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06-04-2012, 04:07 AM   #301
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QuoteOriginally posted by madbrain Quote
I have been interested in this for years but never took the plunge.

1)
I have a few long reach lenses :

DA 18-250 f3.5-6.3
DA 55-300 f4.0-5.8
Rokinon 800mm mirror lens f8 . Also 2x teleconverter to make it 1600mm/f16

My other shorterlenses, which are probably not as useful for astrophotography :

F50 / 1.7
Sigma 10-20
Samyang 8mm fisheye (on the way)

I have been successful taking good shots & movies of of the moon , especially with the mirror lens and a good tripod, without the need to do any stacking.

2)
I would like to also photograph galaxies & nebulas - deep sky.
I am at 700ft elevation in the bay area. I can see all the bay area lights, but there aren't too many near my house on the hill.

There is an observatory that is a 9 miles birds eye distance; 20 mile and 45 minutes drive.I have not visited it yet. It is closed at night. But this might be a better area than my house for observing if light pollution is too much of an issue.

3)
I am really unsure what equipment to get.
I believe I need a tracking mount. Is there a goto & auto tracking mount I can use with my K-r and the existing lenses above ?

4)
I wonder if the lenses I have are sufficient, or if I should also get a telescope ?
Is there a good mount I can get first that would also still work with a telescope, should Ichoose to add one later ? It would seem the alignment would be quite different- in one case the camera is attached to the mount, in other case it's thetelescope tube.

5)
How important is it to get the camera modded ? I have 2 DSLRs if it matters. My other DSLR is aCanon T3i/600D.
Surely, if you really get caught with astrophotography, you will soon want some dedicated lenses and gadgets, but I suggest that before you buy anything, you try out the lenses that you have with camera + tripod.

1)
All the lenses that you have can be used. Normally, one would prefer primes rather than zooms due to the risks of light loss, scatter and internal reflexions, but fine photos have been taken with ordinary zoom lenses. And regarding your wide(r) lenses,you may become surprised how many faint stars your 50mm f/1.7 may capture in a few seconds of exposure. Wide lenses are great for constellation and Milky Way photography. For your first experiments try ISO 1600 and an exposure time of some (275/Focal Length) seconds. I.e.: 2-3 seconds at 100mm and about 8 seconds at 35 mm.

2)
For the larger nebulae and galaxies you will need no more than about a lens in the 100 - 150mm range, but you will need fast lenses and longer exposure times and thus, some kind of tracking device.

3)
You have at least three options: a) Dedicated equatorial mounts for (smaller or larger) astronomical telescopes; b) special, portable mounts dedicated for cameras and telephoto lenses with a combined weight up to a couple of kilograms (example: Vixen Polarie Star Tracker); c) Pentax O-GPS1.


4)
Chances are that you will sooner or later want an astronomical telescope. For planets and high resolution lunar and solar detail they are a must, but not for nebulae and galaxies - and you would have to go for some large light buckets such as a large and fast Newtonian telescope. And your 800mm lens is actually more or less a smal lastronomical telescope too. But what you WILL need is software for stacking (to reduce noise and enhance detail) and some general (simple) digital imaging software for the final touches. All types of astrophotos benefit from post-processing and may appear dark and dull without to the untrained eye.

5)
I guess you are talking about removing the IR-blocking filter? For the ordinary amateur, this is not essential - just look at the photos in this thread and elsewhere in this forum!

06-04-2012, 08:07 AM   #302
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QuoteOriginally posted by madbrain Quote
I would like to also photograph galaxies & nebulas - deep sky.
I am at 700ft elevation in the bay area. I can see all the bay area lights, but there aren't too many near my house on the hill.

There is an observatory that is a 9 miles birds eye distance; 20 mile and 45 minutes drive. I have not visited it yet. It is closed at night. But this might be a better area than my house for observing if light pollution is too much of an issue.

(snip)

How important is it to get the camera modded ? I have 2 DSLRs if it matters. My other DSLR is a Canon T3i/600D.
Three quick notes for you:

As you are in the southbay, you should look up the SJAA (San Jose Astronomical Association) (San Jose Astronomical Association). You can also follow The Astronomy Connection to see what locations in the area are amateur-friendly and be aware of public star parties. I think that the SJAA even has a scope-loaner program.

As far as going to Lick Obs on Mt Hamilton, yes, it's a great place to visit, but they will kick you out after dark. Thus, you'll need to find other spots to go. That's what the TAC website will help you do. I personally go to Montebello OSP and Henry Coe SP.

