Please note that if you intend to use a full frame size CCD be it EOS or any other you must consider a "Wide T" mount. Using a standard bayonet fitting on a standard T2 thread will cause vignetting.
Jeremy
Ah thanks Jeremy! Televue do a wide T-ring adapter 2.4". I might have to get in touch with Televue to see what exactly I will need I think, that way no mistakes are made.
Yeah it's still fresh in my mind, still experimenting but been getting some interesting results! Very exciting times
The Cool Edge basically goes in the hole opened up when you remove the Fastar secondary mirror. This is fine if you want to cool it down quickly at the start of a session, but you have to remove it and put the secondary mirror back in place before you can do any imaging The Tempest system also do a secondary fan, same problem obviously. The more interesting ones are the Tempest fans that replace the side vents on the Edge HD tubes, as these are permanently mounted (it's only 2 little screws) and can be on while you're imaging, drawing a constant stream of air past the back of your mirror. As I've found out, just be careful if the air is moist and the temperature dropping as it'll draw moist air in there too and I've had my corrector mist up on the inside maybe I should have just had the dew heater up higher
I'll be interested on what you find for the powermate... at the moment, I use a Clicklock visual back with Televue 2" to 1.25" adapter before the 2.5x powermate... but my little camera is only the size of a 1.25" plossl
haha yes the 5D is quite a big thing in comparison to yours! I will find out. I will look into the tempest system further, for some reason I thought the Cool Edge still allowed the use of the secondary (not sure why I thought that!). I can always turn the Tempest off as well if I find the tube currents get too strong/mist builds up! Will look into that further tonight!
Yeah the Tempest you can just pull the plug, or flick the switch if you put a switch inline
Down here in Sydney I don't find the temperature drops all that fast after the major post-sunset drop, which is when I have the fan running, but having the fans is better than not as you can somewhat control the temperature inside the tube...the fans move quite a volume of air!
Yeah the Tempest you can just pull the plug, or flick the switch if you put a switch inline
Down here in Sydney I don't find the temperature drops all that fast after the major post-sunset drop, which is when I have the fan running, but having the fans is better than not as you can somewhat control the temperature inside the tube...the fans move quite a volume of air!
Sounds great Dunk thanks. I will do some breakfast reading up on the Televue stuff available as well as the Temp-est systems! So I would still need a heater with the Tempest system though wouldnt I, such as the dew shield that you use? Just making sure I understand it all!
Since the 5D is a full frame sensor I need the powermates to boost up my effective focal length to get me an equivalent resolution image to perhaps what some of the CCDs can achieve...currently I get about 20 pixels across the rings edge to edge at 580mm = about 12x magnification. With the 2350 C9.25 and 4x powermate = 9400mm = about 188x magnification, I should get about 300 pixels across on Saturn. Just my initial calcs/thoughts!
Greetings,
Here are a couple of pics taken a few nights ago, please note the relative sizes of the moon and Saturn.
Interestingly the gear has similar base specs to what you are considering:
Telescope 254mm / F10 ... 2500mm focal length ... 2.5 m
Camera EOS 5D ... pixel size = 8.4 micro-metre ... 8.4e-06 m
Moon exposure ... 1/320 s
Saturn exposure ... 1/8 s
Moon occupies 1800 arc-sec diameter
Saturn largest at 20 arc sec max.
Image scale ... 8.4e-06 / 2.5
= 3.36e-06 radians per pixel
= 57.294 x 3600 x 3.36e-06 arc sec per pixel
= 0.69 arc sec per pixel
Your thoughts and calcs are inline with what I was predicting. I should note that the 5D MK III has 6.25 micron pixels (i know previously in my replies ive just stated "5D" and not the MK III part).
So on your rig if you have 5D MK III would be 2.5 rad/pixel = 0.516 arcsec/pixel. Then 20/0.516 = 39 pixels. Then 9.4/2.5 * 39 = 146 pixels.
using the powermate 5x would yield potentially 146*1.25 = 183 pixels on the disk of Saturn. I suppose trying it out will ultimately show me how happy I am with it. No choice but to go to an expensive CCD after that which I want to avoid doing if I possibly can.
I suppose there is a limit to the magnification madness, how steady mount is, how good seeing is, scope properly cooled and collimated etc.
ive yet to figure out how the powermate installs, but pretty sure now it goes in the Edge HD visual back like an eyepiece would.
The scope will come with a visual back, but I never used mine because it secures accessories with set screws and I replaced it with the Baader visual back immediately. Astro Phyics also make a different one. The Edge 9.25 has the 3.25" threaded cell like the 11 and 14, not the 2" one that the XLT 9.25 has.
The 5x powermate is only a 1.25" device, so you'd need a 2" to 1.25" adapter. Something sturdy. The last thing you want is something that has any play in it, as that can make all the difference when you're trying to get the object on the chip at high magnification! Not sure if it's worth considering, but the 4x powermate is a 2" device, so would clamp right into a 2" visual back. This should eliminate any vignetting from the 1.25" specs, although in reality if you're planetary imaging you probably don't care about that and would be capturing just at the centre of the chip anyhow.
