I'm thinking of starting photometric measurements in the near future, though I have no telescope nor any equipment at all really...
I have recently done a course on observational astronomy (with spectrum/polarization observations) and I'm finishing a bachelors degree in physics/astronomy. I work in an other field, so this is just more of a hobby at the moment.
I haven't bought a telescope before, since I probably would not have been too interested in just looking through the eyepiece. At least, not too many times. Nor to take color images of nebulae etc. But the chance to do photometric measurements (or maybe even spectrum/polarization) with the equipment, might make the investment more interesting!
So... Some time in the future, I might plan to get a mono ccd+filter wheel and a guide scope/camera. And maybe some stuff needed for spectroscopy/polarimetry.
But to start with...
--I would probably need a proper mount with a motor. For this I am planning the Sky-Watcher HEQ5 synscan goto. I think this might get me a long way, what ever I plan to do in the future?
--for a telescope, I have looked at skymax 102/127/150 as an example (all these are around f/12), but as I really don't have any preferences on the targets, is there really any point in getting anything but the cheapest one (skymax 102)? Or do these models have a huge difference in practice?
--before getting a ccd, guide camera or anything else expensive, I have a canon 600d, which I plan to use to learn the equipment with. And to maybe try to get my first photometric measurement done with it.
Any comments? is the mount a good investment for all the mentioned future plans of mine? Other suggestions for a telescope?
The DSLR guide would be a good place to start before purchasing any equipment. You would likely be able to obtain some images of bright variables by placing with your camera on a tripod and having short enough exposures so that they do not trail. The guide would help you reduce the data and upload them. That would give you experience to help you decide your next steps since it is possible to spend a lot of money for camera, mount, and telescope that might not match your interests. Best regards.
I have considered this and maybe even try it this way too some day soon.
Anyway, I will have the interest in buying a telescope and a mount with a motor. I've had the interest also before for just visual observing, but this new idea of a possibility of doing proper measurements with it, really kicked it off. So I would also appreciate thoughts on the telescope and the mount.
I started DSLR photometry years ago with an 80mm f/7.5 refractor. It was what I had. The mount I used most was a HEQ5Pro, driven via ASCOM from a laptop computer.
My advice is to start with what you've got, and when you buy, get the best you can afford. It is not necessary to have the highest quality optics. For DSLR photometry, you will in any case be defocussing slightly.
The main thing is to get started and become familiar with equipment and procedures by regular use. If you continue photometry for many years, it is almost inevitable that your equipment will evolve.
Thank you Roy.
I have estimated myself an example budget of 6000eur, if I later want to get all the stuff I mentioned. For the mount/telescope/small stuff to begin with, I estimated 2000eur should be more than enough, even if I went with the skymax 150.
From the answers in general, I understand that the mount is fine, and all of the skymax models are very good too. All just depends on how much I want to spend. I also understand the comment, start what you have, but I will probably get the telescope and the mount anyway.
Having done a couple of measurements at the university with a 60cm reflector and having done the calibration/reduction processes, I just don't feel a simple tripod with a dslr adds up too much to the experience at the moment. Also, getting a good mount with a motor would also help me to better understand the process of guiding and all the possible problems that might arise during the process. I think this might also help with my studies I have planned for the next few years. And... Probably my kids might also enjoy looking through the scope every once in a while!
AAVSO members have access to AAVSONet:
https://www.aavso.org/aavsonet (Its under Observing Sections)
So you don't need a telescope, but you do need to do a bit of research into the network, your variable interests and you have to submit a proposal. You can get quality images to analyze and you have access to other tools such as VPhot for measuring your variables. All this for less than an eyepiece.
Thanks. I had not noted that before. I'll check into that too!
...very interesting actually as a future possibility! ...But not enough to skip me from getting some kind of a telescope! :)
I do a lot of…
I do a lot of observing with AAVSONet. If I can help you get your 1st proposal in, let me know!
I'll keep that in…
I'll keep that in mind, thank you.
It's not priority one at the moment, but maybe as soon as I have some need for it and a specific target in mind.
You have a DSLR. You can start by doing bright variables with a DSLR + Lens on a star tracker. For my bright variables (less than 10th mag) I use a DSLR + 85mm or 50mm lens on a Skytracker pro. I recently upgraded to a Sky Watcher Star Adventurer GTi because it is GoTo so saves a lot of time finding and framing your target. I do photometry on the TG channel only (I think that the TR and TB are too far off from the photometric R and B unless you go through the extra work of transforming. The TG is very close to the photometric V filter). This will get you started on learning how to capture your images, calibrate them, learn how to select appropriate comparison stars, perform photometry, and submitting data.
Yes, I think the TG channel is the best way to go for with a dslr.
I am at the moment probably going for skymax 150 + heq5 pro. I think there is a good package deal for that (rather than heq5 pro with a smaller skymax). Also checking what else I will be needing with this equipment... a T2 ring for canon dslr, a suitable power converter. A dew shield I might fix myself.
a bit off topic... I believe there is also a lot bigger gain with the green channel on a dslr, since there seems to be more green pixels than red or blue ones. If someone has a good link to detailed info on how taking only the green channel on a dslr converts (demosaicing) to an image, that might be interesting to look at. (or maybe it has already been discussed somewhere in this forum)
The advantage to using just the TG channel is not because there are more green pixels than red or blue, but because the TG is closer photometrically to the Johnson V photometric filter. The red and blue DSLR filters are not as close to the R and B photometric filters so needs transforming if they are going to be used. As far as extracting the green channels, this can be found in the AAVSO DSLR photometry manual. It also discusses some software options. I use to teach the DSLR Choice course so feel free to contact me on getting started.
Thanks Barbara, I'll keep that in mind.
And yes, I realize the closeness to Johnsson V band is the main reason.
Ps. I just realized from your profile that I did actually watch your "how to do dslr photometry" aavso video last week on youtube (among some other aavso videos). That was a great brief to the subject!
Just an update...
Just an update...
I got the skymax 150 and heq5 a few weeks ago and these seem to work fine. I've managed to align it quite easy and find targets very well with synscan. Tracking for visual seems to work very well.
I've also attached my dslr, but I haven't had time take any sky shots with it yet. Hopefully I'll have the time soon and the weather allows to try to take some test exposures of stars and nebulae, to see how the tracking really works and just to get experience.
notes on the equipment...
-Heq 5: the spirit level is severely off and the light on the polar finder is way too bright. Though, it seems these are common problems for this equipment. But, not an impossible issue.
-Synscan: I don't quite understand when you should click the daylight savings time option on the date setting (nor really on any other equipment ever either!). I'm currently on daylight saving time area, but clicking it seems to put the telescope about 15 degrees off. Well... I shall just not click it!
PS. My backyard is at bortle class 6 zone. And I have a good chance to go to class 5 area. And a rather good chance to go to class 4 zone. Would you often travel to a better area? Is it a big effect with photometry? For which reason would you travel from class 6 to class 4 area?
If you are in daylight savings time currently then this should be checked. There must be a UTC offset somewhere and it should be the offset for when you are not in DST. For example, I am on the east coast. My UTC offset is -5 hours. In the settings it should stay -5 hours even if you are in DST. Since you are off by 15 degrees, this is one hour in time offset so it probably is somewhere in UTC offset. Maybe you changed this UTC offset for DST?
As far as traveling, if you are doing variable star photometry and you have the ability to find your target, you don’t have to worry about the degree of light pollution for you photometry.
How is the new setup going? Have you had an opportunity to capture any targets for photometry?