As an local advantage for us in the area, Orion Telescopes has a store on De Anza in Cupertino. They have some good low cost tracking mounts that will help you support your camera for shots of the night sky.

If you are thinking about modding a camera, I'd suggest doing it to the Canon. The astronomy community has many strong tools built to support that platform. These tools are simply leaps and bounds beyond what is available for Pentax.

Last edited by smigol; 06-04-2012 at 08:11 AM. Reason: added more information
06-04-2012, 03:11 PM   #303
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Hi,

QuoteOriginally posted by smigol Quote
Three quick notes for you:

As you are in the southbay, you should look up the SJAA (San Jose Astronomical Association) (San Jose Astronomical Association). You can also follow The Astronomy Connection to see what locations in the area are amateur-friendly and be aware of public star parties. I think that the SJAA even has a scope-loaner program.
Thanks, will do ! Scope-loaner program sounds good. Mount loaner would be even better

QuoteQuote:
As far as going to Lick Obs on Mt Hamilton, yes, it's a great place to visit, but they will kick you out after dark.
I'm on the same hill as Mt Hamilton. Except 3500 ft lower. I will probably go there one of the upcoming weekends.

QuoteQuote:
Thus, you'll need to find other spots to go. That's what the TAC website will help you do. I personally go to Montebello OSP and Henry Coe SP.
I see.

QuoteQuote:
As an local advantage for us in the area, Orion Telescopes has a store on De Anza in Cupertino. They have some good low cost tracking mounts that will help you support your camera for shots of the night sky.
Thanks, I did not know that. Will definitely go there.

I still wonder about the mounts when you use a camera with a regular lens. How can it properly adjust for the varying height of the cameras, with/without grip, and varying position of the center of the lens ? That would seem to be a pretty big issue when you use auto-tracking and goto.
My mirror lens creeps a lot, too. Focus adjustments are very hard.

QuoteQuote:
If you are thinking about modding a camera, I'd suggest doing it to the Canon. The astronomy community has many strong tools built to support that platform. These tools are simply leaps and bounds beyond what is available for Pentax.
I am aware of that, sadly. I will keep that into consideration. I saw one place online that does Canon T3i mods for $200. Not sure how much it would cost for Pentax.
The T3i is 18MP vs the K-r's 12MP, and more MP may actually be better for astro to do crops.
Is there any downside to the mods ? Anything that won't work anymore ?
06-04-2012, 04:21 PM   #304
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QuoteOriginally posted by madbrain Quote
I still wonder about the mounts when you use a camera with a regular lens. How can it properly adjust for the varying height of the cameras, with/without grip, and varying position of the center of the lens ? That would seem to be a pretty big issue when you use auto-tracking and goto.
My mirror lens creeps a lot, too. Focus adjustments are very hard.



I am aware of that, sadly. I will keep that into consideration. I saw one place online that does Canon T3i mods for $200. Not sure how much it would cost for Pentax.
The T3i is 18MP vs the K-r's 12MP, and more MP may actually be better for astro to do crops.
Is there any downside to the mods ? Anything that won't work anymore ?

Regarding using a mount to track the camera questions:

The goto software doesn't need to look through the camera/telescope to assure that it is pointing in the right place -- that's what it's counting you will do. As a part of the setup, you'll be asking the mount to point to something out of its database and then you'll correct it. The software will remember this correction and incorporate the change into its next goto. After a few training points, it'll have a good idea of how to point your camera/telescope to the part of the sky you are seeking.

If you wanted to do it old-school, you can get a reflex finder (red-dot finder) to fit on the hotshoe of your camera and point it that way. You can even get a rangefinder hotshoe eyepiece to help you frame wide angle shots.

I got my K10D converted by Spencer's in Colorado. They did the job well. I had a clear glass replacement installed. This means that I can't use the camera for daytime shots unless I use a UV/IR or other filter in place. These filters are an added expense, so plan for it if you want to convert your main camera. I do still use the IR camera for studio portraits as it renders a creamy skin tone.

Regarding zoom creep, get primes. You could put gaffer tape on your zoom lens to hold it in place but using zoom lenses for astrophotos is not advisable. Star images are very demanding on lens designs and many simply can't hold up.

[edit: I realize that you were talking about your mirror lens. I'm guessing it has a focus ring rather than a focus knob. In this case, gaffer tape might still work. Note to approach focus from one direction (lifting) only. That way gravity will keep the lens against the stop and it won't slip.]

