Go Back   IceInSpace > Equipment > Astrophotography and Imaging Equipment and Discussions

Reply
 
Thread Tools Rate Thread
  #1  
Old 31-07-2008, 12:28 AM
AlexN's Avatar
AlexN
Tunnel Vision

AlexN is offline
 
Join Date: Mar 2008
Location: Brisbane, Australia
Posts: 6,708
How do people mount/piggyback heavy DSLR Lenses?

I just got a 300mm F/2.8 lens on monday, And I've been at a bit of a loss as to how to mount it to my EQ6 Pro for some astro-snaps. With my 70-200 I just used the piggyback adapter on the top of the rings of my 6" refractor, however, due to the enormous weight in the 300mm, if i do that, when the mount rotates on the RA axis, the camera instantly just spins on its tripod colar and points straight towards the ground...

I was thinking of making an adapter out of some aluminum that would support around the sides of the colar that would prohibit rotation.. but thought I'd ask what other people do before I jump in the deep end...

Cheers.
Alex
Reply With Quote
  #2  
Old 31-07-2008, 12:42 AM
Ian Robinson
Registered User

Ian Robinson is offline
 
Join Date: Jan 2007
Location: Gateshead
Posts: 2,205
a) Try mounting it underneith the dovetail bar as close as possible to your fulcrum , and rebalancing the mount.

b) Another option is to get counterweight bar camera adapter and utilising the lens and camera (weight) as a counterweight.

c) Or , to make a side=by=side arrangement to sit ontop the head with the lens and OTA next to each other.

I'd so a or c .... keeps the lever arm very short.
Reply With Quote
  #3  
Old 31-07-2008, 12:49 AM
AlexN's Avatar
AlexN
Tunnel Vision

AlexN is offline
 
Join Date: Mar 2008
Location: Brisbane, Australia
Posts: 6,708
Thanks for the ideas, however, its not the balancing that is a problem, its more, that the lens/camera rotate around and point down to the ground when the mount is not looking down due to the excessive weight in the frontal element. the tripod collars' foot does not have enough surface area to create enough friction to stop it rotating on the screw...

I plan to make a side by side setup for the camera+lens and guidescope, but that wont solve the problem of the lens rotating on the mounting screw..
Reply With Quote
  #4  
Old 31-07-2008, 05:40 AM
gbeal
Registered User

gbeal is offline
 
Join Date: Oct 2004
Location: New Zealand
Posts: 4,289
Scary when they rotate around like that huh? In the nanosecond it takes, you envisage all that money hitting the ground, LOL.
Is the foot square or rectangular? If so, maybe make a braket that incorporates a detent the same shape and size, not as good as two screws, but it may help. The only other option I can think of without actually seeing the foot, is to drill and tap another mounting hole, giving two.
Gary
Reply With Quote
  #5  
Old 31-07-2008, 05:42 AM
montewilson's Avatar
montewilson (Monte)
Registered User

montewilson is offline
 
Join Date: Apr 2007
Location: Sydney
Posts: 374
So its just slipping? Put some thing thin but grippy between the two faces but be careful you dont damage the thread on the camera mount. You may have to consider using one mounting ring for an approx 4" scope and mount that to a plate to hold the front of the lens and mount the camera body to the same plate. Hope that makes sense.
Reply With Quote
  #6  
Old 31-07-2008, 09:06 AM
Tandum's Avatar
Tandum (Robin)
Registered User

Tandum is offline
 
Join Date: Apr 2008
Location: Carindale, Brisbane.
Posts: 4,106
Put a bar on top with guide rings to hold the lens ?
Reply With Quote
  #7  
Old 31-07-2008, 12:56 PM
AlexN's Avatar
AlexN
Tunnel Vision

AlexN is offline
 
Join Date: Mar 2008
Location: Brisbane, Australia
Posts: 6,708
Gary, Hah.. scary? I damn near had 3 heart attacks in 2 seconds..
I had thought about making a plate that goes ontop of the dovebar that has a recessed section for the foot. Its rectangular, but only has one hole, and not enough room for a second really.

