Dovetail converter - DSLR to mount

[Dara]

I'm looking at finally being able to purchase some equipment to allow me to do some astrophotography. The plan is to do it in two stages. First, a tracking mount that I will use with my existing camera gear to take pictures of moon and planets (and to see how badly it copes with nebulae). Secondly, a reflector OTA to sit on the mount for deep space imaging.

My lenses are fitted with Arca-Swiss compatible dovetails (from Really Right Stuff if anyone's heard of them). The issue is that the width (not length! That varies according to lens) of the dovetail is 38mm, and even an expensive mount with a dual saddle has a smallest dovetail size of 45mm.

Are there any good value ways of putting together a converter - it seems like it could be anywhere between £100 - £200 to get two dovetail pieces to bolt together that would do the job - and that's a long way towards the cost of a good size telescope!

[Carbon Brush]

Hi Dara.

Stage 1. The camera + lens.

I use a cheap (Scopes n skies) standard dovetail with holes ready drilled.

1/4" whit screw through to the camera body tripod fixing.

This is OK unless there is a really big and heavy lens.

The heavy duty solution is a cheap plastic scope clamp (SnS again) around the lens, possibly with foam packing, down to the dovetail.

I can't remember what it cost. But certainly change from £20 for the lot.

Drain pipe clamps and a bit of wood on the dovetail also work well.

Messrs Heath & Robinson would be proud!

[E621Keith]

One of this

Deluxe Vixen Style Photo Dovetail (about half way down the page)

Accessories @ Modern Astronomy

[Stephen]

One of this

Deluxe Vixen Style Photo Dovetail (about half way down the page)

Accessories @ Modern Astronomy

Seconded, I really like mine but then again I don't put HUGE lenses on it

[Dara]

Thanks for the ideas.

My largest lens is nearly 5.5 kg, with camera body, batteries, possibly extenders as well it's probably around 7 kg.

Solid would need to be the watchword for any dovetail conversion solution - I'm not sure I'd trust any Heath Robinson device I'd created to hold things safely!

[E621Keith]

If your system is 7kg, it's best if you go for a custom dovetail. I'd guess your lens attaches to your quick release plate with something more rigid than a single 1/4" bolt. While I have no problem hanging a 70-200/2.8 or a 300/4 on the Modern Astronomy dovetail, I certainly would not want to put any big super telephoto on one.

What mount are you going to use. You'll probably need an EQ6 or larger.

[Dara]

Yes, the quick release plate has two bolts connecting it to the lens. How would I go about getting a custom dovetail made?

The mount being looked at was the NEQ6 (depending on the thickness of the wallet when it came to purchase time - although purchase would probably be put back rather than get anything smaller).

[E621Keith]

I think it would be a case of buying a plain dovetail and a bit of DIY or take it to a local machine shop and have them drill the holes.

Astroparts do a bit of custom machining. I've never used them, but I've seen them recommended on SGL before.

[teleskopjo]

I got this 

http://i1356.photobucket.com/albums/q736/niponoptics/Tripods/Dovetail%20plates/dovetail-plate-long1_zps6beffab3.jpg

but the camera just wont stay put as it rotates around the mounting screw!..

Tried to put a thin piece of rubber which helped but it still moves when the mount slews from one area to another so losing the goto model..

any suggestions?

[teleskopjo]

maybe this is the better solution?

http://stargazerslounge.com/uploads/monthly_06_2009/post-13675-133877380551.jpg

[teleskopjo]

bump

[rob0971]

I used to mount my Nikon 600mm f4 using a vixen dovetail onto my AZ EQ6. No problem with the weight (around 7 kg). Just screw it onto your existing tripod foot where there should be a couple of 1/4" fixing holes. I have an Arca swiss foot on mine & I just bolted the vixen dovetail on the bottom of that.

[teleskopjo]

ok but that has a dovetail as part of the lens body.. here i am trying to attach the dslr body itself to the dovetail.

[hobsey]

I think the problem you have with the dovetail you're using is that the bar dips in the middle so there is less surface area for the camera to sit on meaning more chance of it moving.

If you get the one from modern astronomy which has been mentioned which I also have, it has a flat contact area so there is less chance of the camera moving.

Edited August 6, 2014 by hobsey

[rob0971]

You can still screw a short vixen dovetail (about £25) to your camera body or lens. Use 2 screws on the lens & 1 if bolting to the camera body. It will be fine!

[bogdog]

I got this 

http://i1356.photobucket.com/albums/q736/niponoptics/Tripods/Dovetail%20plates/dovetail-plate-long1_zps6beffab3.jpg

but the camera just wont stay put as it rotates around the mounting screw!..

Tried to put a thin piece of rubber which helped but it still moves when the mount slews from one area to another so losing the goto model..

any suggestions?

sounds to me that the bolt you are using to go through dovetail bar into camera is too long?

if so pack out with washers between camera and dovetail,or get a shorter screw,or get a nut and put that down tight before camera

[teleskopjo]

It's as hobsey said!..

anyway i bought this one now

http://stargazerslounge.com/uploads/monthly_06_2009/post-13675-133877380551.jpg

let us see how it goes!

[AndyKeogh]

I have faced the same problem and went for a combination of the dovetail bar from Modern Astronomy ( link in thread above) with Kirk Quick release brackets and a nodal rail as in the attached picture.

http://www.wexphotographic.com/buy-kirk-lrp-1-long-rail-plate/p1006401  The clamp at the end of the nodal rail can be turned through 90 degrees so can be used on lenses or a camera.  The use of a nodal rail makes it easier to get balance in declination as the vixen bar is quite short.

http://www.wexphotographic.com/buy-kirk-4in-standard-quick-release-new-style/p1011198  4" QR clamp with lots of holes to take 1/4 or 3/8 threaded bolts. I fixed this to the vixen dovetail with 2 bolts so I do not have rotation issues. .  There is an issue though as the head of the tightening bolt on the 4" clamp  fouls the dovetail so needs a 6mm spacer  to allow the full length to be used.

This is not a cheap option  but cheaper than having £5000 worth od lens and camera gear falling to the ground.  I suspect it will also have little flexure .... but it is still under test.

Regards

Andy

[jazzzyjay]

On 31/07/2014 at 13:48, teleskopjo said:

maybe this is the better solution?

http://stargazerslounge.com/uploads/monthly_06_2009/post-13675-133877380551.jpg

where was this utilized and is it still available?  just what i am looking for.