#61  
Old 11-10-2011, 10:41 AM
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Originally Posted by gregbradley View Post
That M45 is only 1 hour and 10 minutes - look how deep it is!
That scope shows tremendous promise.

Yes that is definitely coma in the corners. Bummer. Its either a spacing issue or the corrected circle is not as wide as they thought.

Greg.
Yeah, but if I double that exposure to 2h 20min with my f/5 FSQ, I'll blow that one away with better star images out to the corners, and by applying my 11 herbs and spices to the processing, the image would be spectacular. I don't think the RH200 has more than a 60mm image circle. It may be more like 50mm. Compare that to the 80mm image circle that more than covers the 16803 array. So we shall see. I do want to try before buy. Hopefully Geno, Geno, and Geno will be at AIC this year.


jg
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  #62  
Old 11-10-2011, 04:01 PM
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Here is the top left corner of the RH200 image of the Veil Nebula with an image of Martin Pugh's in an animated gif

http://d1355990.i49.quadrahosting.co..._09/RH200_.gif

Martins full res image can be seen here with all details.

http://www.iceinspace.com.au/forum/s...t=65297&page=2

It is just a spacing/alignment issue?

By the way try three times the exposure John and you would be closer.

Bert
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  #63  
Old 11-10-2011, 04:47 PM
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That's pretty telling Bert

Don't worry...I'm quietly confident you're on a winner

8" at F3....veeeery attractive like a 1970/80's Celestron Schmidt for the 21st century - potentially the ultimate imaging machine.

Mike
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  #64  
Old 11-10-2011, 05:08 PM
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Originally Posted by strongmanmike View Post
That's pretty telling Bert

Don't worry...I'm quietly confident you're on a winner

8" at F3....veeeery attractive like a 1970/80's Celestron Schmidt for the 21st century - potentially the ultimate imaging machine.

Mike
Yes Mike to match this speed an FSQ of 530mm FL would have to have an aperture of 176mm!

I am well aware there is no 'perfect' optic, you get the one for the images you are interested in.

Only time will tell.

Bert
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  #65  
Old 12-10-2011, 07:31 AM
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The primary rear mirror on the RH200 is adjustable for collimation by three bolts. These just simply are turned for any adjustment. No locking needed.

The rear plate is adjustable so that the sensor plane can be made orthogonal to the optic axis.

Unless these adjustments are done reiteratively by pixel peeping at the corners of test images any misalignment will appear as 'coma'.

These adjustments will be far easier with a sensor 36.8mm square.

Bert
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  #66  
Old 13-10-2011, 03:03 PM
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Quote:
Originally Posted by avandonk View Post
Here is the top left corner of the RH200 image of the Veil Nebula with an image of Martin Pugh's in an animated gif

http://d1355990.i49.quadrahosting.co..._09/RH200_.gif

Martins full res image can be seen here with all details.

http://www.iceinspace.com.au/forum/s...t=65297&page=2

It is just a spacing/alignment issue?

By the way try three times the exposure John and you would be closer.

Bert
I don't go with that assumption given the large central obstruction and light loss on each reflective surface.
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  #67  
Old 14-10-2011, 07:32 AM
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John, I think Bert is right. I remember Richard Crisp posting Tak Epsilon 180ED F2.8 images and same with FSQ106 images of the same object.

It required something like 3-4 times more exposure in the FSQ to match but to my eye the FSQ images looked better as they were finer.
Its probably on his website somewhere.

With regards to coma in images in the RH200:

Massimo Riccardi responded to a post I made about the images showing coma.

He said that it wasn't coma and was caused by the imager using 50mm round filters which partially block the sharp F3 light cone affecting corner stars.

So I guess that question of the corner stars is up in the air until someone produces an image using 50mm square filters (I assume when he says 2 inch filters he means 2 inch round).

By the way Bert he said it was designed to handle 24 x 36mm cameras.

I am not sure how that works with the 16803 which requires a 52mm diagonal of corrected circle. 24 x 36mm is a 44mm diagonal. So some corner problems may occur which can be handled by cropping the image or by using a smaller chip like 11002 or similar. I'd stick with the 16803 and crop if needed as the 16803 is such a super chip and if you use it with anything else (like your Canon lens) it will be worth the extra chip real estate.

Here is his post:

Greg,

as it often happens dealers can make mistakes on their advertising.
It's the bigger Veloce RH 300 F/3 covering about 60 mm field.
On the contrary I designed the smaller 200mm F/3 for covering the full 24x36mm
format.
For 600mm focal lenght the 43 mm diagonal corresponds to 4 degrees which is just
the field covered by this instrument.

About the coma you mention it is not coma.
I hope Giovanni Paglioli (the astroimager)will post here the explanation but
from what he told me what looks like "coma" is due to the 2" filters size which
is not enough for covering the large F/3 beam reaching the focal plane and this
fact "cut" the stars at the edges.
Without filters this doesn't happens.
I'm not an expert in this field and Giovanni will give you a deeper
explanation.

Massimo


Greg.

Last edited by gregbradley; 14-10-2011 at 07:44 AM.
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  #68  
Old 14-10-2011, 09:56 AM
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Greg it is a moot point what can and cannot be achieved with this astrograph and sensor. I feel confident enough that the PL16803 and RH200 with 50mm square filters will give me a field that is of high enough quality to make large mosaics relatively quickly. The edges can be used for alignment and then discarded or averaged.

