Best way of attaching starsense, DSLR and heavy lens to vixen dovetail

[jimbo747]

I have an SLT mount and 127 mak. Previously I had mounted my modded DSLR and light zoom lens to the mak using rings. Got some ok results, but aligning was a faff and wasn't happy with the lens quality with too much CA to deal with in processing.

I now have a starsense which makes aligning a breeze and I'm up and running in a few minutes observing with the mak.

 

I have a decent Takuma 200mm F/4 lens which has a bit of weight to it - far too much for the mount to handle. I therefore want to to mount the DSLR, Lens and star sense directly to the mount rather than piggyback.

I have a dovetail bar like this: 

http://www.modernastronomy.com/shop/accessories/dovetails/deluxe-vixen-style-photo-dovetail-kit/

I can screw the camera on using the tripod hole, however with the lens its far too heavy to be secure. I guess I need some sort of adapter to hold the lens in place too so its held in by 2 screws.

I also want to attach a synta style findershoe mount so I can attach the starsense, is there a ready made adapter to allow me to mount directly? The other issue I might face is that where the dovetail bar meets the mount, the mount protrudes quite high so can't mount the the camera at the same point where the dove tail meets the mount, I have to position it either fore or aft.

 

If anyone has done anything similar please let me know!

 

 

[Demonperformer]

Could you drill and tap (or get it done) another hole further down the dovetail so that you could screw in a bolt with the lens sitting on top of it to provide some support - or maybe attach a single guidescope ring?

[jimbo747]

The dovetail bar has a gap running through it already so no need to drill, but how would I attach the lens to a screw? Would a variation of this work?

https://www.amazon.co.uk/dp/B0030VHCEI/ref=asc_df_B0030VHCEI58589890/?tag=googshopuk-21&creative=22146&creativeASIN=B0030VHCEI&linkCode=df0&hvadid=310510252538&hvpos=1o4&hvnetw=g&hvrand=4511256290345168694&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9046376&hvtargid=aud-543273805630:pla-575655031852

 

[Carbon Brush]

I once made a camera holder, to fit direct to a mount.

Sorry I can't find a photo of it.

Start with a 12"/30cm Vixen type dovetail bar.

Camera with a 1/4" bolt through the bar supported the body.

A piece of plywood fastened to the bar further along provided a wide platform for the lens support.

Then a drainpipe clamp (happened to be the correct diameter for the lens) clamped the lens and screwed to the plywood.

This can be modified with extra spacers for lens height, or a bit of foam when clamping lens.

If I can find the photo, I will post it for inspiration.

Hope this helps, David.

[PeterCPC]

Not exactly what you are referring to but I made this for putting my camera and a guidescope directly onto mount.

Peter

[Demonperformer]

4 minutes ago, jimbo747 said:

The dovetail bar has a gap running through it already so no need to drill, but how would I attach the lens to a screw? Would a variation of this work?

https://www.amazon.co.uk/dp/B0030VHCEI/ref=asc_df_B0030VHCEI58589890/?tag=googshopuk-21&creative=22146&creativeASIN=B0030VHCEI&linkCode=df0&hvadid=310510252538&hvpos=1o4&hvnetw=g&hvrand=4511256290345168694&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9046376&hvtargid=aud-543273805630:pla-575655031852

 

With a suitable size, yes. Probably cheaper than my guidescope ring suggestion, but that would be variable and so would be suitable for other lenses as well.

[jimbo747]

Some good idea there, looks like I'll have to go 'A Team' on it! For some reason I never considered a diy plywood approach, got some spare 12mm in the shed

 

Thanks all.

[noah4x4]

How are you going to align and calibrate your Starsense camera parallel to the centre of your DSLR FOV with no OTA/eyepiece to look through?  I guess it is possible, but I fear it could be challenging. Suggest you work out that before you spend any money or start drilling.

 

[jimbo747]

21 hours ago, noah4x4 said:

How are you going to align and calibrate your Starsense camera parallel to the centre of your DSLR FOV with no OTA/eyepiece to look through?  I guess it is possible, but I fear it could be challenging. Suggest you work out that before you spend any money or start drilling.

 

Shouldn't be that hard. Align the starsense first, then centre an object on the DSLR and alter the starsense to recognise this as the centre. Worked on my mak using this method and that reliably centered Jupiter with a camera. Maybe attaching an RDF to the hotshoe could help as well if it's completely out.

[noah4x4]

Let us know when you succeed (and how ) as others will wish to do this for grab & go rigs. I personally suspect your optimism is, optimistic.  When you affix a Starsense camera to an OTA the pre drilled holes ensure that  they are 99.9% parallel and your calc-star will start in the FOV of a 25mm eyepiece, hence when you <calibrate> the Starsense camera the adjustment required is minimal. Here you must, in effect, calibrate DSLR camera to the Starsense, hence the reverse.

I once recall manually attempting to align a Sky satellite dish. Got a decent picture on screen, but found even a quarter turn of a bolt when tightening misaligned it.  I suspect aligning two "gun sights" on targets notionally at infinity won't be easy. But good luck. But may your DSLR has a cross hair feature to identify its centre. 

[alanjgreen]

ADM make a variety of adapters that allow StarSense to be attached to various accessory/dovetail bars.

https://www.admaccessories.com/product/vpa-ss-v-series-dovetail-adapter-for-starsense-mounting/