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Mounting a 150-600mm lens to an equatorial mount.

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#1 mjh410

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Posted 13 January 2021 - 10:15 AM

I have quite a lot of camera gear already and I would like to get into the field of AP. I have done some reading and the general consensus is the mount is probably most important. I cannot afford a good mount and a scope all at once so I am looking into using my camera gear with a good mount until such a time that I can get an 80mm triplet refractor to go with it. I have seen quite a few good images taken with Sigma or Tamron 150-600mm lenses and seeing as how I already own the camera gear I figured this would be the best entry into the field of AP until I can get a scope to go with the mount. The next step after the scope would be getting a dedicated AP CCD or CMOS camera with cooling. 

 

For visual observing I have recently gotten a 12" dob so I have that covered for now. Imaging is really where I want to get to though. I guess I should mention that I want to be able to shoot DSO's. I would like to be able to shoot planetary, but there's only so many planets to shoot and I'd rather have the ability to search for and shoot dozens and dozens of things in the night sky. So at this time I would prefer to primarily set up for nebulas and galaxies and if I can manage some planetary with what I have or get then great.

 

Here is the gear I have:

 

Nikon D7200 crop sensor camera

Nikon D850 full frame camera

Tamron 150 - 600mm G2 f5 - 6.3

Tamron 24-70mm G2 f2.8

Tamron 70 - 200mm G2 f2.8

Tokina AT-X Pro DX 11-20mm f2.8 (For dx crop sensor camera only)

 

1 - First off, is the Atlas II EQ-G Equatorial Go To mount a good long term mount? With the idea of moving to a triplet 80mm possibly as large as a 127mm or so refractor?

 

2 - Can I attach my camera and 150-600mm lens to this mount and use it for tracking? I think tracking is the correct word, I have also seen mention of guiding.

 

3 - Assuming it will attach, how do I attach it? I assume it doesn't have a simple plate to accept the mounting bracket on the lens that I use when attaching it to my gimbal head for wildlife photography.

 

Thanks for your assistance.



#2 rgsalinger

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Posted 13 January 2021 - 10:34 AM

I suggest buy a book - the Deep Sky Imaging Primer by Charles Bracken as the best way to learn about DSO imaging. Your lenses are not appropriate for planetary imaging as you will be nowhere near the optimal image scales for planets, even with the dobsonian scope that you own. 

 

You can never buy too much mount until you get to the point where it's too big for you to carry it around. Mounts with greater capacity and better build quality pay back by being more reliable and often more performant.

If you have the budget the minimum mount that I would recommend is the EQ6R for around 1500 USD. That will hold you for a very long time. 

 

Rgrds-Ross



#3 Raginar

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Posted 13 January 2021 - 10:36 AM

I just screw it to the lens via a camera adapter on a d-plate (losmandy and a few others do it).  For the rest of your lenses just use the camera adapter.  You can 3d print some rings too (they're on thingiverse).

 

You'd want another camera to do guiding with these... probably cheaper to buy a guide camera and a small guidescope.

 

I have your exact setup and alot of those lenses.  


Edited by Raginar, 13 January 2021 - 10:37 AM.


#4 BIGBOB70

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Posted 13 January 2021 - 10:55 AM

Camera lens may not give you the very best pictures; but they are great for learning astrophotography processes and procedures, without spending alot of money. 



#5 Kendahl

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Posted 13 January 2021 - 03:08 PM

The Atlas has a longstanding good reputation. So do Celestron mounts with similar payload capacity. My only criticism of them is their weight which is about 40 pounds not counting the tripod. That's more than I (or my back) want to handle. Therefore, I bought an iOptron iEQ45 because it weighs less than 30 pounds. Note that, for mounts in this price range, the payload rating is for visual observing. Drop this by 30% to 50% for photography. That is, you shouldn't put more than 20 to 25 pounds on a mount rated for 40.

 

DSLRs have a 1/4-20 threaded hole in the bottom of the body to attach the camera to a tripod. You can buy a short dovetail and put a short screw through it for the camera. The dovetail fits into the saddle on your mount. Although I don't have any lenses heavy enough to require mounting the lens on a tripod instead of the camera body, I expect they have 1/4-20 threaded holes, too. If you have woodworking skills and equipment, you can make your own dovetail out of a piece of 1x2. Trim the sides at a 15° angle and drill a 1/4" clearance hole.

 

I built this fixture out of oak to mount my Canon T3i on my iEQ45. The camera and red dot finder are screwed to the cross piece. There are two dovetails, one on the bottom and one on the side, to provide two camera orientations. I'm thinking about building another one, with a wider cross piece, to carry a guide scope instead of the finder.

 

Jig 1 CN.JPG Jig 2 CN.JPG

 

The two little blocks on the cross piece (One is hidden by the lens.) keep the camera body from rotating. The cross piece is narrower to the right of the bottom dovetail to provide access to the camera's battery compartment. A mistake during construction was the location of the rear wood screw that holds the bottom dovetail to the cross piece. It interferes with the 1/4-20 screw for the camera. Locating it farther forward would have let me use a countersunk flathead screw for the camera. As it is, the protruding screw head limits where I can position the dovetail in the mount saddle.


