Search the Community
Showing results for tags '500mm'.
Found 3 results
Hi all I've been fiddling around putting a compact imaging setup together (just for fun - I love to tinker!). It's based on the Samyang 500mm, f6.3 Mirror lens. I've basically just put it on a newly acquired Mono, cooled 550d which I've wanted to test. It's been a terrible 6 months with the weather here :(. Still, last night it was clear-ish so took the opportunity to try the above out. Not first light but hadn't done much with it. Here is a pic of the setup on an AVX: The guide scope is a TS deluxe 50mm, guide cam is a qhy5l-ii mono. Only filter used was a cls-ccd clip filter. The tube rings are really just a means to mount the guide scope :). The camera was modded by Luis Campos. The cooler has a delta of about 18 deg C and I set it to be +4 deg. The camera and tube rings are bolted to a couple of dovetails which are in turn mounted on an aluminium bar. The reason for the latter was the need for a flat area to go on the mount. Anyway, amongst other stuff, I managed the following last night (All 180s subs at ISO 800). Transparency wasn't good - could only see a few stars with the naked eye. Luckily, cameras seem to be able to do magic! M13 13 x 180s: M56 17 x 180s: NGC 6885 14 x 180s: I did try processing in Pixinsight (which allows dslr images to be set to pure raw monochrome) but something went wrong - I'll have to have another look and try again . So the images have just been treated as colour ones converted to b+w. I would expect PI to process them better and, of course, it has a gradient removal capability :). The plan is to see if I can add a filter drawyer to do some narrowband. If I add the filter drawyer and can still achieve infinity focus, I'll give it a go. Otherwise the lens might still be useful. Still, I'm quite pleased with the performance of the lens - bearing in mind it was only £114 on Amazon. The setup has pros and cons... The lens doesn't weigh much so overall the setup is quite light. It would be a bit lighter with a standard dslr. Focussing is tricky (I used a Bahtinov mask and APT) because virtually the whole lens is the focussing part! However, once set, it seems to keep focus quite well. The lens does require about 20mins cooldown. Probably there is a diy solution to make focussing easier. I'm not sure if there is enough room to fit microfocussing rings - maybe, maybe not! Anyway, it was good to get a 'fix' last night! Imaging opportunities have been few and far between for a long time. Louise
Hi everyone, looking for advice on buying a cheap 500mm telephoto lens/ mirror lens! I don't know too much about them so any information is appreciated. Would also love to see any examples of astrophotographs taken with these lens. Thanks guys!