Hope this helps!


Last edited by smigol; 06-04-2012 at 04:40 PM. Reason: updated information
06-04-2012, 04:36 PM   #305
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Hi,

QuoteOriginally posted by smigol Quote
Regarding using a mount to track the camera questions:

The goto software doesn't need to look through the camera/telescope to assure that it is pointing in the right place -- that's what it's counting you will do. As a part of the setup, you'll be asking the mount to point to something out of its database and then you'll correct it. The software will remember this correction and incorporate the change into its next goto. After a few training points, it'll have a good idea of how to point your camera/telescope to the part of the sky you are seeking.
I see, thanks for the explanation ! That makes sense now.

QuoteQuote:
If you wanted to do it old-school, you can get a reflex finder (red-dot finder) to fit on the hotshoe of your camera and point it that way. You can even get a rangefinder hotshoe eyepiece to help you frame wide angle shots.
Probably don't want to go old school, that sounds harder

QuoteQuote:
I got my K10D converted by Spencer's in Colorado. They did the job well. I had a clear glass replacement installed. This means that I can't use the camera for daytime shots unless I use a UV/IR or other filter in place. These filters are an added expense, so plan for it if you want to convert your main camera. I do still use the IR camera for studio portraits as it renders a creamy skin tone.
How much did mod that cost ?
I have UV filters for almost my lenses. But not UV/IR filters.
The Canon T3i is not my main camera so it may be the one to convert.

QuoteQuote:
Regarding zoom creep, get primes. You could put gaffer tape on your zoom lens to hold it in place but using zoom lenses for astrophotos is not advisable. Star images are very demanding on lens designs and many simply can't hold up.
I wasn't talking about zoom lens creep. I was talking about a heavy prime lens. The 800mm/f8 Rokinon mirror lens is over 2 lbs. It creeps down a lot. Very hard to adjust. If you add the thin 2x teleconverter in front of it to make it 1600mm/f16, it's even harder to adjust. It's better now that I got a good T-ring for the K-r. But it is still hard. That lens does not have a tripod mount, so you have to attach the camera to the mount.
When I use my T3i with grip, and the mirror lens with the 2x TC, the lens creeps down even more.

The hardest part with the mirror lens is the focus. Getting infinity exactly really is tough. If I have to touch the focus ring, it shakes the entire picture, enough to completely get the moon out of the picture for example, where it normally fills the frame at 1600mm. The moon quickly moves out of the frame too, so a tracking mount would help for it too if I wanted to do stacked exposures. But so far I have been OK with single exposures.
06-04-2012, 04:54 PM   #306
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QuoteOriginally posted by madbrain Quote
Hi,
I wasn't talking about zoom lens creep. I was talking about a heavy prime lens. The 800mm/f8 Rokinon mirror lens is over 2 lbs. It creeps down a lot. Very hard to adjust. If you add the thin 2x teleconverter in front of it to make it 1600mm/f16, it's even harder to adjust. It's better now that I got a good T-ring for the K-r. But it is still hard. That lens does not have a tripod mount, so you have to attach the camera to the mount.
When I use my T3i with grip, and the mirror lens with the 2x TC, the lens creeps down even more.

The hardest part with the mirror lens is the focus. Getting infinity exactly really is tough. If I have to touch the focus ring, it shakes the entire picture, enough to completely get the moon out of the picture for example, where it normally fills the frame at 1600mm. The moon quickly moves out of the frame too, so a tracking mount would help for it too if I wanted to do stacked exposures. But so far I have been OK with single exposures.
Two quick points:

Attaching a lens that doesn't have a mounting ring can be as simple as making a cradle out of some cut plywood and a ring clamp or you could get a device like I have:




There are other systems, including guide scope rings that might work well for an astrophoto setup.

Achieving critical focus with a lens is also a challenge, covered in this thread as well as other threads in the Astrophotography social group on this forum. For your lens, you can do something now that costs little money.

You can make a hartman mask (a screen that goes in front of the lens that has two holes in it). Arrange it so that the two holes are north and south and then point the camera/lens at the sky, at a bright star moving along the celestial equator. As you take pictures - 10-20 second exposures - rack the focus closer and closer to sharpness. You'll see the two star trails merge to one and then diverge into two again. When they are merged the lens is at infinity focus. Mark this point and note the temperature. Expect that you'll need to refocus every 10 degrees temperature shift.