Then you've got your TV powermate to T-adapter.
Another gizmo worth considering is a flip mirror...part of the fun I've had is getting the object (Mars) on the chip at high magnification (1000x)...it's on my wish list
Oh and collimation... Bob's Knobs the default screws are phillips type and precarious to adjust in the dark (I could only watch, with hands over my eyes )
The scope will come with a visual back, but I never used mine because it secures accessories with set screws and I replaced it with the Baader visual back immediately. Astro Phyics also make a different one. The Edge 9.25 has the 3.25" threaded cell like the 11 and 14, not the 2" one that the XLT 9.25 has.
The 5x powermate is only a 1.25" device, so you'd need a 2" to 1.25" adapter. Something sturdy. The last thing you want is something that has any play in it, as that can make all the difference when you're trying to get the object on the chip at high magnification! Not sure if it's worth considering, but the 4x powermate is a 2" device, so would clamp right into a 2" visual back. This should eliminate any vignetting from the 1.25" specs, although in reality if you're planetary imaging you probably don't care about that and would be capturing just at the centre of the chip anyhow.
Then you've got your TV powermate to T-adapter.
Another gizmo worth considering is a flip mirror...part of the fun I've had is getting the object (Mars) on the chip at high magnification (1000x)...it's on my wish list
Oh and collimation... Bob's Knobs the default screws are phillips type and precarious to adjust in the dark (I could only watch, with hands over my eyes )
Dunk thanks for all the fantastic advice you have given!
I think you and the various articles around the place have sold me on the TEMP-est system. Think i'll go for the fastar option as well.
I got a price of $3300 for the Edge 9.25 including insured freight, which is the best price ive been able to find so far. The sales director is extremely helpful and explained their tube checking processes which all made sense.
Good point about the 2" eyepieces, I forgot about the fact that the 5x powermate is a 1.25" device. Yes I will have to decide on whether the vignetting is important to me or not. I wonder how the 1.25 vs 2 inch size difference correlates to the percentage of the image vignetted on the sensor.
I also wonder if you can stack the 2x and 4x powermates together in 2" size. That would be 18800mm equivalent lol.
Looks like flip mirror for DSLR is unnecessary, because it pretty much has one in it already! Focus through viewfinder with Bahtinov Mask (or live view) then take picture!
I also cant believe i havent heard of a Bahtinov mask before, and found an awesome generator online. Ive been struggling for years manually focusing my sigma lens on the Moon/Jupiter/Saturn .
Just checked with my local acrylic cutter, going to get one laser cut out of black acrylic for the scope (when I get it to get accurate measurements) and for my Sigma lens too! $30 flat cost for laser cutting, A3 sheet for around $10. Not bad for 2 masks.
Yeah you're right about the flip mirror - sorry! Must refrain from posting before the coffee is working
Bahtinov masks are pretty awesome, although on my DSLR I don't find it all that hard to get nice little discs of stars...the mask removes the element of ambiguity, and that appeals to the OCD side of me
The scope will come with a visual back, but I never used mine because it secures accessories with set screws and I replaced it with the Baader visual back immediately. Astro Phyics also make a different one. The Edge 9.25 has the 3.25" threaded cell like the 11 and 14, not the 2" one that the XLT 9.25 has.
I've used the Baader Visual back on a C11. FABULOUS bit of kit. Will hold anything like a vice.
I've used the Baader Visual back on a C11. FABULOUS bit of kit. Will hold anything like a vice.
Thanks Rom/Dunk, Baader Visual Back (3.25 to 2") is added to the shopping list. Might be able to get it from the same store as the OTA, will find out tomorrow!
If you try any visual you'll also want to use a diagonal, but iirc Celestron include one in the box.
For prime (f/10) you might want to consider the Celestron T-adapter for Edge HD as it gets the backfocus right when using a Canon You basically remove the visual back and it screws on the rear thread, presenting a male T-thread, see here http://www.optcorp.com/ce-93646-t-ad...ch-edgehd.html
Regarding the Nagler...beautiful piece of kit, but if you'd only be visual occasionally the ES 82 30mm is practically as good at f/10 and a fraction of the price.
The top of the Powermate unscrews and the PTR-4201 screws on instead. The standard camera T-ring screws onto the PTR-4201.
There is a version for the 2x Powermate as we'll as one that is suitable for both 2.5x and 5x Powermates. These adapters allow the Powermates to be used for imaging as designed without vignetting and at the correct magnification.
The top of the Powermate unscrews and the PTR-4201 screws on instead. The standard camera T-ring screws onto the PTR-4201.