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#6 mjh410

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Posted 13 January 2021 - 04:21 PM

Thank you everyone who has responded I appreciate all info. I know I have a lot to learn and I know my current lenses are not ideal for all types of AP, however as I stated in my post I figured why not use what I have and get a good quality mount and tripod now. I can later add on a telescope to replace my 150-600mm lens for AP and even later replace my camera with a dedicated AP camera. I just didn't want to purchase a $1500 - $1700 mount and tripod and have it not work with my camera and lens. Now that I know for sure I can either built a mounting plate or buy a plate to attach to the 1/4" threaded holes on my gear I am confident that I can do what I want and begin learning more about AP while I await the funding to get more equipment.

 

Raginar and Kendahl thank you for the info this is exactly what I have been trying to figure out and I think I just made it more complicated than it had to be. I'm used to my camera gear and I have everything set up with arca swill mounts and I haven't found much in the way of arca swiss in telescopes or astrophotography. I didn't think about simply using the 1/4" threaded holes in the rail/mount on my 150-600 lens to attach a d-style or v-style rail to attach to a telescope mounting plate.

 

Kendahl - thanks for the images, something like that is not a bad idea actually. I am a high school teacher currently teaching some CAD,  Web Development, and Wood Shop classes for high school students. I am working on moving into the computer lab full time and having someone else take over the shop full time, but for now I do have access to the shop and I have all the tools and lumber to make such a rig. The pictures were helpful.



#7 chanrobi

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Posted 13 January 2021 - 07:56 PM

The Atlas has a longstanding good reputation. So do Celestron mounts with similar payload capacity. My only criticism of them is their weight which is about 40 pounds not counting the tripod. That's more than I (or my back) want to handle. Therefore, I bought an iOptron iEQ45 because it weighs less than 30 pounds. Note that, for mounts in this price range, the payload rating is for visual observing. Drop this by 30% to 50% for photography. That is, you shouldn't put more than 20 to 25 pounds on a mount rated for 40.

 

DSLRs have a 1/4-20 threaded hole in the bottom of the body to attach the camera to a tripod. You can buy a short dovetail and put a short screw through it for the camera. The dovetail fits into the saddle on your mount. Although I don't have any lenses heavy enough to require mounting the lens on a tripod instead of the camera body, I expect they have 1/4-20 threaded holes, too. If you have woodworking skills and equipment, you can make your own dovetail out of a piece of 1x2. Trim the sides at a 15° angle and drill a 1/4" clearance hole.

 

I built this fixture out of oak to mount my Canon T3i on my iEQ45. The camera and red dot finder are screwed to the cross piece. There are two dovetails, one on the bottom and one on the side, to provide two camera orientations. I'm thinking about building another one, with a wider cross piece, to carry a guide scope instead of the finder.

 

attachicon.gifJig 1 CN.JPGattachicon.gifJig 2 CN.JPG

 

The two little blocks on the cross piece (One is hidden by the lens.) keep the camera body from rotating. The cross piece is narrower to the right of the bottom dovetail to provide access to the camera's battery compartment. A mistake during construction was the location of the rear wood screw that holds the bottom dovetail to the cross piece. It interferes with the 1/4-20 screw for the camera. Locating it farther forward would have let me use a countersunk flathead screw for the camera. As it is, the protruding screw head limits where I can position the dovetail in the mount saddle.

Even better solution is to mount a green laser directly to the DSLR and eliminate half the bulk.

 

Bonus you don't need to contort yourself to look through a red dot



#8 RogerM

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Posted 13 January 2021 - 10:09 PM

Matt,

 

However method and mount that you pursue I would like to recommend that you carefully check your lens collar for that 150-600mm lens.  My Nikon 80-400mm F4.5 weighs about 3/4 of that Tamron and I needed to replace the collar on my lens.  There was just too much play in the collar that caused star elongation with the slightest breeze.  I went with this collar and the results were immediately obvious that it was the right thing to do.



#9 mjh410

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Posted 13 January 2021 - 11:04 PM

Matt,

 

However method and mount that you pursue I would like to recommend that you carefully check your lens collar for that 150-600mm lens.  My Nikon 80-400mm F4.5 weighs about 3/4 of that Tamron and I needed to replace the collar on my lens.  There was just too much play in the collar that caused star elongation with the slightest breeze.  I went with this collar and the results were immediately obvious that it was the right thing to do.

Thank you I will keep that in mind. I have not yet done any DSO images with that lens but I have used it for birds and the moon while mounted on my gimbal head and tripod. I have not noticed any play in the collar at all. I also have not ever removed or adjusted it's position from where it was from the manufacturer. 

Nevertheless I added the collar you linked to an Amazon wish list as a reminder if I do find it has some play down the road, thanks again.


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#10 Andynator

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Posted 14 January 2021 - 12:38 AM

https://www.aliexpre...2950635942.html

There are many of these on Ali Express in different sizes; I use a 120mm ring with my Rokinon 135mm lens.

#11 michaelwriting

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Posted 16 January 2021 - 01:05 AM

Check out Peter Zelinka videos and website. He is using a lot of the same camera gear that you have (Nikons, 150-600, etc), and he gets some really great results. I'm working my way through his deep space course right now, but he also has a lot of stuff free on his site and on youtube. And he does it all on a little skyguider tracker.


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