There are other ways to get sharper focus. You can read up on Bahtinov masks and make one for yourself, too. These latter masks require a tracking setup, though.

With these steps, you should be able to get great, sharp pictures of the moon even without tracking. Just use the mirror lockup/time delay feature and plan for the movement of the moon in the frame.
06-04-2012, 05:31 PM   #307
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Stephen,

QuoteOriginally posted by smigol Quote
Two quick points:

Attaching a lens that doesn't have a mounting ring can be as simple as making a cradle out of some cut plywood and a ring clamp or you could get a device like I have:




There are other systems, including guide scope rings that might work well for an astrophoto setup.
Thanks, this is immensely helpful ! It looks like a great setup, and it is quite affordable too !
Only thing is that apparently the minimum distance from lens to head is 200mm. The mirror lens is 5.68in max (depends on focus) which is only 144 mm.
I am not sure how much distance the camera would add in front exactly. But it may be less than 56mm.
One possibility to solve that would be to use a lens hood. I don't have one for my mirror lens yet.
Do you think it is a good idea to use one for astrophotography to block side light ? Or would it detract too much ?

It's also unclear from the specs what the height requirements are. If I setup the camera with the grip, it would raise it significantly. How high can the front lens support be raised ?

Also, how easy is it to turn the focus ring with that rig ?

QuoteQuote:
You can make a hartman mask (a screen that goes in front of the lens that has two holes in it). Arrange it so that the two holes are north and south and then point the camera/lens at the sky, at a bright star moving along the celestial equator. As you take pictures - 10-20 second exposures - rack the focus closer and closer to sharpness. You'll see the two star trails merge to one and then diverge into two again. When they are merged the lens is at infinity focus. Mark this point and note the temperature. Expect that you'll need to refocus every 10 degrees temperature shift.
Thanks, very informative. How long does that focusing process usually take once you are experienced ?

QuoteQuote:
With these steps, you should be able to get great, sharp pictures of the moon even without tracking. Just use the mirror lockup/time delay feature and plan for the movement of the moon in the frame.
Edit: I'm already using mirror lockup. I have been shooting with the wireless remote and 3 second delay on the K-r. Sadly, no cable release on it unlike my old K200D. The T3i does have cable release. From my balcony, the wireless remote works better though, since my own footsteps shake the whole rig. Delay allows me to move back and by the time a few seconds elapsed, the mount is stable again.

I believe already have some decent ones. Just not sure how much better I can nail the focus than I already have.

See this short moon movie : https://www.pentaxforums.com/forums/pentax-video-hdslrs/188276-moon-short.html#post1976295 . Not as sharp as I like, but the TC really seems to lose sharpness.

Also :
https://www.pentaxforums.com/forums/lens-clubs/71775-mirror-lens-club-40.html#post1972893

Last edited by madbrain; 06-04-2012 at 05:38 PM.
06-04-2012, 06:15 PM   #308
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QuoteOriginally posted by madbrain Quote
Stephen,
One possibility to solve that would be to use a lens hood. I don't have one for my mirror lens yet.
Do you think it is a good idea to use one for astrophotography to block side light ? Or would it detract too much ?
Dew is the enemy of astrophotography. A lens hood goes a long way to minimizing its formation.

06-04-2012, 06:31 PM   #309
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QuoteOriginally posted by pixelsaurus Quote
Dew is the enemy of astrophotography. A lens hood goes a long way to minimizing its formation.
Thanks ! I was afraid one might detract from light collection and picture quality.

I have a choice of two hoods for my lens.

One is metal and cheap but won't fold back on the lens.

Sonia Metal 105mm 105 Tele Telephoto Lens Hood Shade | eBay

It's threaded on both sides though, allowing for filters to be put on either side. I suppose to prevent dew, filters should be on the back, not front.

The other is pricey, but folds back since it's wider, and also longer and specifically made for the lens :
Samyang 105mm Tele Lens Hood for 800mm f/8.0 Mirror Telephoto Lens | eBay

The second is apparently not threaded in the front, so I probably would have to put filters between the lens and hood. But this might be the best way, anyway.

Are any filters recommended for astrophotography ? Or should UV & polarizer be banned ?
06-04-2012, 10:31 PM   #310
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QuoteOriginally posted by madbrain Quote
Thanks ! I was afraid one might detract from light collection and picture quality.