Monte, adding a ring at the front isnt a bad idea, I dont know how much clearance the front has over the end of the dovetail bar, Its not much.. I dont know if a ring will fit, but i suppose if i were to add an extention under the lenses foot, to bring it up another inch off the dovetail bar, that should give it all the clearance in the world.

Robin, That - may - work, but it would need at least a 4" ring at the front, and only a 70mm/80mm ring at the rear... starts to become expensive if im buying 2 sets of rings for it...
Reply With Quote
  #8  
Old 31-07-2008, 02:30 PM
Ian Robinson
Registered User

Ian Robinson is offline
 
Join Date: Jan 2007
Location: Gateshead
Posts: 2,205
There should be a tripod screw on the bottom of the camera as well as one on the bottom of the big telephoto.

Make a plate that accomodates both these and attach that with the camera and lens , attach to the tube or dovetail. (see sketch)

That should fix the problem.
Attached Files
File Type: doc big lens.doc (19.0 KB, 52 views)

Last edited by Ian Robinson; 31-07-2008 at 06:42 PM.
Reply With Quote
  #9  
Old 31-07-2008, 04:26 PM
AlexN's Avatar
AlexN
Tunnel Vision

AlexN is offline
 
Join Date: Mar 2008
Location: Brisbane, Australia
Posts: 6,708
Ian,

Brilliant!! Will make something like that up next week @ work.

Cheers..
Alex.
Reply With Quote
  #10  
Old 01-08-2008, 02:46 PM
bojan's Avatar
bojan
amateur

bojan is offline
 
Join Date: Jul 2006
Location: Mt Waverley, VIC
Posts: 5,734
LIke this...
Camera must not be separately tightened, unless you want to break something....
Attached Thumbnails
Click for full-size image (Lens_mount.jpg)
100.8 KB75 views
Reply With Quote
  #11  
Old 02-08-2008, 02:50 AM
Tandum's Avatar
Tandum (Robin)
Registered User

Tandum is offline
 
Join Date: Apr 2008
Location: Carindale, Brisbane.
Posts: 4,106
Quote:
Originally Posted by AlexN View Post
Robin, That - may - work, but it would need at least a 4" ring at the front, and only a 70mm/80mm ring at the rear... starts to become expensive if im buying 2 sets of rings for it...
No ... Guide Rings ....
Attached Thumbnails
Click for full-size image (rings.jpg)
82.0 KB17 views
Reply With Quote
  #12  
Old 02-08-2008, 09:04 AM
TrevorW
Registered User

TrevorW is offline
 
Join Date: Aug 2006
Posts: 6,995
MAke your own guide rings out of SW tube rings available cheaply from Bintel and the like.

Cheers
Reply With Quote
  #13  
Old 03-08-2008, 10:17 AM
CometGuy's Avatar
CometGuy
Registered User

CometGuy is offline
 
Join Date: Feb 2005
Location: Brisbane
Posts: 942
Alex,

I made a cradle out of 12mm MDF for the Sigma 300 2.8 I had. So the lens foot mount screwed into one end, and a felt lined ring held the front of the lens. Nice cheap solution.

Terry
Reply With Quote
  #14  
Old 03-08-2008, 06:41 PM
dugnsuz's Avatar
dugnsuz (Doug)
to baldly go...

dugnsuz is offline
 
Join Date: Aug 2005
Location: Hahndorf, South Australia
Posts: 4,200
Hi Alex
I mount my 70-200 f4 and tripod ring onto the dovetail with this handy little accessory from Bintel ($30)...
https://www.bintelshop.com.au/Images/Stock/7734X.jpg
You can find it in the "Mounts" page.

As you know, the 70-200mm isn't the largest of lenses though so something a bit more robust might be needed for your 300mm.
Cheers
Doug
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 09:33 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Advertisement
NexDome Observatories
Advertisement
Lunatico Astronomical
Advertisement
Celestron Australia
Advertisement
SkyWatcher Australia
Advertisement
Bintel
Advertisement
Meade Australia
Advertisement
OzScopes Authorised Dealer
Advertisement
Astronomy and Electronics Centre
Advertisement