There is a version for the 2x Powermate as we'll as one that is suitable for both 2.5x and 5x Powermates. These adapters allow the Powermates to be used for imaging as designed without vignetting and at the correct magnification.
ahh many thanks for the reply, I see now. And since the T adapter is for the 2" size it should inherently be a "wide" version! Then all I need is the canon T-ring from somewhere.
would I be correct in saying:
1) if i wanted to do prime focus id have to take out the Powermate, and get a separate Wide T ring to 2" adapter?
2) if I wanted to go back to normal visual, just remove the powermate and insert eyepiece straight into Baader visual back?
ahh many thanks for the reply, I see now. And since the T adapter is for the 2" size it should inherently be a "wide" version! Then all I need is the canon T-ring from somewhere.
would I be correct in saying:
1) if i wanted to do prime focus id have to take out the Powermate, and get a separate Wide T ring to 2" adapter?
2) if I wanted to go back to normal visual, just remove the powermate and insert eyepiece straight into Baader visual back?
1) Yes. Prime focus = T2 adapter + camera specific T-ring
2) Yes, but you may need extension tube to reach focus or a better solution is to use star diagonal for visual which also gives a more comfortable viewing angle.
Your thoughts and calcs are inline with what I was predicting. I should note that the 5D MK III has 6.25 micron pixels (i know previously in my replies ive just stated "5D" and not the MK III part).
So on your rig if you have 5D MK III would be 2.5 rad/pixel = 0.516 arcsec/pixel. Then 20/0.516 = 39 pixels. Then 9.4/2.5 * 39 = 146 pixels.
using the powermate 5x would yield potentially 146*1.25 = 183 pixels on the disk of Saturn. I suppose trying it out will ultimately show me how happy I am with it. No choice but to go to an expensive CCD after that which I want to avoid doing if I possibly can.
I suppose there is a limit to the magnification madness, how steady mount is, how good seeing is, scope properly cooled and collimated etc.
ive yet to figure out how the powermate installs, but pretty sure now it goes in the Edge HD visual back like an eyepiece would.
Sorry about the late reply just attended a meeting of the " Solar Citizens".
My camera is the EOS 5D Mk 1 ... The old one! and the scope is a Takahashi Mewlon 250CR ... A corrected version of the original Mewlon.
These calcs are correct if not simple as they say nothing about the optics or seeing etc. the main thing to note is the dimensions I've put ar the end of the lines.
I'm sure there is a limit to magnifying an image a big problem is the mount and its stability. With a focal length of 4.9 m it is a real problem keeping things steady. If the wind blows or one walks near the rig one will see movement. seeing will cause a major problem especially as the diameter increases. But for planetary ( put out a call to Mr Paul H.) for all the fine points on this specialised field.
The main thing about all this stuff is to "Do It" and you will get better and better. don't bother with overly expensive stuff ... Some of the niceest images I've taken were with an EOS 350D. if you like I can post a couple for you ... Remember the camera was an EOS 350D.
1) Yes. Prime focus = T2 adapter + camera specific T-ring
2) Yes, but you may need extension tube to reach focus or a better solution is to use star diagonal for visual which also gives a more comfortable viewing angle.
Thanks for the reply. Is a T2 adapter the notation typically used for a wide T adapter as opposed to a normal one? Just trying to understand the jargon!
EdgeHD 9.25 comes with a 2" star diagonal which slips into the 2" visual back and accepts a 2" eyepiece so all good there then!
Sorry about the late reply just attended a meeting of the " Solar Citizens".
My camera is the EOS 5D Mk 1 ... The old one! and the scope is a Takahashi Mewlon 250CR ... A corrected version of the original Mewlon.
These calcs are correct if not simple as they say nothing about the optics or seeing etc. the main thing to note is the dimensions I've put ar the end of the lines.
I'm sure there is a limit to magnifying an image a big problem is the mount and its stability. With a focal length of 4.9 m it is a real problem keeping things steady. If the wind blows or one walks near the rig one will see movement. seeing will cause a major problem especially as the diameter increases. But for planetary ( put out a call to Mr Paul H.) for all the fine points on this specialised field.
The main thing about all this stuff is to "Do It" and you will get better and better. don't bother with overly expensive stuff ... Some of the niceest images I've taken were with an EOS 350D. if you like I can post a couple for you ... Remember the camera was an EOS 350D.
Jeremy.
Thanks Jeremy.
I have the MK I as well, and love the MK III in comparison that's for sure! Since I already have the MK III thought I might as well put it to use on the telescope, hopefully I manage to get some good pictures.
I think the Losmandy G11 (with upgrades) should perform well for me.
Now something I havent thought of is the guiding, but I will talk to the G11 seller to see what is included on that front.
The Tempest system also do a secondary fan, same problem obviously. The more interesting ones are the Tempest fans that replace the side vents on the Edge HD tubes, as these are permanently mounted (it's only 2 little screws) and can be on while you're imaging, drawing a constant stream of air past the back of your mirror. As I've found out, just be careful if the air is moist and the temperature dropping as it'll draw moist air in there too and I've had my corrector mist up on the inside 
maybe I should have just had the dew heater up higher 
.