I have a choice of two hoods for my lens.
Are any filters recommended for astrophotography ? Or should UV & polarizer be banned ?
You have another choice of material for a hood for astrophoto use:
I went to Michaels and bought some pieces of craft foam - they come in sheets about 11x17 for a buck or less. A couple of sheets of black foam either stapled together or using rubber cement and some well placed velcro and you've got a hood that stores flat, absorbs dew, and can be used as a scrim when you're shooting with flash.

I use a hood nearly every time I go out. Even though my refractor already has a dew shield and I use dew heater straps, sometimes there's just too much stray light and I'll put the hood on the setup.

Regarding filters for astronomy, you'll do well to understand how light pollution comes about. In the southbay most light pollution is in the form of orange sodium light although that is slowly changing with the night time light wars of the parking lots. With a good blocking filter you can keep the skyglow at bay and get some decent exposures. Even better if you can get out of town and point away from the light domes.

I use three kinds of filters:
For prime-focus photography where the camera is attached to the scope directly, I use a Baader moon and skyglow filter that's a neodymium material (look on B&H for red-enhancing filters). This is a gentle skyglow filter that does a good job of rejecting the UV and deep IR that will cloud my full spectrum camera and does a decent job of knocking down the local light pollution.

When I use a prime on the sky and still need light pollution control, I'll put an IDAS LPS type 2 on the front of the lens. This works wonders to control purple fringe for undercorrected lenses. Will not work on wide angle lenses.

When I am in the luxury of not having pollution effects, I will either not use a filter at all or I will use a high quality UV/IR filter. This does control purple fringe effects. Again, this is only when I use older lenses on the full spectrum modified camera.

Polarizers are not useful for astrophotos unless you need to stop down the intensity of the moonlight.

You also asked about whether the cradle device (the Manfrotto 293) can handle a shorter lens setup. This webpage shows how one fellow uses it: Manfrotto 293 Telephoto Lens Support Review

For my purposes, I can still rack the focus on the 300mm lens just fine. There is a little binding, but once I have found infinity focus, I'm not touching it anymore. Because the lens support does not change in height, I do have some challenges making sure that a guide scope and the camera point in the same direction, but this is not usually a big deal. It's important to note that the camera is mounted on a swivel so that the angle of the camera axis to the baseplate changes with the diameter of the lens.

It's really hard to see in this shot. I have the camera mounted side by side with a guide scope.




You also asked about how long it takes to focus. For me, when I'm shooting the stars, the process takes about 5-10 minutes depending on the process I'm using. Remember, I use a tracking mount, so I have time on my side to get pinpoint stars. Thus, I use a bahtinov mask.

For using the hartman mask method I noted earlier, expect to take 30 minutes or more just experimenting. It's something that you can do any night you can see a bright star so even a full moon doesn't stop you.

Last edited by smigol; 06-05-2012 at 12:05 AM. Reason: added more information
06-05-2012, 05:20 AM   #311
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QuoteOriginally posted by smigol Quote
You have another choice of material for a hood for astrophoto use:
I went to Michaels and bought some pieces of craft foam - they come in sheets about 11x17 for a buck or less. A couple of sheets of black foam either stapled together or using rubber cement and some well placed velcro and you've got a hood that stores flat, absorbs dew, and can be used as a scrim when you're shooting with flash.

I use a hood nearly every time I go out. Even though my refractor already has a dew shield and I use dew heater straps, sometimes there's just too much stray light and I'll put the hood on the setup.
Thanks. I will keep this option in mind when I get a real telescope. For now I ordered the $15 3" metal hood for my mirror lens.

QuoteQuote:
Regarding filters for astronomy, you'll do well to understand how light pollution comes about. In the southbay most light pollution is in the form of orange sodium light although that is slowly changing with the night time light wars of the parking lots.
Yes, I started reading about this on the Lick Mill website over the weekend.

QuoteQuote:
With a good blocking filter you can keep the skyglow at bay and get some decent exposures. Even better if you can get out of town and point away from the light domes.
Right, but getting out of town involves more time and luck with weather, not something I will likely do as often.

QuoteQuote:
I use three kinds of filters:
For prime-focus photography where the camera is attached to the scope directly, I use a Baader moon and skyglow filter that's a neodymium material (look on B&H for red-enhancing filters). This is a gentle skyglow filter that does a good job of rejecting the UV and deep IR that will cloud my full spectrum camera and does a decent job of knocking down the local light pollution.

When I use a prime on the sky and still need light pollution control, I'll put an IDAS LPS type 2 on the front of the lens. This works wonders to control purple fringe for undercorrected lenses. Will not work on wide angle lenses.

