Search the Community
Showing results for tags 'camera lens'.
Found 6 results
Hi All, I wonder if someone can please help, I'm fairly new to astrophotography and confused about aperture. Basically I'm looking at a Canon EF-S 55-250mm lens. It has the specs f4-f5.6 does this mean that the lowest point of aperture possible is F5.6 or will it go lower. What I find confusing is that I have a lens that's the EF-S 18-55mm lens which has the specs of f/3.5/5.6 however My camera does allow me to set the aperture at f/8 The reason I ask cause it is advised to use a low aperture of f/8 to capture images of the moon. Any help and guidance would be greatly appreciated!
Geoptik Nikon SLR Lens CCD Adaptor Bought 2nd hand in error, as I need the Canon lens adaptor. This is the Geoptiks 30A190 model designed for older (non autofocus) models of Nikon lenses. £ 50 + £5 postage (insured and signed for) to UK mainland. Paypal or cash on collection (from Worcester) or straight swap with the Canon version of this adaptor.
I hope this is not a stupid question (guess I will find out shortly...). Can you use a Bahtinov mask on a normal wide angle camera lens? I have tried taking a few star trail photos using a DSLR and a normal wide angle camera lens but have had an awful job in getting the focus right. Infinity seems to move and is not actually on the infinity marker on the focus scale. It has been a real pain so I am looking for some help here. Tony
Cloud, cloud and more cloud – but looking on the positive side, this presents an opportunity for a ‘project’. Now, I’ve already done the observatory ‘spring clean’ – I even have the photos to prove it – so I thought I’d tackle a project that has been on the back burner for years; auto-focusing my camera lens(s) for wide-field imaging. Despite two attempts at putting the TS Telefokus 105 microfocuser on my Christmas list so that I could accurately focus my Canon 200L telephoto lens on the stars, there were no takers so the project stalled. However, having bought a second motor for my existing autofocus controller to install on a new telescope got me thinking that maybe this would actually be a better way of controlling focus and might even allow autofocus during a long imaging session to compensate for temperature changes. So, I put a third motor on my birthday list and my two sons clubbed together to buy it for me moving the project forwards! Yesterday, I completed it with the addition of a finder-guider that I had in my ‘goodies’ box that is normally used for guiding short focal length review telescopes. Now, in fairness, it is untested on the night sky (cloud, remember, hence the project!) but what I can tell you is that the focuser moves in invisible increments or quickly as required, is ultra smooth and shows no sign of slipping! Unfortunately, much as I’d love to, I can’t install my mono camera as, with its built in filter wheel and OAG, there is insufficient back-focus. This means that the system will be used with my OSC SXVF-M25C coupled to the Canon 200 L lens using a custom adaptor I had made when Adam was a lad. What could possibly go wrong? Front View The two pictures above show the 72mm lens has been stooped down to 52mm using a step-down ring. This reduces the aperture from f2.8 to f3.8 to improve star shapes at the periphery of the FOV but without adding the diffraction spikes that would be a feature of stopping the lens down using the iris. Belt Drive Finder-Guider Connection
Hi I have been thinking about having a go at widefield stuff for a while and wondered if anyone could recommend a used decent camera lens to look out for on ebay etc. I would be using my QHY163C with it I currently have an Altair 102 triplet and a megrez 72 (sold my 8"RC last year ...still keeping an eye ot for a C9.25 to replace it for planetary/luna etc) on a Mesu 200 mount It would be used for wider stuff than I can get with the Megrez 72 ...say...the Heart and Sould Nebs in the same FOV. Just thought it would be something to try if I can pick up an old camera lens for a resonable price ....is a zoom worth considering? ...camera resolution is quite high at 3.4 size pixels so is a fixed fl better then crop after etc. Never done any AP with a camera lens so am total virgin with them....any thoughts/recommedations to put on the shortlist gratefully accepted. Tom
The principle of this triple imaging rig is to have three virtually identical imaging systems using Atik 460EX cameras and vintage ex-SLR high quality camera lenses as used on the Asahi Pentax SLR camera. Various focal lengths are available and these old lenses are readily available at sensible prices on that well known auction site. When used for narrow band imaging these lenses perform superbly and the narrow bandwidth eliminates chromatic aberration. Each lens/camera covers a very narrow part of the spectrum and is individually focussed. Following on from my earlier thread I have decided to start a new thread for my widefield triple imaging rig as there has been a big change in the design. The camera and lens arrangement has gone from three in a row to a triangular (turret) arrangement. The other thread was getting rather long as well. My latest design is also different from the previous turret in that the earlier one used an OAG on one of the lenses for guiding but I have decided to go for a separate guide scope placed between the imagers in the centre. I am going to try the finder scope from an ST80 with LodeStar guide camera (removing the eyepiece and crosshairs and replacing with an adapter to take the LodeStar). The idea of the turret is to enable me to frame the DSO in the oblong imaging frame to best advantage while guaranteeing that all images remain aligned but without changing the balance. Once the image is satisfactorily framed the turret will be locked in position so that it doesn't change during imaging. The guide scope and camera will remain fixed and aligned with either RA or Dec axis of the mount for more reliable and predictable guiding. To provide the above I propose to have a fixed aluminium tube through the middle carrying the guide scope with facility to change the pointing angle to capture a good guide star. As usual, once set this will be fixed during the imaging run. The main triple imaging system turret will rotate on this central tube.