michael8554

Depends on the OTA. Over about 1000mm Focal Length an Off Axis Guiding system is recommended, with a sensitive mono guide cam. Below that focal length, a guidescope/guidecam combination that has a pixel scale of no larger than about 6arcsec/pixel, Up to 3arcsec/pixel is best, according to the PHD2 developers. With a mounting that does not include soft-tipped screws to hold the guidescope, which will lead to Differential Flexture and so elongated stars. Michael

Guiding Rate set to 0.5 Sidereal means: The mount tracks at Sidereal Rate. But if you guide the mount, with a computer, a guide camera, and a guide scope. The tracking is briefly slowed down/speeded up by +/- 0.5 by the guide programme. Michael

So which ASCOM drivers have you tried that don't work ? Michael

Hi Sedna 1) If you did a Ha Mod, by removing only the LPF-2 filter, the LPF-1 filter remains and blocks unwanted IR. So you don't need an external UV/IR filter, which in any case won't give you a daytime spectral response. You can get a good Ha response AND a good daytime response by installing a Baader filter in the LPF-2 position - see vliav's graph. Or get a pretty-close to correct spectral response by using a Custom White Balance. 2) If you did a Full Spectrum Mod, by removing both LPF filters, you will need at least an IR/UV filter, to prevent bloated stars in the case of lens or refractor use. But again, an UV/IR filter will not fix the daytime spectral response. Michael

Hi Nikolai Way back before budget astro cams were available, it was popular to modify a particular Philips webcam that happened to have a CCD imaging chip. That enabled the long exposures that imaging dim DS Objects requires. Most current webcams will only expose up to about 1 second, so are best used for Planetary imaging. As bosun suggests, record video files that can be Stacked in Autostakkert. You will need a long focal length to "magnify" the tiny target that is a planet. Either by a long focal length telescope, or afocal imaging using an eyepiece to magnify the image from the telescope. Michael

Hi Nick I would try this: Place the top of the moveable part of the wedge parallel to the base of the wedge. If the zero on the scale is next to the pointer then the scale is correct. So for Devon set to 50. But you can easily check using Polaris, that should be close enough to allow a full PA if you need to. Michael

It's described as a cooler, as it swaps the "warm" air inside the OTA with cool air from outside, so really it's ventilating the inside of the OTA. Michael

Looks good, but the reviews say the fuses keep falling out - probably easily fixed. Michael

Hi Lee My 8" SCT has a Dew Shield, and I rarely need to have the Corrector dew heater on. But you may have damp air inside the OTA. So you may need to employ one of these SCT Coolers: Michael

That glow on the horizon that some of you in the UK captured is unfortunately right where the Swindon skyglow is for me......,, :-< Looks like it was a southern hemisphere event. Michael

Hi Tim The EVOLUX 62ED .9 Reducer/Flattener has 55mm Backfocus. So will have the correct spacing on a Canon DSLR with the usual 11mm T2 Adapter. But that distance can be increased if the star shape suggests the FF is too close. Which a filter will have already done. Though if you get the Tilt corrected the coma may be gone too. Looks like a the connections are screw-threaded, so I hope the tilt isn't due to the DSLR mod :-< Michael

Hi Tim The image is pretty low-res, only 500MB, you can go up to 1GB with images. But it looks to me that the centre stars are elongated. And the amount of Coma in the corners varies, due to Tilt. Examine a short exposure of a starfield, to minimise guiding and PA errors, stretch that single image if necessary. Michael

Nothing to report here (Wiltshire), clouded over by 3am. Michael

Meade have used the same design for their SCT OTA's for decades, with improvements to the coatings now and then. Watch out for the Corrector, the front piece of glass, having been removed for cleaning, has not been replaced in the same rotational position. You should carry out a Star Test, or ask to see recent astro images. Michael

The coma shape suggests "too close". But sort the Tilt and possible Pinching first. Michael

Hi Steve "I have measured and re-measured and re-measured again the MPCC to sensor distance. " And what was that distance ? And there's nothing stopping you from adding spacers until you get best corner star shape. The corner images look to me like the effects of some of the mirror clips pinching the mirror, and a bit of coma due to FR spacing too close. Michael

You're in a train carriage alongside another carriage. The other carriage starts to depart. The visual illusion is that your carriage is moving. Michael

A Spotting Scope for Bird Watching. On a tripod. Gives an erect image. Can you open the window on the 30th floor, as glass will blur the view ? Michael

"So this should mean that all 58mm T-rings should go with my camera right?" Probably 58mm. And the filter thread is 0.5 mm, 0.75 mm or 1.0 mm pitch, depending on the diameter of the filter thread. But you're not looking for a T-ring. T-rings/T2 Adapters are the specific description of adapters for removable lens cameras. Michael

As Peter said. T2 Adapters are for attaching cameras with the lens removed, DSLRs etc. Michael

I'd say because a Ha modded camera's spectral response has been skewed towards the red end of the spectrum, I don't know that I'd call it purple. Michael

Hi Jack If you only have one 20mm focal length eyepiece, it effectively becomes 10mm with a 2X Barlow. But if you already have a 10mm eyepiece, you don't need the Barlow. That's why we're asking what eyepieces you have already. Michael

The 6D doesn't have any internal leds that could cause this, at least not on mine. You have the camera's eyelevel finder window blanked off ? Run Elp's tests with the current lens, and then with another. Michael

The Canarias island group is a popular destination for holidaymakers, so you cannot predict where and when aircraft will be intercepting your laser beam. Michael