MarkS

Hi Mike, Firstly, I'm pretty sure you need the full Pinpoint - not the MaximDL one. Secondly, there is a document entitled 'Sequence 200' which takes you through the set-up. If you can't find it send me your email address and I'll send it to you. (It's too big for me to upload it here) Mark

Hi Antonio, Another splendid image! All the more interesting because it is over my horizon Thanks for showing! Mark

Hi Andrew, I use the AAF3/ASA10N with ASA Sequence. The reported position can vary by 1 - 3 micron during a run, but this is totally immaterial with either f/3.6 or f/6.8 configurations. I'm not sure what these small shifts mean, but the encoders are very precise, and I suppose they may be reporting very minor flexure - which is present in all systems. Notwithstanding, the whole system is so stable that I have imaged for over 6 hours without using AF and not lost a single subframe. I could not do this with the OK3 although it did not report any shifts. Mark

Hi Waldemar, I run both the DDM60 and the DDM85A. You'll really enjoy the 85 - the extra motor power makes a real difference! I hope you have better luck with the skies than I'm having here!!! Mark

There appears to me to be two issues. First, there appears to be significant coma on the upper right and right of the image. Secondly, there are elongated stars on the lower parts of the image. Because the left side of the image looks basically OK, I would guess that you may have a backfocus AND a tilt problem. It is certainly worthwhile to shoot several images with small focus shifts - say 0.05mm steps for a start. This should give you some idea of what to do next. In my experience, the collimation results from CCDInspector are not always very reliable. I think careful visual inspection is the best, if not the easiest, indicator. Best of luck with your investigation! Mark

You can use CCD Inspector, but I have found that the best way is to take a set of, say, 2min images of a good star field at slightly different focus settings. If there is a setting that gives good round stars all over the specified image circle, then the backfocus is correct - or very close. If there is no focus setting that gives round stars everywhere, change the backfocus distance by 1/10mm or so and repeat the process. Keep doing this until you have the best you can get. This is time consuming and tedious, but have found it very worthwhile. I did it with my Barlow when I changed cameras from a 8300 size to 16200. I found that if I increased the backfocus 0.3mm beyond the specification (!) I could get very good images right to the corners of the bigger chip - but the focuser had to be very precise and stable. Mark

Hi Antonio, Very nice image of a rarely targeted object. Up to your usual high standard! Mark

This looks correct. Presumably you could adjust the 3mm spacer if you need to fine tune the distance. The focus is very critical at ~f/3! Mark

That should be correct. Mark

Hi Luis, Extraordinary collaboration, and extraordinary image! Mark

Hi Lukas, On the OK3 the bolt has an Allen key head. I didn't measure torque, but the key has good purchase. So I would think I got the bolt a lot tighter than you could with a small screw-bit. The best test is whether the focuser can actually hold the camera without slipping. I am using the same camera as you so the weight should certainly be no problem for the OK3Z. Mark

Lukas, When I had this problem with the OK3 I found that the bolt needed much more tightening than I expected. I continued to tighten the bolt until the same position was reached from either side - as measured by a digital caliper. Mark

Great image, Thomas. I'm not sure I'm convinced about the saturation level, but the detail in the image is superb. Mark

Hi Fabrice, The Wynne corrector has a flange at its camera end which seats onto the AAF3 adapter. This flange is about 2mm thick. The camera adapter should have a matching flange approximately 1.5mm thick, so that when it is bolted to the Wynne, the total flange thickness is 3.5mm. The three grubscrews, which have tapered ends, then grip the corrector/adapter assembly firmly by engaging the flange with their tapered ends. The points of the screws should not engage the corrector/adapter barrel. When set up like this, it is quite easy to rotate the camera/Wynne assembly by slightly loosening the grubscrews - NOT TOO MUCH! - rotating the camera, then retightening the grubscrews. I have found this is easier than fiddling with the red wheel - and more accurate. Judging by your photos, your camera adapter will need modification to achieve such a set-up. Hope this helps. Mark

From your photos you do not appear to be using the Wynne corrector. When using it and the correct adapter, the grubscrews on the AAF3 adapter hold the Wynne/camera system in place by engaging the seating ridge on the Wynne and its camera adapter. The rotation can be achieved by slightly loosening the grubscrews, and retightening when you have rotated the camera. This is quite safe provided that the seating ridge on the Wynne+camera adapter is the correct thickness. I find this to be quite convenient, and less tricky than with the red wheel system. However, if you want to use the red wheel system, you need to have a different adapter made. See my post earlier in this thread. Mark

Max, This looks to me like the DE balance is way off. Did the system report a Position Error? Which mount are you using and how heavy is the payload? (My DDM85 seldom registers DE current above 1A) Mark

Antonio, Re vignetting: I calculated that for the Wynne corrector you need at least 49mm diameter clearance due to the f/3.6 focal ratio and the position of the adapter. So I had a new camera nosepiece and matching adapter made with 54mm diameter thread and 49mm inside clearance. This worked. Mark

Hi Lluis, I haven't seen the outer ring like this before. Thanks for showing this - too far north for me! Mark

Unusual subject, Antonio. The cloud is very well caught - interesting image! (Love the camera ) Mark

Antonio, This diagram is derived from measurements I did on my OK3 lead. I cannot answer for the OK3Z, and because I have no idea what getting it wrong might cause, I think you should ask ASA before doing anything. Regards, Mark

Hi Antonio, See attached diagram Mark

Hi Colin, Are you absolutely sure of the balance? Balance is very critical, and in my experience the DDM60 can get into trouble even when I think I've got the balance good. As my payload has increased with heavier focuser, camera etc, the problem has become more acute. Sequence has a feature to enable relaxation slews at given intervals during a run.These slews 'reset' the motor currents to lower values. I always use the feature, as it often prevents Position Errors. If you are periodically autofocusing during a run by slewing to a AF star, as Sequence does, this also provides the relaxation effect. Maybe you should try to incorporate a similar feature if you are not using Sequence. Mark

Not really. The galaxy is about 100Mly beyond the cometary globule, which is about 1300ly away. The tail of this, like other nearby cometary globules, points away from the Vela supernova remnant. ASA10N at f/6.8; Moravian G3-16200; Astrodon filters; DDM60. Seeing 3", SQL 20.9, windy night, so not the greatest.... L, R, G, B 1hr each, all binned X2. Image fov is about 40' X 32'. The dusty object is very faint - barely visible in individual colour sub-frames. All subs were combined to make the final L frame. Processed in Pixinsight Mark

Hi Lukas, If it is like the OK3, there is a single allen head screw for adjusting the holding friction. I set this by placing the OTA on a bench with the focuser facing up, loading the camera etc on the focuser (or an equivalent weight) and tightening the screw GENTLY until the focuser can drive the camera and return to the original focus point. The OK3 readout of focus position may not represent the actual focus position unless the friction screw is properly tensioned! Maybe the OK3Z is different??? Mark

Excellent colour rendering and detail. Very nice image. Mark