When I am in the luxury of not having pollution effects, I will either not use a filter at all or I will use a high quality UV/IR filter. This does control purple fringe effects. Again, this is only when I use older lenses on the full spectrum modified camera.
Thanks for the great info on this once again!

QuoteQuote:
Polarizers are not useful for astrophotos unless you need to stop down the intensity of the moonlight.
That's what I thought , just confirming.

QuoteQuote:
You also asked about whether the cradle device (the Manfrotto 293) can handle a shorter lens setup. This webpage shows how one fellow uses it: Manfrotto 293 Telephoto Lens Support Review
I actually found that page by googling for reviews earlier, and ordered the mount on Amazon based on that.
I may not have to reverse the plate if I use the 2x TC but it's good to know that it's an option.

QuoteQuote:
It's important to note that the camera is mounted on a swivel so that the angle of the camera axis to the baseplate changes with the diameter of the lens.
Yes, I understand that part, without this adjustment the mount would only work with a very limited of cameras & lenses. Presumably this is just an up/down swivel, with no horizontal adjustment, right ?

QuoteQuote:
It's really hard to see in this shot. I have the camera mounted side by side with a guide scope.
Thanks - but I couldn't quite tell.
06-05-2012, 08:29 PM   #312
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Hi Stephen,

QuoteOriginally posted by smigol Quote
Three quick notes for you:
As an local advantage for us in the area, Orion Telescopes has a store on De Anza in Cupertino. They have some good low cost tracking mounts that will help you support your camera for shots of the night sky.
I stopped at the Orion store this afternoon after I went to buy a used camera bag in Cupertino that can hold both of my DSLRs.

Pretty nice store. They had a few of the telescopes out in the parking lot, looking at the sun. Venus was not in front of the sun yet, though.

The mounts are not that inexpensive The cheapest one is the Skyview Pro at $850 . Max weight is 20 lbs however, which may not cut it if I want to switch to a nice telescope tube later on.

They had the CPC 800 and CPC 925 in the store. Those look pretty impressive. But the weight of the OTA alone are listed at 42 and 58 lbs respectively ! I guess if I want a Celestron, I have to spend the big bucks all at once and buy their combo. But the CPC mounts didn't look like they would accommodate anything other than the scope.

Seems like Celestron has some lighter OTAs standalone too, but Orion doesn't sell them.

Lots to think about now
06-05-2012, 11:42 PM   #313
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As was said to me recently:
"Sadly the truth about this hobby is you can spend far less time and frustration
if you shell out more money. You do get what you pay for and shed a lot of
frustration..."

Look at the used market, too. Check astromart and cloudynights.
I look at the marketplace here for the right primes to fill out my own collection!
06-06-2012, 09:05 AM   #314
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I was reminded of this by Smigol's shot of his Manfrotto support. It's a post I originally sent to Camera-enthusiast.com which might be of interest in the current thread.

This is an inexpensive answer to a known problem; when you put a long lens on your slr the world starts to wobble. The answer, if we are to believe those with glossy sites on t'interweb, is just to throw about 250 at it and buy a beautifully and expensively engineered specialist bracket. My answer is just as effective and appeals to me as a Scot living in Yorkshire - I'm assured they don't come much tighter!
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06-06-2012, 05:33 PM   #315
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QuoteOriginally posted by The Jannie Quote
I was reminded of this by Smigol's shot of his Manfrotto support. It's a post I originally sent to Camera-enthusiast.com which might be of interest in the current thread.

This is an inexpensive answer to a known problem; when you put a long lens on your slr the world starts to wobble. The answer, if we are to believe those with glossy sites on t'interweb, is just to throw about 250 at it and buy a beautifully and expensively engineered specialist bracket. My answer is just as effective and appeals to me as a Scot living in Yorkshire - I'm assured they don't come much tighter!
Thanks. Looks nice and cheap
However, a cheap macro slide on ebay was only 215g , or 0.5 lbs . I don't think that's good enough to hold the camera + mirror lens which are over 3 lbs. The mirror lens alone is 2.1 lbs.
The Manfrotto is 1.54 lbs and rated for a load capacity of 5.51 lbs also which is perfect and allows some room to add the TC and lens hood.

The Manfrotto 293 was only $65 shipped on Amazon . It is really not all that expensive, certainly not compared to the prices of anything related to astrophotography like mounts .
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