Wide feild imaging rig

[DIYASTRO]

Thought I would post some pics of my wide feild imaging rig.

It shows the Film format arrangement which now I usually use two DSLR camera Canon 350d Modded and 1000d std. The DSLR's have modded Bronica lenses which are still very good for wide feild. Could post images of these if anyone is interested.

The guidescope is a Helios 102 / 500mm f5 with a meade 2" flip mirror to use as large finder with the 25 -30mm ep and then flip up mirror to guide with modded (astonomiser ) webcam with the B&W ICX098BL ccd and PHD guiding.

The Two weights are needed on my HEQ5 to balance it but works fine.

The Guidescope can also be used as an imaging scope using DSLR since I have reduced the tube length by 30 odd mm to get the back focus required by virtue of the flip mirror remaing in the system.

Boyd

[steppenwolf]

Nice, I'd love to hook one of those Bronica lenses up to my CCD camera.

[DIYASTRO]

Steve

Thanks for reply,

What you need is a Bronica SQ or ETR Lens (SQ are best) but make sure they are Zenzanon. Reason, as you may know Most medium format lenses have integral shutter the Zenzanon have the ability to open the shutter manualy VERY IMPORTANT.

To attach to CCD or DSLR you simply use the lens rear cap and turn a cenrtal hole in it to take a threaded flange which then screws on to the DSLR adaptor.

This is an image of M45 which I have to say was very kindly tweeked by Blinky (Craig). It was taken with a 150mm f3.5 and I think from memory was about 10 2min exp. with CLS clip filter.

I have not had time to sit down and play around with PS and image manipulation. Waiting for Blinky to teach me...Hint there Craig....Again!

Boyd

[davew]

Hi Boyd,

That looks an interesting setup. Are you still using film at all or just with the DSLRs ?

I've still got an ETRSi with 50mm lens that I used to use for landscape photos. It's now in a dark place feeling sorry for it's self. Abandoned.

You have given me the idea the lens may work. I looked at a proper adaptor but they are a little expensive just to experiment with. Unfortunately I don't think I have a rear lens cap, damn, but they must be available somewhere ?

Could you post some pictures of the adaptor you made please ?

I'm also rather taken with the guide scope mod and the flip mirror. You are going to cost me money.

Cheers,

Dave.

[jgs001]

Looks great Boyd, and works a treat too.

[DIYASTRO]

Dave,

Thanks for your reply.

I do still very occasionally use film if I can be bothered to proccess the negs!

Mostly now I use the DSLR Canon cameras but I also have a large format camera 5x4" and have had that on the HEQ5 a few times extreme Wide field!

I am not long home from work and have to go out for hospital visit very soon to see a friend but I will trey and post some info this evening. In the meantime have a look on Ebay, plenty of lens back caps usually.

Boyd

[beamish]

Great !

I've wondered if anyone uses medium format cameras with the digital back to do astro stuff

[Ant]

thats and amazing widefield rig.

The M45 image is really nice, seems strange seeing M45 so small in an image. Loads of nebulosity!

How much does the rig weigh? that you need two weights for it!!!

[davew]

Thanks Boyd, no rush, summer is just begining

I've got a few 120 rolls of E200 left in the fridge. Thinks.............

Nah. I think I'll wait until I've seen your adaptor and have a go that way.

Dave.

PS. I can understand using a 5x4 but how do you use the negs ? Do you get them commercially scanned ?

[DIYASTRO]

Dave

as promised some pics of the Bronica lens attached to Canon DSLR

First pic shows the lens rear cap with a 42mm male thread plate from old zenit lens screwed to the back of the cap after the hole has been turned out of the plastic cap using some small 6 or 8BA screws. The plastic is hard and thick enought to tap so making a threaded hole for the screws. The adapter to the side is the Canon low profile 42mm female thread adapter. You need low profile with ETR lenses in order to get focus.

The cap is then fitted with optional 1.25 screw thead insert to take filters Astronomik, nice and low in width.

The Lens is then simply screwed on to the back cap with a little black insulation tape for safety! (As you know these lenses are a bit heavy)and you are away!

I like to use the larger lenses with the lens hood which not only keeps stray light out but acts as dew sheild.

Boyd

[DIYASTRO]

Sorry ... here are the pics.

Boyd

[davew]

Hi Boyd,

Thanks for taking the time to show us this. It looks a very neat job.

That's now three jobs lined up for summer.

I have checked tonight and no, I don't have a cap. So better make that four jobs. I'll have to buy a cap !

Do you run wide open ? The 50mm f2.8 I have opens up fully when off the camera and closes with the DOF lever. I've already sussed that it can be held closed ( The DOF lever that is ) with a plastic tie wrap if I need to go to f4.

I'm still thinking about running a film through the camera.

Dave.

[DIYASTRO]

Dave,

All Bronica lenses work best stopped down one stop however the pic of m45 was wide open on the 150mm at f3.5.

The real advantage of medium format lenses for wide field is that they are designed to deliver an image accross a neg 6cm x 6cm, so the sweet spot of the image is more than enough for the sensors in DSLR cameras. This gives good full coverage accross the sensor with no fall out giving accurate round stars righr to the edge... When focused well!

Boyd

PS Go on... run some film through your ETRSi should be fun to see images on the negs once again.

[davew]

It's been a long time. Can I remember how to do it ?

Go on then. This Autumn I'll have a try.

Cheers,

Dave.