Trimming the entrance aperture is also an option to increase the 'perfect' field. There is enough excess speed to make this practical. There will be an optimum aperture to compromise for all elements of the image train.

My best guess is the system would be equivalent to a 150mm+ diameter FSQ.

Only by actually doing this will we know for sure. All the rest is conjecture.

Bert
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  #69  
Old 14-10-2011, 11:24 AM
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That's true Bert.

Greg.
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Old 14-10-2011, 03:46 PM
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Quote:
Originally Posted by strongmanmike View Post
That's pretty telling Bert

Don't worry...I'm quietly confident you're on a winner

8" at F3....veeeery attractive like a 1970/80's Celestron Schmidt for the 21st century - potentially the ultimate imaging machine.

Mike
I am of the same opinion. The images I have seen so far around the traps suggest very tight stars on large sensors.
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  #71  
Old 14-10-2011, 04:53 PM
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We will soon find out!
I for one can't wait to see how the new piece of equipment goes.
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  #72  
Old 22-10-2011, 07:58 AM
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Quote:
Originally Posted by gregbradley View Post
John, I think Bert is right. I remember Richard Crisp posting Tak Epsilon 180ED F2.8 images and same with FSQ106 images of the same object.

It required something like 3-4 times more exposure in the FSQ to match but to my eye the FSQ images looked better as they were finer.
Its probably on his website somewhere.

With regards to coma in images in the RH200:

Massimo Riccardi responded to a post I made about the images showing coma.

He said that it wasn't coma and was caused by the imager using 50mm round filters which partially block the sharp F3 light cone affecting corner stars.

So I guess that question of the corner stars is up in the air until someone produces an image using 50mm square filters (I assume when he says 2 inch filters he means 2 inch round).

By the way Bert he said it was designed to handle 24 x 36mm cameras.

I am not sure how that works with the 16803 which requires a 52mm diagonal of corrected circle. 24 x 36mm is a 44mm diagonal. So some corner problems may occur which can be handled by cropping the image or by using a smaller chip like 11002 or similar. I'd stick with the 16803 and crop if needed as the 16803 is such a super chip and if you use it with anything else (like your Canon lens) it will be worth the extra chip real estate.

Here is his post:

Greg,

as it often happens dealers can make mistakes on their advertising.
It's the bigger Veloce RH 300 F/3 covering about 60 mm field.
On the contrary I designed the smaller 200mm F/3 for covering the full 24x36mm
format.
For 600mm focal lenght the 43 mm diagonal corresponds to 4 degrees which is just
the field covered by this instrument.

About the coma you mention it is not coma.
I hope Giovanni Paglioli (the astroimager)will post here the explanation but
from what he told me what looks like "coma" is due to the 2" filters size which
is not enough for covering the large F/3 beam reaching the focal plane and this
fact "cut" the stars at the edges.
Without filters this doesn't happens.
I'm not an expert in this field and Giovanni will give you a deeper
explanation.

Massimo


Greg.

yes you are right about aperture winning over the FSQ. My comments were in a refractory biased haze. We'll just have to see how this all pans out.
I do have an AP RH 400 on order if the little RH 200 does not work out.
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  #73  
Old 22-10-2011, 08:03 AM
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yes you are right about aperture winning over the FSQ. My comments were in a refractory biased haze. We'll just have to see how this all pans out.
I do have an AP RH 400 on order if the little RH 200 does not work out.
Don't we all have an AP RH 400 on order!

Greg.
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  #74  
Old 22-10-2011, 08:22 AM
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Don't we all have an AP RH 400 on order!

Greg.
yes, which makes me believe I will probably get my notification in 2016
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  #75  
Old 02-12-2011, 04:12 PM
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Just an update. I have the FLI camera and ten position filter wheel and the Astrodon Filters arrived today. I did order the 3nm NB filters HA O3 and Si and LRGB. I did not know that the tax department knew about levying 10% on things they barely understand.

The optic RH200 should arrive when the red colour is perfect.

The PMX will arrive some time down the track.

Bert
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  #76  
Old 02-12-2011, 06:05 PM
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Originally Posted by avandonk View Post
Just an update. I have the FLI camera and ten position filter wheel and the Astrodon Filters arrived today. I did order the 3nm NB filters HA O3 and Si and LRGB. I did not know that the tax department knew about levying 10% on things they barely understand.

The optic RH200 should arrive when the red colour is perfect.

The PMX will arrive some time down the track.

Bert
Oh dear, 3nm filters with f3 optics ?. That might be a problem, have you looked into that Bert ?
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  #77  
Old 03-12-2011, 10:17 AM
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Yes Fred see further down on this page

http://www.astrodon.com/Orphan/astro...arrowband/#h10


What About Using Narrowband Filters with Faster Optics?


Bert
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  #78  
Old 03-12-2011, 12:42 PM
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Ah, ok then. Whew !
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  #79  
Old 15-12-2011, 08:05 PM
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Bert
Just a heads-up in that sky and telescope has an image of comet 45p/Honda-mtkos-pajdusakova in it's gallery section tahen with the ASA 8" f3 astrograph. While not a large photo is certainly looks the goods and a 24 minute shot really shines with detail in the comet and stars.
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