5x powermate with a C8 SCT

[Aenima 397]

Hi, 

Can anyone tell me whether a C8 will accept a 5xpowermate for planetary imaging?

I have seen a number of great images with similar combinations to the above, and recently tried 3x barlow with the C8 and it seemed to be pushing the scope a bit, but ive no idea whether the scope can handle 5x easily or whether its depending on seeing conditions being good. etc.

The actual scope is in need of better colimation so that might be a factor affecting the test using 3x barlow.

Any ideas hugely welcome 

[hobsey 1,937]

I think using the X3 is pushing it a bit so I think think the X5 will be a bit too much.

I use a 2.5 which is boarder line if not a fraction too much, thinking about get a good quality X2.

Edited October 7, 2014 by hobsey

[Aenima 397]

Thank you, yes the 3x was quite a jump up - i have seen the 5x used with SCT's generally and was unsure of its design being different from barlows.

I wonder what kind of situation the 5x powermate can be used?

[michael.h.f.wilkinson 21,036]

It all depends on the pixel size of the camera. The DMK21 I use is best at F/20 to F/25, or for bright objects perhaps F/30. Most cameras have smaller pixels which reach their optimum at faster focal ratios.

[Aenima 397]

My camera is a toss-up between the ASI120MC and the Lu070m (icx424al)

The scopes are those in my signature if its any use

I knew for visual purposes the magnification is way too high, esp for the SCT -  but for imaging its not quite so extreme.

There are formulas and such that apply but my maths is awful

Edited October 7, 2014 by Aenima

[michael.h.f.wilkinson 21,036]

Those two cameras are very different.The ASI120 has smaller pixels  than the DMK21 (3.75 micron square vs 5.6 micron or so). These work best at about F/16 to F/20. The ICX424AL has big ones: 7.4 micron, which work optimally around F/30-F/36.

[Ruud 3,255]

The maths are not difficult. The C8 is an F/10.

With a 5x powermate it becomes an F/50. And with a 3x barlow it becomes an F/30.

[Aenima 397]

The maths are not difficult. The C8 is an F/10.

With a 5x powermate it becomes an F/50. And with a 3x barlow it becomes an F/30.

No its pretty simple i just have trouble doing it lol

I still not sure whether the optimal pixel/focal length is the 'maximum' or  just the best match results wise..?

Something like that. i'm figuring out if the actual scope is performing properly (and collimated), regarding C8's in general.

Edited October 7, 2014 by Aenima

[riklaunim 535]

Pic the camera with more sensitive and less noisy sensor (ICX424 is old and history). As for optimal f/ratio it depends on the target. Mars likes to overscale and Drizzle in processing. Saturn is dim and that's not possible with current imaging technology (doesn't bright and clean enough image at short exposures) as well disk features doesn't seems to take as much advantage as Mars does. Jupiter is somewhere in between. It can overscale/Drizzle easily but only if the seeing is perfect. At average it's better to stick to the "safe" lower max f/ratio.

[Aenima 397]

Great info - thank you for posting

Was trying to figure out the best combination of scope camera and barlow to use for planets.. haven't really used the SCT much so still theory at this point.