nonlinear

Seeing the current entries I feel my effort is not really worthy, but this is my first attempt at entering a challenge so I'll give it a go. Shot using an unmodified Nikon D7100 at f2.8, ISO 800. A stack of 55 x 15 sec exposures on a Move Shoot Move tracker. I used a 2" Optolong L-Pro filter blu-tacked to the front of the lens! Orion was low in the sky and Rigel was starting to set behind a palm tree at the end of the exposure. I am impressed that about 10 minutes of exposure will (just) bring out part of Barnard's Loop to the NW of the belt, the horsehead nebula, flame nebula, M78 and NGC2071 as well as M42. All processing was done with IRIS. I have taken a central crop to remove the palm tree, and strong gradient. I prefer stacking short exposures to help avoid blowing out the centre of M42 too much.

Any update on the APM140? I'd be interested in hearing your opinion of it.

It looks like it is worth trying with two ES 24s. Thanks for your thoughts guys.

Thanks for your replies. I've measured the ES 24 and it is 56mm diameter, my IPD is about 66mm so 10mm clearance which is certainly tight. I'm hoping to get away with using just the lowest power GPC with my f7 scope, so hopefully no slower than about f9. Two 24mm Panoptics would be great but seems overkill and expensive at f9? Conversely I suspect that f9 is a little too fast for good performance from the Svbony. Any thoughts on 68 degree eyepieces that are good at f9 that won't break the bank when buying two of them?

I'm considering using a pair of ES 24mm 68 degree eyepieces in a binoviewer. I have one of the eyepieces already and I'm wondering if the bodies might be a little too large. Before I buy a second, has anyone tried this? thanks Stuart

Actually I can see both sides of the argument. We are lucky to live an a free society and people are free to make (and spend) money as they please. It does seem a strange market however where a trader adds nothing but cost to the end item. If he aggregated items from sources I had no access to, or eased access somehow to those items then he is adding value, and I respect that, and pay appropriately. Just to buy and re-sell at a higher price in the same market seems peculiarly parasitic. One solution is play him at his own game, there is clearly still plenty of money to be made.

I was for a while. I worked for a US company for 4 years. I like Americans a lot, they are certainly very good at marketing and promotion. No offence intended. Only a few years ago used prices were typically 2/3 to 3/4 of new for mint high end gear. I've seen this guy recently sell used equipment for MORE than a retailer was selling it new. The retailer has to offer a warranty and returns as well.

This may be contentious, but here goes: Am I the only one really fed up with a certain dealer (who I won't name to comply with forum rules) who buys from the same online sites/ forums as we do, and sells it back to us with a hefty price increase? I'm not against dealers, if they bring something of value to the community, but to my mind this is taking the mickey. As an example: ZEISS Abbe-Barlow Telescope Eyepieces bought at the end of Aug for £2245, sold for £3840, a Vixen VC200L bought for £410, currently for sale at £1200, with a load of patter about how his mate thinks it's too cheap. He buys from ABS as well. I've got it off my chest, I think I'll just block items from him on ebay, stop using ABS and move on...

Great news! Good job getting it repaired. SS2K still my favourite system so well worth the effort.

Thanks for posting the driver type, very interesting. Yes, the outputs are protected, but the application notes make the following points: Be careful when switching the input because rush current may occur. When switching, stop mode should be entered or current limitation resister R should be inserted. The IC functions cannot be guaranteed when turning power on of off. Before using the IC for application, check that there are no problems. Utmost care is necessary in the design of the output, VCC, VM, and GND lines since the IC may be destroyed by short-circuiting between outputs, air contamination faults, or faults due to improper grounding, or by short-circuiting between contiguous pins. ...all of which can happen if wires are pulled out of a connector when powered up.

I've just bought a lightly used D7100 (5k shutter operations) off ebay. My current camera is a (draw breath) D50 that I bought new 15 years ago. 6M pixels may not sound a lot but it's been a real joy to own. It really showed it's age a few days ago photographing comet Neowise. A non tracking mount limited my exposure time and the noise at even ISO 400 really showed the sensors age. Anything higher would be unusable. I control the D50 from a laptop with Nikon Camera Control, which works very well. Another big improvement I am hoping for is to use live view with a bahtinof mask for focussing. If that works it will save an enormous amount of time.

Thanks Dave I had read that some users have reported the 7100 has banding in the shadows. This may be fixed pattern noise which will process out though. The 7200 has a faster processor, which is always nice and built in wifi. I suspect for casual astrophotography (if there is such a thing) there is little to choose between them. The biggest factor is going to be the operator, so me. I'll probably go with whichever one I see a good deal on first. cheers Stuart

Hi I'm thinking of upgrading my DSLR to either a D7100 or D7200. I see the latter has a much higher native ISO range. Does anyone have experience of whether this makes a real difference with astrophotography. My quess is that it relates more to how the camera processes images rather than sensor s/n ratio. I believe both camera have the same sensor. Many thanks Stuart

I agree. I had one myself a while back and it is still my favourite system. Way better than the Sphinx starbook that replaced it. Electronics has moved on a lot in the last 30 or so years, and there is a big difference between putting a diode in the power line, and implementing comprehensive protection on the motor drivers. I'm not saying it's not there, I don't know, but I wouldn't assume is was either! We really need to know how the cable was damaged.

This is an old design, I wouldn't assume the drivers had short circuit protection. I'd be interested to know what the driver IC's are. It's also possible the encoders were damaged, resulting in an invalid input signal which the CPU doesn't recognise. Some idea of the cable damage would be useful.

Hi Michael I know this is a very late reply, but did you get it going? I would guess that when you damaged the cable you shorted some of the drivers out which damaged them. best Stuart

I have a gm8 with the digital drives, which works really well as a push to and track system. I'm thinking about upgrading to a goto but the gemini system seems very expensive as an upgrade path. I'm curious to know if anyone has tried fitting a Vixen skysensor 2000 to a gm8. I had one before on an eq5 and really liked it. I know you can program the encoder ratios, so it could potentially work on any mount. The main issue will be mounting the motors. Alternatively has anyone tried the EQStar system from Ukraine, available on ebay for around £300? thanks Stuart

I spoke to Steve a couple of weeks ago due to a problem I had with mould and he said he wasn't working on scopes at the moment because he was too busy.

Can you post an example? Preferably without the flattener or filter wheel.

Telescopehouse used to offer scope alignment before they were taken over. Might be worth a call. Have you tried Teleskop-Service themselves?

I've just noticed that TS-Optics are selling a wide field binoviewer. This has a clear aperture of 28 mm, 30 mm prisms and the optical path length is 118mm. Has anyone used these? On paper they appear to have a better spec than the upcoming Baader Maxbright II.

Wow, stunning, a real sense of drama in the winning image.

Thanks Russ. I've done that myself many times, it's REALLY annoying!

I've recently acquired an Altair Starwave 80ED-R. It's on an skywatcher AZ-GTI mount and the whole setup is light and surprisingly stable. I was looking at jupiter last night at about 160x without even aligning the mount and it was tracking really well.

I know I'm late to this thread but I had exactly the same problem with the current version of this finder (red anodised trim). Your suggestion worked a treat. I can now get the crosshairs and the sky in focus at the same time. Thanks! Stuart