegreek]

That makes a big differrence when compared with the unmodded cameras !

 I 'll keep mine as is .I'm fine as long as I have H and K .

Have fun
 Alex